"Triple R" tonsillar technique for the management of adult Chiari I malformation: surgical note

BACKGROUND

Chiari type I malformation is a congenital disorder that is characterized by the caudal extension of the cerebellar tonsils through the foramen magnum into the cervical canal and by a reduced posterior fossa volume.

METHODS

We report our surgical technique of reposition, reduction, or resection of the cerebellar tonsils for the management of Chiari I malformation. The procedure was performed in 22 adult patients, in three different centers, with a mean age of 37 years. Clinical complaints included headaches, nuchalgia, vertigo, and upper-limb weakness or numbness. Seven patients had cervical syringomyelia. Symptoms developed within a mean time of 36 months (range, 12-70 months).

RESULTS

The cerebellar tonsils were exposed through a dura mater-arachnoid incision at the atlanto-occipital space after a 0.5-cm rimming craniectomy of the occipital bone in all patients. In seven patients the tonsils were resected, in other seven were reduced by subpial coagulation and aspiration, and in the remaining eight patients the tonsils were repositioned after coagulating their surfaces. Three patients had also a posterior fossa arachnoid cyst that was fenestrated in two of them. All patients improved postoperatively. Syringomyelia was reduced in five of seven patients. The mean length of the follow-up period was 12 months.

CONCLUSIONS

Selective reposition, reduction, or resection of herniated cerebellar tonsils may improve symptoms in adult patients with Chiari I malformation.

Micro-fabricated shunt to mimic arachnoid granulations for the treatment of communicating hydrocephalus

Hydrocephalus is the abnormal accumulation of cerebrospinal fluid (CSF) within the confines of the skull that if left untreated results in significant morbidity and mortality. The treatment for hydrocephalus has remained essentially unchanged for over 50 years. It was a technological advance in materials that allowed John Holter, in conjunction with neurosurgeons Spitzer and Nulsen, to devise a valve and shunt system that diverted excess CSF from the ventricular space to the peritoneum. This ventriculo-peritoneal (VP) shunt is far from ideal, with problems associated with under/over shunting, mechanical mismatch, infection, high failure rates, disconnection and erosion. With the advances in the field of micro-fabrication and micro-machines we propose an innovative shunt system that would mimic the function of arachnoid granulations. This micro-fabricated shunting device, or micro-mechanical arachnoid granulation (MAG), consists of a multiplicity of micro-valves each 210 μm in diameter that each adhere to individual micro-needles. This work demonstrates the design and initial test results of the micro-valve with parameters for low cracking pressure, optimal flow rate, and reflux that would mimic the function of the native arachnoid granulations.

Evaluation of tenoxicam on prevention of arachnoiditis in rat laminectomy model

Post laminectomy arachnoiditis has been shown by experiments with rats and post operative radiological imaging in humans. The purpose of this experimental study was to determine the efficacy of tenoxicam in preventing arachnoiditis in rats. Twenty-four Wistar rats were divided into two groups, and L3 laminectomy was performed. In the tenoxicam group, 0.5 mg/kg tenoxicam was applied intraperitoneally. Normal saline was applied intraperitoneally in the control group. Later, the rats were killed at weeks 3 and 6, and the laminectomy sites were evaluated pathologically for arachnoiditis. The results showed that 6 weeks after surgery, the tenoxicam group showed lowest arachnoiditis grades. However, statistically significant difference was not found in arachnoiditis between the control group and the tenoxicam group. Based on these findings it is concluded that application of the tenoxicam after lumbar laminectomy did not effectively reduce arachnoiditis. Performing the most effective surgical technique without damage around tissue in a small surgical wound and having meticulous hemostasis in surgery seem to be the key for preventing arachnoiditis effectively.

Microsurgical and endoscopic anatomy of Liliequist's membrane and the prepontine membranes: cadaveric study and clinical implications

BACKGROUND

Liliequist's membrane is mostly described as having a diencephalic leaf, mesencephalic leaf, and diencephalic-mesencephalic leaves in the literature. Also different descriptions of the prepontine membranes were reported. In this study, we visualized the regular structural forms of membranes without disturbing any attachments and defined infrachiasmatic and prepontine safety zones. We discussed the clinical significance of these structures.

MATERIALS AND METHODS

The study was carried out on 24 adult human cadavers at the Morgue Specialization Department of the Forensic Medicine Institution following the initial autopsy examination. Liliequist's membrane and the prepontine membranes were explored after retraction of the frontal lobes. Dissections were performed under the operative microscope. A 0- and 30-degree, 2.7-mm angled rigid endoscope (Aesculap, Tuttlingen, Germany) was advanced through the prepontine cistern from the natural holes of membranes, or small holes were opened without damaging the surrounding structures.

RESULTS

The basal arachnoid membrane (BAM) continued as Liliequist's membrane (LM) without any distinct separation in all specimens. The LM coursed over the posterior clinoids and split into two leaves as the diencephalic leaf (DL) and mesencephalic leaf (ML) in 18 specimens; the medial pontomesencephalic membrane (MPMM) coursed anterolaterally as a continuation of the ML and attached to the medial surfaces of the fifth and sixth nerves, joining with the lateral pontomesencephalic membrane (LPMM), which was also a posterolateral continuation of the ML in all specimens. The medial pontomedullar membrane (MPMdM) and lateral pontomedullar membrane (LPMdM) were observed in 21 specimens. The MPMdM membrane was a continuation of the MPMM, and the LPMdM was a continuation of the LPMM in all 21 specimens.

CONCLUSION

We observed that the LM is a borderless continuation of the BAM. The MPMM and LPMM split from the ML without any interruptions. The MPMdM and LPMdM were a single membrane continuing from the MPMM and LPMM. We determined infrachiasmatic and prepontine areas that can be important for inferior surgical approaches.

Management of infratentorial subdural hygroma complicating foramen magnum decompression: a report of three cases

Decompression of the foramen magnum for symptomatic Chiari malformation attends a small but significant risk of infratentorial subdural extra-arachnoid hygroma when an arachnoid-sparing procedure is attempted. We present three cases whereby an arachnoid-sparing procedure was carried out and resulted in infratentorial subdural hygroma and hydrocephalus. The complication was managed by re-exploration of the posterior fossa and wide arachnoidotomy. In cases whereby the decision has been made to open the dura, we recommend routine arachnoidotomy in foramen magnum decompression, avoiding the risks of infratentorial subdural hygroma. In cases where arachnoid-sparing procedures have been attempted and subdural hygroma subsequently develops, we advocate re-exploration of the posterior fossa rather than cerebrospinal fluid diversion.

Low-grade CSF leaks in endoscopic trans-sphenoidal pituitary surgery: efficacy of a simple and fully synthetic repair with a hydrogel sealant

BACKGROUND

Intra-operative CSF leak during endoscopic trans-sphenoidal surgery is not uncommon. Surgical repair with a variety of autologous grafts, rigid buttresses and CSF diversion techniques that add time and complexity have been reported.

OBJECTIVE

To describe a simple and purely synthetic closure for low-grade CSF leaks following endoscopic trans-sphenoidal pituitary surgery.

METHODS

A retrospective review of all endoscopic trans-sphenoidal surgery undertaken for pituitary pathology between 2005 and 2010 was carried out. The grade of CSF leak and success of graded repair was noted. Patients with no CSF leak (grade 0) had gelatin sponge placed in the tumour cavity. In those with low-grade CSF leak through small arachnoid defects (grade 1), repair was carried out using gelatin sponge and hydrogel sealant overlay. CSF diversion was not employed for low-grade CSF leaks.

RESULTS

Of the 255 endoscopic trans-sphenoidal surgeries, 158 (62%) had no leak (grade 0) and 74 (29%) had a low-grade leak (grade 1). Repairs in all cases were of grade 0, and all but two cases of grade 1 CSF leak were successful at a mean follow-up of 29 months. The 2 (2.7%) post-operative CSF leaks were seen within 6 weeks of surgery. Both cases were related to bouts of sneezing and were repaired using further trans-sphenoidal surgery and/or lumbar CSF diversion.

CONCLUSIONS

A simple purely synthetic repair of low-grade CSF leaks is described. This repair is safe and comparable in efficacy whilst avoiding the morbidity related to more complex sellar reconstructions previously described.

Anatomic relations of the arachnoidea around the pituitary stalk: relevance for surgical removal of craniopharyngiomas

Purpose

The growth pattern of craniopharyngiomas (CP) is yet to be understood due to challenges arising from the diversity of morphological features that exist. This in turn has had implications on the development of safe surgical strategies for management of these lesions. The aim of this study is to propose a morphological classification of CP based on their tumor–membrane relationship. It is hoped that this will contribute to better understanding of CP morphology and prediction of the intraoperative classification.

Methods

Histological techniques were used to study eight fetuses. Following Masson staining, the membranes around the pituitary stalk were observed under microscope. Pre-operative MRI and intraoperative images of 195 patients with CP were also analyzed.

Findings

The arachnoidal sleeve around the pituitary stalk (ASPS) was noted to be comprised of a compact fibrous component and a related loose trabecular component. The pituitary stalk was divided into four segments in accordance with the folds of the ASPS. Correspondingly, the growth of CPs was divided into four basic patterns—infra-diaphragmatic (ID), extra-arachnoidal (EA), intra-arachnoidal (IA) and sub-arachnoidal (SA) growth. The IA growth pattern can be further subdivided into two subtypes—namely, IA1 (with tumor growing within the fibrous component of the ASPS) and IA2 (with tumor growing within the trabecular component). This method of topographical division can be used to understand the growth of CP—infra-diaphragmatic CP show growth pattern ID or ID together with EA. Suprasellar CP can show an extra-ventricular growth pattern (EA or IA2), an extra- and intra-ventricular (IA2 + SA) growth pattern, a trans-infundibular growth pattern (ID + IA1 + SA) and an infundibulo-tuberal growth pattern (SA or SA + IA1). There is a statistically significant difference between CP growth patterns in children and adults. A predominance of ID growth is noted in children while adults tend to show a pattern of predominantly Extra-ventricular (EV) growth.

Conclusion

Our proposed classification details the relationship of the surrounding structures to CPs and purports to predict and identify the intraoperative anatomical stratification. It also attempts to help predict the growth patterns of these tumors. A knowledge of the intimate relations of the tumor and its key surrounding structures allows for safe surgical removal.

Extra-arachnoidal cranio-cervical decompression for syringomyelia associated with Chiari I malformation in adults: technique assessment

BACKGROUND

The osteo-dural decompression of the cerebellar tonsils at the cranio-cervical junction is generally considered the most effective treatment for syringomyelia-Chiari I complex. However much controversy concerning a great number of surgical adjuvants to the standard bony decompression is still present. In this work an extra-arachnoidal cranio-cervical decompression (CCD) without duroplasty is described and the surgical results are reported.

METHOD

Between 2000 and 2005, 24 adult patients underwent surgery for symptomatic syringomyelia-Chiari I complex not associated with hydrocephalus. In all cases, the surgical procedure consisted of a limited suboccipital craniectomy and laminectomy of C1 (when necessary C2 as well) followed by dural opening leaving the arachnoid membrane intact. The dura mater is left open and stitched laterally to the muscles.

FINDINGS

With a mean clinical long term follow-up of 44 months (range, 12-78 mo), neurological disturbances improved in 21 of 24 patients (87.5%) as result of extra-arachnoidal CCD. The postoperative complications occurred when the arachnoid was accidentally violated (4 cases, 16.6%). The complications included aseptic meningitis (one patient), nucal pseudomeningocele (two patients) and postoperative hydrocephalus requiring a ventriculoperitoneal shunt (one patient). Finally, one patient received an additional C2 laminectomy in order to obtain symptoms improvement and syrinx shrinkage. Postoperative MRI studies demonstrated that the syrinx decreased in size or collapsed in 20 patients (83.3%) and stabilized in 4 (16.7%).

CONCLUSIONS

The extra-arachnoidal CCD is a safe and effective treatment for syringomyelia associated with Chiari I malformation in adults without intraoperative evidence of adhesive arachnoiditis. However a larger number of patients and longer follow-up will be necessary to determine the efficacy of extra-arachnoidal CCD.

Atypical growth pattern of a meningioma in an adult

A 49-year-old woman presented with a rare atypical growth pattern of meningioma without evidence of dural attachment manifesting as chronic headache associated with transient paresthesia and left motor disorders. On admission, neurological examination showed no abnormalities. Magnetic resonance (MR) imaging revealed a right temporo-parieto-occipital lesion, which appeared to involve the subdural space and filling the cortical sulci. The lesion caused peritumoral white matter edema. The tumor appeared hypointense on T(1)-weighted and hyperintense on T(2)-weighted MR images, with homogeneous enhancement after contrast administration. A biopsy of the lesion was performed. Histological examination indicated that the lesion was a meningioma. Intraparenchymal meningiomas should be considered in the differential diagnosis of intraaxial lesions in patients of any age.

Pial and arachnoid welding for restoration of normal cord anatomy after excision of intramedullary spinal cord tumors

A significant postoperative problem in patients undergoing excision of intramedullary tumors is painful dysesthesiae, attributed to various causes, including edema, arachnoid scarring and cord tethering. The authors describe a technique of welding the pia and arachnoid after the excision of intramedullary spinal cord tumors used in seven cases. Using a fine bipolar forcep and a low current, the pial edges of the myelotomy were brought together and welded under saline irrigation. A similar method was used for closing the arachnoid while the dura was closed with a running 5-0 vicryl suture. Closing the pia and arachnoid restores normal cord anatomy after tumor excision and may reduce the incidence of postoperative painful dysesthesiae.

Papilledema as a manifestation of a spinal subdural abscess

Papilledema is an uncommon presentation of spinal cord processes. Spinal subdural abscess (SSA) is a rare site of post-operative infection. We report a patient who developed papilledema as the primary manifestation of a post-operative lumbar subdural abscess. A spinal abscess should be considered in the post-operative spinal surgery patient who develops papilledema in the setting of persistent back pain. The increased intracranial pressure associated with lumbar spinal cord abscess most likely results from a markedly elevated cerebrospinal fluid (CSF) protein or the disruption of CSF flow in the spinal cul-de-sac.

Meningioma in the Posterior Fossa Without Dural Attachment -Case Report-

A 14-year-old boy presented with a very rare meningioma in the posterior cranial fossa without dural attachment. Magnetic resonance imaging revealed a 3-cm, well-circumscribed, heterogeneously enhanced, round mass without dural tail sign in the right side of the posterior fossa. Right vertebral angiography revealed very faint tumor staining supplied by the right posterior inferior cerebellar artery. Total removal of the tumor was performed. Intraoperatively, the mass exhibited no attachment to the dura mater, cerebellar parenchyma, or choroid plexus, but was firmly attached to the arachnoid tissue near the foramen of Luschka. Histological and immunohistochemical studies established the diagnosis of meningothelial meningioma (World Health Organization grade I).

Multiple bur hole surgery for the treatment of moyamoya disease in children

OBJECT

The authors' aim in this study was to review their experience in the use of indirect revascularization alone in a series of 14 children with moyamoya disease, in which numerous bur holes and arachnoid openings were made over each affected hemisphere.

METHODS

Revascularization through multiple bur holes and arachnoid openings was performed in 14 children (mean age at diagnosis 6.5 years [range 3-15 years]) who suffered from progressive moyamoya disease. The authors performed surgery in a total of 24 hemispheres during 18 procedures. Ten children underwent bilateral multiple bur hole procedures, three underwent a unilateral procedure in the more severely affected hemisphere, and one child had previously undergone an encephaloduroarteriomyosynangiosis on the contralateral side. Ten to 24 bur holes were made in the frontotemporoparietooccipital area of each hemisphere, depending on the site and extent of the disease. Early postoperative perfusion magnetic resonance imaging studies, performed in the five most recent cases, showed restoration of cortical perfusion as early as 3 months, which was confirmed on subsequent angiography studies (performed between 8 and 12 months postoperatively) that showed excellent revascularization of the ischemic brain by external carotid artery collateral vessels. None of the children sustained further ischemic attacks postoperatively. Motor improvement was noted in those who had presented with paresis. A single seizure episode occurred in two patients at 2 weeks and 5 months after surgery; both children had presented with epilepsy. There were no postoperative deaths, and only one complication (an infected lumbar shunt in the patient who required cerebrospinal fluid [CSF] drainage). Five of the 18 procedures were complicated by subcutaneous CSF collections, which resolved with tapping and compressive head dressings; a transient lumbar drain was necessary in one case.

CONCLUSIONS

The results obtained in this series suggest that in children with moyamoya disease this simple technique is both effective and safe. Furthermore, it is effective as a sole treatment without supplementary revascularization procedures.

Arachnoid cysts in adults: long-term follow-up of patients treated with internal shunts to the subdural compartment

BACKGROUND

We have previously presented an alternative method for surgical decompression of intracranial arachnoid cysts. This minimally invasive method, with insertion of an internal shunt from the cyst to the subdural compartment, seemed to be an efficient and simple, and hence promising technique. The aim of the present study was to investigate the long-term results of this procedure.

METHODS

This study is a questionnaire-based retrospective study that includes 31 adult patients (>18 years) who were operated on in our department for an arachnoid cyst in the temporal fossa or overlying the frontal convexity with the internal shunt technique between April 1990 and October 2003. Follow-up ranged from 15 months to 14.8 years (mean = 8.2 years).

RESULTS

Of the patients, 83% were asymptomatic or had insignificant complaints at follow-up. A total of 17% reported no reduction of the preoperative complaints. No patient experienced worsening of the symptoms. The cyst was no longer visible on postoperative radiologic examinations in 37% of the patients. In 37%, the postoperative fluid volume was less than 50% of the original volume. In 13%, the cyst volume was reduced but the postoperative volume was greater than 50% of the original cyst volume. Thus, the cyst was unchanged in only 13% of the patients. There was no correlation between volume reduction and clinical improvement. A complication (subdural hygroma or hematoma) occurred in 7 patients, all with temporal cysts, leading to reoperation in 4. None of the complications caused permanent neurologic deficits or invalidity. Seven patients were reoperated on because of suspected or established treatment failure.

CONCLUSIONS

The internal shunt technique is a relatively simple, safe, and efficient alternative method for treatment of arachnoid cysts. It should be considered a valuable alternative in the treatment of arachnoid cysts.

Variations of disseminated choroid plexus papilloma: 2 case reports and a review of the literature

BACKGROUND

Choroid plexus papillomas are typically considered benign lesions, but histology is not always predictive of their behavior. These tumors can metastasize anywhere along the neuraxis and may be intraventricular, subarachnoid, or intraparenchymal. We present 2 cases that illustrate the wide diversity with which choroid plexus papillomas can disseminate.

CASE DESCRIPTIONS

The patient described in case 1 had a primary fourth ventricular choroid plexus papilloma that produced diffuse cystic subarachnoid and leptomeningeal lesions. Patient 2 also had a primary fourth ventricular tumor but with subsequent suprasellar and spinal drop metastases. Patient 1 was treated with temozolomide, resulting in regression of symptoms including headache and dizziness. Patient 2 has been treated with several modalities, including radiation therapy and chemotherapy, with slowing of symptom progression.

CONCLUSIONS

Variations of choroid plexus papilloma dissemination include intraventricular, subarachnoid, and leptomeningeal nodules or cystic lesions, and intraparenchymal locations. There is no consensus on the most effective treatment for choroid plexus papilloma metastases; surgical resection, chemotherapy, and radiation therapy may all yield benefits. The prognosis for patients with disseminated choroid plexus papilloma can range from prolonged stable disease and symptoms to death within months.

Effect of arachnoid plasty using fibrin glue membrane after clipping of ruptured aneurysm on the occurrence of complications and outcome in the elderly patients

BACKGROUND

In elderly patients with aneurysmal subarachnoid hemorrhage (SAH), complications including vasosopasm, subdural effusion, and late hydrocephalus, are liable to occur even after aneurysmal surgery. We examined prospectively the efficacy of arachnoid plasty using fibrin glue membrane during surgery of ruptured aneurysms in the elderly patients for preventing complications. The effects on the modified Rankin scale (mRS) and the Glasgow outcome scale (GOS) 3 months after SAH were noted.

METHODS

Total of 31 patients aged more than 70 years selected from a consecutive series of patients with aneurysmal SAH, were divided into two groups alternately, a group with arachnoid plasty (n = 16) and a control group without arachnoid plasty (n = 15). Statistical analyses were performed to assess relationships among various clinical and neuroradiological variables, especially between arachnoid plasty and occurrence of symptomatic vasospasm, subdural effusion, late hydrocephalus, or outcome such as mRS and GOS 3 months after onset.

FINDINGS

Statistical analyses revealed that arachnoid plasty were associated with late hydrocephalus and subdural effusion negatively, but with better mRS at 3 months after SAH. A tendency to be associated with less frequent symptomatic vasospasm was also noted.

CONCLUSION

Arachnoid plasty using fibrin glue is suggested to be effective in preventing complications associated with SAH and aneurysmal surgery. A better outcome in the elderly patients can be achieved.

Non-traumatic intradiploic arachnoid cyst

In this report, we present a case of non-traumatic intradiploic arachnoid cyst in a 65 year-old woman with a slow growing swelling in the right frontotemporal region without a history of head trauma, which was diagnosed intra-operatively. Extradural intracranial location of non-traumatic arachnoid cyst is a rare clinical entity with a few reported cases in the literature. Characteristic features of non-traumatic intradiploic arachnoid cysts are also described in this mini-review article.

Extradural spinal arachnoid cysts associated with spina bifida occulta

INTRODUCTION

Spinal extradural arachnoid cysts are an uncommon cause of neural compression in children. Even more uncommon is the association of such cysts with spina bifida occulta.

MATERIAL

Two girls, 12 and 8-years-old, presented with left leg pain, deteriorating gait, clinical signs of left L5 and S1 root compression, without bladder or bowel symptoms. The first patient had left foot drop. The second patient had muscle wasting and smaller left foot with pes cavus. Radiographs showed spina bifida occulta of S1 in both. MRI revealed an extradural cyst at the S1 level, indenting the thecal sac and the L5 and S1 roots. At operation in both patients a large arachnoid cyst arising from a small dural defect in the axilla of the left S1 root was compressing and displacing it and the dural sac. It was removed and the defect was repaired. The first patient improved with complete recovery of the foot drop. An MRI at 12 months showed no cyst recurrence. The second patient made good recovery initially, but at 10 months developed recurrent symptoms. An MRI scan showed recurrence of the cyst with root compression. On repeat exploration a different dural defect was identified in a more anterior position and was repaired.

DISCUSSION

The coexistence of extradural arachnoid cyst and corresponding bifid spinal segment has not been described previously. It raises the suspicion that the dural defect giving rise to the arachnoid cyst may be due to segmental dural dysgenesis in the context of the dysrhaphic neuroectodermal malformation.

Endoscopic management of intracranial cysts

Object

Endoscopic fenestration has been recognized as an accepted treatment choice for patients with symptomatic arachnoid cysts. The success of this procedure, however, is greatly influenced by individual cyst anatomy and location as well as the endoscopic technique used. This review was conducted to assess what variables influence the treatment success for different categories of arachnoid cysts.

Methods

Thirty-three consecutive patients who underwent endoscopic fenestration for treatment of an intracranial arachnoid cyst were identified from a prospective database. The surgical indications and techniques were reviewed, and surgical success rates and patient outcomes were assessed. Specific examples of each cyst category are included to illustrate the technical aspects of endoscopic cyst fenestration.

Endoscopic fenestration of arachnoid cysts was successful when judged by cyst decompression, and symptom resolution was noted in 32 (97%) of 33 cases. The one patient with short-term treatment failure underwent a successful repetition of the operation. There were no surgery-related morbidities or deaths.

Conclusions

Arachnoid cysts are a relatively benign pathological entity that can be managed by performing endoscopically guided cyst wall fenestrations into the ventricular system or cerebrospinal fluid–containing cisterns. Proper patient selection, preoperative planning of endoscope trajectory, use of frameless navigation, and advances in endoscope lens technology and light intensity combine to make this a safe procedure with excellent outcomes.