- Email: [email protected]
Neonatal Hydrocephalus Treatment with Ultrasmall Valve Implantation
Original Article
Neonatal Hydrocephalus Treatment with Ultrasmall Valve Implantation Samuel W. Reed, Michael J. Cools, Carolyn S. Quinsey, Scott W. Elton
OBJECTIVE: Neonatal hydrocephalus remains a difficult condition to manage, due to high failure rates among all management strategies. Neurosurgeons commonly manage hydrocephalus with ventriculoperitoneal shunt (VPS) implantation, and valves of variable sizes and profiles are available for implantation. This study examines primary ventricular shunt valve implantation complication rates based on valve profiles in pediatric patients with hydrocephalus.
-
METHODS: This study retrospectively reviews pediatric patients younger than 1 year of age who underwent ventricular shunt placement at a single institution from January 2001 to January 2017. Patients were classified by valve profile and categorized as either ultrasmall valves or regular-sized valves. Time until complication and type of complication were studied.
-
RESULTS: A total of 156 patients met the inclusion criteria. Forty-eight (31%) patients received an ultrasmall shunt valve, while 108 patients received a regular valve. On average, patients undergoing ultrasmall valve placement were younger (2.1 months) than patients undergoing placement of regular valves (3.1 months) (P [ 0.03). The overall complication rate within 2 years of VPS placement was 37.5% in patients with the ultrasmall valve and 41.7% in the regular valve population. There was no difference in 1-year shunt survival rate between the 2 cohorts.
-
CONCLUSION: Our review did not find a significant difference in complication rates between ultrasmall and regular valves in patients under 1 year of age. However, the etiology of shunt malfunction did differ between the groups. This work further supports evidence suggesting a
-
Key words Hydrocephalus - Ultra-small valve - Ventriculoperitoneal shunt -
Abbreviations and Acronyms ETV: Endoscopic third ventriculostomy VPS: Ventriculoperitoneal shunt
surgeon’s preference for shunt hardware alone does not significantly impact outcome.
INTRODUCTION
H
ydrocephalus remains a prevalent disease surgically treated by pediatric neurosurgeons. Neurosurgeons commonly manage hydrocephalus with ventriculoperitoneal shunts (VPS); unfortunately, despite significant advances in technology, complication rates remain high.1 Although many studies compare success and complication rates between valve mechanisms,2,3 insufficient evidence exists in the literature to recommend 1 shunt hardware design over another for the treatment of pediatric hydrocephalus.1,4 The majority of these studies focused on valve mechanism (i.e., programmable vs. nonprogrammable), without consideration for the consequences of valve profile or dimensions. While endoscopic third ventriculostomy (ETV) reduces the need for VPS in some patients, it carries a poorer success rate in children <1 month5 and fails in some patients. The variability of ETV success among hydrocephalus patients highlights the need to optimize valve selection. Hydrocephalus treatment in the neonatal populations poses several unique challenges including a less developed immune system, smaller anatomy, and more friable skin.6,7 Multiple studies address these challenges with the goal of improving neonatal outcomes. Outcomes have been evaluated in terms of valve opening pressure,8,9 valve placement in periosteum,6 or burying the valve in the skull10 to prevent pressure on the skin and subsequent wound breakdown. However, the influence of valve profile and size on outcomes remains largely unexamined. The smaller and lower profile of ultrasmall valves may reduce wound breakdown complications, but the smaller profile may
Department of Neurosurgery, University of North Carolina at Chapel Hill, North Carolina, USA To whom correspondence should be addressed: Samuel W. Reed, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.09.043 Journal homepage: www.journals.elsevier.com/world-neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY -: e1-e4, - 2019
www.journals.elsevier.com/world-neurosurgery
e1
ORIGINAL ARTICLE SAMUEL W. REED ET AL.
ULTRASMALL VALVE IMPLANTATION
also make the valve prone to obstruction and failure requiring revision. Despite the dichotomy of opinions on valve size and complication rate, a literature search identifies only 2 studies evaluating “neonatal,” “ultra-small,” or “micro valve” outcomes.11,12 A prospective study by Warf et al12 comparing the Codman-Hakim micro valve to the less expensive Chhabra valve in pediatric patients in Uganda found no difference in overall complication rates between the 2 valves. A retrospective valve study stratifying patients by valve profile and examining subsequent shunt complications found a reduction in the number of infections and wound breakdowns in patients with ultrasmall valves, but overall complication rates did not differ significantly based on valve size.11 The paucity in data equating valve profile with success and outcomes in neonatal patients complicates a neurosurgeon’s ability to optimize valve selection in this population. Here, we compare outcomes in neonatal patients stratified by valve size at a single academic institution. METHODS This study was approved by the University of North Carolina Institutional Review Board. We conducted a retrospective medical record review of all patients 12 months of age or younger undergoing primary shunt placement at our institution between 2001 and 2017. Patient age, gestational age, weight at shunt placement, etiology of hydrocephalus, valve type, location of shunt, time until complication, complication type, and last recorded follow-up at our institution were collected. Shunt complications were defined as wound breakdown, infection, and mechanical failure requiring operative management. Complications were categorized as proximal obstruction, distal obstruction, valve failure, shunt infection, or wound breakdown. Operative findings within the operative note were reviewed to determine etiology of the failure. Results were stratified by valve type. Valves were classified as either ultrasmall, small, or regular sized. Table 1 lists valve dimensions. Patients with a small valve implanted are not reported due to a very small number implanted and resulting lack of comparability or significance. Patients reported to be full term were described as 38 weeks, and patients described as late preterm were described as 36 weeks, when no specific dating was recorded. Statistical analysis was performed using StataSE (College Station, Texas, USA). The proportion test was used to compare rates between the 2 groups. A 2-tailed t-test was used to compare continuous variables.
A total of 156 patients met inclusion criteria, 68 (44%) of which were female (Table 2). A total of 48 (31%) patients received an ultrasmall shunt valve, while 108 patients received a regular valve. On average, patients undergoing ultrasmall valve placement were younger (2.1 months) than patients undergoing placement of regular valves (3.4 months) (P < 0.01). Weight also differed significantly between the ultrasmall valve cohort (4.1 kg) and the regular valve cohort (5.0 kg) (P < 0.01).
www.SCIENCEDIRECT.com
Valve Sizes Valve Design
Length
Width
Height
Neonatal
20 mm
10 mm
5.5 mm
Small
36 mm
13 mm
6 mm
Regular
40 mm
16.5 mm
8 mm
Complication rates between valve types were similar, the majority of which was attributable to shunt failure. The overall complication rate within 2 years of VPS placement was 37.5% in patients with the ultrasmall valve and 41.7% in the regular valve population (Table 3). Of patients receiving ultrasmall valves, 12.5% experienced proximal obstruction, 8.3% experienced distal obstruction, and 18.8% of patients experienced valve failure. In the regular valve patient group, 24% of patients suffered proximal obstruction, 13% experienced distal obstruction, and 6% developed valve failure. The infection rate in the ultrasmall group was 2.1%, and the infection rate in the regular valve group was 10.2%. Wound breakdown occurred in only 1 patient in each group. Subgroup analysis of patients shunted at 30 days of age found higher overall complication rates in both ultrasmall valves (55%) and regular valves (56.8%) compared with full cohort analysis. The composition of complication etiologies in subgroup analysis remained comparable with whole-group analysis (Table 4).
Table 2. Patient Characteristics Study Population Characteristics
Total
Neonatal Valve
Regular Valve
156
48
108
Male
88 (56)
26 (54)
62 (57)
Female
68 (44)
22 (46)
46 (43)
0.64
34.5
34.7
34.4
0.63
3
2.1
3.4
<0.01
4.7
4.1
5
<0.01
Congenital
49 (31)
11 (23)
38 (35)
Myelomeningocele
48 (31)
20 (42)
28 (26)
IVH
38 (24)
13 (27)
25 (23)
Other
21 (14)
44 (8)
17 (16)
Characteristic Number of patients
Average gestational age (weeks) Average age at shunt placement (months) Average weight at shunt placement (kg)
RESULTS
e2
Table 1. Valve Dimensions
P Value
Hydrocephalus etiology
Values are number of patients (%) unless otherwise noted.
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.09.043
ORIGINAL ARTICLE SAMUEL W. REED ET AL.
ULTRASMALL VALVE IMPLANTATION
Table 3. Complications by Valve Type
Table 4. Subgroup Analysis of Complications
Complications by Valve Type
Subgroup Analysis Neonatal Valve
Regular Valve
P Value
Total number of complications in first 2 years
18 (38)
45 (42)
0.75
Proximal obstruction (% of total complications)
6 (33)
17 (47)
Distal obstruction
4 (22)
14 (39)
Valve failure
9 (50)
7 (19)
Infections
1 (6)
11 (31)
Wound breakdown
1 (6)
1 (3)
Total number of complications at anytime
20 (42)
52 (48)
Variable
Median time until complication (weeks)
7.3
12.7
Patients £30 days Old at Time of Shunt Placement
Neonatal Valve
Regular Valve
Total number of patients
20
37
Total complications
11
18
55%
57%
Proximal complications (% of total complications)
3 (15)
11 (35)
Distal complications
2 (10)
6 (33)
Infections
1 (5)
5 (28)
Wound breakdowns
1 (5)
0
Valve failures
4 (20)
2 (11)
28
71
Total complication rate
0.36 0.36
Total complications
9
25
32%
44%
Proximal complications (% of total complications)
3 (11)
13 (18)
Distal complications
2 (7)
8 (11)
Total complication rate
Similarly, subgroup analysis of patients 4.5 kg found higher rates of total complications in both the ultrasmall valves (50%) and regular valves (55.4%), relative to full cohort analysis. The median time to complication was 7.3 weeks in the patients with ultrasmall valves and 12.7 weeks in patients with regular valves (P ¼ 0.36). There was no difference in 1-year shunt survival rate between the ultrasmall and regular valves.
0.56
Patients >30 days old at time of shunt placement Total number of patients
Values are number of patients (%) unless otherwise noted.
P Value
Infections
0
6 (9)
Wound breakdowns
0
1 (1)
5 (18)
5 (7)
Valve failures
0.23
Values are number of patients (%) unless otherwise noted.
DISCUSSION Managing hydrocephalus in the neonatal population with VPS remains an imperfect solution, primarily due to the high rate of complications. Prospective studies of several different valve mechanism designs show overall complication rates of 43.6% within 2 years of initial placement.2 Our study seeks to identify the impact of valve size on complication rates in patients younger than 1 year of age with hydrocephalus managed by VPS implantation. The results do not support superiority of 1 valve size over another, as no significant difference in overall complication incidence in the 2 years after VPS placement exists between patients receiving an ultrasmall valve (37.5%) and those receiving a regular-sized valve (41.7%). Our overall complication rate within 2 years of shunt implantation for all patients (40.1%) compares to rates in the literature, which also encompass all valve sizes.2,3 While the incidence of shunt complication did not differ significantly between patients receiving ultrasmall valves and patients receiving regular valves, the etiology of complication did vary between the 2 groups. Our data suggest the ultrasmall valve group experiences a larger proportion of valve failures than the regular valve group (19% vs. 6%). This difference could be attributable to a true difference in valve function or due to small sample size.
WORLD NEUROSURGERY -: e1-e4, - 2019
Infection presents a particularly troublesome complication as it requires a removal and reinsertion surgery, prolonged hospitalization for IV antibiotics, and subsequent increased risk of infection when reimplanted. Incidence of VPS infection in the literature ranges from 6.5% to 23.5%.13-18 Our study finds the overall incidence of shunt infection for the combined cohort to be 7.7%, consistent with other reported outcomes. However, we report lower infection rates than those with ultrasmall valve placement (2%) compared with regular valve placement (10%). Similarly, Kahilogullari et al11 report lower infection rates in ultrasmall valves. In contrast to Kahilogullari et al,11 which finds a decrease in wound breakdown with ultrasmall valves compared with regular-size valves, our data observe only 2 cases of wound breakdown. Therefore wound breakdown does not represent a notable complication in our patient population. In the absence of wound breakdown, the increased infection rate observed in the regular valve group cannot be directly attributed to valve size. This suggests an artefactual difference in infection rate between the 2 groups and highlights the need for further research to parse out the difference between valve size and infection rate. The subgroup analysis compares complication rates by valve size in 2 high-risk groups to the lower-risk counterparts; patients
www.journals.elsevier.com/world-neurosurgery
e3
ORIGINAL ARTICLE SAMUEL W. REED ET AL.
ULTRASMALL VALVE IMPLANTATION
with implantation at 30 days of life compared with implantation >30 days old, and implantation in patients weighing 4.5 kg compared with those >4.5 kg. The patients in these high-risk cohorts receiving implantation at 30 days of age or at 4.5 kg experience higher complication rates relative to the full cohort. In patients 30 days of life at implantation, the overall complication rate was 55% for those receiving an ultrasmall valve and was 57% for those receiving regular-sized valves; again, not supporting superiority of 1 valve size over another in these high-risk groups. These values compare to other reported shunt failures in infants younger than 1 month of age.19,20 The retrospective nature and small size limits the conclusiveness of this study. This study also relies on operative notes to document failure types, which results in high variability of documentation and interpretation. Ideally, a study examining valve malfunction would prospectively record failure reasons and study the device after explant.
REFERENCES 1. Baird LC, Mazzola CA, Auguste KI, Klimo P Jr, Flannery AM, Pediatric Hydrocephalus Systematic Review and Evidence-Based Guidelines Task Force. Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 5: effect of valve type on cerebrospinal fluid shunt efficacy. J Neurosurg Pediatr. 2014;14(suppl 1):35-43. 2. Drake JM, Kestle JR, Milner R, et al. Randomized trial of cerebrospinal fluid shunt valve design in pediatric hydrocephalus. Neurosurgery. 1998;43: 294-303. 3. Pollack IF, Albright AL, Adelson PD. A randomized, controlled study of a programmable shunt valve versus a conventional valve for patients with hydrocephalus. Hakim-medos Investigator Group. Neurosurgery. 1999;45: 1399-1408. 4. Hoshide R, Meltzer H, Dalle-Ore C, Gonda D, Guillaume D, Chen CC. Impact of ventricularperitoneal shunt valve design on clinical outcome of pediatric patients with hydrocephalus: lessons learned from randomized controlled trials. Surg Neurol Int. 2017;8:49. 5. Warf BC, Mugamba J, Kulkarni AV. Endoscopic third ventriculostomy in the treatment of childhood hydrocephalus in Uganda: report of a scoring system that predicts success. J Neurosurg Pediatr. 2010;4:143-148. 6. Bot GM, Ismail NJ, Usman B, et al. Subpericranial shunt valve placement: a technique in patients with friable skin. Childs Nerv Syst. 2014;30: 1431-1433. 7. Radmanesh F, Nejat F, Khashab M, Ghodsi SM, Ardebili HE. Shunt complications in children with
e4
www.SCIENCEDIRECT.com
CONCLUSIONS In conclusion, our data did not find a significant difference in complication rates between ultrasmall and regular valves in patients younger than 1 year of age. However, the etiology of shunt malfunction did differ between the groups. This work further supports evidence suggesting surgeon’s preference for shunt hardware alone does not likely significantly affect outcome. Despite thoughtful choices in shunt hardware, this device remains problematic with infectious and malfunction complications well demonstrated in our literature.
ACKNOWLEDGEMENTS The authors would like to thank Kathryn Pietrosimone, Ph.D., for her help in preparing this manuscript.
myelomeningocele: effect of timing of shunt placement. J Neurosurg Pediatr. 2009;3:516-520. 8. Robinson S, Kaufman BA, Park TS. Outcome analysis of initial neonatal shunts: does the valve make a difference? Pediatr Neurosurg. 2002; 37:287-294. 9. Sinha A, Sharma A, Gupta C. Pediatric hydrocephalus: does the shunt device pressure selection affect the outcome? J Indian Assoc Pediatr Surg. 2012;17:54-57. 10. Ammar A, Nasser M. A long-term complication of burying a shunt valve in the skull. Neurosurg Rev. 1995;18:65-67. 11. Kahilogullari G, Etus V, Tugba Morali G, Hakan K, Agahan U. Does shunt selection affect the rate of early shunt complications in neonatal myelomeningocele-associated hydrocephalus? A multi-center report. Turk Neurosurg. 2016;28:303-306. 12. Warf BC. Comparison of 1-year outcomes for the Chhabra and Codman-Hakim Micro Precision shunt systems in Uganda: a prospective study in 195 children. J Neurosurg Pediatr. 2005;102:358-362. 13. Amacher AL, Wellington J. Infantile hydrocephalus: longterm results of surgical therapy. Childs Brain. 1984;11:217-229. 14. Borgbjerg BM, Gjerris F, Albeck MJ, Borgesen SE. Risk of infection after cerebrospinal fluid shunt: an analysis of 884 first time shunts. Acta Neurochir. 1995;136:1-7. 15. Cochrane DD, Kestle JR. The influence of surgical operative experience on the duration of first ventriculoperitoneal shunt function and infection. Pediatr Neurosurg. 2003;38:295-301.
16. Di Rocco C, Marchese E, Velardi F. A survey of the first complication of newly implanted CSF shunt devices for the treatment of nontumoral hydrocephalus. Cooperative survey of the 1991e1992 Education Committee of the ISPN. Childs Nerv Syst. 1994;10:321-327. 17. Kestle J, Drake J, Milner R. Long-term follow-up data from the shunt design trial. Pediatr Neurosurg. 2000;33:230-236. 18. Vinchon M, Dhellemmes P. Cerebrospinal fluid shunt infection: risk factors and long-term followup. Childs Nerv Syst. 2006;22:692-697. 19. Maruyama H, Nakata Y, Kanazawa A, et al. Ventriculoperitoneal shunt outcomes among infants. Acta Med Okayama. 2015;69:87-93. 20. Wu Y, Green NL, Wrensch MR, Zhao S, Gupta N. Ventriculoperitoneal shunt complications in California: 1990 to 2000. Neurosurgery. 2007;61:557-563.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 8 July 2019; accepted 6 September 2019 Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.09.043 Journal homepage: www.journals.elsevier.com/worldneurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.09.043
Neonatal Hydrocephalus Treatment with Ultrasmall Valve Implantation Samuel W. Reed, Michael J. Cools, Carolyn S. Quinsey, Scott W. Elton
OBJECTIVE: Neonatal hydrocephalus remains a difficult condition to manage, due to high failure rates among all management strategies. Neurosurgeons commonly manage hydrocephalus with ventriculoperitoneal shunt (VPS) implantation, and valves of variable sizes and profiles are available for implantation. This study examines primary ventricular shunt valve implantation complication rates based on valve profiles in pediatric patients with hydrocephalus.
-
METHODS: This study retrospectively reviews pediatric patients younger than 1 year of age who underwent ventricular shunt placement at a single institution from January 2001 to January 2017. Patients were classified by valve profile and categorized as either ultrasmall valves or regular-sized valves. Time until complication and type of complication were studied.
-
RESULTS: A total of 156 patients met the inclusion criteria. Forty-eight (31%) patients received an ultrasmall shunt valve, while 108 patients received a regular valve. On average, patients undergoing ultrasmall valve placement were younger (2.1 months) than patients undergoing placement of regular valves (3.1 months) (P [ 0.03). The overall complication rate within 2 years of VPS placement was 37.5% in patients with the ultrasmall valve and 41.7% in the regular valve population. There was no difference in 1-year shunt survival rate between the 2 cohorts.
-
CONCLUSION: Our review did not find a significant difference in complication rates between ultrasmall and regular valves in patients under 1 year of age. However, the etiology of shunt malfunction did differ between the groups. This work further supports evidence suggesting a
-
Key words Hydrocephalus - Ultra-small valve - Ventriculoperitoneal shunt -
Abbreviations and Acronyms ETV: Endoscopic third ventriculostomy VPS: Ventriculoperitoneal shunt
surgeon’s preference for shunt hardware alone does not significantly impact outcome.
INTRODUCTION
H
ydrocephalus remains a prevalent disease surgically treated by pediatric neurosurgeons. Neurosurgeons commonly manage hydrocephalus with ventriculoperitoneal shunts (VPS); unfortunately, despite significant advances in technology, complication rates remain high.1 Although many studies compare success and complication rates between valve mechanisms,2,3 insufficient evidence exists in the literature to recommend 1 shunt hardware design over another for the treatment of pediatric hydrocephalus.1,4 The majority of these studies focused on valve mechanism (i.e., programmable vs. nonprogrammable), without consideration for the consequences of valve profile or dimensions. While endoscopic third ventriculostomy (ETV) reduces the need for VPS in some patients, it carries a poorer success rate in children <1 month5 and fails in some patients. The variability of ETV success among hydrocephalus patients highlights the need to optimize valve selection. Hydrocephalus treatment in the neonatal populations poses several unique challenges including a less developed immune system, smaller anatomy, and more friable skin.6,7 Multiple studies address these challenges with the goal of improving neonatal outcomes. Outcomes have been evaluated in terms of valve opening pressure,8,9 valve placement in periosteum,6 or burying the valve in the skull10 to prevent pressure on the skin and subsequent wound breakdown. However, the influence of valve profile and size on outcomes remains largely unexamined. The smaller and lower profile of ultrasmall valves may reduce wound breakdown complications, but the smaller profile may
Department of Neurosurgery, University of North Carolina at Chapel Hill, North Carolina, USA To whom correspondence should be addressed: Samuel W. Reed, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.09.043 Journal homepage: www.journals.elsevier.com/world-neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY -: e1-e4, - 2019
www.journals.elsevier.com/world-neurosurgery
e1
ORIGINAL ARTICLE SAMUEL W. REED ET AL.
ULTRASMALL VALVE IMPLANTATION
also make the valve prone to obstruction and failure requiring revision. Despite the dichotomy of opinions on valve size and complication rate, a literature search identifies only 2 studies evaluating “neonatal,” “ultra-small,” or “micro valve” outcomes.11,12 A prospective study by Warf et al12 comparing the Codman-Hakim micro valve to the less expensive Chhabra valve in pediatric patients in Uganda found no difference in overall complication rates between the 2 valves. A retrospective valve study stratifying patients by valve profile and examining subsequent shunt complications found a reduction in the number of infections and wound breakdowns in patients with ultrasmall valves, but overall complication rates did not differ significantly based on valve size.11 The paucity in data equating valve profile with success and outcomes in neonatal patients complicates a neurosurgeon’s ability to optimize valve selection in this population. Here, we compare outcomes in neonatal patients stratified by valve size at a single academic institution. METHODS This study was approved by the University of North Carolina Institutional Review Board. We conducted a retrospective medical record review of all patients 12 months of age or younger undergoing primary shunt placement at our institution between 2001 and 2017. Patient age, gestational age, weight at shunt placement, etiology of hydrocephalus, valve type, location of shunt, time until complication, complication type, and last recorded follow-up at our institution were collected. Shunt complications were defined as wound breakdown, infection, and mechanical failure requiring operative management. Complications were categorized as proximal obstruction, distal obstruction, valve failure, shunt infection, or wound breakdown. Operative findings within the operative note were reviewed to determine etiology of the failure. Results were stratified by valve type. Valves were classified as either ultrasmall, small, or regular sized. Table 1 lists valve dimensions. Patients with a small valve implanted are not reported due to a very small number implanted and resulting lack of comparability or significance. Patients reported to be full term were described as 38 weeks, and patients described as late preterm were described as 36 weeks, when no specific dating was recorded. Statistical analysis was performed using StataSE (College Station, Texas, USA). The proportion test was used to compare rates between the 2 groups. A 2-tailed t-test was used to compare continuous variables.
A total of 156 patients met inclusion criteria, 68 (44%) of which were female (Table 2). A total of 48 (31%) patients received an ultrasmall shunt valve, while 108 patients received a regular valve. On average, patients undergoing ultrasmall valve placement were younger (2.1 months) than patients undergoing placement of regular valves (3.4 months) (P < 0.01). Weight also differed significantly between the ultrasmall valve cohort (4.1 kg) and the regular valve cohort (5.0 kg) (P < 0.01).
www.SCIENCEDIRECT.com
Valve Sizes Valve Design
Length
Width
Height
Neonatal
20 mm
10 mm
5.5 mm
Small
36 mm
13 mm
6 mm
Regular
40 mm
16.5 mm
8 mm
Complication rates between valve types were similar, the majority of which was attributable to shunt failure. The overall complication rate within 2 years of VPS placement was 37.5% in patients with the ultrasmall valve and 41.7% in the regular valve population (Table 3). Of patients receiving ultrasmall valves, 12.5% experienced proximal obstruction, 8.3% experienced distal obstruction, and 18.8% of patients experienced valve failure. In the regular valve patient group, 24% of patients suffered proximal obstruction, 13% experienced distal obstruction, and 6% developed valve failure. The infection rate in the ultrasmall group was 2.1%, and the infection rate in the regular valve group was 10.2%. Wound breakdown occurred in only 1 patient in each group. Subgroup analysis of patients shunted at 30 days of age found higher overall complication rates in both ultrasmall valves (55%) and regular valves (56.8%) compared with full cohort analysis. The composition of complication etiologies in subgroup analysis remained comparable with whole-group analysis (Table 4).
Table 2. Patient Characteristics Study Population Characteristics
Total
Neonatal Valve
Regular Valve
156
48
108
Male
88 (56)
26 (54)
62 (57)
Female
68 (44)
22 (46)
46 (43)
0.64
34.5
34.7
34.4
0.63
3
2.1
3.4
<0.01
4.7
4.1
5
<0.01
Congenital
49 (31)
11 (23)
38 (35)
Myelomeningocele
48 (31)
20 (42)
28 (26)
IVH
38 (24)
13 (27)
25 (23)
Other
21 (14)
44 (8)
17 (16)
Characteristic Number of patients
Average gestational age (weeks) Average age at shunt placement (months) Average weight at shunt placement (kg)
RESULTS
e2
Table 1. Valve Dimensions
P Value
Hydrocephalus etiology
Values are number of patients (%) unless otherwise noted.
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.09.043
ORIGINAL ARTICLE SAMUEL W. REED ET AL.
ULTRASMALL VALVE IMPLANTATION
Table 3. Complications by Valve Type
Table 4. Subgroup Analysis of Complications
Complications by Valve Type
Subgroup Analysis Neonatal Valve
Regular Valve
P Value
Total number of complications in first 2 years
18 (38)
45 (42)
0.75
Proximal obstruction (% of total complications)
6 (33)
17 (47)
Distal obstruction
4 (22)
14 (39)
Valve failure
9 (50)
7 (19)
Infections
1 (6)
11 (31)
Wound breakdown
1 (6)
1 (3)
Total number of complications at anytime
20 (42)
52 (48)
Variable
Median time until complication (weeks)
7.3
12.7
Patients £30 days Old at Time of Shunt Placement
Neonatal Valve
Regular Valve
Total number of patients
20
37
Total complications
11
18
55%
57%
Proximal complications (% of total complications)
3 (15)
11 (35)
Distal complications
2 (10)
6 (33)
Infections
1 (5)
5 (28)
Wound breakdowns
1 (5)
0
Valve failures
4 (20)
2 (11)
28
71
Total complication rate
0.36 0.36
Total complications
9
25
32%
44%
Proximal complications (% of total complications)
3 (11)
13 (18)
Distal complications
2 (7)
8 (11)
Total complication rate
Similarly, subgroup analysis of patients 4.5 kg found higher rates of total complications in both the ultrasmall valves (50%) and regular valves (55.4%), relative to full cohort analysis. The median time to complication was 7.3 weeks in the patients with ultrasmall valves and 12.7 weeks in patients with regular valves (P ¼ 0.36). There was no difference in 1-year shunt survival rate between the ultrasmall and regular valves.
0.56
Patients >30 days old at time of shunt placement Total number of patients
Values are number of patients (%) unless otherwise noted.
P Value
Infections
0
6 (9)
Wound breakdowns
0
1 (1)
5 (18)
5 (7)
Valve failures
0.23
Values are number of patients (%) unless otherwise noted.
DISCUSSION Managing hydrocephalus in the neonatal population with VPS remains an imperfect solution, primarily due to the high rate of complications. Prospective studies of several different valve mechanism designs show overall complication rates of 43.6% within 2 years of initial placement.2 Our study seeks to identify the impact of valve size on complication rates in patients younger than 1 year of age with hydrocephalus managed by VPS implantation. The results do not support superiority of 1 valve size over another, as no significant difference in overall complication incidence in the 2 years after VPS placement exists between patients receiving an ultrasmall valve (37.5%) and those receiving a regular-sized valve (41.7%). Our overall complication rate within 2 years of shunt implantation for all patients (40.1%) compares to rates in the literature, which also encompass all valve sizes.2,3 While the incidence of shunt complication did not differ significantly between patients receiving ultrasmall valves and patients receiving regular valves, the etiology of complication did vary between the 2 groups. Our data suggest the ultrasmall valve group experiences a larger proportion of valve failures than the regular valve group (19% vs. 6%). This difference could be attributable to a true difference in valve function or due to small sample size.
WORLD NEUROSURGERY -: e1-e4, - 2019
Infection presents a particularly troublesome complication as it requires a removal and reinsertion surgery, prolonged hospitalization for IV antibiotics, and subsequent increased risk of infection when reimplanted. Incidence of VPS infection in the literature ranges from 6.5% to 23.5%.13-18 Our study finds the overall incidence of shunt infection for the combined cohort to be 7.7%, consistent with other reported outcomes. However, we report lower infection rates than those with ultrasmall valve placement (2%) compared with regular valve placement (10%). Similarly, Kahilogullari et al11 report lower infection rates in ultrasmall valves. In contrast to Kahilogullari et al,11 which finds a decrease in wound breakdown with ultrasmall valves compared with regular-size valves, our data observe only 2 cases of wound breakdown. Therefore wound breakdown does not represent a notable complication in our patient population. In the absence of wound breakdown, the increased infection rate observed in the regular valve group cannot be directly attributed to valve size. This suggests an artefactual difference in infection rate between the 2 groups and highlights the need for further research to parse out the difference between valve size and infection rate. The subgroup analysis compares complication rates by valve size in 2 high-risk groups to the lower-risk counterparts; patients
www.journals.elsevier.com/world-neurosurgery
e3
ORIGINAL ARTICLE SAMUEL W. REED ET AL.
ULTRASMALL VALVE IMPLANTATION
with implantation at 30 days of life compared with implantation >30 days old, and implantation in patients weighing 4.5 kg compared with those >4.5 kg. The patients in these high-risk cohorts receiving implantation at 30 days of age or at 4.5 kg experience higher complication rates relative to the full cohort. In patients 30 days of life at implantation, the overall complication rate was 55% for those receiving an ultrasmall valve and was 57% for those receiving regular-sized valves; again, not supporting superiority of 1 valve size over another in these high-risk groups. These values compare to other reported shunt failures in infants younger than 1 month of age.19,20 The retrospective nature and small size limits the conclusiveness of this study. This study also relies on operative notes to document failure types, which results in high variability of documentation and interpretation. Ideally, a study examining valve malfunction would prospectively record failure reasons and study the device after explant.
REFERENCES 1. Baird LC, Mazzola CA, Auguste KI, Klimo P Jr, Flannery AM, Pediatric Hydrocephalus Systematic Review and Evidence-Based Guidelines Task Force. Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 5: effect of valve type on cerebrospinal fluid shunt efficacy. J Neurosurg Pediatr. 2014;14(suppl 1):35-43. 2. Drake JM, Kestle JR, Milner R, et al. Randomized trial of cerebrospinal fluid shunt valve design in pediatric hydrocephalus. Neurosurgery. 1998;43: 294-303. 3. Pollack IF, Albright AL, Adelson PD. A randomized, controlled study of a programmable shunt valve versus a conventional valve for patients with hydrocephalus. Hakim-medos Investigator Group. Neurosurgery. 1999;45: 1399-1408. 4. Hoshide R, Meltzer H, Dalle-Ore C, Gonda D, Guillaume D, Chen CC. Impact of ventricularperitoneal shunt valve design on clinical outcome of pediatric patients with hydrocephalus: lessons learned from randomized controlled trials. Surg Neurol Int. 2017;8:49. 5. Warf BC, Mugamba J, Kulkarni AV. Endoscopic third ventriculostomy in the treatment of childhood hydrocephalus in Uganda: report of a scoring system that predicts success. J Neurosurg Pediatr. 2010;4:143-148. 6. Bot GM, Ismail NJ, Usman B, et al. Subpericranial shunt valve placement: a technique in patients with friable skin. Childs Nerv Syst. 2014;30: 1431-1433. 7. Radmanesh F, Nejat F, Khashab M, Ghodsi SM, Ardebili HE. Shunt complications in children with
e4
www.SCIENCEDIRECT.com
CONCLUSIONS In conclusion, our data did not find a significant difference in complication rates between ultrasmall and regular valves in patients younger than 1 year of age. However, the etiology of shunt malfunction did differ between the groups. This work further supports evidence suggesting surgeon’s preference for shunt hardware alone does not likely significantly affect outcome. Despite thoughtful choices in shunt hardware, this device remains problematic with infectious and malfunction complications well demonstrated in our literature.
ACKNOWLEDGEMENTS The authors would like to thank Kathryn Pietrosimone, Ph.D., for her help in preparing this manuscript.
myelomeningocele: effect of timing of shunt placement. J Neurosurg Pediatr. 2009;3:516-520. 8. Robinson S, Kaufman BA, Park TS. Outcome analysis of initial neonatal shunts: does the valve make a difference? Pediatr Neurosurg. 2002; 37:287-294. 9. Sinha A, Sharma A, Gupta C. Pediatric hydrocephalus: does the shunt device pressure selection affect the outcome? J Indian Assoc Pediatr Surg. 2012;17:54-57. 10. Ammar A, Nasser M. A long-term complication of burying a shunt valve in the skull. Neurosurg Rev. 1995;18:65-67. 11. Kahilogullari G, Etus V, Tugba Morali G, Hakan K, Agahan U. Does shunt selection affect the rate of early shunt complications in neonatal myelomeningocele-associated hydrocephalus? A multi-center report. Turk Neurosurg. 2016;28:303-306. 12. Warf BC. Comparison of 1-year outcomes for the Chhabra and Codman-Hakim Micro Precision shunt systems in Uganda: a prospective study in 195 children. J Neurosurg Pediatr. 2005;102:358-362. 13. Amacher AL, Wellington J. Infantile hydrocephalus: longterm results of surgical therapy. Childs Brain. 1984;11:217-229. 14. Borgbjerg BM, Gjerris F, Albeck MJ, Borgesen SE. Risk of infection after cerebrospinal fluid shunt: an analysis of 884 first time shunts. Acta Neurochir. 1995;136:1-7. 15. Cochrane DD, Kestle JR. The influence of surgical operative experience on the duration of first ventriculoperitoneal shunt function and infection. Pediatr Neurosurg. 2003;38:295-301.
16. Di Rocco C, Marchese E, Velardi F. A survey of the first complication of newly implanted CSF shunt devices for the treatment of nontumoral hydrocephalus. Cooperative survey of the 1991e1992 Education Committee of the ISPN. Childs Nerv Syst. 1994;10:321-327. 17. Kestle J, Drake J, Milner R. Long-term follow-up data from the shunt design trial. Pediatr Neurosurg. 2000;33:230-236. 18. Vinchon M, Dhellemmes P. Cerebrospinal fluid shunt infection: risk factors and long-term followup. Childs Nerv Syst. 2006;22:692-697. 19. Maruyama H, Nakata Y, Kanazawa A, et al. Ventriculoperitoneal shunt outcomes among infants. Acta Med Okayama. 2015;69:87-93. 20. Wu Y, Green NL, Wrensch MR, Zhao S, Gupta N. Ventriculoperitoneal shunt complications in California: 1990 to 2000. Neurosurgery. 2007;61:557-563.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 8 July 2019; accepted 6 September 2019 Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.09.043 Journal homepage: www.journals.elsevier.com/worldneurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.09.043