Non-acoustic tumors of the cerebellopontine angle

Outcomes of Trigeminal Ganglion Sparing Surgical Resection of Nonacoustic Cerebellopontine Angle Tumors Causing Trigeminal Neuralgia

OBJECTIVE

Tumors may be responsible for up to 5% of trigeminal neuralgia cases. Predictors of long-term pain relief after surgical resection of various cerebellopontine angle tumor types are not well understood. Previous studies found that size and extent of resection predict long-term pain status, although resection of tumor involving the trigeminal ganglion may be associated with high morbidity. This study evaluated predictors of TN pain freedom after resection of a nonacoustic CPA tumor, with avoidance of any portion involving the TG.

METHODS

In a retrospective cohort study, we evaluated clinical outcomes and complications after surgical resection of nonacoustic CPA tumors with purposeful avoidance of the TG causing trigeminal neuralgia. The primary outcome was pain-freedom. We performed logistic regression analyses to examine the relationship between pain-freedom at last follow-up and age, side of symptoms, preoperative symptom duration, tumor diameter, tumor type, and concurrent neurovascular compression (NVC).

RESULTS

Of 18 patients with nonacoustic CPA tumors causing TN treated with surgical resection, 83.3% were pain-free at last follow-up (mean 44.6 months). Age (P = 0.12), side (P = 0.41), preoperative symptom duration (P = 0.85), tumor diameter (P = 0.29), tumor type (P = 0.37), and NVC presence (P = 0.075) were not associated with long-term pain freedom.

CONCLUSIONS

This study provides additional evidence that various tumor types causing TN may safely undergo surgical resection and decompression of the trigeminal nerve to treat TN. This study presents a cohort of patients that underwent resection of a nonacoustic CPA tumor, with purposeful avoidance of the TG to minimize complications, demonstrating high rates of long-term pain freedom.

Open surgery vs. stereotactic radiosurgery for tumour-related trigeminal neuralgia: A systematic review

BACKGROUND

Secondary trigeminal neuralgia is a facial pain in trigeminal nerve dermatome caused by an underlying disease, such as cerebellopontine angle tumours. Treatment options to relieve the pains were surgical tumour resection and stereotactic radiosurgery of the tumour or trigeminal nerve. This study aims to review the efficacy of open surgery and stereotactic radiosurgery and recommend the treatment of choice for secondary trigeminal neuralgia due to cerebellopontine angle tumours.

METHOD

The inclusion criteria were studies covering patients with trigeminal neuralgia associated with cerebellopontine angle tumours that were treated with either open surgery or stereotactic radiosurgery and reported pain outcomes after treatment. Non-English articles or studies with a population of less than five were excluded. We systematically searched studies from PubMed, Ebscohost, and Cochrane Library from inception until December 20, 2021. Several works of literature from manual search were also added. Selected articles were appraised using a critical appraisal tool for prognostic studies.

RESULT

Included articles were 26 retrospective studies and one prospective study comprising 517 patients. Of 127 schwannomas, 226 epidermoids, 154 meningiomas, and ten other tumours, 320 cases received surgical tumour excision with or without MVD, 196 had tumour-targeted radiosurgery, and 22 underwent nerve-targeted radiosurgery. In surgical series, 92.2 % gained pain improvement, 2.8 % were unchanged, and 4.5 % had recurrence; none of the patients had worsened outcomes. In cases treated with tumour-targeted radiosurgery, the improvement rate was 79.1 %, unchanged at 14.3 %, recurrence at 26.5 %, and worse symptoms rate after the intervention was 6.6 %. Six patients with recurrent pain after tumour-targeted radiosurgery received secondary nerve-targeted radiosurgery with improved outcomes. Only one patient in our review underwent primary nerve-targeted radiosurgery, and the result was satisfactory. One study treated 15 patients with a single session of tumour-targeted and nerve-targeted radiosurgery, with an improvement rate of 93.3 % and a recurrence rate of 21.4 %.

CONCLUSION

Open surgery releasing the nerve root from compressive lesions is advocated to be the first-line treatment to gain satisfactory outcomes. Total removal surgery is recommended if possible. Nerve-targeted radiosurgery should be reserved as a secondary treatment for recurrent cases.

Stereotactic radiosurgery for cerebellopontine meningiomas: a systematic review and meta-analysis

OBJECTIVE

To (1) measure surgical outcomes associated with stereotactic radiosurgery treatment of cerebellopontine angle meningiomas, and (2) determine if differences in radiation dosages or preoperative tumor volumes affect surgical outcomes.

METHODS

A systematic search was performed on the PubMed, Medline, Embase and Cochrane Library databases searching for patients under stereotactic radiosurgery for meningiomas of the cerebellopontine angle. After data extraction and Newcastle-Ottawa scale quality assessment, meta-analysis of the data was performed with Review Manager 3.4.5.

RESULTS

In total, 6 studies including 406 patients were included. Postprocedure, patients had minimal cranial nerve complications while having an overall tumor control rate of 95.6%. Complications were minimal with facial nerve deficits occurring in 2.4%, sensation deficits of the trigeminal nerve in 4.0%, hearing loss in 5.9%, hydrocephalus in 2.0% and diplopia in 2.6% of all patients. Individuals with tumors extending into the internal auditory canal extension did not have significantly increases in hearing loss. There was a higher likelihood of tumor regression on postprocedure imaging in studies with a median prescription dose of >13 Gy (RR 1.27 [95% CI 1.04-1.56, p = 0.0225). There was no evidence of publication bias detected.

CONCLUSIONS

Radiosurgery is an effective modality for offering excellent tumor control of CPA meningiomas while allowing for only minimal complications postprocedure. A higher prescription dose may achieve higher tumor regression at follow up. Future studies should aim at establishing and optimizing accurate dosimetric guidelines for this patient population.

Surgeons' experience of venous risk with CPA surgery

The study aims to systematize neurosurgeons' practical knowledge of venous sacrifice as applied to the posterior fossa region and to analyze the collected data to present and preserve relevant experience and expert knowledge for current and future practicing neurosurgeons. The venous structures assessed were the superior petrosal vein (SPV), sigmoid sinus (SS), and the tentorial veins (TV). The survey is constructed to obtain surgeons' idea of assessed risk when sacrificing specific venous structures during posterior fossa surgery. They were asked how they prep for surgery, number of operations conducted, and their basis of knowledge. Collected data were mainly qualitative and analyzed with a mixed-method approach. A mean absolute deviation was calculated measuring rate of disagreement for a given substructure. Consensus existed among the participating surgeons that sacrificing the SPV and the TV was considered safe. Although, the risk of death when occluding major structures like the main trunk of the SPV, one of the SS' and or a total occlusion of all TV yielded high risk of death. The risk of infarction was often too apparent to discredit even with low risk of death among an experienced class of surgeons. Our findings provide an overview of surgical risk associated with venous sacrifice. This will minimize cases where indispensable practical knowledge on safe handling veins in the cerebellopontine angle is either to be lost or taught among few when the neurosurgeons retire. This will lower the disagreement regarding risks and increase the quality of surgical decision-making.

CT- and MRI-based gross target volume comparison in vestibular schwannomas

AIM

This study represents an enumeration and comparison of gross target volumes (GTV) as delineated independently on contrast-enhanced computed tomography (CT) and T1 and T2 weighted magnetic resonance imaging (MRI) in vestibular schwannomas (VS).

BACKGROUND

Multiple imaging in radiotherapy improves target localization.

METHODS AND MATERIALS

42 patients of VS were considered for this prospective study with one patient showing bilateral tumor. The GTV was delineated separately on CT and MRI. Difference in volumes were estimated individually for all the 43 lesions and similarity was studied between CT and T1 and T2 weighted MRI.

RESULTS

The male to female ratio for VS was found to be 1:1.3. The tumor was right sided in 34.9% and left sided in 65.1%. Tumor volumes (TV) on CT image sets were ranging from 0.251 cc to 27.27 cc. The TV for CT, MRI T1 and T2 weighted were 5.15 ± 5.2 cc, 5.8 ± 6.23 cc, and 5.9 ± 6.13 cc, respectively. Compared to MRI, CT underestimated the volumes. The mean dice coefficient between CT versus T1 and CT versus T2 was estimated to be 68.85 ± 18.3 and 66.68 ± 20.3, respectively. The percentage of volume difference between CT and MRI (%VD: mean ± SD for T1; 28.84 ± 15.0, T2; 35.74 ± 16.3) and volume error (%VE: T1; 18.77 ± 10.1, T2; 23.17 ± 13.93) were found to be significant, taking the CT volumes as the baseline.

CONCLUSIONS

MRI with multiple sequences should be incorporated for tumor volume delineation and they provide a clear boundary between the tumor and normal tissue with critical structures nearby.

Microvascular anatomy of the cerebellar parafloccular perforating space

OBJECT

The cerebellopontine angle is a common site for tumor growth and vascular pathologies requiring surgical manipulations that jeopardize cranial nerve integrity and cerebellar and brainstem perfusion. To date, a detailed study of vessels perforating the cisternal surface of the middle cerebellar peduncle—namely, the paraflocculus or parafloccular perforating space—has yet to be published. In this report, the perforating vessels of the anterior inferior cerebellar artery (AICA) in the parafloccular space, or on the cisternal surface of the middle cerebellar peduncle, are described to elucidate their relevance pertaining to microsurgery and the different pathologies that occur at the cerebellopontine angle.

METHODS

Fourteen cadaveric cerebellopontine cisterns (CPCs) were studied. Anatomical dissections and analysis of the perforating arteries of the AICA and posterior inferior cerebellar artery at the parafloccular space were recorded using direct visualization by surgical microscope, optical histology, and scanning electron microscope. A comprehensive review of the English-language and Spanish-language literature was also performed, and findings related to anatomy, histology, physiology, neurology, neuroradiology, microsurgery, and endovascular surgery pertaining to the cerebellar flocculus or parafloccular spaces are summarized.

RESULTS

A total of 298 perforating arteries were found in the dissected specimens, with a minimum of 15 to a maximum of 26 vessels per parafloccular perforating space. The average outer diameter of the cisternal portion of the perforating arteries was 0.11 ± 0.042 mm (mean ± SD) and the average length was 2.84 ± 1.2 mm. Detailed schematics and the surgical anatomy of the perforating vessels at the CPC and their clinical relevance are reported.

CONCLUSIONS

The parafloccular space is a key entry point for many perforating vessels toward the middle cerebellar peduncle and lateral brainstem, and it must be respected and protected during surgical approaches to the cerebellopontine angle.

Hearing disorders in brainstem lesions

Auditory processing can be disrupted by brainstem lesions. It is estimated that approximately 57% of brainstem lesions are associated with auditory disorders. However diseases of the brainstem usually involve many structures, producing a plethora of other neurologic deficits, often relegating "auditory symptoms in the background." Lesions below or within the cochlear nuclei result in ipsilateral auditory-processing abnormalities detected in routine testing; disorders rostral to the cochlear nuclei may result in bilateral abnormalities or may be silent. Lesions in the superior olivary complex and trapezoid body show a mixture of ipsilateral, contralateral, and bilateral abnormalities, whereas lesions of the lateral lemniscus, inferior colliculus, and medial geniculate body do not affect peripheral auditory processing and result in predominantly subtle contralateral abnormalities that may be missed by routine auditory testing. In these cases psychophysical methods developed for the evaluation of central auditory function should be employed (e.g., dichotic listening, interaural time perception, sound localization). The extensive connections of the auditory brainstem nuclei not only are responsible for binaural interaction but also assure redundancy in the system. This redundancy may explain why small brainstem lesions are sometimes clinically silent. Any disorder of the brainstem (e.g., neoplasms, vascular disorders, infections, trauma, demyelinating disorders, neurodegenerative diseases, malformations) that involves the auditory pathways and/or centers may produce hearing abnormalities.

Management of cerebellopontine angle lipomas: need for long-term radiologic surveillance?

OBJECTIVE

To date, only a very limited number of lipomas of the cerebellopontine angle (CPA) have been reported. Our objective was to examine clinical and radiologic features of CPA lipomas and determine the most appropriate management plan.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

Patients with CPA lipomas were identified through the skull base multidisciplinary meeting database.

INTERVENTIONS

Radiologic surveillance and clinical assessment.

MAIN OUTCOME MEASURES

Tumor growth, assessed through radiologic measurements on serial magnetic resonance imaging, demographics, presenting symptoms, and any correlation between weight gain and lipoma growth were among the examined factors.

RESULTS

Of the 15 patients with CPA lipomas, six were female and nine were male, with an average age at presentation of 50.2 years (range, 31.7-76.4 yr) and an average follow-up time of 51.7 months (range, 6-216 mo). The lipomas were unilateral in all cases, nine on the right (60%) and six on the left (40%) side. None of the lipomas increased in size. All patients were treated conservatively. Sensorineural hearing loss was the main presenting symptom (80%) followed by tinnitus (46.7%) and vertigo (20%). None of the patients suffered from facial nerve dysfunction. There was no correlation between weight gain and tumor growth.

CONCLUSION

CPA lipomas can be diagnosed accurately with appropriate magnetic resonance imaging techniques and be managed conservatively with safety. Cochleovestibular are the most common presenting symptoms, whereas facial nerve involvement is rare. CPA lipomas do not tend to grow and can be monitored on a less regular basis.

Risk factors and tumor response associated with hydrocephalus after gamma knife radiosurgery for vestibular schwannoma

BACKGROUND

This study was designed to investigate the clinical characteristics and risk factors of hydrocephalus after gamma knife radiosurgery (GKRS) for vestibular schwannoma.

METHODS

The authors retrospectively reviewed clinical and neuroimaging findings of 221 patients who underwent GKRS for newly diagnosed vestibular schwannoma. Mean patient age was 54.1 years (range 7-83 years), mean tumor volume was 3,010.4 mm(3) (range 34.7 to 14,300 mm(3)), mean marginal dose was 12.5 Gy (range 11 to 15 Gy), and mean follow-up duration was 31.9 months (range 1 to 107.6 months).

RESULTS

Surgical intervention for cerebrospinal fluid (CSF) diversion after GKRS was necessary in 11 (5 %) of the patients. Median time between GKRS and ventriculoperitoneal (VP) shunt placement was 15.5 months (range 1.8-37.8 months). These 11 patients showed female predominance (11 females) and mean tumor volume was significantly larger than in the other without hydrocephalus (6,509 vs. 2,726 mm(3); p < 0.01). Decreases in tumor enhancement and swelling were observed in all 221 patients, and CSF protein was found to be elevated in five of nine patients with available data at the time of the shunt procedure. Hydrocephalic symptoms improved after VP shunt and tumor sizes further decreased at last follow-up in all patients.

CONCLUSIONS

Hydrocephalus after radiosurgery may co-occur with a temporary change of tumor volume after radiation treatment. Therefore, hydrocephalus should be kept in mind during the time of tumor volume transition. Furthermore, the authors suggest that frequent patient monitoring for hydrocephalus be maintained for up to 3-4 years after GKRS.

What is the best treatment of drug-resistant trigeminal neuralgia in patients affected by multiple sclerosis? A literature analysis of surgical procedures

OBJECTIVE

Drug-resistant trigeminal neuralgia (TN) can complicate the clinical course of patients affected by multiple sclerosis (MS). Various surgical procedures have been reported for the treatment of this condition, but there is no agreement on the best management of these patients. To our knowledge, there is no critical literature analysis focusing on this particular topic. The aim of this study was to evaluate the clinical outcome of different surgical procedures utilized for drug-resistant TN in MS patients.

METHODS

We reviewed the literature about the studies reporting on surgical treatment of drug-resistant TN in MS patients. Case reports and case series less than 4 patients were excluded from the analysis. Nineteen studies were selected for the statistical analysis. To reduce the variability of the data, the selected studies were evaluated for the following outcome parameters: acute pain relief rate (APR), rate of recurrence (RR), pain free at follow-up rate (PF at FU) and complication rate (CR). For the statistical analysis, chi-square statistic, using the Fisher's exact test was utilized.

RESULTS

There was no procedure statistically superior in terms of APR rate in MS patients following the surgical treatment of TN. The highest RR was observed for percutaneous balloon compression (PBC) (60.2±14.4%). This result was statistically significant when compared to gamma knife surgery (GKS) (p=0.0129) and microvascular decompression (MVD) (p=0.0281). MVD together with percutaneous radiofrequency rhizothomy (PRR) was associated with a statistically better PF at FU rate (56.5±16.8% and 73.5±14.2%, respectively). However PBC and MVD showed statistical significant minor CR compared to other techniques (no complications and 18.7±17.4%, respectively).

CONCLUSION

Our study shows no differences in the short term results among different procedures for TN in MS patients. Each technique demonstrate advantages and limits in terms of long term pain, recurrence rate and complication rate. Each patient should be accurately informed on pros and cons of each procedure in order to be involved in the most appropriate choice.

The Effect of Microvascular Decompression in Patients With Multiple Sclerosis and Trigeminal Neuralgia

BACKGROUND

Trigeminal neuralgia (TN) in patients with multiple sclerosis (MS) is thought to be caused by demyelinating plaques within the nerve root entry zone, the trigeminal nucleus, or the trigeminal tracts.

OBJECTIVE

To review our experience of microvascular decompression (MVD) in patients with MS and symptomatic TN.

METHODS

All first-time MVDs for symptomatic trigeminal neuralgia in patients with MS performed by the senior author during an 8-year period (1999–2007) in this department were reviewed. The preoperative pain components were differentiated as being 100% episodic pain, &gt; 50% episodic pain, or &gt; 50% constant pain. At follow-up, pain relief was assessed with a standard mail questionnaire; those still having residual pain were further examined in the outpatient clinic or interviewed by phone.

RESULTS

Of the 19 MS patients, 15 were available for follow-up. The median observation period was 55 months (range, 17–99 months). At follow-up, 7 of 15 patients (47%) were completely free of their episodic pain, and an additional 4 (27%) had significant relief of episodic pain (ie, worst pain marked as 0 to 3 cm on a 10-cm visual analog scale). Among the subgroup of 8 patients with a constant pain component, all were free of their constant pain, and 4 (50%) were free of their episodic pain.

CONCLUSION

In our 8-year experience of doing MVD in MS patients with TN, we found complete and significant relief of episodic TN in a large proportion of patients. Even those with a constant pain component before MVD were completely relieved of their constant pain. Thus, in patients with TN (with or without a constant pain component), the presence of MS should not prevent patients from being offered MVD.

Epidermoids of the cerebellopontine angle: a 20-year experience

BACKGROUND

There is considerable debate within the current literature whether total or subtotal removal of CPA epidermoids yields better long-term outcomes. The aim of this study was to review our experience with cerebellopontine-angle epidermoid tumors, as well as the current literature, focusing on the correlation between long-term outcome and the extent of surgical removal.

METHODS

We performed a retrospective review of 24 patients with epidermoid tumors of the CPA surgically treated at our institution between 1985 and 2005.

RESULTS

The mean duration from onset of symptoms to surgery was 3.1 years. Cranial nerve dysfunction was noted in 83% of patients preoperatively. Total removal was achieved in 13 patients, near total removal in 6 patients, and subtotal removal in 5 patients. Patients who underwent total removal had a median MRS score of 0, whereas those who underwent near/subtotal removal had a median MRS score of 1. The rate of recurrence was 23% in tumors considered totally removed and 27% in those near/subtotally removed. Of the 6 patients with recurrences, 5 underwent a second operation. The mean duration of follow-up was 4.2 years.

CONCLUSIONS

Total removal of CPA epidermoids does not result in significantly increased morbidity and mortality and should be the goal of surgical treatment. However, near/subtotal resection of lesions that extend far beyond the CPA or are densely adherent to neurovascular structures is justified, as there is no significant difference in the rate of recurrence.

Normal pressure hydrocephalus after gamma knife radiosurgery for cerebellopontine angle meningioma

There are no reports of hydrocephalus following radiosurgery for a meningioma. We report on a case where gamma knife therapy for a 4 cm diameter right cerebellopontine meningioma accelerated hydrocephalus three months post treatment. Examination of the cerebrospinal fluid (CSF) revealed a high protein level and thus, CSF malabsorption and CSF obstruction might have occurred after the radio surgery. It is important to consider this pathology, and the need for long term follow up.

Some patients with multiple sclerosis have neurovascular compression causing their trigeminal neuralgia and can be treated effectively with MVD: report of five cases

The role of trigeminal ganglion percutaneous injection and radio-frequency lesioning procedures for the treatment of trigeminal neuralgia (TGN) in multiple sclerosis (MS) is well established. There is general acceptance that microvascular decompression (MVD) cannot be an appropriate treatment due to the view that the underlying aetiology is a demyelinating plaque affecting the root entry zone of the trigeminal pathway. Recently, MR-imaging has been used in the preoperative investigation of this group of patients demonstrating that neurovascular compression can occasionally be the responsible mechanism and that MVD can be the treatment of choice. We present five cases with MS and TGN. All the patients had failed to respond to medical treatment or percutaneous procedures. Magnetic resonance imaging demonstrated evidence of neurovascular compression in four cases. All the patients underwent MVD. Postoperatively four of the five patients made an uncomplicated recovery, were pain-free and fully satisfied with the result (mean follow-up 38.75 months; range 8-59 months). One patient developed recurrent pain 1 week following surgery and went on to have a total sensory rhizotomy. TGN in MS can be caused by neurovascular compression, which may be identified on MR-imaging. MVD has offered satisfactory short-term outcome for at least 2 years and does not inflict sensory loss. Longer follow-up will determine whether the outcome in MS patients will be as successful as in the TGN patients who do not suffer from MS.

Lipoma of the cerebellopontine angle

Lipomas of the cerebellopontine angle (CPA) are unusual tumors that typically present with hearing loss, tinnitus, dizziness, and occasionally facial neuropathies. We describe the case of a healthy 42-year-old woman who presented with left-sided hearing loss and facial synkinesis. T1-weighted magnetic resonance imaging revealed an enhancing lesion of the left CPA with no signal on fat suppression sequences. Despite conservative therapy, the patient developed progressive hemifacial spasm, and a suboccipital craniotomy approach was used to debulk the tumor, which encased cranial nerves V, VII, VIII, IX, X, and XI. Surgical histopathology demonstrated mature adipocytes, consistent with lipoma. Two years after surgery, the patient remains free of facial nerve symptoms. Cerebellopontine angle lipomas are rare lesions of the skull base and are reliably diagnosed with T1-weighted and fat suppression magnetic resonance sequences, which we recommend in the routine radiologic workup of CPA tumors. Accurate preoperative diagnosis is crucial because most CPA lipomas should be managed conservatively. Partial surgical resection is indicated only to alleviate intractable cranial neuropathies or relieve brainstem compression.

[Epidemiologic studies of cerebellopontine angle tumors surgically treated in Maracaibo, Venezuela, in 1985-1999]

OBJECTIVE

To analyze the epidemiological, clinical and neuropathological data of cases of cerebellopontine angle (CPA) tumors.

MATERIAL AND METHODS

The clinical records, neuroimaging and neuropathological studies of 50 patients with diagnosis of CPA tumor operated in different hospitals of Maracaibo, Venezuela, during the lapse January 1st, 1985-December 31, 1999 were reviewed. The variables age, gender, side of the lesion and neuropathological diagnosis were analyzed.

RESULTS

A 2:1 female to male ratio was observed. Median age was 48 +/- 12.7 years. Acoustic neuromas (AN) represented 48% of the cases, whereas nonacoustic neuroma tumors (NANT) made up for the rest (52%). Meningiomas were the second more commonly diagnosed lesions, they constituted 32% of the cases. Meningiomas and AN were more frequent in women, their ratios being 7:1 and 1.6:1, respectively. In 60% of the cases the signs and symptoms became eloquent in patients of the fourth and fifth decades of life.

CONCLUSIONS

The difference between our results and the ones previously reported in the medical literature are due in part to the predominance of female patients in our series. Endocrinologic, genetic and biochemical factors could also be responsible; nevertheless, this does not constitute the objective of the present study.

Cerebellopontine angle meningioma with a high jugular bulb

A cerebellopontine angle meningioma originating from the skull base over a high jugular bulb is quite rare. We report a case of a 68-year-old woman who had a right cerebellopontine angle meningioma with a prominent high jugular bulb. CT and MRI revealed a round tumour which attached to a bony prominence over the high jugular bulb. The apex of the jugular bulb was 3 mm higher than the floor of the internal auditory canal. The tumour was removed via a suboccipital retrosigmoid approach. The bony projection was drilled off carefully using a diamond drill; the jugular bulb became visible through the thinned bone. When a meningioma of this type is removed including bony changes, special attention is needed to avoid injury to the jugular bulb.

Clinical features and outcomes in patients with non-acoustic cerebellopontine angle tumours

OBJECTIVES

Non-acoustic tumours of the cerebellopontine angle differ from vestibular schwannomas in their prevalence, clinical features, operative management, and surgical outcome. These features were studied in patients presenting to the regional neuro-otological unit.

METHODS

A retrospective analysis of clinical notes identified 42 patients with non-acoustic tumours of the cerebellopontine angle. Data were extracted regarding presenting clinical features, histopathological data after surgical resection, surgical morbidity and mortality, and clinical outcome (mean 32 months follow up).

RESULTS

The study group comprised 25 meningiomas (60%), 12 epidermoid cysts/cholesteatomata (28%), and five other tumours. In patients with meningiomas, symptoms differed considerably from patients presenting with vestibular schwannomas. Cerebellar signs were present in 52% and hearing loss in only 68%. Twenty per cent of patients had hydrocephalus at the time of diagnosis. After surgical resection, normal facial nerve function was preserved in 75% of cases. In the epidermoid group, fifth, seventh, and eighth nerve deficits were present in 42%, 33%, and 66% respectively. There were no new postoperative facial palsies. There were two recurrences (17%) requiring reoperation. Overall, there were two perioperative deaths from pneumonia and meningitis.

CONCLUSIONS

Patients with non-acoustic lesions of the cerebellopontine angle often present with different symptoms and signs from those found in patients with schwannomas. Hearing loss is less prevalent and cerebellar signs and facial paresis are more common as presenting features. Hydrocephalus is often present in patients presenting with cerebellopontine angle meningiomas. Non-acoustic tumours can usually be resected with facial nerve preservation.

Cerebellopontine angle lipoma: case report

Lipomas of the cerebellopontine angle are rare, although well described in the literature. A review of the literature with an emphasis on pathogenesis and management is presented.

Trigeminal involvement in intracranial tumours. Anatomical and clinical observations on 73 patients

Neoplastic involvement of the trigeminal nerve was observed in 73 patients operated on in our institution for extra-axial tumours of the posterior and middle cranial fossae. It was defined as contact, compression, or infiltration. The nerve root was involved in 58 patients, the ganglion and/or the peripheral divisions in 9, all portions of the Vth nerve system in 6. A clinical trigeminal dysfunction was present in 44 patients (60%). Anatomico-surgical findings are correlated with clinical features and with tumour type. Typical trigeminal neuralgia was the complaint in 7 subjects; all of them presented an involvement of the sensory root. Post-operatively, 11 patients were relieved of their symptoms. The outcome is correlated with the anatomical findings and with the extent of surgical removal of the tumours. The importance of a careful evaluation of patients with trigeminal symptomatology is stressed.