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Shunting for hydrocephalus: analysis of techniques and failure patterns
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Available online at www.sciencedirect.com
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Shunting for hydrocephalus: analysis of techniques and failure patterns Fares Nigim, MD,a Jonathan F. Critchlow, MD,b Benjamin E. Schneider, MD,b Clark Chen, MD, PhD,a and Ekkehard M. Kasper, MD, PhDa,* a b
Department of Neurosurgery, Harvard Medical School, Boston, Massachusetts Department of Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts
article info
abstract
Article history:
Background: Hydrocephalus is characterized by ventricular dilatation because of progres-
Received 4 January 2014
sive accumulation of cerebrospinal fluid. Normal pressure hydrocephalus (NPH) affects a
Received in revised form
subset of patients representing a reversible clinical triad of gait disturbance, urinary in-
17 March 2014
continence, and dementia with normal cerebrospinal fluid pressure and composition.
Accepted 25 March 2014
Various shunting procedures have been used for treatment, but techniques and outcomes
Available online xxx
remain under debate. The objective of this study was to evaluate the clinical outcomes of 232 patients with and without NPH after the first-time Ventriculoperitoneal shunt place-
Keywords:
ment and assessed patterns of failure between December 2004 and December 2012.
Ventriculoperitoneal shunt (VPS)
Results: Mean age was 54.7 y in non-NPH and 71.9 y in NPH patients. We used open tech-
Laparoscopic technique
nique in 34.3% and laparoscopic technique in 65.7% of NPH patients and 32.7% and 67.3% of
(Lap technique) Normal pressure hydrocephalus
the non-NPH patients, respectively. A total of 36 of 232 patients displayed shunt failure, 16.4% in NPH and 15.2% in non-NPH patients. Twenty-three of 155 patients failed after laparoscopic and 13 of 77 failed after open placement. Proximal shunt failure was more
(NPH) Cerebrospinal fluid (CSF)
frequent in the non-NPH cohort. Distal failures accounted for 13 of 232 cases, and the difference between laparoscopic (six of 155) and open failures (seven of 77) was profound, but not between NPH- and non-NPH patients. Conclusions: Shunt failures are related to the placement method. Non-NPH patients showed more proximal failures. NPH patients showed fewer proximal failures. Less distal failures were observed after laparoscopic ventriculoperitoneal shunt placement without significant differences between NPH and non-NPH patients. Beyond this, laparoscopic surgery carries distinct advantages such as shorter operating room times and hospital stays, which should translate into less use of pain medications, earlier mobilization, and a lower incidence of ileus. ª 2014 Elsevier Inc. All rights reserved.
1.
Introduction
Ventriculoperitoneal shunting (VPS) is the mainstay for the treatment of hydrocephalus and remains a frequently performed procedure in general neurosurgical practice. Among
all patients with hydrocephalus, there are various etiologies leading to ventricular dilatation and neurologic decline, ultimately requiring a cerebrospinal fluid (CSF) diversion procedure. However, these implanted devices may fail over time.
* Corresponding author. Department of Surgery, Beth Israel Medical Center and Department of Neurosurgery, Harvard Medical School, 110 Francis Street Suite 3B, Boston, MA 02215. Tel.: þ1 617 632 7246; fax: þ 1 617 632 0949. E-mail address: [email protected] (E.M. Kasper). 0022-4804/$ e see front matter ª 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jss.2014.03.075
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We investigated a cohort of elderly normal pressure hydrocephalus (NPH) patients against the background of a large suitable reference cohort of other hydrocephalus patients also requiring a VPS, and we report comparative data regarding surgical outcomes and shunt survival in these patients and investigate respective shunt failure patterns. NPH patients differ from the other cohort of patients with, for example, posthemorrhagic hydrocephalus, hydrocephalus in the setting of metastatic disease, hydrocephalus in the presence of a central nervous system tumor, or pseudotumor cerebri, and so forth. In at least two important aspects: First, NPH patients are generally older and second, the CSF or NPH patients is considered to be normal, which means unaltered by any increase in protein or cells, for example, after infection, intracranial hemorrhage, or in the presence of tumors. The hypothesis that can be addressed with this study are as follows: (1) Patients with NPH may show a higher VPS failure rate, as older patients are more likely to suffer from comorbidities (e.g., those resulting in abdominal surgery and adhesions causing distal catheter obstruction); (2) NPH patients have a CSF composition that differs from the CSF of hydrocephalic patients with other etiologies, and hence they may show a different failure rate and pattern [1]; (3) We wanted to see whether laparoscopic placement of VPS may translate into a lower failure rate as assumed by other laparoscopic studies or show a different pattern of VPS failures over time. This data set is suitable to corroborate the validity and safety of the laparoscopic and open VPS procedures and looks at the longevity of the first-time shunts placed. We furthermore look in detail into the observed cases of VPS failures by assessing both location and possible causes. Among the large number of patients requiring a shunt for various indications is a more homogenous patient group with NPH. This cohort is of particular interest, because NPH is one of the few treatable conditions of cognitive decline among other symptoms and affects as many as 3%e6% of patients with dementia [2e9]. The syndrome was first described by Hakim and Adams [10] in 1965 and included gait apraxia, imbalance, progressive memory loss, urinary incontinence, and normal CSF composition and pressure on lumbar puncture. Currently, there is no effective medical treatment for neurocognitive decline from hydrocephalus in NPH, and drugs such as acetazolamide or osmotic diuretics have been found not to work reliably. Ventricular shunting is the only treatment to provide a lasting benefit. Success after shunting is reflected in a lasting remission of symptoms in these patients with a normal life expectancy. This requires long-term follow-up and regular patient assessment, as well as management of potential shunt complications via revisions. There is an ongoing debate as to whether the benefits outweigh the risk in shunting in NPH patients, because NPH affects predominantly the elderly population who often suffer from significant comorbidities (e.g., cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary disease, and so forth) [11e13]. We therefore set out to look at shunting in these NPH patients and analyzed their complication rate and failure patterns in comparison with a large cohort of other patients undergoing first-time VPS placement for different
etiologies. To this end, longitudinal observation and assessment of these patients is essential. Several authors have thus far reported good outcomes with follow-up periods mostly ranging from 3 mo to 2 y [14e17]. To date, one of the seminal studies reported was done by Savolainen et al.[18] who followed 25 patients for 5 y. However, only a small number of studies has elucidated the long-term effects of shunting and few report on the associated surgical morbidities [19e23]. Here, we report our surgical experience and outcome in patients undergoing surgery for NPH in comparison with patients requiring shunt placement for different etiologies. Shunt failures do occur rather frequently as reported in the present literature, and we wanted to see, whether these may be possibly related to the placement method chosen. We therefore compared metrics from patients who underwent VPS via the conventional open surgical approach to data from patients who had laparoscopic VPS surgery, and we followed these patients longitudinally to find a significant difference in shunt failure rates and pattern when comparing the two cohorts and the two techniques investigated.
2.
Material and methods
This is an institutional review board (IRB No. 2011P-000101/4 and 2013P-000253/1)-approved retrospective cohort study of a prospectively collected data set of consecutive adult patients who underwent first-time insertion of a VPS for various etiologies of hydrocephalus. The study cohort consisted of patients treated at Beth Israel Deaconess Medical Center between December 2004 and December 2012. New VPS placement was strictly defined as insertion of a proximal cerebral catheter, a new valve, and new distal placement of a peritoneal catheter. To avoid contamination of data, any shunt revisions and previously shunt-treated patients, who underwent complete shunt removal (for infection or other indication) and who later underwent placement of a new VPS, were also excluded. Distal catheters were placed either via a standard small open laparotomy or via a laparoscopic technique using two or three access ports. The decision what technique to use was based on (1) past medical history of the individual patient (e.g., prior abdominal surgery), (2) patients body habitus, or (3) the neurosurgeon’s preference and experience with both techniques. Independent variables investigated in this study included demographics (e.g., age and gender), indication for surgery, and past medical history (e.g., comorbidities and previous abdominal operations). For all patients, we carefully examined the preoperative imaging (head computed tomography or magnetic resonance imaging scan when available), the description of the operative encounter (open or laparoscopic and intraoperative findings), and the specifics of the implanted valve type as well as clinical notes and radiographic studies during the entire follow-up period for each patient. Dependent variables analyzed included operative time, length of hospital stay, findings on postoperative head computed tomography scan (obtained immediately and 4e8 wk after surgery and annually thereafter to assess early as well as delayed postoperative complications), occurrence of any
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shunt failure, assessment of the cause of shunt failure, and any other complications. Shunt failures were categorized as proximal to the valve, at the level of the valve, or distally at the abdominal catheter. Clinical relevant shunt failure was defined as any return to surgery for management of a shunt-related problem. Causes of shunt failure were categorized as proximal mechanical shunt obstruction or infection, distal shunt obstruction, malpositioning, infection, or valve malfunction. Shunt infection was broadly defined as a positive CSF culture or an increase in white blood cells from a shunt tap in the setting of respective clinical central nervous system symptoms or revision in a patient with a positive wound culture at the time of revision surgery. Shunt obstruction was diagnosed preoperatively or intraoperatively by testing all implanted hardware. Intracranial or abdominal catheter obstruction due to malpositioning was radiographically diagnosed and then confirmed at surgery. All patients in this cohort study had adjustable valves (Strada; Medtronic, Framingham, MA), so they could undergo multiple valve setting adjustments before undergoing revision surgery. Abdominal pain or distal shunt failure was considered to be a complication if new symptoms occurred and persisted after catheter placement and if complaints were not attributable to alternative diagnoses and remained refractory to conservative management. The most recent patient encounter (clinic visit or hospital discharge) was taken as the end point for the clinical and radiographic follow-up period. For the purpose of the study, we assume that patients who did not present to this or any other local hospital or office for any shunt-related problems had a functioning shunt for the interim period. This is a reasonable assumption, given that the patient cohort only consisted of patients living in a 40-mile radius around the hospital and given the established management strategy that patients are being sent to their parent institution to care for shunt-related problems. If patients were to be admitted to any other local hospital, we thus would have received notification and request for transfer. Other end points of the study were occurrence of shunt revision, timing of shunt revision, or shunt removal.
2.1.
Statistical analysis
Data were recorded on Excel spreadsheets. Differences in outcome and complication rates were compared between the two cohorts undergoing the two respective VPS placement techniques, and group data were compared using t-and f-tests (analysis of variance). P values were considered statistically significant when the value was <0.05.
2.2.
Surgical technique
The cranial procedure consisted of a standard intracranial catheter placement for each VPS patient and was identical for patients undergoing open and laparoscopic VPS placement; in cases of conventional VPS placement, the neurosurgical team performed open abdominal catheter placement, and in cases of endoscopic placement, a general surgeon performed the laparoscopic portion of the case. Both the neurosurgical and
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general surgical part of the procedure commenced simultaneously. For the group undergoing conventional open VPS placement, a 4e5-cm subcostal incision was made to gain access to the peritoneum. After dividing the overlying layer, a small incision was made and the peritoneal cavity was inspected to confirm entry into the abdomen and to verify that no visceral injury had occurred. The distal shunt catheter was placed into the peritoneal cavity after CSF flow was observed from the distal catheter tip. The abdominal incision was closed in layers. For patients undergoing laparoscopic VPS placement, a supraumbilical curvilinear incision is made and the dissection is carried down to the linea alba. The fascia is then elevated and a Hasson catheter is introduced. Pneumoperitoneum is created and a 5-mm port is then placed approximately 8 cm below the right costal margin, and the peritoneal cavity is accessed using the Seldinger technique to place and introducer sheath. The distal catheter is then placed intraperitoneally via that introducer and directed into the superior retrohepatic recess. Observing CSF flow from the catheter tip corroborates adequate shunt function. The fascia and skin incisions are closed in layers. Patients underwent routine postoperative care and were discharged for a wound check and with scheduled regular follow-up appointments.
3.
Results
Between December 2003 and December 2012, a total of 232 patients underwent first-time placement of a VPS. Of those, 67 patients were diagnosed with NPH, whereas 165 patients were showing hydrocephalus from different etiologies (e.g., posthemorrhagic hydrocephalus, hydrocephalus in the setting of metastatic disease, hydrocephalus in the presence of a central nervous system tumor, and pseudotumor cerebri). All demographic data were compared between the NPH and non-NPH groups, and there were no significant differences between the two populations. The mean age was somewhat lower in the non-NPH group, but this difference was not statistically significant (see Table 1). Other metrics are shown in subsequent tables. Operative time was considered the surgical time from skin incision to skin closure. The mean operative time in the NPH group was significantly shorter with laparoscopy, with 42.3 min (range, 22e102) compared with patients operated via the open technique, which required 62.1 min (range, 35e118), (P < 0.05). This observation held also true in the cohort of all other VPS patients, where the mean operative time was significantly longer with the open technique (63.0 versus 43.7, respectively), P < 0.05 (Tables 2 and 3). There were no cases of direct or early surgical postoperative complications in either group. The mean length of stay in the hospital in the NPH group was 4 d with the open technique versus 2 d with the laparoscopic technique; this difference was statistically significant, (P < 0.05). Length of hospital stay in the non-NPH group was slightly longer (see Tables 2 and 3), which was expected since those patients had other comorbidities, were scheduled for other investigations, or required prolonged medical care (e.g., radiation therapy or
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Table 1 e Study cohort description. NPH group (n ¼ 67)
Non-NPH group (n ¼ 165)
P value
71.9 10.9 (75.0, 28.5e88.0)
54.7 15.9 (55.8, 19.2e88.3)
NS
Demographic data Mean age (Y) Gender Male % (n) Female % (n) Previous abdominal operation Surgical technique: Open % (n) Laparoscopic % (n)
64.1 (43) 35.9 (24) 20.9 (14)
47.3 (78) 52.7 (87) 27.8% (46)
34.3 (23) 65.7 (44)
NS NS NS
32.7 (54) 67.3 (111)
NS NS
NS ¼ not significant.
chemotherapy in patients with metastatic disease), precluding earlier discharge. Follow-up consisted of clinical and radiological evaluation and was performed at 1, 3, 6, and 12 mo after surgery and yearly thereafter. At the time of the follow-up, patients and their families were routinely assessed by questionnaire and also reminded of the possibility of shunt malfunction potentially causing a return of their NPH symptoms, and families were instructed to contact us in such circumstances. The mean follow-up time in the NPH group was 45 mo (median 42.3, range 0.5e103.0) and was thus longer than the non-NPH group that had a mean follow-up of 27.6 mo (median 28.5, range 0.3e107.3), this difference was statistically significant, (P < 0.05; Tables 2 and 3), but this may not be meaningful because VPS patients with metastatic disease in this group would succumb to their cancer and drop out of the study and thus shorten mean follow-up time. Survival after shunt placement surgery was compared between the patients in the NPH and those in the non-NPH groups. Such shunt survival in the NPH group was estimated to be 94.0% at 12 mo and 60.0% at 3-y follow-up (data not shown). Hydrocephalus symptoms were classified as “improved” if they resulted in an improvement in the patient’s day-to-day functioning. Nearly all patients had profound and lasting improvement postoperatively for the duration of the follow-up period. Further neurologic assessments will be reported elsewhere. The details of the clinical course and shunt longevity assessment as well as failure rates and analysis are listed in Tables 2 and 3 and Tables 4 and 5. Shunt failure was defined as any return of the patient to the hospital with symptoms related to shunt failure and ultimately requiring surgery. Causes of shunt failure have been categorized as at the proximal catheter (e.g., obstruction, malpositioning, or infection), at the distal catheter (obstruction, malpositioning, or infection), or valve malfunction. The
overall number of shunt failures in NPH patients during our observation period was rather low with 11 patients (16.4%) affected, and of those three shunts failed in the first 12 mo postoperatively (Figure). There was no statistically significant difference between the open and the laparoscopic technique in terms of overall failure rate in NPH patients, (n ¼ 3/23 or 13.0% versus n ¼ 8/44 or 18.2%, respectively; Tables 4 and 5). However, the pattern of failure showed some striking differences. Proximal shunt revision was reported in three of 67 NPH patients (4.5%) but in 17 of 165 non-NPH patients (10.3%). However, there was no significant difference between the open and the laparoscopic technique in each patient cohort (Tables 4 and 5). Valve dysfunction occurred in four of 67 NPH patients (6.0%) and in nine of 165 non-NPH patients (5.5%), without any significant difference between techniques (Tables 4 and 5). Distal catheter revision was required in four of 67 NPH patients (6.0%) and in nine of 165 non-NPH patients (5.5%) with no significant difference between the open and the laparoscopic technique (Tables 4 and 5). However, when analyzed as aggregates of technique, there where seven of 77 patients (9%) after open VPS placement who underwent revision surgery, whereas only six of 155 (3.6%) laparoscopically placed peritoneal catheters ultimately required a revision. Malpositioning of the distal catheter (clinically presenting with abdominal pain) was rarely observed with either technique (in two NPH patients operated with the open technique and in two NPH patients operated with the laparoscopic technique). Once needed, distal shunt revisions were done laparoscopically, in two of those four patients who had developed distal catheter kinking. The associated pain resolved after shunt revision in all four affected patients of the NPH cohort. There were no patients requiring shunt removal for refractory abdominal pain from either technique. We did not have any case of infection in the distal catheter (Table 4).
Table 2 e Surgical metrics in NPH group. Outcomes Operative time (min) Length in stay (d) Mean follow-up time (mo) median
All NPH shunts
Open technique
Lap technique
P value
49.2 18.2 (47.0, 25e118) 3.0 3.0 (2.0, 1.0e25.0) 45.0 29.6 (42.3)
62.1 18.3 (60.0, 35e118) 4.0 5.0 (3.0, 1.0e25.0) 32.1 28.9 (22.2)
42.3 14.8 (39.5, 22e102) 2.0 1.0 (2.0, 1.0e5.0) 26.7 23.1 (20.7)
<0.05 <0.05 NS
Lap ¼ laparoscopic; NS ¼ not significant.
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Table 3 e Surgical metrics in non-NPH group. Outcomes Operative time (min) Length in stay (d) Mean follow-up time (mo) median
All non-NPH shunts
Open technique
Lap technique
P value
50.4 21.2 (46.0, 18.0e151.0) 6.0 5.0 (4.0, 1.0e50.0) 27.6 28.5 (17.1)
63.0 23.4 (58.0, 30.0e151.0) 5.0 3.5 (3.0, 1.0e30.0) 35.7 29.8 (22.1)
43.7 15.6 (41.0, 18.0e102.0) 5.0 5.0 (3.0, 1.0e50.0) 25.9 22.0 (20.7)
<0.05 NS NS
Lap ¼ laparoscopic; Ns ¼ not significant.
Noteworthy, none of the patients had any distal shunt revision after being discharged from the hospital.
4.
Discussion
CSF diversion remains the mainstay for the treatment of hydrocephalus, and new shunt technologies and surgical techniques have evolved over the past decades [24,25]. Diversion can be achieved via a ventriculoatrial shunt, a lumboperitoneal shunt, or a VPS, the latter being the most frequent procedure performed. In this study, we report the outcomes of 232 VPS patients in total and 67 NPH patients in particular, who underwent firsttime VPS placement by either a laparoscopic or open VPS placement technique. In our cohort, mean operative time differed between the two surgical groups; it was 31.9% shorter in the laparoscopic group (42.3 versus 62.1, P < 0.05; Tables 2 and 3). Other series reported the mean operative time for the open placement as ranging from 40e130 min [26e28] and for laparoscopic placement as ranging from 30e115 min [24e27], but the definitions of surgical time differ somewhat. Certainly, the operative time depends on both patient and surgeon-specific factors; obese patients, patients with a history of previous abdominal operations, or distorted abdominal anatomy require more time compared with other patients, because the abdominal surgeon often has to lyse adhesions to avoid malpositioning or obstruction of the distal catheter. Furthermore, obese patients have a higher risk of shunt malpositioning because of more abundant preperitoneal fat that can be mistaken for omentum [27]. We also noticed that the mean operative time has decreased over time in our center, likely due to growing experience and efforts to improve coordinating the two surgeon’s timing and the intraoperative workflow. The mean length of hospital stay was about 3 d with both techniques, which was somewhat shorter than in other
studies published [26,29]. Patients operated laparoscopically had a shorter length of hospital stay than patients operate by conventionally (2 versus 4 d, respectively, P < 0.05), and this difference was statistically significant, although the NPH cohort examined here was relatively small, and hence the cohort size may not allow for sufficient power (see Tables 2 and 3). The difference in operative time and length of hospital stay may translate into a difference in overall outcome of VPS surgery. By reducing operative time and with shorter hospitalizations, the provider can achieve earlier mobilization and likely fewer postoperative complications (e.g., thrombosis, pain, and postoperative ileus), and thus a reduction in the overall cost associated with VPS placement, with a likely significant impact on overall annual health care costs [30]. We used a stringent hydrocephalus and VPS definition to define suitable patient cohorts and followed these longitudinally with a stringent assessment of neurologic improvement allowing us to focus on the surgical techniques used in this study and to compare outcomes of patients treated with either a conventional or a laparoscopic surgical approach. More than 90% of our NPH patients showed neurologic improvement after surgery at 3-mo and 1-y follow-up, and 70% of the patients maintained this improvement at 3-y follow-up (data not shown); in our cohort, gait was the most frequently improved symptom postsurgically, whereas urinary incontinence and cognitive impairment showed less improvement after surgery, but further neurologic outcome details will be reported elsewhere. In our two cohorts, the rate of shunt failure after VPS surgery was 11 of 67 (16.4%) in the NPH group and 36 of 232 (15.5%) in the reference cohort for non-NPH etiologies. There was no significant difference between the two techniques in term of overall shunt failure rate, with three shunts in need of revision within the first 12-mo follow-up. Eight patients had to undergo VPS revision during later follow-up. Among these, there were three proximal failures (two patients presented with fever and confusion from infection, the third patient had
Table 4 e Surgical failure rates illustrated by location in NPH group. Cause of shunt failure Overall N of shunt failure Cause of shunt failure Proximal catheter (obstruction or infection) Distal catheter (obstruction or infection) Valve dysfunction
All NPH shunts, n ¼ 67 (%)
Open technique, n ¼ 23 (%)
Laparoscopic technique, n ¼ 44 (%)
11 (16.4)
3 (13.0)
8 (18.2)
3 (4.5) 4 (6.0) 4 (6.0)
1 (4.3) 2 (8.7) 0 (0)
2 (4.6) 2 (4.6) 4 (9.1)
None of the variables showed significant differences between groups.
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Table 5 e Surgical failure rates illustrated by location in non-NPH group. Cause of shunt failure Overall N of shunt failure Cause of shunt failure Proximal catheter (obstruction or infection) Distal catheter (obstruction or infection) Valve dysfunction
All non-NPH shunts, n ¼ 165 (%)
Open technique, n ¼ 54 (%)
Laparoscopic technique, n ¼ 111 (%)
25 (15.2)
10 (18.4)
15 (13.5)
17 (10.3) 9 (5.5) 9 (5.5)
8 (14.8) 5 (9.3) 2 (3.7)
9 (8.1) 4 (3.6) 7 (6.3)
None of the variables showed significant differences between groups.
a proximal catheter obstruction and presented with recurrent signs of NPH); there were also three cases of valve dysfunction, and finally two distal abdominal catheter obstructions were encountered that required revision. Significant complication rates after VPS have been reported frequently in the literature and range between 6% and 53% and both our cohorts are well positioned at the lower end of this range. We focused on understanding the causes of distal shunt failure by carefully looking at two cohorts in which the peritoneal catheter was placed with differing techniques. We noticed that distal failures were more prevalent in patients who had open VPS placement compared with patients who had laparoscopically placed VPS. Among the principal failures, the following were observed in the literature: mechanical shunt failures (e.g., obstruction in the intracranial or abdominal catheter) and abdominal injury (ascites, peritonitis, abdominal perforations, and volvulus) [2,31,32]. In the latter cases, obesity, previous abdominal operation, and distorted abdominal anatomy seem to correlate with the observed rate of distal mechanical shunt failure and several studies have established a correlation between previous abdominal operations and the incidence of distal shunt failure [25,27,28,33]. This can be due to adhesions, calcifications, and fibrosis causing distal catheter obstruction, malposition, and migration. In our study, distal catheter malfunction resulting in shunt failure occurred in only four of 67 NPH patients (6.0%), none of whom had a history of previous abdominal operations, (Table 4). We attempted to analyze whether there is a correlation between the occurrence of distal shunt failure and any history of previous abdominal operation, but given the low incidence of failure events in our NPH cohort, previous
Figure e Shunt failure rates and pattern overtime for the study cohort. (Color version of figure is available online.)
abdominal surgery could not be established as a significant predictor for distal shunt failure. This is consistent with the study of 111 patients reported by Turner et al. [34]. Little is known about the long-term prognosis of patients after shunting and various studies showed differing shunt survival over long-term follow-up [35e38]. In our opinion, caregivers should continuously monitor all VPS patients for shunt complications with longitudinal follow-up. Pujari et al. [39]. involved a retrospective analysis of 55 patients followed for at least 3 y after shunt surgery; of those, a stunningly high rate of 53% needed a revision but no specifics were given. Some authors have reported an increased infection rate with the laparoscopic technique, [28] but we cannot confirm that observation in both our cohorts. Previous studies have shown that the number of surgeons, circulating personnel, start time, and duration of the operation codetermine the infection rate [40,41]. These are factors, which we have tried to optimize, but when assessed, we did not find a correlation to the incidence of infections, possibly because they were already at a low rate in our cohorts. This type of analysis hence needs to be performed in a much larger study population. Compared with traditional laparotomy, the laparoscopic technique offers several significant advantages: First, the ability of the surgeon to inspect the abdominal cavity and perform adhesiolysis. This prevents placement of the distal catheter in a pocket of adhesions or in kinked position especially in obese patients and in patients with previous abdominal surgeries [24,33,34,40]. Second, laparoscopy also reduces abdominal wall trauma and postoperative morbidity, because it requires smaller incision with smaller peritoneal and fascia openings, resulting in fewer secondary adhesions, less postoperative pain, a decrease in the incidence of postoperative ileus, less risk of perforating abdominal organs, and a decrease in the frequency of incisional hernias [42,43]. We are currently studying these aspects prospectively. We are aware of the fact that our study also has some limitations. First of all, the study is a retrospective cohort study. Second, patient’s body mass index was not always reported, so we could not correlate patient selection or outcome parameters to obesity, which should be assessed in future studies. However, we could not demonstrate a clear difference in overall failure rates or failure patterns in our two patient populations (NPH versus non-NPH patients), except that nonNPH patients displayed an increased rate of proximal shunt failures, which could be related to the altered CSF composition
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in non-NPH patients. But when comparing in detail the two differing placement techniques, which were used, a lower abdominal failure rate was found in the laparoscopic group (six of 155) than in the open VPS group (seven of 77). This deserves further study. Such studies should also address the impact of shorter OR times, shorter hospital stays, less use of pain medications, and earlier mobilization as well as a likely lower incidence of ileus, which may be particularly beneficial in the potentially frail elderly population such as our NPH patients.
5.
Conclusions
Based on our experience of a cohort of 67 NPH patients and 165 non-NPH patients undergoing first-time shunt placement surgery, we can confidently conclude that VPS placement with the laparoscopic technique is a safe approach because no significant complications were encountered. As far as the failure patterns are concerned, we consider a slightly lower distal failure rate with laparoscopic VPS placement worth reporting and we encourage further studies of potentially suitable target patient groups. Laparoscopic abdominal catheter placement seems to offer distinct advantages over the traditional minilaparotomy. It shortens the operative time, allows the surgeon to explore the abdominal cavity, lyse adhesions if necessary, allows to assess incidental abdominal pathology, and it finally ensures optimal positioning of the distal catheter. Based on low postoperative distal VPS catheter failure rates, we strongly suggest to study the laparoscopic technique as an alternative technique especially in obese patients and in patients with previous abdominal operations.
Acknowledgment This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. Authors’ contributions: F.N. and E.K. contributed to conception and design. F.N., E.K., C.C., J.F.C., and B.E.S. were responsible for the acquisition of data. F.N. analyzed the data. F.N. and E.K. interpreted the data. C.C. designed the data. J.F.C. edited the data. C.C. and J.F.C. were also responsible manuscript editing.
Disclosure The authors reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.
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[2] Hill ME, Lougheed WM, Barnett HJ. A treatable form of dementia due to normal-pressure, communicating hydrocephalus. Can Med Assoc J 1967;97:1309. [3] Vanneste JA. Diagnosis and management of normal-pressure hydrocephalus. J Neurol 2000;247:5. [4] Verrees M, Selman WR. Management of normal pressure hydrocephalus. Am Fam Physician 2004;70:1071. [5] Bradley WG. Normal pressure hydrocephalus: new concepts on etiology and diagnosis. AJNR Am J Neuroradiol 2000;21:1586. [6] Vale FA, Miranda SJ. Clinical and demographic features of patients with dementia attended in a tertiary outpatient clinic. Arq Neuropsiquiatr 2002;60:548. [7] Hiraoka K, Meguro K, Mori E. Prevalence of idiopathic normal-pressure hydrocephalus in the elderly population of a Japanese rural community. Neurol Med Chir (Tokyo) 2008; 48:197. [8] Clarfield AM. The reversible dementias: do they reverse? Ann Intern Med 1988;109:476. [9] Larson EB, Reifler BV, Featherstone HJ, English DR. Dementia in elderly outpatients: a prospective study. Ann Intern Med 1984;100:417. [10] Hakim S, Adams RD. The special clinical problem of symptomatic hydro-cephalus with normal cerebrospinal fluid pressure: observations on cerebrospinal fluid hydrodynamics. J Neurol Sci 1965;2:307. [11] Brean A, Fred HL, Sollid S, Muller T, Sundstrom T, Eide PK. Five year incidence of surgery for idiopathic normal pressure hydrocephalus in Norway. Acta Neurol Scand 2009;120:314. [12] Vanneste J, Augustijn P, Dirven C, Tan WF, Goedhart ZD. Shunting normal-pressure hydrocephalus: do the benefits outweigh the risks? A multicenter study and literature review. Neurology 1992;42:54. [13] Brean A, Eide PK. Prevalence of probable idiopathic normal pressure hydrocephalus in a Norwegian population. Acta Neurol Scand 2008;118:48. [14] Aguas-Valiente J, Martinez-Man˜as R, Ferrer-Rodriguez E. Criterios diagnosticos y terapeuticos en la hidrocefalia normoten- siva del adulto. Estudio nacional multicentrico descriptivo. Rev Neurol 1997;25:27 (1997). [15] Boon AJ, Tans JT, Delwel EJ, et al. Dutch normal pressure hydrocephalus study: prediction of outcome after shunting by resistance of outflow of cerebrospinal fluid. J Neurosurg 1997;87:687. [16] Droste DW, Krauss JK. Simultaneous recording of cerebrospinal fluid pressure and middle cerebral artery blood flow velocity in patients with suspected symptomatic normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry 1993;56:75. [17] Haan J, Thomeer RT. Predictive value of temporary external lumbar drainage in normal pressure hydrocephalus. Neurosurgery 1988;22:388. [18] Savolainen S, Hurskainen H, Paljarvi L, Alafuzoff I, Vapalahti M. Five-year outcome of normal pressure hydrocephalus with or without a shunt: predictive value of the clinical signs, neuropsychological evaluation and infusion test. Acta Neurochir (Wien) 2002;144:515. [19] Meier U, Zeilinger FS, Kintzel D. Signs, symptoms and course of normal pressure hydrocephalus in comparison with cerebral atrophy. Acta Neurochir (Wien) 1999;141:1039. [20] Aygok G, Marmarou A, Young HF. Three-year outcome of shunted idiopathic NPH patients. Acta Neurochir Suppl 2005; 95:241. [21] Malm J, Kristensen B, Stegmayr B, Fagerlund M, Koskinen LO. Three-year survival and functional outcome of patients with idiopathic adult hydrocephalus syndrome. Neurology 2000; 55:576. [22] Meier U, Miethke C. Predictors of outcome in patients with normal-pressure hydrocephalus. J Clin Neurosci 2003;10:453.
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[23] Tisell M, Hellstrom P, Ahl-Borjesson G, et al. Long-term outcome in 109 adult patients operated on for hydrocephalus. Br J Neurosurg 2006;20:214. [24] Roth J, Sagie B, Szold A, Elran H. Laparoscopic versus nonlaparoscopic- assisted ventriculoperitoneal shunt placement in adults. A retrospective analysis. Surg Neurol 2007;68:177. [25] Handler MH, Callahan B. Laparoscopic placement of distal ventriculoperitoneal shunt catheters. J Neurosurg Pediatr 2008;2:282. [26] Argo JL, Yellumahanthi DK, Ballem N, et al. Laparoscopic versus open approach for implantation of the peritoneal catheter during ventriculoperitoneal shunt placement. Surg Endosc 2009;23:1449. [27] Khosrovi H, Kaufman HH, Hrabovsky E, Bloomfield SM, Prabhu V, el-Kadi HA. Laparoscopic-assisted distal ventriculoperitoneal shunt placement. Surg Neurol 1998;49:127. [28] Naftel RP, Argo JL, Shannon CN, et al. Laparoscopic versus open insertion of the peritoneal catheter in ventriculoperitoneal shunt placement: review of 810 consecutive cases. J Neurosurg 2011;115:151. [29] Tepetes K, Tzovaras G, Paterakis K, Spyridakis M, Xautouras N, Hatzitheofilou C. One trocar laparoscopic placement of peritoneal shunt for hydrocephalus: a simplified technique. Clin Neurol Neurosurg 2006;108:580. [30] Patwardhan RV, Nanda A. Implanted ventricular shunts in the United States: the billion-dollar-a-year cost of hydrocephalus treatment. Neurosurgery 2005;56:139. [31] Hebb AO, Cusimano MD. Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome. J Neurosurg 2001;49:1166. [32] Krauss JK, Halve B. Normal pressure hydrocephalus: survey of contemporary diagnostic algorithms and therapeutic decision-making in clinical practice. Acta Neurochir (Wien) 2004;146:379.
[33] Esposito C, Colella G, Settimi A, et al. One-trocar laparoscopy: a valid procedure to treat abdominal complications in children with peritoneal shunt for hydrocephalus. Surg Endosc 2003;17:828. [34] Turner RD, Rosenblatt SM, Chand B, Luciano MG. Laparoscopic peritoneal catheter placement: results of a new method in 111 patients. Neurosurgery 2007;61(3 Suppl l):167. [35] Meier U, Lemcke J, Al-Zain F. Course of disease in patients with idiopathic normal pressure hydrocephalus (iNPH): a follow-up study 3, 4 and 5 years following shunt implantation. Acta Neurochir Suppl 2008;102:125. [36] Anile C, De Bonis P, Albanese A, et al. Selection of patients with idiopathic normal-pressure hydrocephalus for shunt placement: a single-institution experience. J Neurosurg; 2010 Feb 12 [Epub ahead of print]. [37] Black PM. Idiopathic normal-pressure hydrocephalus. Results of shunting in 62 patients. J Neurosurg 1980;52:371. [38] Esmonde T, Cooke S. Shunting for normal pressure hydrocephalus. Cochrane Database Syst Rev; 2001:CD003157. [39] Pujari S, Kharkar S, Metellus P, Shuck J, Williams MA, Rigamonti D. Normal pressure hydrocephalus: long-term outcome after shunt surgery. J Neurol Neurosurg Psychiatry 2008;79:1282. [40] Reimer R, Wharen RE Jr, Pettit PD. Ventriculoperitoneal shunt placement with video-laparoscopic guidance. J Am Coll Surg 1998;187:637. [41] Lazareff JA, Peacock W, Holly L, Ver Halen J, Wong A, Olmstead C. Multiple shunt failures: an analysis of relevant factors. Child’s Nerv Syst 1998;14:271. [42] Gutt CN, Oniu T, Schemmer P. Fewer adhesions induced by laparoscopic surgery? Surg Endosc 2004;18:898. [43] Novitsky YW, Litwin DE, Callery MP. The net immunologic advantage of laparoscopic surgery. Surg Endosc 2004;18: 1411.
Available online at www.sciencedirect.com
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Shunting for hydrocephalus: analysis of techniques and failure patterns Fares Nigim, MD,a Jonathan F. Critchlow, MD,b Benjamin E. Schneider, MD,b Clark Chen, MD, PhD,a and Ekkehard M. Kasper, MD, PhDa,* a b
Department of Neurosurgery, Harvard Medical School, Boston, Massachusetts Department of Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts
article info
abstract
Article history:
Background: Hydrocephalus is characterized by ventricular dilatation because of progres-
Received 4 January 2014
sive accumulation of cerebrospinal fluid. Normal pressure hydrocephalus (NPH) affects a
Received in revised form
subset of patients representing a reversible clinical triad of gait disturbance, urinary in-
17 March 2014
continence, and dementia with normal cerebrospinal fluid pressure and composition.
Accepted 25 March 2014
Various shunting procedures have been used for treatment, but techniques and outcomes
Available online xxx
remain under debate. The objective of this study was to evaluate the clinical outcomes of 232 patients with and without NPH after the first-time Ventriculoperitoneal shunt place-
Keywords:
ment and assessed patterns of failure between December 2004 and December 2012.
Ventriculoperitoneal shunt (VPS)
Results: Mean age was 54.7 y in non-NPH and 71.9 y in NPH patients. We used open tech-
Laparoscopic technique
nique in 34.3% and laparoscopic technique in 65.7% of NPH patients and 32.7% and 67.3% of
(Lap technique) Normal pressure hydrocephalus
the non-NPH patients, respectively. A total of 36 of 232 patients displayed shunt failure, 16.4% in NPH and 15.2% in non-NPH patients. Twenty-three of 155 patients failed after laparoscopic and 13 of 77 failed after open placement. Proximal shunt failure was more
(NPH) Cerebrospinal fluid (CSF)
frequent in the non-NPH cohort. Distal failures accounted for 13 of 232 cases, and the difference between laparoscopic (six of 155) and open failures (seven of 77) was profound, but not between NPH- and non-NPH patients. Conclusions: Shunt failures are related to the placement method. Non-NPH patients showed more proximal failures. NPH patients showed fewer proximal failures. Less distal failures were observed after laparoscopic ventriculoperitoneal shunt placement without significant differences between NPH and non-NPH patients. Beyond this, laparoscopic surgery carries distinct advantages such as shorter operating room times and hospital stays, which should translate into less use of pain medications, earlier mobilization, and a lower incidence of ileus. ª 2014 Elsevier Inc. All rights reserved.
1.
Introduction
Ventriculoperitoneal shunting (VPS) is the mainstay for the treatment of hydrocephalus and remains a frequently performed procedure in general neurosurgical practice. Among
all patients with hydrocephalus, there are various etiologies leading to ventricular dilatation and neurologic decline, ultimately requiring a cerebrospinal fluid (CSF) diversion procedure. However, these implanted devices may fail over time.
* Corresponding author. Department of Surgery, Beth Israel Medical Center and Department of Neurosurgery, Harvard Medical School, 110 Francis Street Suite 3B, Boston, MA 02215. Tel.: þ1 617 632 7246; fax: þ 1 617 632 0949. E-mail address: [email protected] (E.M. Kasper). 0022-4804/$ e see front matter ª 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jss.2014.03.075
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We investigated a cohort of elderly normal pressure hydrocephalus (NPH) patients against the background of a large suitable reference cohort of other hydrocephalus patients also requiring a VPS, and we report comparative data regarding surgical outcomes and shunt survival in these patients and investigate respective shunt failure patterns. NPH patients differ from the other cohort of patients with, for example, posthemorrhagic hydrocephalus, hydrocephalus in the setting of metastatic disease, hydrocephalus in the presence of a central nervous system tumor, or pseudotumor cerebri, and so forth. In at least two important aspects: First, NPH patients are generally older and second, the CSF or NPH patients is considered to be normal, which means unaltered by any increase in protein or cells, for example, after infection, intracranial hemorrhage, or in the presence of tumors. The hypothesis that can be addressed with this study are as follows: (1) Patients with NPH may show a higher VPS failure rate, as older patients are more likely to suffer from comorbidities (e.g., those resulting in abdominal surgery and adhesions causing distal catheter obstruction); (2) NPH patients have a CSF composition that differs from the CSF of hydrocephalic patients with other etiologies, and hence they may show a different failure rate and pattern [1]; (3) We wanted to see whether laparoscopic placement of VPS may translate into a lower failure rate as assumed by other laparoscopic studies or show a different pattern of VPS failures over time. This data set is suitable to corroborate the validity and safety of the laparoscopic and open VPS procedures and looks at the longevity of the first-time shunts placed. We furthermore look in detail into the observed cases of VPS failures by assessing both location and possible causes. Among the large number of patients requiring a shunt for various indications is a more homogenous patient group with NPH. This cohort is of particular interest, because NPH is one of the few treatable conditions of cognitive decline among other symptoms and affects as many as 3%e6% of patients with dementia [2e9]. The syndrome was first described by Hakim and Adams [10] in 1965 and included gait apraxia, imbalance, progressive memory loss, urinary incontinence, and normal CSF composition and pressure on lumbar puncture. Currently, there is no effective medical treatment for neurocognitive decline from hydrocephalus in NPH, and drugs such as acetazolamide or osmotic diuretics have been found not to work reliably. Ventricular shunting is the only treatment to provide a lasting benefit. Success after shunting is reflected in a lasting remission of symptoms in these patients with a normal life expectancy. This requires long-term follow-up and regular patient assessment, as well as management of potential shunt complications via revisions. There is an ongoing debate as to whether the benefits outweigh the risk in shunting in NPH patients, because NPH affects predominantly the elderly population who often suffer from significant comorbidities (e.g., cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary disease, and so forth) [11e13]. We therefore set out to look at shunting in these NPH patients and analyzed their complication rate and failure patterns in comparison with a large cohort of other patients undergoing first-time VPS placement for different
etiologies. To this end, longitudinal observation and assessment of these patients is essential. Several authors have thus far reported good outcomes with follow-up periods mostly ranging from 3 mo to 2 y [14e17]. To date, one of the seminal studies reported was done by Savolainen et al.[18] who followed 25 patients for 5 y. However, only a small number of studies has elucidated the long-term effects of shunting and few report on the associated surgical morbidities [19e23]. Here, we report our surgical experience and outcome in patients undergoing surgery for NPH in comparison with patients requiring shunt placement for different etiologies. Shunt failures do occur rather frequently as reported in the present literature, and we wanted to see, whether these may be possibly related to the placement method chosen. We therefore compared metrics from patients who underwent VPS via the conventional open surgical approach to data from patients who had laparoscopic VPS surgery, and we followed these patients longitudinally to find a significant difference in shunt failure rates and pattern when comparing the two cohorts and the two techniques investigated.
2.
Material and methods
This is an institutional review board (IRB No. 2011P-000101/4 and 2013P-000253/1)-approved retrospective cohort study of a prospectively collected data set of consecutive adult patients who underwent first-time insertion of a VPS for various etiologies of hydrocephalus. The study cohort consisted of patients treated at Beth Israel Deaconess Medical Center between December 2004 and December 2012. New VPS placement was strictly defined as insertion of a proximal cerebral catheter, a new valve, and new distal placement of a peritoneal catheter. To avoid contamination of data, any shunt revisions and previously shunt-treated patients, who underwent complete shunt removal (for infection or other indication) and who later underwent placement of a new VPS, were also excluded. Distal catheters were placed either via a standard small open laparotomy or via a laparoscopic technique using two or three access ports. The decision what technique to use was based on (1) past medical history of the individual patient (e.g., prior abdominal surgery), (2) patients body habitus, or (3) the neurosurgeon’s preference and experience with both techniques. Independent variables investigated in this study included demographics (e.g., age and gender), indication for surgery, and past medical history (e.g., comorbidities and previous abdominal operations). For all patients, we carefully examined the preoperative imaging (head computed tomography or magnetic resonance imaging scan when available), the description of the operative encounter (open or laparoscopic and intraoperative findings), and the specifics of the implanted valve type as well as clinical notes and radiographic studies during the entire follow-up period for each patient. Dependent variables analyzed included operative time, length of hospital stay, findings on postoperative head computed tomography scan (obtained immediately and 4e8 wk after surgery and annually thereafter to assess early as well as delayed postoperative complications), occurrence of any
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shunt failure, assessment of the cause of shunt failure, and any other complications. Shunt failures were categorized as proximal to the valve, at the level of the valve, or distally at the abdominal catheter. Clinical relevant shunt failure was defined as any return to surgery for management of a shunt-related problem. Causes of shunt failure were categorized as proximal mechanical shunt obstruction or infection, distal shunt obstruction, malpositioning, infection, or valve malfunction. Shunt infection was broadly defined as a positive CSF culture or an increase in white blood cells from a shunt tap in the setting of respective clinical central nervous system symptoms or revision in a patient with a positive wound culture at the time of revision surgery. Shunt obstruction was diagnosed preoperatively or intraoperatively by testing all implanted hardware. Intracranial or abdominal catheter obstruction due to malpositioning was radiographically diagnosed and then confirmed at surgery. All patients in this cohort study had adjustable valves (Strada; Medtronic, Framingham, MA), so they could undergo multiple valve setting adjustments before undergoing revision surgery. Abdominal pain or distal shunt failure was considered to be a complication if new symptoms occurred and persisted after catheter placement and if complaints were not attributable to alternative diagnoses and remained refractory to conservative management. The most recent patient encounter (clinic visit or hospital discharge) was taken as the end point for the clinical and radiographic follow-up period. For the purpose of the study, we assume that patients who did not present to this or any other local hospital or office for any shunt-related problems had a functioning shunt for the interim period. This is a reasonable assumption, given that the patient cohort only consisted of patients living in a 40-mile radius around the hospital and given the established management strategy that patients are being sent to their parent institution to care for shunt-related problems. If patients were to be admitted to any other local hospital, we thus would have received notification and request for transfer. Other end points of the study were occurrence of shunt revision, timing of shunt revision, or shunt removal.
2.1.
Statistical analysis
Data were recorded on Excel spreadsheets. Differences in outcome and complication rates were compared between the two cohorts undergoing the two respective VPS placement techniques, and group data were compared using t-and f-tests (analysis of variance). P values were considered statistically significant when the value was <0.05.
2.2.
Surgical technique
The cranial procedure consisted of a standard intracranial catheter placement for each VPS patient and was identical for patients undergoing open and laparoscopic VPS placement; in cases of conventional VPS placement, the neurosurgical team performed open abdominal catheter placement, and in cases of endoscopic placement, a general surgeon performed the laparoscopic portion of the case. Both the neurosurgical and
3
general surgical part of the procedure commenced simultaneously. For the group undergoing conventional open VPS placement, a 4e5-cm subcostal incision was made to gain access to the peritoneum. After dividing the overlying layer, a small incision was made and the peritoneal cavity was inspected to confirm entry into the abdomen and to verify that no visceral injury had occurred. The distal shunt catheter was placed into the peritoneal cavity after CSF flow was observed from the distal catheter tip. The abdominal incision was closed in layers. For patients undergoing laparoscopic VPS placement, a supraumbilical curvilinear incision is made and the dissection is carried down to the linea alba. The fascia is then elevated and a Hasson catheter is introduced. Pneumoperitoneum is created and a 5-mm port is then placed approximately 8 cm below the right costal margin, and the peritoneal cavity is accessed using the Seldinger technique to place and introducer sheath. The distal catheter is then placed intraperitoneally via that introducer and directed into the superior retrohepatic recess. Observing CSF flow from the catheter tip corroborates adequate shunt function. The fascia and skin incisions are closed in layers. Patients underwent routine postoperative care and were discharged for a wound check and with scheduled regular follow-up appointments.
3.
Results
Between December 2003 and December 2012, a total of 232 patients underwent first-time placement of a VPS. Of those, 67 patients were diagnosed with NPH, whereas 165 patients were showing hydrocephalus from different etiologies (e.g., posthemorrhagic hydrocephalus, hydrocephalus in the setting of metastatic disease, hydrocephalus in the presence of a central nervous system tumor, and pseudotumor cerebri). All demographic data were compared between the NPH and non-NPH groups, and there were no significant differences between the two populations. The mean age was somewhat lower in the non-NPH group, but this difference was not statistically significant (see Table 1). Other metrics are shown in subsequent tables. Operative time was considered the surgical time from skin incision to skin closure. The mean operative time in the NPH group was significantly shorter with laparoscopy, with 42.3 min (range, 22e102) compared with patients operated via the open technique, which required 62.1 min (range, 35e118), (P < 0.05). This observation held also true in the cohort of all other VPS patients, where the mean operative time was significantly longer with the open technique (63.0 versus 43.7, respectively), P < 0.05 (Tables 2 and 3). There were no cases of direct or early surgical postoperative complications in either group. The mean length of stay in the hospital in the NPH group was 4 d with the open technique versus 2 d with the laparoscopic technique; this difference was statistically significant, (P < 0.05). Length of hospital stay in the non-NPH group was slightly longer (see Tables 2 and 3), which was expected since those patients had other comorbidities, were scheduled for other investigations, or required prolonged medical care (e.g., radiation therapy or
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Table 1 e Study cohort description. NPH group (n ¼ 67)
Non-NPH group (n ¼ 165)
P value
71.9 10.9 (75.0, 28.5e88.0)
54.7 15.9 (55.8, 19.2e88.3)
NS
Demographic data Mean age (Y) Gender Male % (n) Female % (n) Previous abdominal operation Surgical technique: Open % (n) Laparoscopic % (n)
64.1 (43) 35.9 (24) 20.9 (14)
47.3 (78) 52.7 (87) 27.8% (46)
34.3 (23) 65.7 (44)
NS NS NS
32.7 (54) 67.3 (111)
NS NS
NS ¼ not significant.
chemotherapy in patients with metastatic disease), precluding earlier discharge. Follow-up consisted of clinical and radiological evaluation and was performed at 1, 3, 6, and 12 mo after surgery and yearly thereafter. At the time of the follow-up, patients and their families were routinely assessed by questionnaire and also reminded of the possibility of shunt malfunction potentially causing a return of their NPH symptoms, and families were instructed to contact us in such circumstances. The mean follow-up time in the NPH group was 45 mo (median 42.3, range 0.5e103.0) and was thus longer than the non-NPH group that had a mean follow-up of 27.6 mo (median 28.5, range 0.3e107.3), this difference was statistically significant, (P < 0.05; Tables 2 and 3), but this may not be meaningful because VPS patients with metastatic disease in this group would succumb to their cancer and drop out of the study and thus shorten mean follow-up time. Survival after shunt placement surgery was compared between the patients in the NPH and those in the non-NPH groups. Such shunt survival in the NPH group was estimated to be 94.0% at 12 mo and 60.0% at 3-y follow-up (data not shown). Hydrocephalus symptoms were classified as “improved” if they resulted in an improvement in the patient’s day-to-day functioning. Nearly all patients had profound and lasting improvement postoperatively for the duration of the follow-up period. Further neurologic assessments will be reported elsewhere. The details of the clinical course and shunt longevity assessment as well as failure rates and analysis are listed in Tables 2 and 3 and Tables 4 and 5. Shunt failure was defined as any return of the patient to the hospital with symptoms related to shunt failure and ultimately requiring surgery. Causes of shunt failure have been categorized as at the proximal catheter (e.g., obstruction, malpositioning, or infection), at the distal catheter (obstruction, malpositioning, or infection), or valve malfunction. The
overall number of shunt failures in NPH patients during our observation period was rather low with 11 patients (16.4%) affected, and of those three shunts failed in the first 12 mo postoperatively (Figure). There was no statistically significant difference between the open and the laparoscopic technique in terms of overall failure rate in NPH patients, (n ¼ 3/23 or 13.0% versus n ¼ 8/44 or 18.2%, respectively; Tables 4 and 5). However, the pattern of failure showed some striking differences. Proximal shunt revision was reported in three of 67 NPH patients (4.5%) but in 17 of 165 non-NPH patients (10.3%). However, there was no significant difference between the open and the laparoscopic technique in each patient cohort (Tables 4 and 5). Valve dysfunction occurred in four of 67 NPH patients (6.0%) and in nine of 165 non-NPH patients (5.5%), without any significant difference between techniques (Tables 4 and 5). Distal catheter revision was required in four of 67 NPH patients (6.0%) and in nine of 165 non-NPH patients (5.5%) with no significant difference between the open and the laparoscopic technique (Tables 4 and 5). However, when analyzed as aggregates of technique, there where seven of 77 patients (9%) after open VPS placement who underwent revision surgery, whereas only six of 155 (3.6%) laparoscopically placed peritoneal catheters ultimately required a revision. Malpositioning of the distal catheter (clinically presenting with abdominal pain) was rarely observed with either technique (in two NPH patients operated with the open technique and in two NPH patients operated with the laparoscopic technique). Once needed, distal shunt revisions were done laparoscopically, in two of those four patients who had developed distal catheter kinking. The associated pain resolved after shunt revision in all four affected patients of the NPH cohort. There were no patients requiring shunt removal for refractory abdominal pain from either technique. We did not have any case of infection in the distal catheter (Table 4).
Table 2 e Surgical metrics in NPH group. Outcomes Operative time (min) Length in stay (d) Mean follow-up time (mo) median
All NPH shunts
Open technique
Lap technique
P value
49.2 18.2 (47.0, 25e118) 3.0 3.0 (2.0, 1.0e25.0) 45.0 29.6 (42.3)
62.1 18.3 (60.0, 35e118) 4.0 5.0 (3.0, 1.0e25.0) 32.1 28.9 (22.2)
42.3 14.8 (39.5, 22e102) 2.0 1.0 (2.0, 1.0e5.0) 26.7 23.1 (20.7)
<0.05 <0.05 NS
Lap ¼ laparoscopic; NS ¼ not significant.
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Table 3 e Surgical metrics in non-NPH group. Outcomes Operative time (min) Length in stay (d) Mean follow-up time (mo) median
All non-NPH shunts
Open technique
Lap technique
P value
50.4 21.2 (46.0, 18.0e151.0) 6.0 5.0 (4.0, 1.0e50.0) 27.6 28.5 (17.1)
63.0 23.4 (58.0, 30.0e151.0) 5.0 3.5 (3.0, 1.0e30.0) 35.7 29.8 (22.1)
43.7 15.6 (41.0, 18.0e102.0) 5.0 5.0 (3.0, 1.0e50.0) 25.9 22.0 (20.7)
<0.05 NS NS
Lap ¼ laparoscopic; Ns ¼ not significant.
Noteworthy, none of the patients had any distal shunt revision after being discharged from the hospital.
4.
Discussion
CSF diversion remains the mainstay for the treatment of hydrocephalus, and new shunt technologies and surgical techniques have evolved over the past decades [24,25]. Diversion can be achieved via a ventriculoatrial shunt, a lumboperitoneal shunt, or a VPS, the latter being the most frequent procedure performed. In this study, we report the outcomes of 232 VPS patients in total and 67 NPH patients in particular, who underwent firsttime VPS placement by either a laparoscopic or open VPS placement technique. In our cohort, mean operative time differed between the two surgical groups; it was 31.9% shorter in the laparoscopic group (42.3 versus 62.1, P < 0.05; Tables 2 and 3). Other series reported the mean operative time for the open placement as ranging from 40e130 min [26e28] and for laparoscopic placement as ranging from 30e115 min [24e27], but the definitions of surgical time differ somewhat. Certainly, the operative time depends on both patient and surgeon-specific factors; obese patients, patients with a history of previous abdominal operations, or distorted abdominal anatomy require more time compared with other patients, because the abdominal surgeon often has to lyse adhesions to avoid malpositioning or obstruction of the distal catheter. Furthermore, obese patients have a higher risk of shunt malpositioning because of more abundant preperitoneal fat that can be mistaken for omentum [27]. We also noticed that the mean operative time has decreased over time in our center, likely due to growing experience and efforts to improve coordinating the two surgeon’s timing and the intraoperative workflow. The mean length of hospital stay was about 3 d with both techniques, which was somewhat shorter than in other
studies published [26,29]. Patients operated laparoscopically had a shorter length of hospital stay than patients operate by conventionally (2 versus 4 d, respectively, P < 0.05), and this difference was statistically significant, although the NPH cohort examined here was relatively small, and hence the cohort size may not allow for sufficient power (see Tables 2 and 3). The difference in operative time and length of hospital stay may translate into a difference in overall outcome of VPS surgery. By reducing operative time and with shorter hospitalizations, the provider can achieve earlier mobilization and likely fewer postoperative complications (e.g., thrombosis, pain, and postoperative ileus), and thus a reduction in the overall cost associated with VPS placement, with a likely significant impact on overall annual health care costs [30]. We used a stringent hydrocephalus and VPS definition to define suitable patient cohorts and followed these longitudinally with a stringent assessment of neurologic improvement allowing us to focus on the surgical techniques used in this study and to compare outcomes of patients treated with either a conventional or a laparoscopic surgical approach. More than 90% of our NPH patients showed neurologic improvement after surgery at 3-mo and 1-y follow-up, and 70% of the patients maintained this improvement at 3-y follow-up (data not shown); in our cohort, gait was the most frequently improved symptom postsurgically, whereas urinary incontinence and cognitive impairment showed less improvement after surgery, but further neurologic outcome details will be reported elsewhere. In our two cohorts, the rate of shunt failure after VPS surgery was 11 of 67 (16.4%) in the NPH group and 36 of 232 (15.5%) in the reference cohort for non-NPH etiologies. There was no significant difference between the two techniques in term of overall shunt failure rate, with three shunts in need of revision within the first 12-mo follow-up. Eight patients had to undergo VPS revision during later follow-up. Among these, there were three proximal failures (two patients presented with fever and confusion from infection, the third patient had
Table 4 e Surgical failure rates illustrated by location in NPH group. Cause of shunt failure Overall N of shunt failure Cause of shunt failure Proximal catheter (obstruction or infection) Distal catheter (obstruction or infection) Valve dysfunction
All NPH shunts, n ¼ 67 (%)
Open technique, n ¼ 23 (%)
Laparoscopic technique, n ¼ 44 (%)
11 (16.4)
3 (13.0)
8 (18.2)
3 (4.5) 4 (6.0) 4 (6.0)
1 (4.3) 2 (8.7) 0 (0)
2 (4.6) 2 (4.6) 4 (9.1)
None of the variables showed significant differences between groups.
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Table 5 e Surgical failure rates illustrated by location in non-NPH group. Cause of shunt failure Overall N of shunt failure Cause of shunt failure Proximal catheter (obstruction or infection) Distal catheter (obstruction or infection) Valve dysfunction
All non-NPH shunts, n ¼ 165 (%)
Open technique, n ¼ 54 (%)
Laparoscopic technique, n ¼ 111 (%)
25 (15.2)
10 (18.4)
15 (13.5)
17 (10.3) 9 (5.5) 9 (5.5)
8 (14.8) 5 (9.3) 2 (3.7)
9 (8.1) 4 (3.6) 7 (6.3)
None of the variables showed significant differences between groups.
a proximal catheter obstruction and presented with recurrent signs of NPH); there were also three cases of valve dysfunction, and finally two distal abdominal catheter obstructions were encountered that required revision. Significant complication rates after VPS have been reported frequently in the literature and range between 6% and 53% and both our cohorts are well positioned at the lower end of this range. We focused on understanding the causes of distal shunt failure by carefully looking at two cohorts in which the peritoneal catheter was placed with differing techniques. We noticed that distal failures were more prevalent in patients who had open VPS placement compared with patients who had laparoscopically placed VPS. Among the principal failures, the following were observed in the literature: mechanical shunt failures (e.g., obstruction in the intracranial or abdominal catheter) and abdominal injury (ascites, peritonitis, abdominal perforations, and volvulus) [2,31,32]. In the latter cases, obesity, previous abdominal operation, and distorted abdominal anatomy seem to correlate with the observed rate of distal mechanical shunt failure and several studies have established a correlation between previous abdominal operations and the incidence of distal shunt failure [25,27,28,33]. This can be due to adhesions, calcifications, and fibrosis causing distal catheter obstruction, malposition, and migration. In our study, distal catheter malfunction resulting in shunt failure occurred in only four of 67 NPH patients (6.0%), none of whom had a history of previous abdominal operations, (Table 4). We attempted to analyze whether there is a correlation between the occurrence of distal shunt failure and any history of previous abdominal operation, but given the low incidence of failure events in our NPH cohort, previous
Figure e Shunt failure rates and pattern overtime for the study cohort. (Color version of figure is available online.)
abdominal surgery could not be established as a significant predictor for distal shunt failure. This is consistent with the study of 111 patients reported by Turner et al. [34]. Little is known about the long-term prognosis of patients after shunting and various studies showed differing shunt survival over long-term follow-up [35e38]. In our opinion, caregivers should continuously monitor all VPS patients for shunt complications with longitudinal follow-up. Pujari et al. [39]. involved a retrospective analysis of 55 patients followed for at least 3 y after shunt surgery; of those, a stunningly high rate of 53% needed a revision but no specifics were given. Some authors have reported an increased infection rate with the laparoscopic technique, [28] but we cannot confirm that observation in both our cohorts. Previous studies have shown that the number of surgeons, circulating personnel, start time, and duration of the operation codetermine the infection rate [40,41]. These are factors, which we have tried to optimize, but when assessed, we did not find a correlation to the incidence of infections, possibly because they were already at a low rate in our cohorts. This type of analysis hence needs to be performed in a much larger study population. Compared with traditional laparotomy, the laparoscopic technique offers several significant advantages: First, the ability of the surgeon to inspect the abdominal cavity and perform adhesiolysis. This prevents placement of the distal catheter in a pocket of adhesions or in kinked position especially in obese patients and in patients with previous abdominal surgeries [24,33,34,40]. Second, laparoscopy also reduces abdominal wall trauma and postoperative morbidity, because it requires smaller incision with smaller peritoneal and fascia openings, resulting in fewer secondary adhesions, less postoperative pain, a decrease in the incidence of postoperative ileus, less risk of perforating abdominal organs, and a decrease in the frequency of incisional hernias [42,43]. We are currently studying these aspects prospectively. We are aware of the fact that our study also has some limitations. First of all, the study is a retrospective cohort study. Second, patient’s body mass index was not always reported, so we could not correlate patient selection or outcome parameters to obesity, which should be assessed in future studies. However, we could not demonstrate a clear difference in overall failure rates or failure patterns in our two patient populations (NPH versus non-NPH patients), except that nonNPH patients displayed an increased rate of proximal shunt failures, which could be related to the altered CSF composition
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in non-NPH patients. But when comparing in detail the two differing placement techniques, which were used, a lower abdominal failure rate was found in the laparoscopic group (six of 155) than in the open VPS group (seven of 77). This deserves further study. Such studies should also address the impact of shorter OR times, shorter hospital stays, less use of pain medications, and earlier mobilization as well as a likely lower incidence of ileus, which may be particularly beneficial in the potentially frail elderly population such as our NPH patients.
5.
Conclusions
Based on our experience of a cohort of 67 NPH patients and 165 non-NPH patients undergoing first-time shunt placement surgery, we can confidently conclude that VPS placement with the laparoscopic technique is a safe approach because no significant complications were encountered. As far as the failure patterns are concerned, we consider a slightly lower distal failure rate with laparoscopic VPS placement worth reporting and we encourage further studies of potentially suitable target patient groups. Laparoscopic abdominal catheter placement seems to offer distinct advantages over the traditional minilaparotomy. It shortens the operative time, allows the surgeon to explore the abdominal cavity, lyse adhesions if necessary, allows to assess incidental abdominal pathology, and it finally ensures optimal positioning of the distal catheter. Based on low postoperative distal VPS catheter failure rates, we strongly suggest to study the laparoscopic technique as an alternative technique especially in obese patients and in patients with previous abdominal operations.
Acknowledgment This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. Authors’ contributions: F.N. and E.K. contributed to conception and design. F.N., E.K., C.C., J.F.C., and B.E.S. were responsible for the acquisition of data. F.N. analyzed the data. F.N. and E.K. interpreted the data. C.C. designed the data. J.F.C. edited the data. C.C. and J.F.C. were also responsible manuscript editing.
Disclosure The authors reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.
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