Improved preservation of hearing and facial nerve function in vestibular schwannoma surgery via the retrosigmoid approach in a series of 200 patients

Object

The aim of this study was to evaluate and present the results of current surgical treatment of vestibular schwannomas (VSs) and to report the refinements in the operative technique.

Methods

The authors performed a retrospective study of 200 consecutive patients who had undergone VS surgery over a 3-year period. Patient records, operative reports, follow-up data, and neuroradiological findings were analyzed. The main outcome measures were magnetic resonance imaging, neurological status, patient complaints, and surgical complications.

Complete tumor removal was achieved in 98% of patients. Anatomical preservation of the facial nerve was possible in 98.5% of patients. In patients treated for tumors with extension Classes T1, T2, and T3, the rate of facial nerve preservation was 100%. By the last follow-up examination, excellent or good facial nerve function had been achieved in 81% of the cases. By at least 1 year postsurgery, no patients had total facial palsy. In the patients with preserved hearing, the rate of anatomical preservation of the cochlear nerve was 84%. The overall rate of functional hearing preservation was 51%. There was no surgery-related permanent morbidity in this series of patients. Cerebrospinal fluid leakage was diagnosed in 2% of the patients. The mortality rate was 0%.

Conclusions

The goal of VS treatment should be total removal in one stage and preservation of neurological function, as they determine a patient’s quality of life. This goal can be safely and successfully achieved using the retrosigmoid approach.

Microsurgical resection of extensive craniopharyngiomas using a frontolateral approach: operative technique and outcome

OBJECT

An extensive craniopharyngioma is a tumor that extends into multiple compartments (subarachnoid spaces) and attains a size larger than 4 cm. A wide spectrum of approaches and strategies has been used for resection of such craniopharyngiomas. In this report the authors focused on the feasibility and efficacy of microsurgical resection of extensive craniopharyngiomas using a frontolateral approach.

METHODS

A retrospective analysis was performed on 16 patients with extensive craniopharyngiomas who underwent operations using a frontolateral approach at one institution. The preoperative and postoperative clinical and radiological data, as well as the operative videos, were reviewed. The main focus of the review was the extent of radical tumor removal, early postoperative outcome, and approach-related complications.

RESULTS

Gross-total resection of craniopharyngioma was achieved in 14 (87.5%) of 16 cases. Early after surgery (within 3 months), 1 patient showed improvement in hormonal status, while in the remaining 15 patients it worsened. No major neurological morbidity was observed. Two patients experienced temporary psychotic disorders. Visual function improved in 6 patients and remained unchanged in 9. One patient experienced a new bitemporal hemianopsia. Three patients with features of short-term memory disturbances at presentation did show improvement after surgery. There were no deaths or significant approach-related morbidity in this patient series. Only 1 patient required revision surgery for a CSF leak.

CONCLUSIONS

The safe and simple frontolateral approach provides adequate access even to extensive craniopharyngiomas and enables their complete removal with a reasonable morbidity and approach-related complication rate.

Microsurgery management of vestibular schwannomas in neurofibromatosis type 2: indications and results

AIM

To analyze the senior author's experience and strategy of treatment of patients with neurofibromatosis type 2 (NF2), with particular emphasis on vestibular schwannoma (VS) surgery.

MATERIALS AND METHODS

Over a period of more than 35 years, the senior author (M.S.) has operated on more than 165 patients with NF2. The total number of VS surgeries was 210. This retrospective analysis includes 145 consecutively operated patients. Medical records, operative reports, follow-up neurological, audiometric examinations, and neuroradiological findings were analyzed.

RESULTS

Total tumor removal was achieved in 85% of the operated tumors. In 15%, deliberately subtotal removal was performed for brain stem decompression and hearing preservation in the only hearing ear. The overall rate of hearing preservation was 35%. When only patients with preserved useful preoperative hearing were included, the rate was 65%. Bilateral hearing after surgery was preserved in 23% of the patients. The anatomical integrity of the facial nerve was preserved in 89%.

CONCLUSIONS

The goal of VS surgery in patients with NF2 should be complete removal but not at the expense of functional impairment. Carefully individualized treatment strategy offers the possibility of prolongation of life and preservation of neurological functions.

Comparison of Direct Side-to-End and End-to-End Hypoglossal-Facial Anastomosis for Facial Nerve Repair

BACKGROUND

The hypoglossal facial anastomosis (HFA) is the gold standard for facial reanimation in patients with severe facial nerve palsy. The major drawbacks of the classic HFA technique are lingual morbidities due to hypoglossal nerve transection. The side-to-end HFA is a modification of the classic technique with fewer tongue-related morbidities.

OBJECTIVES

In this study we compared the outcome of the classic end-to-end and the direct side-to-end HFA surgeries performed at our center in regards to the facial reanimation success rate and tongue-related morbidities.

METHODS

Twenty-six successive cases of HFA were enrolled. In 9 of them end-to-end anastomoses were performed, and 17 had direct side-to-end anastomoses. The House-Brackmann (HB) and Pitty and Tator (PT) scales were used to document surgical outcome. The hemiglossal atrophy, swallowing, and hypoglossal nerve function were assessed at follow-up.

RESULTS

The original pathology was vestibular schwannoma in 15, meningioma in 4, brain stem glioma in 4, and other pathologies in 3. The mean interval between facial palsy and HFA was 18 months (range: 0-60). The median follow-up period was 20 months. The PT grade at follow-up was worse in patients with a longer interval from facial palsy and HFA (P value: 0.041). The lesion type was the only other factor that affected PT grade (the best results in vestibular schwannoma and the worst in the other pathologies group, P value: 0.038). The recovery period for facial tonicity was longer in patients with radiation therapy before HFA (13.5 vs. 8.5 months) and those with a longer than 2-year interval from facial palsy to HFA (13.5 vs. 8.5 months). Although no significant difference between the side-to-end and the end-to-end groups was seen in terms of facial nerve functional recovery, patients from the side-to-end group had a significantly lower rate of lingual morbidities (tongue hemiatrophy: 100% vs. 5.8%, swallowing difficulty: 55% vs. 11.7%, speech disorder 33% vs. 0%).

CONCLUSION

With the side-to-end HFA technique the functional restoration outcome is at least as good as that following the classic end-to-end HFA, but the complications related to the complete hypoglossal nerve transection can be avoided. Best results are achieved if this procedure is performed within the first 2 years after facial nerve injury. Patients with facial palsy of longer duration also have the chance for good functional restoration after HFA.

Trigeminocardiac reflex during skull base surgery: mechanism and management

BACKGROUND

We study the occurrence and management of the trigeminocardiac reflex (TCR) during neurosurgical procedures for lesions of the skull base.

METHOD

Two hundred patients underwent neurosurgical procedures for various skull base lesions and were evaluated retrospectively for the occurrence of the TCR during surgery. This phenomenon was defined as the onset of bradycardia lower than 60 beats/minute and hypotension with a drop in mean arterial blood pressure of 20% or more due to intra-operative manipulation or traction on the trigeminal nerve.

FINDINGS

Sixteen patients (8%) had a TCR intra-operatively (7 vestibular schwannomas, 5 sphenoid wing meningiomas, 3 petroclival meningiomas, 1 intracavernous epidermoid cyst). In all 16 patients with a TCR the postoperative courses presented no complications that could be directly related to this intra-operative phenomenon.

CONCLUSIONS

Due to the intracranial course of the trigeminal nerve several surgical procedures at the anterior, middle and posterior skull base may elicit the trigeminocardiac reflex. Continuous monitoring of hemodynamic parameters allows the surgeon to interrupt surgical manoeuvres immediately upon the occurrence of the TCR. This technique is sufficient for the heart rate and the arterial blood pressure to return to normal levels without the necessity of additional anticholinergic medication.

Hearing preservation after complete microsurgical removal in vestibular schwannomas

AIM

To evaluate and present the treatment strategy and hearing preservation in a recent series of vestibular schwannoma cases.

MATERIALS AND METHODS

A retrospective analysis of 200 patients operated consecutively over a 3 year period was performed. Patient records, operative reports, including data from the electrophysiological monitoring, follow-up audiometric examinations, and neuroradiological findings were analyzed.

RESULTS

The anatomical integrity of the cochlear nerve was preserved in 75.8% of the cases. When only patients with preserved preoperative hearing were included, the rate was 84%. The overall rate of functional hearing preservation was 51%. It was highest in small tumors--60% in class T1 and 72% in class T2. In tumors extending to and compressing the brain stem, preservation of some hearing was possible in up to 43%.

CONCLUSIONS

Vestibular schwannomas are benign lesions whose total removal leads to definitive healing of the patient. The goal of every surgery should be functional preservation of all cranial nerves. Using the retrosigmoid approach with the patient in the semi-sitting position, hearing preservation is possible even for large schwannomas.

Two step approach for surgical removal of petroclival meningiomas with large supratentorial extension

The treatment of petroclival meningiomas is still a matter of controversy in literature. In the last decades, many approaches have been introduced. Our strategy for the treatment of such tumors having large supratentorial extension with encasement of the internal carotid artery or compression of optic and oculomotor nerves has evolved in the attempt to improve the outcome. Currently, we favor a surgical technique consisting of two steps. As first step, we perform a retrosigmoid suprameatal approach in order to resect the posterior part of the tumor and obtain brainstem decompression. In the second step, carried out after patient's recovery from the first surgery, we remove the supratentorial portion of the lesion using a frontotemporal craniotomy to achieve the decompression of the optic nerve, oculomotor nerve, and carotid artery. The retrosigmoid suprameatal approach allows for adequate brainstem decompression: the tumor itself creates a surgical channel increasing the accessibility to the lower and upper petroclival surface. Moreover, this route allows for early visualization of cranial nerves in the posterior fossa and safe tumor removal under direct visual control, reducing the risk of postoperative deficits. Via the simple and safe frontotemporal craniotomy, the supratentorial part of the lesion can be removed thus avoiding the need of invasive approaches. We propose a two-stage surgery for treatment of petroclival meningiomas combining two simple routes such as retrosigmoid suprameatal and frontotemporal craniotomy. This approach reflects our philosophy to use simple and less invasive approaches in order to preserve neurological function and a good quality of life of the patient.

Efficacy of microsurgical tumor removal for treatment of patients with intracanalicular vestibular schwannoma presenting with disabling vestibular symptoms

OBJECTIVE

The aim of this study was to analyze the efficacy and risks of microsurgery via the hearing-preserving retrosigmoid approach in patients with intracanalicular vestibular schwannoma (VS) suffering from disabling vestibular symptoms, with special attention to vertigo.

METHODS

This is a retrospective analysis of 19 patients with intracanalicular VS and disabling vestibular dysfunction as the main or only symptom (Group A). All of the patients reported having had disabling vertigo attacks. Subjective evaluation of the impairment of patients was performed before surgery, 3 weeks after surgery, 3 months after surgery, and 1 year after surgery, using the Dizziness Handicap Inventory (DHI). The main outcome measures were improvement in quality of life as measured using the DHI, and general and functional outcomes, in particular facial function and hearing. Patient age, preoperative tumor size, preoperative DHI score, and preservation of the nontumorous vestibular nerve were tested using a multivariate regression analysis to determine factors affecting the postoperative DHI score. The Mann-Whitney U-test was used to compare the postoperative DHI score at 3 weeks, 3 months, and 1 year after surgery with a control group of 19 randomly selected patients with intracanalicular VSs, who presented without vestibular symptoms (Group B). The occurrence of early postoperative discrete vertigo attacks was also compared between groups.

RESULTS

The preoperative DHI score was ≥ 54 in all patients. All patients reported having had disabling rotational vertigo before surgery. The only significant factor to affect the DHI outcome 3 weeks and 3 months after surgery was the preoperative DHI score. The DHI outcome after 1 year was not affected by the preoperative DHI score. Compared with the control group, the DHI score at 3 weeks and 3 months after surgery was significantly worse. There was no significant difference between the groups after 1 year. Vertigo was improved in all patients and completely resolved after 1 year in 17 patients.

CONCLUSIONS

Disabling vestibular dysfunction that affects quality of life should be considered an indication for surgery, even in otherwise asymptomatic patients with intracanalicular VS. Surgical removal of the tumor is safe and very effective in regard to symptom relief. All patients had excellent facial nerve function within 1 year after surgery, with a very good chance of hearing preservation.

Endoscope-Assisted Retrosigmoid Intradural Suprameatal Approach for Surgical Treatment of Trigeminal Schwannomas

BACKGROUND:

Trigeminal schwannomas are the most common intracranial nonvestibular schwannomas, and the dumbbell-shaped subtype is the most challenging.

OBJECTIVE:

To evaluate the efficiency and safety of the endoscope-assisted retrosigmoid intradural suprameatal approach (EA-RISA) for dumbbell trigeminal schwannomas and to compare EA-RISA with classic RISA.

METHODS:

A retrospective study of all patients with trigeminal schwannomas was performed with a focus on dumbbell tumors. Tumors were classified according to a modified Samii classification. Extent of tumor removal, outcome, and morbidity rates in the 2 subgroups were compared.

RESULTS:

Twenty patients were enrolled: 8 had dumbbell-shaped tumors (type C1), 8 had middle fossa tumors (A1-3), 3 had extracranial extension (D2), and 1 had posterior fossa tumor. Gross total resection was achieved in 15 and near-total resection in 5 patients. In 4 patients with dumbbell tumors, the classic RISA (Samii approach) was used; EA-RISA was used in the other 4 patients. The extent of petrous apex drilling was determined individually on the basis of the anatomic variability of suprameatal tubercle and degree of tumor-induced petrous apex erosion; in 2 patients, only minimal drilling was needed. The endoscope was applied after microsurgical tumor removal and in 3 of 4 patients revealed a significant unrecognized tumor remnant in the anterolateral and superolateral aspects of the Meckel cave. Thus, the EA-RISA technique allowed gross total resection of the tumor.

CONCLUSION:

The EA-RISA enlarges the exposure obtained with the classic RISA. Its judicious use can help achieve safe and radical removal of dumbbell-shaped trigeminal schwannomas (C1 type).

Endoscope-assisted retrosigmoid infralabyrinthine approach to jugular foramen tumors

OBJECT

Removal of jugular foramen (JF) tumors usually requires extensive skull base approaches and is frequently associated with postoperative morbidities such as lower cranial nerve injury. The endoscope-assisted retrosigmoid infralabyrinthine approach is a relatively new approach to tumors extending into the bony canal of the JF. The authors present their experience with this approach.

METHODS

The endoscope-assisted retrosigmoid infralabyrinthine approach was used in 7 patients, including 5 with schwannomas and 2 with paragangliomas. The access to the tumor, extent of its removal, postoperative neurological outcome, and approach-related morbidities were evaluated.

RESULTS

Two patients had a history of previous partial tumor removal, and 1 was treated by embolization followed by two courses of Gamma Knife radiosurgery. In this latter patient near-total resection was achieved. Gross-total resection was possible in the remaining 6 patients. Five patients benefited from endoscopic assistance: in 2 patients it showed a tumor remnant after microscopic tumor removal, while in 3 patients it allowed safe removal of the intraforaminal tumor by visualizing the surrounding structures. No permanent neurological deficit was observed after the operation. Two patients presenting with swallowing disturbance had temporary postoperative worsening that improved later. One patient developed CSF leakage that was managed with a lumbar drain.

CONCLUSIONS

This study shows that the judicious application of the endoscope-assisted retrosigmoid infralabyrinthine approach is safe and effective for removal of the schwannomas extending into the JF and selected paragangliomas without significant luminal invasion of the sigmoid-jugular system.

Microsurgical management of vestibular schwannoma after failed previous surgery

OBJECTIVE Microsurgical treatment of recurrent vestibular schwannoma (VS) is difficult and poses specific challenges. The authors report their experience with 53 cases of surgically treated recurrent VS. Outcome of these tumors was compared to that of primarily operated on VS. Special attention was given to the facial nerve functional outcome. METHODS A retrospective analysis was performed of the patients who underwent surgery for recurrent VS at one institution from 2000 to 2013. The preoperative data, intraoperative findings, and outcome in terms of facial nerve function and improvement of the preoperative symptoms were analyzed and compared with those in a control group of 30 randomly selected patients with primarily operated on VS. A multivariate regression analysis was performed to test the factors that could affect the facial nerve outcome in each group. RESULTS Fifty-three consecutive patients underwent surgery for recurrent VS. Seventeen patients were previously operated on and received postoperative radiosurgery (Group A). Thirty-six patients were previously operated on but did not receive postoperative radiosurgery (Group B). The overall postoperative facial nerve function was significantly worse in Groups A and B in comparison with the control group (Group C). Interestingly, there was no significant difference in the facial nerve outcome among the 3 groups in patients who had good preoperative facial nerve function. The tumor size and the preoperative facial nerve function are variables that significantly affect the facial nerve outcome. Most of the patients showed improvement of the preoperative symptoms, such as trigeminal hypesthesia, gait disturbance, and headache. CONCLUSIONS Complete microsurgical tumor removal is the optimal management for patients with recurrent or regrowing VS. The procedure is safe, associated with favorable facial nerve outcome, and may also improve existing neurological symptoms.

Fat Implant is Superior to Muscle Implant in Vestibular Schwannoma Surgery for the Prevention of Cerebrospinal Fluid Fistulae

Objective:

Meticulous sealing of opened air cells in the petrous bone is necessary for the prevention of cerebrospinal fluid (CSF) fistulae after vestibular schwannoma surgery. We performed a retrospective analysis to determine whether muscle or fat tissue is superior for this purpose.

Methods:

Between January 2001 and December 2006, 420 patients underwent retrosigmoidal microsurgical removal by a standardized procedure. The opened air cells at the inner auditory canal and the mastoid bone were sealed with muscle in 283 patients and with fat tissue in 137 patients. Analysis was performed regarding the incidence of postoperative CSF fistulae and correlation with the patient's sex and tumor grade.

Results:

The rate of postoperative CSF leak after application of fat tissue was lower (2.2%) than after use of muscle (5.7%). Women had less postoperative CSF leakage (3.4%) than men (5.6%). There was an inverse correlation with tumor grade. Patients with smaller tumors seemed to have a higher rate of CSF leakage than those with large tumors without hydrocephalus. Only large tumors with severe dislocation of the brainstem causing hydrocephalus showed a higher incidence of CSF leaks.

Conclusion:

Fat implantation is superior to muscle implantation for the prevention of CSF leakage after vestibular schwannoma surgery and should, therefore, be used for the sealing of opened air cells in cranial base surgery.

Combined endonasal and sublabial endoscopic transmaxillary approach to the pterygopalatine fossa and orbital apex

BACKGROUND

The pterygopalatine fossa (PPF) and inferomedial orbital apex are difficult regions for open neurosurgical access. The traditional extensive anterior approach (transfacial or transmandibular) and lateral/posterolateral (transcranial) approach were used to access the PPF. The combined endonasal and sublabial transmaxillary approach is a less invasive access route for these lesions. In this study, we present the technical and clinical details of our experience with the combined endoscopic endonasal and transmaxillary approach.

METHODS

A retrospective analysis of our patients operated on using a combined endoscopic endonasal and transmaxillary approach was done. The preoperative, intraoperative and postoperative images and all the clinical data were evaluated. The accessibility to the area and extent of surgical resection were reviewed. The surgery-related complications and postoperative morbidities were analyzed. The main items of interest were the exposure of the target area and possibility for safe removal.

RESULTS

Five patients with pathologies located in the area of the PPF and orbital apex were operated on using the combined endoscopic sublabial and endonasal transmaxillary approach. The technique provided sufficient exposure of the area and allowed for safe removal of the preoperatively determined target in all of the patients. One patient developed dry eye and a neurotrophic corneal ulcer, and another patient developed temporary postoperative facial numbness. In the follow-up, only one patient with skull base chordoma had an asymptomatic tumor regrowth. The other patients had no recurrence or regrowth.

CONCLUSIONS

The combined endoscopic sublabial and endonasal transmaxillary approach is a safe and effective method for resection of lesions in the PPF and inferomedial orbital apex.

Petrous bone pneumatization is a risk factor for cerebrospinal fluid fistula following vestibular schwannoma surgery

BACKGROUND

For the prevention of postoperative CSF fistula a better understanding of origins and risk factors is necessary.

OBJECTIVE

To identify the petrous bone air cell volume as a risk factor for developing CSF fistula, we performed a retrospective analysis.

METHODS

From 2000 to 2007 519 patients had a retrosigmoidal surgical removal of a vestibular schwannoma. The 22 who had a postoperative CSF fistula were chosen for evaluation in addition to 78 patients who were randomly selected in 4 equally sized cohorts: male/female with small/large tumors. Preoperative CT scans were analyzed regarding petrous bone air cell volume, area of visible pneumatization at the level of the internal auditory canal (IAC), tumor grade, and sex.

RESULTS

: Women developed nearly half as many CSF fistulas (2.7%) as men (5.2%). The mean volume of the petrous bone air cells was 10.97 mL (SD, 4.9; range, 1.38-27.25). It was significantly lower for women (mean, 9.23 mL; SD, 3.8) than for men (mean, 12.5 mL; SD, 5.28; P = .0008). The mean air cell volume of CSF-fistula patients was 13.72 mL (SD, 5.22). The difference concerning the air cell volume between patients who developed CSF fistulas and patients from the control group was significant (P = .0042). There was a significant positive correlation between the air cell volume and the area of pneumatization in one CT slide at the level of the IAC.

CONCLUSION

The higher incidence of CSF fistulas in men compared with women can be explained by means of differently pneumatized petrous bones. A high amount of petrous bone pneumatization has to be considered as a risk factor for the development of postoperative CSF fistula after vestibular schwannoma surgery.

Cystic trochlear nerve schwannoma. Case report

BACKGROUND

Twenty-six cases of pathologically verified schwannomas of the trochlear nerve have been reported in the literature. Five of them had a large cystic component and a smaller solid portion. Complex skull base approaches have been usually applied for their removal.

CASE DESCRIPTION

We report on a rare case of cystic trochlear schwannoma in a 52-year-old female patient. The patient presented with double vision, facial palsy, decreased hearing, hemiparesis on the right side, and severe gait instability. Magnetic resonance imaging revealed a 2.5-cm left-sided extra-axial lesion compressing the brain stem at the lower midbrain and upper pontine level. Total resection was performed via a retrosigmoid craniotomy. After the surgery, the neurological deficit diminished considerably. At 28 months follow-up, her only complaint was mild double vision when walking down the stairs and hypesthesia in the right half of her face.

CONCLUSIONS

This case represents a rare pontomesencephalic lesion removed successfully via the simple retrosigmoid route.

Retrosigmoid intradural inframeatal approach: indications and technique

BACKGROUND

Surgery of lesions of the petrous apex involving the inframeatal/infralabyrinthine area is challenging and related to a high risk of complications. Various extensive skull-base approaches have been used.

OBJECTIVE

To present and evaluate our experience with a new hearing-preserving extension of the retrosigmoid approach to the inframeatal/infralabyrinthine area.

METHODS

The approach was used in 3 patients harboring lesions in the petrous apex with variable extension in the inframeatal/infralabyrinthine region. The surgical accessibility of the lesions offered by the approach, the completeness of tumor removal, and the outcome, in particular, the functional outcome and complication rate, were assessed.

RESULTS

The tumor could be resected from the target area in all cases. No approach-related complications occurred. Serviceable hearing and normal facial nerve functions were preserved in all cases.

CONCLUSION

Our initial experience with the retrosigmoid inframeatal approach showed that it provides sufficient access to the area and offers the possibility of complete tumor removal. It allows for hearing and facial nerve functional preservation. The approach is safe and related to a very low complication rate.

Fat implant is superior to muscle implant in vestibular schwannoma surgery for the prevention of cerebrospinal fluid fistulae

OBJECTIVE

Meticulous sealing of opened air cells in the petrous bone is necessary for the prevention of cerebrospinal fluid (CSF) fistulae after vestibular schwannoma surgery. We performed a retrospective analysis to determine whether muscle or fat tissue is superior for this purpose.

METHODS

Between January 2001 and December 2006, 420 patients underwent retrosigmoidal microsurgical removal by a standardized procedure. The opened air cells at the inner auditory canal and the mastoid bone were sealed with muscle in 283 patients and with fat tissue in 137 patients. Analysis was performed regarding the incidence of postoperative CSF fistulae and correlation with the patient's sex and tumor grade.

RESULTS

The rate of postoperative CSF leak after application of fat tissue was lower (2.2%) than after use of muscle (5.7%). Women had less postoperative CSF leakage (3.4%) than men (5.6%). There was an inverse correlation with tumor grade. Patients with smaller tumors seemed to have a higher rate of CSF leakage than those with large tumors without hydrocephalus. Only large tumors with severe dislocation of the brainstem causing hydrocephalus showed a higher incidence of CSF leaks.

CONCLUSION

Fat implantation is superior to muscle implantation for the prevention of CSF leakage after vestibular schwannoma surgery and should, therefore, be used for the sealing of opened air cells in cranial base surgery.

Optic nerve mobilization to enhance the exposure of the pituitary stalk during craniopharyngioma resection: early experience

OBJECT Preservation of the pituitary stalk and its vasculature is a key step in good postoperative endocrinological outcome in patients with craniopharyngiomas. In this article, the authors describe the surgical technique of medial optic nerve mobilization for better inspection and preservation of the pituitary stalk. METHODS This operative technique has been applied in 3 patients. Following tumor exposure via a frontolateral approach, the pituitary stalk could be seen partially hidden under the optic nerve and the optic chiasm. The subchiasmatic and opticocarotid spaces were narrow, and tumor dissection from the pituitary stalk under direct vision was not possible. The optic canal was therefore unroofed, the falciform ligament was incised, and the lateral part of the tuberculum sellae was drilled medial to the optic nerve. The optic nerve could be mobilized medially to widen the opticocarotid triangle, which enhanced visualization of and access to the pituitary stalk. RESULTS By using the optic nerve mobilization technique, the tumor could be removed completely, and the pituitary stalk and its vasculature were preserved in all patients. In 2 patients, vision improved after surgery, while in 1 patient it remained normal, as it was before surgery. The hormonal status remained normal after surgery in 2 patients. In the patient with preoperative hormonal deficiencies, improvement occurred early after surgery and hormonal levels were normal after 3 months. No approach-related complications occurred. CONCLUSIONS This early experience shows that this technique is safe and could be used as a complementary step during microsurgery of craniopharyngiomas. It allows for tumor dissection from the pituitary stalk under direct vision. The pituitary stalk can thus be preserved without jeopardizing the optic nerve.

Imaging features and classification of peritumoral edema in vestibular schwannoma

BACKGROUND

Peritumoral edema (PTE) is rarely present in patients with vestibular schwannomas (VS). We studied the correlation between radiological tumor characteristics and the presence of edema, describe its magnetic resonance imaging features and classify the different edema patterns.

METHODS

We analysed 605 consecutive patients treated for VS at our Institute. PTE was found in 30 patients, studied on fluid attenuated inversion recovery sequences and categorised as involving the brachium pontis, cerebellum and/or brainstem. Tumor volume, shape, surface, internal structure and axis of growth were evaluated and compared to a matched series of 30 patients without PTE.

RESULTS

In our population of patients, 5% showed PTE. Edema involved the brachium pontis in 22 cases (88%), cerebellum in 15 (60%) and brainstem in 3 (12%). PTE was classified as mild (one region involved), moderate (two regions) and severe (three regions). Edema was present not only perpendicular to the major tumor growth axis but also parallel to it (91%). The difference between the two groups in regards to tumor shape and surface was not significant. We found no correlation between tumor and edema volumes.

CONCLUSIONS

VS can cause PTE, but its incidence is less frequent than in skull base meningiomas. PTE involves most frequently the brachium pontis, followed by the cerebellum and brainstem. Its occurrence correlates with tumor size but not with other radiological VS features. PTE is not always located perpendicular to the major axis of tumor growth, which indicated that the compressive theory proposed for meningiomas is not plausible explanation for its manifestation.