Technical Case Report
Endoscopic Treatment of a Fourth Ventricle Arachnoid Cyst via the Third Ventricle: A Case Report BACKGROUND AND IMPORTANCE: Arachnoid cysts within the fourth ventricle have rarely been reported in the literature. Different procedures have been performed to restore a normal cerebrospinal fluid dynamic or pressure, including shunting and partial or complete excision of the cyst by open microsurgery. Cerebrospinal fluid shunts give only partial improvement of symptoms and are prone to malfunctions. The microsurgical excision of the cyst seems to offer the best chance of success. CLINICAL PRESENTATION: We report the case of a fourth ventricle arachnoid cyst successfully treated with a complete endoscopic cerebral procedure via the third ventricle. CONCLUSION: Endoscopic fenestration of fourth ventricle arachnoid cysts may be considered an effective neurosurgical treatment.
Matteo Martinoni, MD* Francesco Toni, MD‡ Mariella Lefosse, MD* Eugenio Pozzati, MD* Anna Federica Marliani, MD‡ Carmelo Mascari, MD* IRCCS Institute of Neurological Sciences of Bologna, *Departments of Neurosurgery and ‡Neuroradiology, Bellaria Hospital, Bologna, Italy Correspondence: Matteo Martinoni MD, IRCCS Institute of Neurological Sciences of Bologna, Department of Neurosurgery, Bellaria Hospital, Via Altura 3, 40100, Bologna, Italy. E-mail: [email protected] Received, November 22, 2013. Accepted, February 16, 2014. Published Online, February 28, 2014. Copyright © 2014 by the Congress of Neurological Surgeons.
KEY WORDS: Arachnoid cyst, Endoscopy, Fourth ventricle, Hydrocephalus, Third ventriculocisternostomy Operative Neurosurgery 10:E374–E378, 2014
A
rachnoid cysts within the fourth ventricle have rarely been reported in the literature. Only 13 cases have been reported thus far.1-4 Typical manifestations are normal-pressure hydrocephalus, progressive vertigo, and ataxia.5 Different procedures have been performed to restore a normal cerebrospinal fluid (CSF) dynamic or pressure, including shunting procedures and partial or complete excision of the cyst by open microsurgery.4-8 CSF shunts give only partial improvement of symptoms and are prone to malfunctions, sometimes with serious complications. Microsurgical excision of the cyst seems to offer the best chance of success.5 We report here the case of a fourth ventricle arachnoid cyst successfully treated with a complete endoscopic cerebral procedure via the third ventricle.
CASE REPORT History and Clinical Examinations A 38-year-old female patient presented a 2year history of worsening headache, progressive ataxia, and episodic morning vomiting. She was first admitted to another institute where she underwent a cranial computed tomography scan and magnetic resonance imaging (MRI) that
E374 | VOLUME 10 | NUMBER 2 | JUNE 2014
DOI: 10.1227/NEU.0000000000000335
revealed a fourth ventricle arachnoid cyst with mild enlargement of the third and lateral ventricles. In that institute, surgeons also performed a whole-spine MRI that gave suspicion of a tethered cord, for which she underwent the excision of filum terminale with no clinical improvement. A few weeks later, her symptoms worsened, and we admitted the patient to our neurosurgical department. Cerebral MRI confirmed the presence of a fourth ventricle arachnoid cyst with associated noncommunicating hydrocephalus. Spinal MRI excluded any type of neurosurgical lesion and complication. Neurological examination revealed right horizontal nystagmus, ataxic, and broad-based gait with small steps and bilateral hyperactivity of the lower-limb tendon reflexes. Radiological Findings Brain MRI performed at admission (Figures 1, 2A, and 2B) confirmed the presence of the arachnoid cyst that enlarged the fourth ventricle, causing a mild obstructive triventricular hydrocephalus and compressing the adjacent portions of the brainstem and cerebellum. Turbulent flow was seen within the aqueduct of Sylvius (Figure 2A). The cyst extended through the foramen of Luschka and Magendie (Figures 1, 2A, and 2B).
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Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
ENDOSCOPIC TREATMENT OF A FOURTH VENTRICLE ARACHNOID CYST
FIGURE 1. Sagittal volumetric T1-weighted sequence (A), coronal fast-spin-echo T2-weighted image (B), and axial fluid-attenuated inversion-recovery T2-weighted sequence (C). The fourth ventricle cystic formation displays signal intensity comparable to that of the cerebrospinal in all the sequences performed. A, the aqueduct of Sylvius is dilated with a diameter of approximately 4.8 mm. B, the cystic content is separated from the turbulent flow seen within the upper portion of the fourth ventricle by a clear cystic lining (arrowhead). C, the cyst extends on the left side through the foramen of Luschka into the cerebellomedullary cistern (asterisk).
FIGURE 2. Sagittal and axial fast-spin-echo T2-weighted sequences before surgery (A and B) and 12 days (C and D), 2 months (E and F), and 34 months (G and H) after endoscopic intervention. Turbulent flow is visible through the third ventriculostomy (white asterisk) and the aqueduct of Sylvius. Cerebrospinal fluid (CSF) circulation within the fourth ventricle is quickly restored, and the cyst displays a progressive volume reduction (arrowhead). The caudal portion of the cyst is no longer extended through the foramen of Magendie and Luschka on the left side, and accelerated CSF is apparent through the latter (black asterisk).
OPERATIVE NEUROSURGERY
VOLUME 10 | NUMBER 2 | JUNE 2014 | E375
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
MARTINONI ET AL
Operation and Postoperative Course Once a possible parasitic or tumoral nature of the cyst was ruled out, we supposed it was a congenital cyst because the patient denied prior possible causes of an acquired arachnoid cyst (meningitis and head trauma). Indeed, considering the evident dilatation of the Sylvius aqueduct (4.8 mm) and the supratentorial ventricular system, we decided to perform a fenestration of the cystic wall via the third ventricle. The approach, burr hole position, and proper trajectory were planned preoperatively on MRIs without intraoperative neuronavigation. We also took into account an endoscopic approach through the foramen of Magendie that could have had the advantage of a 2-side opening without going through brain tissue. We preferred the transventricular route because it allowed us to perform a third ventriculocisternostomy during the same procedure (to achieve a protective procedure for a sudden unexpected obstructive hydrocephalus). A right burr hole
2 cm in front of the coronal suture was performed, and a rigid endoscope (GAAB Miniature Neuroscope 0°; diameter, 3.2 mm; length, 21 cm; Karl Storz, Karl Storz endoscope sets for pediatric neurosurgery) was inserted through a peel-away (12.5F) sheath into the frontal horn of the right lateral ventricle. Through the foramen of Monro, we reached the third ventricle, where we identified the entrance of the Sylvius aqueduct. We went through it until we could see, inside the fourth ventricle, the wall of the cyst, which appeared thin and slightly white (Figure 3). We carried out a wide fenestration of the cyst wall by first using a blunt instrument (monopolar coagulator) guided inside the sheath of the neuroendoscope and then widening the hole with a Fogarty balloon (3F) because we noticed an evident flow through it, together with a slow but progressive collapse of the cyst itself. We also decided to concurrently perform a third ventriculocisternostomy to promote CSF outflow and to prevent
FIGURE 3. Once the fourth ventricle was entered, the cyst wall (continuous arrow) was easily recognized (A). A Fogarty catheter was then introduced and used to fenestrate the cyst wall (B and C). At the end of the procedure, the cyst appeared soft and floating, and the pericystic space (dotted arrow) was clearly enlarged (D).
E376 | VOLUME 10 | NUMBER 2 | JUNE 2014
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Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
ENDOSCOPIC TREATMENT OF A FOURTH VENTRICLE ARACHNOID CYST
a possible subacute noncommunicating hydrocephalus. Because there were already a marked ventricular dilatation and enlarged Monro foramina, we did not need to use a flexible endoscope; all procedures could be carried out without excessive forniceal retraction. We usually do not practice the “mother-baby technique” to enter the third ventricle because we prefer using a small-diameter instrument through a peel-away (12.5F) sheath to limit parenchymal damage. The day after surgery, the patient developed a transient Parinaud syndrome that lasted 1 day. Then all her symptoms disappeared. The postoperative MRI revealed accelerated CSF flow through the third ventriculostomy and the aqueduct of Sylvius; a gush of CSF was therefore directed against and around the wall of the cyst, pushing and squeezing its content. As a result, the cyst gradually displayed a diminished volume with evident reduction of the mass effect on the brainstem and cerebellum (Figure 2C-2H). The patient is still completely asymptomatic after a 4-year follow-up.
We are aware that our study lacks histological confirmation, and this is an evident limitation. However, we felt it inappropriate to take any operative risk to obtain pathological material for this kind of lesion, and for that reason, we performed only a simple fenestration of the cyst. Furthermore, MRI intraoperative findings and postoperative course lead us to hypothesize a benign arachnoid cyst.
CONCLUSION Neuroendoscopic fenestration of the cyst of the fourth ventricle through the third ventricle could represent a feasible and safe procedure that can promptly resolve the symptomatology and the neuroradiological signs by restoring a normal CSF flow. Disclosure The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
REFERENCES DISCUSSION Today, fenestration represents the procedure of choice for the treatment of symptomatic arachnoid cysts.2 Even though endoscopic fenestration has already been described as having good postoperative results for arachnoid cysts, to date, there have been only a few attempts to treat cysts located in the fourth ventricle in a purely endoscopic fashion.2 When anatomic favorable conditions exist such as an obstructive hydrocephalus associated with dilatation of the Sylvius aqueduct, an endoscopic procedure via the third ventricle can be attempted. Although microsurgical excision or fenestration of the cyst through suboccipital craniotomy is the standard treatment, endoscopy represents a less invasive approach. By fenestrating the wall of the cyst, we allow the outflow of the trapped CSF, reducing the intracystic hydrostatic pressure and the overall volume, removing the obstacle to the circulation of CSF, and restoring a pericystic CSF flow that progressively squeezes the cyst. Furthermore, endoscopy allows the surgeon to perform a third ventriculocisternostomy at the same time. This procedure could prevent the development of a delayed hydrocephalus if there is a not completely free pericystic CSF circulation (adherence, sepimentations, or incomplete collapse) or if a cyst recurrence occurs. In fact, it is worth noting that the only case of sudden death caused by a fourth ventricle arachnoid cyst reported so far occurred as a result of CSF shunt failure.5 The postoperative course of the patient has been characterized by the appearance of transient Parinaud syndrome. We hypothesized that it could have been caused by the passage of the rigid neuroendoscope through the aqueduct of Sylvius and that it could have induced a functional impairment of the periaqueductal gray matter by increasing neuronal distortion.9 However, some authors have proposed that a rapid inversion of transtentorial pressure could lead to periaqueductal damage in patients treated endoscopically for aqueductal stenosis.
OPERATIVE NEUROSURGERY
1. Bonde V, Muzumdar D, Goel A. Fourth ventricle arachnoid cyst. J Clin Neurosci. 2008;15(1):26-28. 2. Oertel JM, Wagner W, Mondorf Y, Baldauf J, Schroeder HW, Gaab MR. Endoscopic treatment of arachnoid cysts: a detailed account of surgical techniques and results. Neurosurgery. 2010;67(3):824-836. 3. Turgut M, Ozcan OE, Onol B. Case report and review of the literature: arachnoid cyst of the fourth ventricle presenting as a syndrome of normal pressure hydrocephalus. J Neurosurg Sci. 1992;36(1):55-57. 4. Westermaier T, Vince GH, Meinhardt M, Monoranu C, Roosen K, Matthies C. Arachnoid cysts of the fourth ventricle-short illustrated review. Acta Neurochir (Wien). 2010;152(1):119-124. 5. Prezerakos GK, Kouyialis AT, Ziaka DS, Boviatsis EJ. Sudden death due to 4th ventricle arachnoid cyst. Ir J Med Sci. 2011;180(3):769-770. 6. Acar O, Kocaogullar Y, Güney O. Arachnoid cyst within the fourth ventricle: a case report. Clin Neurol Neurosurg. 2003;105(2):93-94. 7. Azzimondi G, Calbucci F, Rinaldi R, Vignatelli L, D’Alessandro R. Arachnoid cyst in the region of the fourth ventricle mimicking clinical picture of normal pressure hydrocephalus. Neurosurg Rev. 1995;18(4):269-271. 8. Di Rocco C, Di Trapani G, Iannelli A. Arachnoid cyst of the fourth ventricle and “arrested” hydrocephalus. Surg Neurol. 1979;12(6):467-471. 9. Shin M, Nishihara T, Iai S, Eguchi T. Benign aqueductal cyst causing bilateral internuclear ophthalmoplegia after external ventricular drainage: case report. J Neurosurg. 2000;92(3):490-492.
Acknowledgment We would like to thank Cecilia Baroncini, MA, for linguistic support.
COMMENTS
T
he authors present a 38-year-old female complaining of worsening headache, progressive ataxia and episodic morning vomiting. CT and MR imaging revealed a fourth ventricle arachnoid cyst with a mild enlargement of the third and lateral ventricles. The authors performed an endoscopic fenestration via a transaqueductal approach. Finally, the patient made an excellent recovery and the cyst decreased in size. This is a nice and concise report of a rare arachnoid cyst. We had a very similar case 6 years ago and treated it via the same approach. But, we resected a part of the cyst wall to create a larger hole. Since we trusted in our fenestration, we did not perform a third ventriculostomy. And we got a histology revealing an arachnoid cyst. However, the long-term follow-up
VOLUME 10 | NUMBER 2 | JUNE 2014 | E377
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
MARTINONI ET AL
of the authors proved that the simple fenestration seems to be equally effective. I agree that the endoscopic transaqueductal approach is ideal to treat this kind of lesion. Henry W.S. Schroeder Greifswald, Germany
T
his is a nice case report with good illustrations on a large arachnoid cyst treated in a minimally invasive way by a transventricular approach from above, using the “long way” from a frontal burr hole; the cyst could then be opened and collapsed giving way to the normal CSF flow as is nicely documented by MRI sequences in the follow-up. An alternative would have been an approach from below through the foramen of Magendie2,3,5; but I agree that in this patient with a straight trajectory through the third ventricle and an enlarged aqueduct, the approach from above was more adequate, as we already used in the case mentioned in3; the minifiber endoscope was especially designed as a relatively long rigid endoscope with a small overall outer diameter of 3.8 mm including two instrument- and one irrigation channel.1 This relatively long, small rigid scope may be used through its special puncture cannula or with a peelaway-sheath and can precisely be guided by neuronavigation,1,4 also for lesions in greater distance like as in the case reported from a frontal burr hole approach, then through the lateral ventricles and the foramen of Monro to the third ventricle, finally through the dilated aqueduct (1 mm larger than the endoscope diameter) down to the fourth ventricle. This approach offers the advantage of an ETV in case of problems with the approach through the aqueduct, or with opening the cyst (e.g. bleeding); as the permanent success of the cyst opening could not be guaranteed, it was adequate to perform a third ventriculostomy as a “back up” in addition.
E378 | VOLUME 10 | NUMBER 2 | JUNE 2014
An alternative technique could also have been the use of a rigid high performance HOKPKINS endoscope (full HD quality) for the approach to the third ventricle and for an ETV, then the use of a small flexible scope through a space-type rigid scope1,2 in a “mother-daughter-principle” to advance into the fourth ventricle for the cyst opening. However, here the use of our long rigid minifiber endoscope offered the advantage of a better optical quality (more fibers = better resolution than a small flexible scope, 1), and it provides a more effective surgical manipulation with 2 instruments simultaneously if required, and with a more powerful coagulation/hemostasis. This case report gives another example how even deep seated lesions blocking the CSF flow can be effectively be treated in a minimally invasive and fully optical controlled way using adequate endoscopic technique; and the paper does also provide an actual overview of the pertinent literature. Michael R. Gaab Hannover, Germany
1. Gaab MR. Intrumentation: Endoscopes and Equipment. World Neurosurg. 2013;79 (2 suppl):S14.e11-S14.e21. 2. Oertel JM, Baldauf J, Schroeder HW, Gaab MR. Endoscopic cystoventriculostomy for treatment of paraxial arachnoid cysts. J Neurosurg. 2009;110(4):792-799 3. Oertel JM, Wagner W, Mondorf Y, Baldauf J, Schroeder HW, Gaab MR. Endoscopic treatment of arachnoid cysts: a detailed account of surgical techniques and results. Neurosurgery. 2010;67(3):824-836. 4. Schroeder HW, Wagner W, Tschiltschke W, Gaab MR. Frameless neuronavigation in intracranial endoscopic neurosurgery. J Neurosurg. 2001;94(1):72-79. 5. Westermaier T, Vince GH, Meinhardt M, Monoranu C, Roosen K, Matthies C. Arachnoid cysts of the fourth ventricle—short illustrated review. Acta Neurochir (Wien). 2010;152(1):119-124.
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Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
Endoscopic Treatment of a Fourth Ventricle Arachnoid Cyst via the Third Ventricle: A Case Report BACKGROUND AND IMPORTANCE: Arachnoid cysts within the fourth ventricle have rarely been reported in the literature. Different procedures have been performed to restore a normal cerebrospinal fluid dynamic or pressure, including shunting and partial or complete excision of the cyst by open microsurgery. Cerebrospinal fluid shunts give only partial improvement of symptoms and are prone to malfunctions. The microsurgical excision of the cyst seems to offer the best chance of success. CLINICAL PRESENTATION: We report the case of a fourth ventricle arachnoid cyst successfully treated with a complete endoscopic cerebral procedure via the third ventricle. CONCLUSION: Endoscopic fenestration of fourth ventricle arachnoid cysts may be considered an effective neurosurgical treatment.
Matteo Martinoni, MD* Francesco Toni, MD‡ Mariella Lefosse, MD* Eugenio Pozzati, MD* Anna Federica Marliani, MD‡ Carmelo Mascari, MD* IRCCS Institute of Neurological Sciences of Bologna, *Departments of Neurosurgery and ‡Neuroradiology, Bellaria Hospital, Bologna, Italy Correspondence: Matteo Martinoni MD, IRCCS Institute of Neurological Sciences of Bologna, Department of Neurosurgery, Bellaria Hospital, Via Altura 3, 40100, Bologna, Italy. E-mail: [email protected] Received, November 22, 2013. Accepted, February 16, 2014. Published Online, February 28, 2014. Copyright © 2014 by the Congress of Neurological Surgeons.
KEY WORDS: Arachnoid cyst, Endoscopy, Fourth ventricle, Hydrocephalus, Third ventriculocisternostomy Operative Neurosurgery 10:E374–E378, 2014
A
rachnoid cysts within the fourth ventricle have rarely been reported in the literature. Only 13 cases have been reported thus far.1-4 Typical manifestations are normal-pressure hydrocephalus, progressive vertigo, and ataxia.5 Different procedures have been performed to restore a normal cerebrospinal fluid (CSF) dynamic or pressure, including shunting procedures and partial or complete excision of the cyst by open microsurgery.4-8 CSF shunts give only partial improvement of symptoms and are prone to malfunctions, sometimes with serious complications. Microsurgical excision of the cyst seems to offer the best chance of success.5 We report here the case of a fourth ventricle arachnoid cyst successfully treated with a complete endoscopic cerebral procedure via the third ventricle.
CASE REPORT History and Clinical Examinations A 38-year-old female patient presented a 2year history of worsening headache, progressive ataxia, and episodic morning vomiting. She was first admitted to another institute where she underwent a cranial computed tomography scan and magnetic resonance imaging (MRI) that
E374 | VOLUME 10 | NUMBER 2 | JUNE 2014
DOI: 10.1227/NEU.0000000000000335
revealed a fourth ventricle arachnoid cyst with mild enlargement of the third and lateral ventricles. In that institute, surgeons also performed a whole-spine MRI that gave suspicion of a tethered cord, for which she underwent the excision of filum terminale with no clinical improvement. A few weeks later, her symptoms worsened, and we admitted the patient to our neurosurgical department. Cerebral MRI confirmed the presence of a fourth ventricle arachnoid cyst with associated noncommunicating hydrocephalus. Spinal MRI excluded any type of neurosurgical lesion and complication. Neurological examination revealed right horizontal nystagmus, ataxic, and broad-based gait with small steps and bilateral hyperactivity of the lower-limb tendon reflexes. Radiological Findings Brain MRI performed at admission (Figures 1, 2A, and 2B) confirmed the presence of the arachnoid cyst that enlarged the fourth ventricle, causing a mild obstructive triventricular hydrocephalus and compressing the adjacent portions of the brainstem and cerebellum. Turbulent flow was seen within the aqueduct of Sylvius (Figure 2A). The cyst extended through the foramen of Luschka and Magendie (Figures 1, 2A, and 2B).
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Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
ENDOSCOPIC TREATMENT OF A FOURTH VENTRICLE ARACHNOID CYST
FIGURE 1. Sagittal volumetric T1-weighted sequence (A), coronal fast-spin-echo T2-weighted image (B), and axial fluid-attenuated inversion-recovery T2-weighted sequence (C). The fourth ventricle cystic formation displays signal intensity comparable to that of the cerebrospinal in all the sequences performed. A, the aqueduct of Sylvius is dilated with a diameter of approximately 4.8 mm. B, the cystic content is separated from the turbulent flow seen within the upper portion of the fourth ventricle by a clear cystic lining (arrowhead). C, the cyst extends on the left side through the foramen of Luschka into the cerebellomedullary cistern (asterisk).
FIGURE 2. Sagittal and axial fast-spin-echo T2-weighted sequences before surgery (A and B) and 12 days (C and D), 2 months (E and F), and 34 months (G and H) after endoscopic intervention. Turbulent flow is visible through the third ventriculostomy (white asterisk) and the aqueduct of Sylvius. Cerebrospinal fluid (CSF) circulation within the fourth ventricle is quickly restored, and the cyst displays a progressive volume reduction (arrowhead). The caudal portion of the cyst is no longer extended through the foramen of Magendie and Luschka on the left side, and accelerated CSF is apparent through the latter (black asterisk).
OPERATIVE NEUROSURGERY
VOLUME 10 | NUMBER 2 | JUNE 2014 | E375
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
MARTINONI ET AL
Operation and Postoperative Course Once a possible parasitic or tumoral nature of the cyst was ruled out, we supposed it was a congenital cyst because the patient denied prior possible causes of an acquired arachnoid cyst (meningitis and head trauma). Indeed, considering the evident dilatation of the Sylvius aqueduct (4.8 mm) and the supratentorial ventricular system, we decided to perform a fenestration of the cystic wall via the third ventricle. The approach, burr hole position, and proper trajectory were planned preoperatively on MRIs without intraoperative neuronavigation. We also took into account an endoscopic approach through the foramen of Magendie that could have had the advantage of a 2-side opening without going through brain tissue. We preferred the transventricular route because it allowed us to perform a third ventriculocisternostomy during the same procedure (to achieve a protective procedure for a sudden unexpected obstructive hydrocephalus). A right burr hole
2 cm in front of the coronal suture was performed, and a rigid endoscope (GAAB Miniature Neuroscope 0°; diameter, 3.2 mm; length, 21 cm; Karl Storz, Karl Storz endoscope sets for pediatric neurosurgery) was inserted through a peel-away (12.5F) sheath into the frontal horn of the right lateral ventricle. Through the foramen of Monro, we reached the third ventricle, where we identified the entrance of the Sylvius aqueduct. We went through it until we could see, inside the fourth ventricle, the wall of the cyst, which appeared thin and slightly white (Figure 3). We carried out a wide fenestration of the cyst wall by first using a blunt instrument (monopolar coagulator) guided inside the sheath of the neuroendoscope and then widening the hole with a Fogarty balloon (3F) because we noticed an evident flow through it, together with a slow but progressive collapse of the cyst itself. We also decided to concurrently perform a third ventriculocisternostomy to promote CSF outflow and to prevent
FIGURE 3. Once the fourth ventricle was entered, the cyst wall (continuous arrow) was easily recognized (A). A Fogarty catheter was then introduced and used to fenestrate the cyst wall (B and C). At the end of the procedure, the cyst appeared soft and floating, and the pericystic space (dotted arrow) was clearly enlarged (D).
E376 | VOLUME 10 | NUMBER 2 | JUNE 2014
www.neurosurgery-online.com
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
ENDOSCOPIC TREATMENT OF A FOURTH VENTRICLE ARACHNOID CYST
a possible subacute noncommunicating hydrocephalus. Because there were already a marked ventricular dilatation and enlarged Monro foramina, we did not need to use a flexible endoscope; all procedures could be carried out without excessive forniceal retraction. We usually do not practice the “mother-baby technique” to enter the third ventricle because we prefer using a small-diameter instrument through a peel-away (12.5F) sheath to limit parenchymal damage. The day after surgery, the patient developed a transient Parinaud syndrome that lasted 1 day. Then all her symptoms disappeared. The postoperative MRI revealed accelerated CSF flow through the third ventriculostomy and the aqueduct of Sylvius; a gush of CSF was therefore directed against and around the wall of the cyst, pushing and squeezing its content. As a result, the cyst gradually displayed a diminished volume with evident reduction of the mass effect on the brainstem and cerebellum (Figure 2C-2H). The patient is still completely asymptomatic after a 4-year follow-up.
We are aware that our study lacks histological confirmation, and this is an evident limitation. However, we felt it inappropriate to take any operative risk to obtain pathological material for this kind of lesion, and for that reason, we performed only a simple fenestration of the cyst. Furthermore, MRI intraoperative findings and postoperative course lead us to hypothesize a benign arachnoid cyst.
CONCLUSION Neuroendoscopic fenestration of the cyst of the fourth ventricle through the third ventricle could represent a feasible and safe procedure that can promptly resolve the symptomatology and the neuroradiological signs by restoring a normal CSF flow. Disclosure The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
REFERENCES DISCUSSION Today, fenestration represents the procedure of choice for the treatment of symptomatic arachnoid cysts.2 Even though endoscopic fenestration has already been described as having good postoperative results for arachnoid cysts, to date, there have been only a few attempts to treat cysts located in the fourth ventricle in a purely endoscopic fashion.2 When anatomic favorable conditions exist such as an obstructive hydrocephalus associated with dilatation of the Sylvius aqueduct, an endoscopic procedure via the third ventricle can be attempted. Although microsurgical excision or fenestration of the cyst through suboccipital craniotomy is the standard treatment, endoscopy represents a less invasive approach. By fenestrating the wall of the cyst, we allow the outflow of the trapped CSF, reducing the intracystic hydrostatic pressure and the overall volume, removing the obstacle to the circulation of CSF, and restoring a pericystic CSF flow that progressively squeezes the cyst. Furthermore, endoscopy allows the surgeon to perform a third ventriculocisternostomy at the same time. This procedure could prevent the development of a delayed hydrocephalus if there is a not completely free pericystic CSF circulation (adherence, sepimentations, or incomplete collapse) or if a cyst recurrence occurs. In fact, it is worth noting that the only case of sudden death caused by a fourth ventricle arachnoid cyst reported so far occurred as a result of CSF shunt failure.5 The postoperative course of the patient has been characterized by the appearance of transient Parinaud syndrome. We hypothesized that it could have been caused by the passage of the rigid neuroendoscope through the aqueduct of Sylvius and that it could have induced a functional impairment of the periaqueductal gray matter by increasing neuronal distortion.9 However, some authors have proposed that a rapid inversion of transtentorial pressure could lead to periaqueductal damage in patients treated endoscopically for aqueductal stenosis.
OPERATIVE NEUROSURGERY
1. Bonde V, Muzumdar D, Goel A. Fourth ventricle arachnoid cyst. J Clin Neurosci. 2008;15(1):26-28. 2. Oertel JM, Wagner W, Mondorf Y, Baldauf J, Schroeder HW, Gaab MR. Endoscopic treatment of arachnoid cysts: a detailed account of surgical techniques and results. Neurosurgery. 2010;67(3):824-836. 3. Turgut M, Ozcan OE, Onol B. Case report and review of the literature: arachnoid cyst of the fourth ventricle presenting as a syndrome of normal pressure hydrocephalus. J Neurosurg Sci. 1992;36(1):55-57. 4. Westermaier T, Vince GH, Meinhardt M, Monoranu C, Roosen K, Matthies C. Arachnoid cysts of the fourth ventricle-short illustrated review. Acta Neurochir (Wien). 2010;152(1):119-124. 5. Prezerakos GK, Kouyialis AT, Ziaka DS, Boviatsis EJ. Sudden death due to 4th ventricle arachnoid cyst. Ir J Med Sci. 2011;180(3):769-770. 6. Acar O, Kocaogullar Y, Güney O. Arachnoid cyst within the fourth ventricle: a case report. Clin Neurol Neurosurg. 2003;105(2):93-94. 7. Azzimondi G, Calbucci F, Rinaldi R, Vignatelli L, D’Alessandro R. Arachnoid cyst in the region of the fourth ventricle mimicking clinical picture of normal pressure hydrocephalus. Neurosurg Rev. 1995;18(4):269-271. 8. Di Rocco C, Di Trapani G, Iannelli A. Arachnoid cyst of the fourth ventricle and “arrested” hydrocephalus. Surg Neurol. 1979;12(6):467-471. 9. Shin M, Nishihara T, Iai S, Eguchi T. Benign aqueductal cyst causing bilateral internuclear ophthalmoplegia after external ventricular drainage: case report. J Neurosurg. 2000;92(3):490-492.
Acknowledgment We would like to thank Cecilia Baroncini, MA, for linguistic support.
COMMENTS
T
he authors present a 38-year-old female complaining of worsening headache, progressive ataxia and episodic morning vomiting. CT and MR imaging revealed a fourth ventricle arachnoid cyst with a mild enlargement of the third and lateral ventricles. The authors performed an endoscopic fenestration via a transaqueductal approach. Finally, the patient made an excellent recovery and the cyst decreased in size. This is a nice and concise report of a rare arachnoid cyst. We had a very similar case 6 years ago and treated it via the same approach. But, we resected a part of the cyst wall to create a larger hole. Since we trusted in our fenestration, we did not perform a third ventriculostomy. And we got a histology revealing an arachnoid cyst. However, the long-term follow-up
VOLUME 10 | NUMBER 2 | JUNE 2014 | E377
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
MARTINONI ET AL
of the authors proved that the simple fenestration seems to be equally effective. I agree that the endoscopic transaqueductal approach is ideal to treat this kind of lesion. Henry W.S. Schroeder Greifswald, Germany
T
his is a nice case report with good illustrations on a large arachnoid cyst treated in a minimally invasive way by a transventricular approach from above, using the “long way” from a frontal burr hole; the cyst could then be opened and collapsed giving way to the normal CSF flow as is nicely documented by MRI sequences in the follow-up. An alternative would have been an approach from below through the foramen of Magendie2,3,5; but I agree that in this patient with a straight trajectory through the third ventricle and an enlarged aqueduct, the approach from above was more adequate, as we already used in the case mentioned in3; the minifiber endoscope was especially designed as a relatively long rigid endoscope with a small overall outer diameter of 3.8 mm including two instrument- and one irrigation channel.1 This relatively long, small rigid scope may be used through its special puncture cannula or with a peelaway-sheath and can precisely be guided by neuronavigation,1,4 also for lesions in greater distance like as in the case reported from a frontal burr hole approach, then through the lateral ventricles and the foramen of Monro to the third ventricle, finally through the dilated aqueduct (1 mm larger than the endoscope diameter) down to the fourth ventricle. This approach offers the advantage of an ETV in case of problems with the approach through the aqueduct, or with opening the cyst (e.g. bleeding); as the permanent success of the cyst opening could not be guaranteed, it was adequate to perform a third ventriculostomy as a “back up” in addition.
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An alternative technique could also have been the use of a rigid high performance HOKPKINS endoscope (full HD quality) for the approach to the third ventricle and for an ETV, then the use of a small flexible scope through a space-type rigid scope1,2 in a “mother-daughter-principle” to advance into the fourth ventricle for the cyst opening. However, here the use of our long rigid minifiber endoscope offered the advantage of a better optical quality (more fibers = better resolution than a small flexible scope, 1), and it provides a more effective surgical manipulation with 2 instruments simultaneously if required, and with a more powerful coagulation/hemostasis. This case report gives another example how even deep seated lesions blocking the CSF flow can be effectively be treated in a minimally invasive and fully optical controlled way using adequate endoscopic technique; and the paper does also provide an actual overview of the pertinent literature. Michael R. Gaab Hannover, Germany
1. Gaab MR. Intrumentation: Endoscopes and Equipment. World Neurosurg. 2013;79 (2 suppl):S14.e11-S14.e21. 2. Oertel JM, Baldauf J, Schroeder HW, Gaab MR. Endoscopic cystoventriculostomy for treatment of paraxial arachnoid cysts. J Neurosurg. 2009;110(4):792-799 3. Oertel JM, Wagner W, Mondorf Y, Baldauf J, Schroeder HW, Gaab MR. Endoscopic treatment of arachnoid cysts: a detailed account of surgical techniques and results. Neurosurgery. 2010;67(3):824-836. 4. Schroeder HW, Wagner W, Tschiltschke W, Gaab MR. Frameless neuronavigation in intracranial endoscopic neurosurgery. J Neurosurg. 2001;94(1):72-79. 5. Westermaier T, Vince GH, Meinhardt M, Monoranu C, Roosen K, Matthies C. Arachnoid cysts of the fourth ventricle—short illustrated review. Acta Neurochir (Wien). 2010;152(1):119-124.
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