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The diagnosis and neuroendoscopic treatment of noncommunicating intracranial arachnoid cysts
Surgical Neurology 68 (2007) 149 – 154 www.surgicalneurology-online.com
Imaging
The diagnosis and neuroendoscopic treatment of noncommunicating intracranial arachnoid cysts Qibing Huang, MD, Donghai Wang, MD, Yuan Guo, MM, Xudong Zhou, MD, Xinyu Wang, MD, Xingang Li4 Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, PR China Received 3 May 2006; accepted 19 October 2006
Abstract
Background: The aim of this study was to explore the CTC classification, establish surgical indication, and evaluate neuroendoscopic treatment of IAC. Methods: Computed tomographic cisternography was applied to screen NCIAC cases out of 22 patients with IAC. Noncommunicating intracranial arachnoid cyst cases were treated with neuroendoscopic fenestration between IAC and cerebral cistern/ventricle with rigid neuroendoscope. Results: All the NCIAC patients had definite neurologic findings. Postoperatively, the clinical status and situations of all the patients were improved, and some patients were even cured. Only 1 case suffered complicated chronic subdural hematoma and was cured by burr hole drainage. Follow-up CT scan of 9 cases showed that the cysts decreased markedly in size; most of the surrounding spaces were filled by normal cerebral tissue. Conclusion: (1) CTC is specific for the differential diagnosis of IAC, which can be classified into CIAC and NCIAC with CTC. (2) NCIAC with definite neurologic findings have surgical indication. (3) Compared with traditional treatments, neuroendoscopic cystic fenestration is more effective and minimally invasive with less mortality and morbidity. D 2007 Elsevier Inc. All rights reserved.
Keywords:
IAC; CTC; Neuroendoscopic treatment
1. Introduction In recent years, with the development of radiological techniques, the clinical detectability of IAC seems to have increased. Many patients have received different kinds of surgical treatments. However, a sizable fraction failed to or did not achieve satisfactory effect. From April 2001 to April 2004, we applied CTC to 22 IAC patients, among whom 15 NCIAC patients were diagnosed and received neuro-
Abbreviations: CIAC, communicating intracranial arachnoid cyst; CSF, cerebrospinal fluid; CT, computed tomography; CTC, computed tomographic cisternography; IAC, intracranial arachnoid cyst; ICP, intracranial pressure; MR, magnetic resonance; NCIAC, noncommunicating intracranial arachnoid cyst. 4 Corresponding author. Tel.: +86 531 85296146. E-mail address: [email protected] (X. Li). 0090-3019/$ – see front matter D 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2006.10.059
endoscopic treatment. The results are encouraging and reported below. 2. Clinical materials 2.1. Patient population There were 14 males and 8 females. The age ranged from 6 to 54 years. Seventeen patients were younger than 16 years. The history of symptoms was 1 week to 12 years. Trauma history was absent. 2.2. Clinical manifestations The early symptoms included intermittent headache in 11 cases, epileptic attack in 4, blurred vision in 5, oculomotor nerve palsy in 1, and motor aphasia in 1. The main concomitant symptoms were poor concentration, hypomnesia,
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Fig. 3. Axial CTC of the CIAC patient revealed the IAC posterior to the left cerebellar hemisphere showed hyperdense changes. Fig. 1. Axial CTC revealed right frontal meanly low density NCIAC with no contrast concentrated in the cysts, involved cortex compressed, proximal cistern enhanced, and hyperdense changes.
and others. Physical examinations disclosed unilateral prominence of cranial skull in 6 cases, impaired visual acuity in 5, ataxia in 2, and papilledema in 7. 2.3. Imageological manifestations All the patients received a nonenhanced CT scan. The IAC was in the fissure of Sylvius-temporal region in 12 cases, in the parietooccipital region in 4, in the posterior
Fig. 2. Axial CTC revealed that the cortex in the cyst-involved side was compressed and deviated inwardly, with lateral ventricle compressed and obliterated, no contrast concentrated in the cyst, and hypodense changes.
cranial fossa in 4, and in the suprasellar region in 2 (one of them was accompanied by hydrocephalus). All the lesions were clearly demarcated and extracranially located. The contents of the cysts were homogeneously hypodense, with the CT value ranging from 2 to 18 Hounsfield units. Cerebral compression was found in 8 cases. 2.3.1. Computed tomographic cisternography examination After 5 mL of CSF was released and 5 mL of Omnipaque (Anshen Pharmacy Company, ShangHai) was injected into the subarachnoid space in the lumbar region, the patient was then kept in the Trendelenburg’s position for 15 to 30 minutes and received a CT scan. The high-density contrast could be seen from the spinal subarachnoid space to the intracranial
Fig. 4. Internal wall of the cyst excised under the rigid neuroendoscope, the debris of the cyst wall could be seen waved as the fluctuation of the CSF which demonstrated that there is a communication between the subarachnoid space and cyst space. No vascular tissue was found in the cyst wall.
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cisterns in all the cases, and more concentrated contrast could be seen proximally to the cranial base. Noncommunicating intracranial arachnoid cyst could be diagnosed if no contrast concentrated in the cysts (Figs. 1 and 2), and CIAC would be diagnosed if contrast highly concentrated in the cysts (Fig. 3). 2.4. Surgical procedures Fifteen NCIAC cases received neuroendoscopic treatment. Burr hole was made with annular bit, and dura mater was incised in a cross-shaped fashion. The neuroendoscope was then placed into position manually. The internal wall of the cysts was partially excised under direct vision, and then the residual brim of the wall could be seen fluctuating with the flowing of CSF (Fig. 4). Major blood vessels or nerves were protected, and maximal communication was achieved between the cysts and the proximal cistern, such as suprasellar cistern, cisterna magna, and sylvian fissure.
Fig. 5. Hematoxylin and eosin staining of the excised cyst wall and 40 light microscopy mainly composed of fibrous connective tissue and small amount of lymphocytes.
2.5. Results and follow-up Computed tomographic cisternography classified IAC into 15 NCIAC patients and 7 patients. Contrast of the major clinical manifestation between NCIAC and CIAC can be seen in Table 1. Computed tomographic scans of the 15 cases demonstrated that 8 cases had midline deviation and local brain tissue and ventricle compression, which had surgical indication concerning clinical symptoms. Fifteen NCIAC patients underwent neuroendoscopic NCIAC-to-cistern fenestration. Walls of the cysts showed a thin membrane formation, with mild pallor, and the cystic fluid was colorless, transparent, and watery in all cases. Headache disappeared in 7 cases with NCIAC after the operation, and was relieved completely the second day after the operation in one case that also had paralyzed oculomotor nerve. Of the 3 cases with seizure, 2 were cured, and the symptoms in the other 1 case were improved. The eyesight of all the patients was improved within 1 week to 1 month postoperatively.
postoperative CT scan of 13 cases revealed that the cysts were obviously diminished in 9 cases compared with the preoperative state, and slightly diminished in 4 cases. Ventricles shrank and hydrocephalus was released in the patients with hydrocephalus. Computed tomographic cisternography examination in all patients showed high density of contrast engorged in the cysts (Figs. 6 and 7). There was no postoperative mortality, and only 1 suprasellar IAC patient had a sudden bilateral hemianopsia 3 months postoperatively. Follow-up CT scan revealed a chronic
2.5.1. Pathologic examination results The pathologic tissue examination of the cyst walls revealed fibrous connective tissue and small amount of lymphocyte infiltration (Fig. 5). 2.5.2. Follow-up The follow-up processes were arranged from 2 months to 3 years. All the patients’ clinical symptoms improved. A Table 1 Contrast of the major clinical picture between the NCIAC and CIAC Headache Epileptic attack Blurred vision Aphasia Papilledema Oculomotor nerve palsy Brain tissue compressed in CT
NCIAC 7 3 3 1 7 1 8
IAC 4 1 2 0 0 0 0
Fig. 6. Follow-up CTC scan for NCIAC patients 5 months after the operation revealed the cysts lumen obliterated obviously and previously involved neighboring brain tissue relieved dramatically. Contrast filling has been found in the cysts, which revealed a hyperdense presentation, suggesting that the recommunication of CSF is verified.
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Fig. 7. Follow-up CTC scan for NCIAC patients 5 months after the operation revealed the restoration of frontoparietal brain tissues and the cysts lumen almost disappeared.
subdural hematoma at right parietooccipital region, which was cured after drainage of hematoma by burr hole. 3. Discussion Intracranial arachnoid cyst is a benign intracranial lesion, defined as cyst formation that contains CSF-like fluid encased and compacted by arachnoid membrane. It may cause clinical neurologic disorders. The definite description of IAC was first introduced by Bright in 1831, and the incidence accounts for 1% of all intracranial lesions. In recent years, with the development of radiologic techniques, its incidence has shown a tendency of increasing [1]. Intracranial arachnoid cyst can be classified according to the etiology, as follows: congenital, embryological development deformation or deviating developmental process of tissue as primary or idiopathic IAC; acquired, mainly due to inflammatory or traumatic processes and defined as traumatic and inflammatory IAC. Our group of patients had no definite traumatic and inflammatory history, so they are mainly considered as congenital IAC. Intracranial arachnoid cyst could also be classified as intraarachnoid and subarachnoid pathologically. However, neither etiologic nor pathologic classification has shown an instructive significance for the diagnosis and treatment for IAC. Therefore, we used CTC to develop a radiological classification and also developed the NCIAC as the indication for the neuroendoscopic approach. The results are promising according to the follow-up. Naidich et al [5] insist that the diagnostic criteria of IAC are cysts covered by arachnoid membrane and cyst walls
composed of arachnoid cells and collagen component. The contents of cyst are colorless, transparent, and CSF-like. The criteria accords with both the gross findings during the operation and the pathologic findings in all NCIAC patients of our group. Intracranial arachnoid cyst can be diagnosed and differentiated from other intracranial lesions such as head trauma, hemorrhage, porencephaly, epidermoid cyst by plain CT scan [7]. All the 22 patients in this group received routine CT scan for the diagnosis, but CTC is necessary for the further qualitative diagnosis, which is to confirm whether the cyst communicates with subarachnoid space. The examination of CTC helps to establish the qualitative diagnosis of the cysts that were enhanced by the contrast. Demonstration of enhancement will determine whether or not a cyst will be diagnosed as CIAC or not. At present no unanimous opinion have been reached as to whether further surgical procedure is indicated for IAC patients. According to the literature, most of the authors suggest that IAC with typical symptoms or signs is indication for operation. However, the follow-up radiological examination revealed no evident shrinkage of the cysts in some patients [1,4]. Erdincler et al [2] thinks that it may not be of any significance to estimate if there is communication between the lumen of cysts and subarachnoid space shown by CTC. Because the passage for the contrast filling of CIAC may be from subarachnoid space to the lumen of cysts (early filling) or from the lumen of cysts to subarachnoid space (late filling), the communication between the cysts fluid and CSF is unidirectional, but in fact, the circulation of CSF between CIAC and subarachnoid space should exist. Supposing that the pressure in the IAC is higher than in the subarachnoid space, the cyst fluid would have a unidirectional flow to subarachnoid space, and no contrast would concentrate in the cysts; then the NCIAC will be diagnosed. Although, if the pressure in the cysts were lower, the CSF would flow from subarachnoid space to the lumen of cysts, which would not cause the high ICP that commonly happened to the involved patients. Therefore, the obvious pressure gradient between the inside and outside of the cysts may not exist, so the cysts may not compress the neighboring brain tissue, which may explain why the involved brain tissue did not have obvious postoperative restoration, as reported in the literature. Some authors applied 24 to 48 hours ICP monitoring to screen the IAC and define the increase of ICP as the relative surgical indication. As listed in Table 1, most of the NCIAC resulted in, caused, and led to definite neurologic signs and symptoms such as seizure, papilledema, the manifestation of compression to brain tissue, and midline deviation from CT examination, whereas the CIAC only resulted in, caused, and led to some atypical symptoms such as headache. Therefore, if the surgical indication is based only on the nonenhanced CT scan and the existent symptoms, some CIAC cases may be included, which would undermine the value of this method. Although, if the surgical indication is based on CTC examination, it would be ensured that NCIAC
Q. Huang et al. / Surgical Neurology 68 (2007) 149 – 154
patients would receive a timely operation and result in high clinical practicability and applicability. Computed tomographic cisternography is specific for the diagnosis of NCIAC according to the data of our group. Encouraging results have been achieved by applying CTC to select NCIAC patients for the neuroendoscopic procedure. The NCIAC is indicated for operation once diagnosed. The aim of the operation for IAC is to decrease the intracranial pressure and release the compression on the neighboring brain tissue from the cysts [1]. The traditional treatment for IAC includes tapping and drainage of the cysts, partial or wide excision of the cyst wall via craniotomy, wide excision of the cyst wall plus cyst-toventricle/cistern shunt and cyst-to-ventricle/abdominal cavity shunt [1,2]. Some treatment has been abandoned due to poor curative effect; some have limited spectrum for clinical application because of the disadvantages such as massive injury and complications, prolonged duration for the postoperative recovery, etc. As shown in Fig. 3, nonvascularity and transparency of IAC enable a clear window for the neuroendoscopic procedure and facilitate a better observation for the communication between the fenestration and subarachnoid space to confirm the operative result. Therefore, the IAC should be an absolute indication for the neuroendoscope. Lori [4] pointed out that cyst-to-ventricle fenestration only is liable and vulnerable to recurrence and enlargement of cysts in the long term, but no relapse was observed in our group. Yoshie et al [8] performed IAC-toventricle fenestration with neuroendoscope; CSF flowrelated signal loss had been observed in the cyst-to-ventricle fenestration window on MR examination, which confirmed that this type of surgical procedure, was able to achieve a bidirectional CSF flow between cysts and ventricles and thus reach the therapeutic aim. According to the literature, as a minimally invasive operation, neuroendoscopic IAC-tocistern/ventricle fenestration has several advantages: (1) craniotomy with sole burr hole is simple to manipulate, and all the procedures are completed under the minimally invasive endoscope; (2) compared with the traditional operation, the operation field under neuroendoscope has minimal hemorrhage, which precludes the adhesion of the internal cyst wall as the result of the hemorrhage in the operative field, thus, an encouraging therapeutic efficacy can be achieved, and the recurrence of the cysts can be minimized; (3) patent communication between IAC and cisterns/ventricles has been established, and the cyst fluid flows through via fenestration into subarachnoid space; this kind of intracranial drainage is more suitable for the physiologic requirement as compared with the peritoneal shunt, and problems such as the existence of the alien substances and the obstruction of the shunt caused by the application of the shunt can be avoided; and (4) lower complication rate, shorter hospitalization duration, and less expenditure in the operation. The common complications of CTC are allergic reaction to iodine, intracranial pneumatosis, and complications with
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the lumbar puncture. It is also reported that the CTC examination may cause rupture of the cysts and secondary hemorrhage [6]. The Omnipaque was administrated for intrathecal injection in our group, and no allergic reactions were observed. During the lumbar puncture, 5 ml of CSF was released slowly, and then the same volume of contrast was injected to avoid rupture of the cysts and hemorrhage, which may be precipitated by the rapid alteration and change of the ICP during the procedure. Intracranial pneumatosis occurred in 4 cases in our group without any malaise-like fever or headache and no indication for any intervention. Hemorrhage, intracranial pneumatosis, fever, and infection are all the possible complications of the neuroendoscopic procedure [3]. No obvious bleeding was observed during the procedure in our group, and under the magnified window supplied by the neuroendoscope, the injury to the major blood vessels and the cerebral parenchyma during the operation was avoided. All the mild bleeding caused by the rupture of the small blood vessels during the fenestration procedure was stopped after repeated irrigation. The prophylactic antibiotics were routinely administered once during the operation. Irrigation with normal saline was then performed until a clear operative field was obtained. A large amount of normal saline was administrated to rinse the CSF and fill in the lumen of cyst to let the remaining small amount of blood and ruptured tissue to be washed adequately and to expel the remaining air in the field of operation, which effectively prevents postoperative aseptic fever and intracranial pneumatosis. Cerebrospinal fluid was clear when the operation was finished in our group, and no drainage tube had been deposited to minimize the possibility of the low ICP and hemorrhage, which may be triggered by excessive drainage of the CSF. The criteria of the surgical indication for this group of patients should be (1) symptomatic IAC and (2) NCIAC diagnosed by CTC. Acceptable results have been achieved after the treatment for this group; however, because of the limitation of the number of patients and the duration of the follow-up, further follow-up and long-term large-scale clinical research is advocated. References [1] Daneyemez M, Gezen F, Akboru M, et al. Presentation and management of supratentorial and infratentorial arachnoid cysts: review of 25cases. J Neurosurg Sci 1999;43(2):115 - 21 [discussion 122-3]. [2] Erdincler P, Kaynar MY, Bozkus H, et al. Posterior fossa arachnoid cysts. Br J Neurosurg 1999;13(1):10 - 7. [3] Hopf NJ, Demeczny A. Endosopic neurosurgery and assisted microneurosurgery for the treatment of intracranial cysts. Neurosurgery 1998; 43:1330 - 5. [4] Lori AM, Ken RW, Jane EF, McBride LA, Ken R, et al. Cystoventricular shunting of intracranial arachnoid cysts. Pediatr Neurosurg 2003;39:323 - 9. [5] Naidich TP, Mclone DG, Radkowski MA. Intracranial arachnoid cysts. Pediatr Neurosci 1986;12:112 - 22.
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[6] Sun QF, Shen JK, Ding MX. Intracranial arachnoid cysts. Neurol Neurosurg 1998;25:17 - 21. [7] Wu EH. CT diagnosis of head disease. Beijing7 People’s Medical Publishing House; 1996. p. 164 - 6. [8] Yoshie N, Katsu M, Kazuki Y, et al. Endoscopic treatment for a huge neoonatal prepontine-suprasellar arachnoid cyst: a case report. Pediatr Neurosurg 2001;35:220 - 4.
Commentary The authors report their experience with the diagnosis and surgical treatment of symptomatic NCIAC. Among 22 patients enrolled in the study, 15 subjects were diagnosed with a possible NCIAC after cisternal CT scan and received surgical treatment by means of a neuroendoscopic fenestration of the cyst with the adjacent arachnoidal cisterns. Although intracranial arachnoid cysts may present with various symptoms and in different locations, the optimal treatment is still controversial, although cyst fenestration or shunt insertion are recognized as standard procedures.
In our experience, both standard procedures, fenestration, and shunting are equally effective for treatment, and the factors that influence outcome are the rate of volume reduction and cyst location. Regardless, when possible and when indicated, the endoscopic cyst cisternostomy represents the best choice in terms of effectiveness and minimal invasiveness. I do not completely agree with the diagnostic procedures chosen by the authors (ie, the CT cisternography) because the evaluation of communication between intracranial arachnoid cysts and cisterns is possible today with phasecontrast cine MR imaging or gadolinium (gadopentetate dimeglumine)–enhanced MR cisternography, which are less invasive, and permit avoidance of the lumbar tap and the injection of the iodine-based contrast medium. Paolo Cappabianca, MD Unit of Neurosurgery Department of Neurological Sciences Universita degli Studi di Napoli Federico II 80131 Naples, Italy
Imaging
The diagnosis and neuroendoscopic treatment of noncommunicating intracranial arachnoid cysts Qibing Huang, MD, Donghai Wang, MD, Yuan Guo, MM, Xudong Zhou, MD, Xinyu Wang, MD, Xingang Li4 Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, PR China Received 3 May 2006; accepted 19 October 2006
Abstract
Background: The aim of this study was to explore the CTC classification, establish surgical indication, and evaluate neuroendoscopic treatment of IAC. Methods: Computed tomographic cisternography was applied to screen NCIAC cases out of 22 patients with IAC. Noncommunicating intracranial arachnoid cyst cases were treated with neuroendoscopic fenestration between IAC and cerebral cistern/ventricle with rigid neuroendoscope. Results: All the NCIAC patients had definite neurologic findings. Postoperatively, the clinical status and situations of all the patients were improved, and some patients were even cured. Only 1 case suffered complicated chronic subdural hematoma and was cured by burr hole drainage. Follow-up CT scan of 9 cases showed that the cysts decreased markedly in size; most of the surrounding spaces were filled by normal cerebral tissue. Conclusion: (1) CTC is specific for the differential diagnosis of IAC, which can be classified into CIAC and NCIAC with CTC. (2) NCIAC with definite neurologic findings have surgical indication. (3) Compared with traditional treatments, neuroendoscopic cystic fenestration is more effective and minimally invasive with less mortality and morbidity. D 2007 Elsevier Inc. All rights reserved.
Keywords:
IAC; CTC; Neuroendoscopic treatment
1. Introduction In recent years, with the development of radiological techniques, the clinical detectability of IAC seems to have increased. Many patients have received different kinds of surgical treatments. However, a sizable fraction failed to or did not achieve satisfactory effect. From April 2001 to April 2004, we applied CTC to 22 IAC patients, among whom 15 NCIAC patients were diagnosed and received neuro-
Abbreviations: CIAC, communicating intracranial arachnoid cyst; CSF, cerebrospinal fluid; CT, computed tomography; CTC, computed tomographic cisternography; IAC, intracranial arachnoid cyst; ICP, intracranial pressure; MR, magnetic resonance; NCIAC, noncommunicating intracranial arachnoid cyst. 4 Corresponding author. Tel.: +86 531 85296146. E-mail address: [email protected] (X. Li). 0090-3019/$ – see front matter D 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2006.10.059
endoscopic treatment. The results are encouraging and reported below. 2. Clinical materials 2.1. Patient population There were 14 males and 8 females. The age ranged from 6 to 54 years. Seventeen patients were younger than 16 years. The history of symptoms was 1 week to 12 years. Trauma history was absent. 2.2. Clinical manifestations The early symptoms included intermittent headache in 11 cases, epileptic attack in 4, blurred vision in 5, oculomotor nerve palsy in 1, and motor aphasia in 1. The main concomitant symptoms were poor concentration, hypomnesia,
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Q. Huang et al. / Surgical Neurology 68 (2007) 149 – 154
Fig. 3. Axial CTC of the CIAC patient revealed the IAC posterior to the left cerebellar hemisphere showed hyperdense changes. Fig. 1. Axial CTC revealed right frontal meanly low density NCIAC with no contrast concentrated in the cysts, involved cortex compressed, proximal cistern enhanced, and hyperdense changes.
and others. Physical examinations disclosed unilateral prominence of cranial skull in 6 cases, impaired visual acuity in 5, ataxia in 2, and papilledema in 7. 2.3. Imageological manifestations All the patients received a nonenhanced CT scan. The IAC was in the fissure of Sylvius-temporal region in 12 cases, in the parietooccipital region in 4, in the posterior
Fig. 2. Axial CTC revealed that the cortex in the cyst-involved side was compressed and deviated inwardly, with lateral ventricle compressed and obliterated, no contrast concentrated in the cyst, and hypodense changes.
cranial fossa in 4, and in the suprasellar region in 2 (one of them was accompanied by hydrocephalus). All the lesions were clearly demarcated and extracranially located. The contents of the cysts were homogeneously hypodense, with the CT value ranging from 2 to 18 Hounsfield units. Cerebral compression was found in 8 cases. 2.3.1. Computed tomographic cisternography examination After 5 mL of CSF was released and 5 mL of Omnipaque (Anshen Pharmacy Company, ShangHai) was injected into the subarachnoid space in the lumbar region, the patient was then kept in the Trendelenburg’s position for 15 to 30 minutes and received a CT scan. The high-density contrast could be seen from the spinal subarachnoid space to the intracranial
Fig. 4. Internal wall of the cyst excised under the rigid neuroendoscope, the debris of the cyst wall could be seen waved as the fluctuation of the CSF which demonstrated that there is a communication between the subarachnoid space and cyst space. No vascular tissue was found in the cyst wall.
Q. Huang et al. / Surgical Neurology 68 (2007) 149 – 154
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cisterns in all the cases, and more concentrated contrast could be seen proximally to the cranial base. Noncommunicating intracranial arachnoid cyst could be diagnosed if no contrast concentrated in the cysts (Figs. 1 and 2), and CIAC would be diagnosed if contrast highly concentrated in the cysts (Fig. 3). 2.4. Surgical procedures Fifteen NCIAC cases received neuroendoscopic treatment. Burr hole was made with annular bit, and dura mater was incised in a cross-shaped fashion. The neuroendoscope was then placed into position manually. The internal wall of the cysts was partially excised under direct vision, and then the residual brim of the wall could be seen fluctuating with the flowing of CSF (Fig. 4). Major blood vessels or nerves were protected, and maximal communication was achieved between the cysts and the proximal cistern, such as suprasellar cistern, cisterna magna, and sylvian fissure.
Fig. 5. Hematoxylin and eosin staining of the excised cyst wall and 40 light microscopy mainly composed of fibrous connective tissue and small amount of lymphocytes.
2.5. Results and follow-up Computed tomographic cisternography classified IAC into 15 NCIAC patients and 7 patients. Contrast of the major clinical manifestation between NCIAC and CIAC can be seen in Table 1. Computed tomographic scans of the 15 cases demonstrated that 8 cases had midline deviation and local brain tissue and ventricle compression, which had surgical indication concerning clinical symptoms. Fifteen NCIAC patients underwent neuroendoscopic NCIAC-to-cistern fenestration. Walls of the cysts showed a thin membrane formation, with mild pallor, and the cystic fluid was colorless, transparent, and watery in all cases. Headache disappeared in 7 cases with NCIAC after the operation, and was relieved completely the second day after the operation in one case that also had paralyzed oculomotor nerve. Of the 3 cases with seizure, 2 were cured, and the symptoms in the other 1 case were improved. The eyesight of all the patients was improved within 1 week to 1 month postoperatively.
postoperative CT scan of 13 cases revealed that the cysts were obviously diminished in 9 cases compared with the preoperative state, and slightly diminished in 4 cases. Ventricles shrank and hydrocephalus was released in the patients with hydrocephalus. Computed tomographic cisternography examination in all patients showed high density of contrast engorged in the cysts (Figs. 6 and 7). There was no postoperative mortality, and only 1 suprasellar IAC patient had a sudden bilateral hemianopsia 3 months postoperatively. Follow-up CT scan revealed a chronic
2.5.1. Pathologic examination results The pathologic tissue examination of the cyst walls revealed fibrous connective tissue and small amount of lymphocyte infiltration (Fig. 5). 2.5.2. Follow-up The follow-up processes were arranged from 2 months to 3 years. All the patients’ clinical symptoms improved. A Table 1 Contrast of the major clinical picture between the NCIAC and CIAC Headache Epileptic attack Blurred vision Aphasia Papilledema Oculomotor nerve palsy Brain tissue compressed in CT
NCIAC 7 3 3 1 7 1 8
IAC 4 1 2 0 0 0 0
Fig. 6. Follow-up CTC scan for NCIAC patients 5 months after the operation revealed the cysts lumen obliterated obviously and previously involved neighboring brain tissue relieved dramatically. Contrast filling has been found in the cysts, which revealed a hyperdense presentation, suggesting that the recommunication of CSF is verified.
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Fig. 7. Follow-up CTC scan for NCIAC patients 5 months after the operation revealed the restoration of frontoparietal brain tissues and the cysts lumen almost disappeared.
subdural hematoma at right parietooccipital region, which was cured after drainage of hematoma by burr hole. 3. Discussion Intracranial arachnoid cyst is a benign intracranial lesion, defined as cyst formation that contains CSF-like fluid encased and compacted by arachnoid membrane. It may cause clinical neurologic disorders. The definite description of IAC was first introduced by Bright in 1831, and the incidence accounts for 1% of all intracranial lesions. In recent years, with the development of radiologic techniques, its incidence has shown a tendency of increasing [1]. Intracranial arachnoid cyst can be classified according to the etiology, as follows: congenital, embryological development deformation or deviating developmental process of tissue as primary or idiopathic IAC; acquired, mainly due to inflammatory or traumatic processes and defined as traumatic and inflammatory IAC. Our group of patients had no definite traumatic and inflammatory history, so they are mainly considered as congenital IAC. Intracranial arachnoid cyst could also be classified as intraarachnoid and subarachnoid pathologically. However, neither etiologic nor pathologic classification has shown an instructive significance for the diagnosis and treatment for IAC. Therefore, we used CTC to develop a radiological classification and also developed the NCIAC as the indication for the neuroendoscopic approach. The results are promising according to the follow-up. Naidich et al [5] insist that the diagnostic criteria of IAC are cysts covered by arachnoid membrane and cyst walls
composed of arachnoid cells and collagen component. The contents of cyst are colorless, transparent, and CSF-like. The criteria accords with both the gross findings during the operation and the pathologic findings in all NCIAC patients of our group. Intracranial arachnoid cyst can be diagnosed and differentiated from other intracranial lesions such as head trauma, hemorrhage, porencephaly, epidermoid cyst by plain CT scan [7]. All the 22 patients in this group received routine CT scan for the diagnosis, but CTC is necessary for the further qualitative diagnosis, which is to confirm whether the cyst communicates with subarachnoid space. The examination of CTC helps to establish the qualitative diagnosis of the cysts that were enhanced by the contrast. Demonstration of enhancement will determine whether or not a cyst will be diagnosed as CIAC or not. At present no unanimous opinion have been reached as to whether further surgical procedure is indicated for IAC patients. According to the literature, most of the authors suggest that IAC with typical symptoms or signs is indication for operation. However, the follow-up radiological examination revealed no evident shrinkage of the cysts in some patients [1,4]. Erdincler et al [2] thinks that it may not be of any significance to estimate if there is communication between the lumen of cysts and subarachnoid space shown by CTC. Because the passage for the contrast filling of CIAC may be from subarachnoid space to the lumen of cysts (early filling) or from the lumen of cysts to subarachnoid space (late filling), the communication between the cysts fluid and CSF is unidirectional, but in fact, the circulation of CSF between CIAC and subarachnoid space should exist. Supposing that the pressure in the IAC is higher than in the subarachnoid space, the cyst fluid would have a unidirectional flow to subarachnoid space, and no contrast would concentrate in the cysts; then the NCIAC will be diagnosed. Although, if the pressure in the cysts were lower, the CSF would flow from subarachnoid space to the lumen of cysts, which would not cause the high ICP that commonly happened to the involved patients. Therefore, the obvious pressure gradient between the inside and outside of the cysts may not exist, so the cysts may not compress the neighboring brain tissue, which may explain why the involved brain tissue did not have obvious postoperative restoration, as reported in the literature. Some authors applied 24 to 48 hours ICP monitoring to screen the IAC and define the increase of ICP as the relative surgical indication. As listed in Table 1, most of the NCIAC resulted in, caused, and led to definite neurologic signs and symptoms such as seizure, papilledema, the manifestation of compression to brain tissue, and midline deviation from CT examination, whereas the CIAC only resulted in, caused, and led to some atypical symptoms such as headache. Therefore, if the surgical indication is based only on the nonenhanced CT scan and the existent symptoms, some CIAC cases may be included, which would undermine the value of this method. Although, if the surgical indication is based on CTC examination, it would be ensured that NCIAC
Q. Huang et al. / Surgical Neurology 68 (2007) 149 – 154
patients would receive a timely operation and result in high clinical practicability and applicability. Computed tomographic cisternography is specific for the diagnosis of NCIAC according to the data of our group. Encouraging results have been achieved by applying CTC to select NCIAC patients for the neuroendoscopic procedure. The NCIAC is indicated for operation once diagnosed. The aim of the operation for IAC is to decrease the intracranial pressure and release the compression on the neighboring brain tissue from the cysts [1]. The traditional treatment for IAC includes tapping and drainage of the cysts, partial or wide excision of the cyst wall via craniotomy, wide excision of the cyst wall plus cyst-toventricle/cistern shunt and cyst-to-ventricle/abdominal cavity shunt [1,2]. Some treatment has been abandoned due to poor curative effect; some have limited spectrum for clinical application because of the disadvantages such as massive injury and complications, prolonged duration for the postoperative recovery, etc. As shown in Fig. 3, nonvascularity and transparency of IAC enable a clear window for the neuroendoscopic procedure and facilitate a better observation for the communication between the fenestration and subarachnoid space to confirm the operative result. Therefore, the IAC should be an absolute indication for the neuroendoscope. Lori [4] pointed out that cyst-to-ventricle fenestration only is liable and vulnerable to recurrence and enlargement of cysts in the long term, but no relapse was observed in our group. Yoshie et al [8] performed IAC-toventricle fenestration with neuroendoscope; CSF flowrelated signal loss had been observed in the cyst-to-ventricle fenestration window on MR examination, which confirmed that this type of surgical procedure, was able to achieve a bidirectional CSF flow between cysts and ventricles and thus reach the therapeutic aim. According to the literature, as a minimally invasive operation, neuroendoscopic IAC-tocistern/ventricle fenestration has several advantages: (1) craniotomy with sole burr hole is simple to manipulate, and all the procedures are completed under the minimally invasive endoscope; (2) compared with the traditional operation, the operation field under neuroendoscope has minimal hemorrhage, which precludes the adhesion of the internal cyst wall as the result of the hemorrhage in the operative field, thus, an encouraging therapeutic efficacy can be achieved, and the recurrence of the cysts can be minimized; (3) patent communication between IAC and cisterns/ventricles has been established, and the cyst fluid flows through via fenestration into subarachnoid space; this kind of intracranial drainage is more suitable for the physiologic requirement as compared with the peritoneal shunt, and problems such as the existence of the alien substances and the obstruction of the shunt caused by the application of the shunt can be avoided; and (4) lower complication rate, shorter hospitalization duration, and less expenditure in the operation. The common complications of CTC are allergic reaction to iodine, intracranial pneumatosis, and complications with
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the lumbar puncture. It is also reported that the CTC examination may cause rupture of the cysts and secondary hemorrhage [6]. The Omnipaque was administrated for intrathecal injection in our group, and no allergic reactions were observed. During the lumbar puncture, 5 ml of CSF was released slowly, and then the same volume of contrast was injected to avoid rupture of the cysts and hemorrhage, which may be precipitated by the rapid alteration and change of the ICP during the procedure. Intracranial pneumatosis occurred in 4 cases in our group without any malaise-like fever or headache and no indication for any intervention. Hemorrhage, intracranial pneumatosis, fever, and infection are all the possible complications of the neuroendoscopic procedure [3]. No obvious bleeding was observed during the procedure in our group, and under the magnified window supplied by the neuroendoscope, the injury to the major blood vessels and the cerebral parenchyma during the operation was avoided. All the mild bleeding caused by the rupture of the small blood vessels during the fenestration procedure was stopped after repeated irrigation. The prophylactic antibiotics were routinely administered once during the operation. Irrigation with normal saline was then performed until a clear operative field was obtained. A large amount of normal saline was administrated to rinse the CSF and fill in the lumen of cyst to let the remaining small amount of blood and ruptured tissue to be washed adequately and to expel the remaining air in the field of operation, which effectively prevents postoperative aseptic fever and intracranial pneumatosis. Cerebrospinal fluid was clear when the operation was finished in our group, and no drainage tube had been deposited to minimize the possibility of the low ICP and hemorrhage, which may be triggered by excessive drainage of the CSF. The criteria of the surgical indication for this group of patients should be (1) symptomatic IAC and (2) NCIAC diagnosed by CTC. Acceptable results have been achieved after the treatment for this group; however, because of the limitation of the number of patients and the duration of the follow-up, further follow-up and long-term large-scale clinical research is advocated. References [1] Daneyemez M, Gezen F, Akboru M, et al. Presentation and management of supratentorial and infratentorial arachnoid cysts: review of 25cases. J Neurosurg Sci 1999;43(2):115 - 21 [discussion 122-3]. [2] Erdincler P, Kaynar MY, Bozkus H, et al. Posterior fossa arachnoid cysts. Br J Neurosurg 1999;13(1):10 - 7. [3] Hopf NJ, Demeczny A. Endosopic neurosurgery and assisted microneurosurgery for the treatment of intracranial cysts. Neurosurgery 1998; 43:1330 - 5. [4] Lori AM, Ken RW, Jane EF, McBride LA, Ken R, et al. Cystoventricular shunting of intracranial arachnoid cysts. Pediatr Neurosurg 2003;39:323 - 9. [5] Naidich TP, Mclone DG, Radkowski MA. Intracranial arachnoid cysts. Pediatr Neurosci 1986;12:112 - 22.
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[6] Sun QF, Shen JK, Ding MX. Intracranial arachnoid cysts. Neurol Neurosurg 1998;25:17 - 21. [7] Wu EH. CT diagnosis of head disease. Beijing7 People’s Medical Publishing House; 1996. p. 164 - 6. [8] Yoshie N, Katsu M, Kazuki Y, et al. Endoscopic treatment for a huge neoonatal prepontine-suprasellar arachnoid cyst: a case report. Pediatr Neurosurg 2001;35:220 - 4.
Commentary The authors report their experience with the diagnosis and surgical treatment of symptomatic NCIAC. Among 22 patients enrolled in the study, 15 subjects were diagnosed with a possible NCIAC after cisternal CT scan and received surgical treatment by means of a neuroendoscopic fenestration of the cyst with the adjacent arachnoidal cisterns. Although intracranial arachnoid cysts may present with various symptoms and in different locations, the optimal treatment is still controversial, although cyst fenestration or shunt insertion are recognized as standard procedures.
In our experience, both standard procedures, fenestration, and shunting are equally effective for treatment, and the factors that influence outcome are the rate of volume reduction and cyst location. Regardless, when possible and when indicated, the endoscopic cyst cisternostomy represents the best choice in terms of effectiveness and minimal invasiveness. I do not completely agree with the diagnostic procedures chosen by the authors (ie, the CT cisternography) because the evaluation of communication between intracranial arachnoid cysts and cisterns is possible today with phasecontrast cine MR imaging or gadolinium (gadopentetate dimeglumine)–enhanced MR cisternography, which are less invasive, and permit avoidance of the lumbar tap and the injection of the iodine-based contrast medium. Paolo Cappabianca, MD Unit of Neurosurgery Department of Neurological Sciences Universita degli Studi di Napoli Federico II 80131 Naples, Italy