Cerebellopontine Angle Syndrome Research Articles

893 Posterior Location of the Facial Nerve in Vestibular Schwannoma: Report of a Rare Case and a Brief Literature Review

Abstract Background The commonest location of the facial nerve on the surface of a vestibular schwannoma (VS) is ventral. The posterior location of the facial nerve on the surface of a VS is extremely rare and is reported to be between 0.6-3.8%. In this illustrative case report, we present a case of a large VS with posterior location of the facial nerve on its surface. The surgical strategy in this situation to preserve the facial nerve both anatomically and physiologically is discussed. Ours is the first illustrative case of the posterior location of the seventh nerve on these tumours. Case Description An elderly man presented with right cerebellopontine (CP) angle syndrome. MRI showed a partly cystic and partly solid right CP angle lesion extending to the internal auditory meatus. Electrophysiological stimulation of the tumour showed that the facial nerve was located on the posterior surface of the tumour. Under the microscope, the facial nerve was identified on the posterior surface of the tumour. Partial excision of the tumour was done with preservation of the facial nerve both anatomically and physiologically. Conclusions This case reiterates the fact that even though rare, surgeons should anticipate the posterior location of the facial nerve on the surface of VS. Electrophysiological stimulation of the posterior surface of the tumour should be done before tumour resection in all cases to look for the posterior location of the facial nerve. Careful microsurgical dissection should be done to achieve maximal cytoreduction of the tumour, preserving the facial nerve.

Surgical Clipping of a Ruptured Distal Anterior Inferior Cerebellar Artery Aneurysm: A Technical Note.

Aneurysms of the distal anterior inferior cerebellar artery (AICA) are uncommon. They can present with subarachnoid hemorrhage (SAH), cerebellopontine angle syndrome, or a combination of the two. We describe the technique and nuances of microsurgical clipping of a ruptured distal AICA aneurysm using a retrosigmoid approach.After performing the craniotomy, the AICA was exposed in a distal to proximal fashion and the aneurysm and the proximal parent vessel were identified. After establishing proximal control, a clip was placed across the neck of the aneurysm to obliterate it while maintaining flow within the parent vessel. Finally, the flow within the parent vessel was confirmed and the final clip position was checked to ensure that it was not compressing any of the cranial nerves in the vicinity. The aneurysm was completely obliterated, and the parent vessel remained patent.Distal AICA aneurysms are rare and challenging to treat. The retrosigmoid approach is commonly used to treat these aneurysms. Careful planning, which includes studying the vascular anatomy and the aneurysm characteristics, and proficient execution of the procedure can increase the safety and improve outcomes of surgical clipping of these aneurysms.

Primary Cerebellopontine Angle Melanocytoma: Review

Introduction Primary cerebellopontine angle melanocytomas (PCPAMs) are very rare. Their natural history and prognosis are not fully understood. We reviewed the literature and add a new case to analyze PCPAM's presentation, radiological features, and outcome of treatment.Methods We performed a literature review using Medline, Embase, PubMed, and Cochrane databases. We searched for melanocytoma, melanoma, and pigmented tumors in the posterior cranial fossa and CPA to identify PCPAM. We have also searched our institution's neuro-oncology database.Results We identified 23 PCPAM from the literature and one case of our own. The mean age at presentation was 44.4 years with slight male preponderance. PCPAM presented with cerebellopontine angle (CPA) syndrome with or without hydrocephalus. Preoperative diagnosis was difficult; they appeared hyperintense on T1 and isointense on T2 magnetic resonance imaging (MRI) and enhanced with gadolinium. However, the final diagnosis was only made by immunohistochemical examination. Total surgical resection of PCPAM was associated with prolonged survival while subtotal excision was associated with frequent recurrence.Conclusion PCPAM are very rare and should be considered in the differential diagnosis of all CPA lesions that appear hyperintense on T1 and isointense on T2 MRI images. Patients with PCPAM should undergo total surgical resection to avoid fatal recurrences.

Endolymphatic Sac Tumors

Tumors of the endolymphatic sac are rare and can be found in patients with Von Hippel Lindau disease. They most often develop within the intrapetrosal part of the sac but can sometimes be located in the distal part. Their growth is slow and they spread in two directions: laterally toward the external and middle ear and in the direction of the jugular foramen and medially into the ponto-cerebellar angle. The symptoms are usually auditive, with a constant neurosensorial deafness of sudden onset in 50 % of cases and sometimes associated with a tinnitus and dizziness. The varieties with medial extension result in a cerebellopontine angle syndrome. Diagnosis is made by imaging (CT scan and MRI) that reveals a heterogeneous tumor between the lateral sinus and the internal auditory meatus, hypervascularized showing contrast, with cystic zones and associated with bone lysis. Histological examination of a papillary cystadenoma is performed and the differential diagnosis is essentially made with a papillary of the choroïd plexus. They require total surgical excision in order to avoid possible recurrence and can be performed by retrosigmoïd approach, or more ideally, by transpetrosal approach.

Poster 25 Barriers to the Acute Rehabilitation of Patients With Cerebellopontine Angle Syndrome: A Case Series

Poster 25 Barriers to the Acute Rehabilitation of Patients With Cerebellopontine Angle Syndrome: A Case Series

Primary meningeal melanocytoma of cerebellopontine angle: A case report with 12 years follow up

The authors describe a case of cerebellopontine (CP) angle melanotic lesion in a 38-year-old man who presented with features of CP angle syndrome 12 years ago. Computed tomography scan showed a mass lesion in the left CP angle, which was excised. Biopsy was suggestive of melanoma due to abundance of melanin. After 12 years, he had local recurrence and was re-operated. On reviewing the previous and later biopsy, final diagnosis of melanocytoma was made because of additional finding of absence of mitosis and macronucleoli, which were overlooked in the previous biopsy. Awareness of this finding reduces the possibility of diagnostic error in melanotic tumors. Reliance on the presence of abundance of melanin as the sole criterion for diagnosing melanoma resulted in erroneous diagnosis in our case. The case is discussed in the light of available literature.

Imaging of cerebellopontine angle lesions: an update. Part 2: intra-axial lesions, skull base lesions that may invade the CPA region, and non-enhancing extra-axial lesions

Computed tomography (CT) and magnetic resonance (MR) imaging reliably demonstrate typical features of vestibular schwannomas or meningiomas in the vast majority of mass lesions responsible for cerebellopontine angle (CPA) syndrome. However, a large variety of unusual lesions can also be encountered in the CPA. Covering the entire spectrum of lesions potentially found in the CPA, these articles explain the pertinent neuroimaging features that radiologists need to know to make clinically relevant diagnoses in these cases, including data from diffusion- and perfusion-weighted imaging or MR spectroscopy, when available. A diagnostic algorithm based on the lesion's site of origin, shape and margins, density, signal intensity and contrast material uptake is also proposed. Non-enhancing extra-axial CPA masses are cystic (epidermoid cyst, arachnoid cyst, neurenteric cyst) or contain fat (dermoid cyst, lipoma). Tumours can also extend into the CPA by extension from the skull base (paraganglioma, chondromatous tumours, chordoma, cholesterol granuloma, endolymphatic sac tumour). Finally, brain stem or ventricular tumours can present with a significant exophytic component in the CPA that may be difficult to differentiate from an extra-axial lesion (lymphoma, hemangioblastoma, choroid plexus papilloma, ependymoma, glioma, medulloblastoma, dysembryoplastic neuroepithelial tumour).

CPA Melanoma

Melanoma rarely invades the cerebellopontine angle (CPA) and can evade accurate diagnosis, which may alter management decisions. Diagnosis may be facilitated via careful history, magnetic resonance imaging (MRI) findings, and cerebrospinal fluid (CSF) analysis. Retrospective case review. Tertiary referral center. Thirteen internal auditory canal/CPA lesions in eight patients who presented with CPA syndrome and who had a pathological diagnosis consistent with malignant melanoma. There were four bilateral and four unilateral lesions. Six of eight patients had a history of melanoma. One was apparently primary CPA lesion, whereas all others were metastatic. T1- and T2-weighted precontrast and postcontrast gadolinium-enhanced MRI were obtained, including fat suppression and fluid-attenuated inversion recovery sequence images in two patients; lumbar puncture with CSF centrifugation and cytological analysis confirmed the diagnosis in two patients. Translabyrinthine craniotomy was performed for tumor extirpation in five patients. Symptoms at presentation, MRI findings, presence of malignant cells in CSF, tumor progression, intraoperative findings, response to treatment, time interval from initial diagnosis of melanoma elsewhere, and survival. Seven of eight patients had history and/or MRI findings suggestive of malignancy in the internal auditory canal and/or CPA, and diagnosis was confirmed via CSF analysis in two patients. In one patient, diagnosis was made at surgery. Internal auditory canal melanoma portends a grim prognosis, can occur up to 17 years after initial melanoma diagnosis/treatment, and can be detected with appropriate MRI sequences, especially enhanced fluid-attenuated inversion recovery images. In disseminated cases, diagnosis can be confirmed with lumbar puncture demonstrating malignant cells. Management includes tumor resection when melanoma seems to be solitary and malignant cells are not present in CSF. Intrathecal chemotherapy and radiation are recommended for dissemination, although the survival rate is still poor.

Vaskuläre Ursachen des „Kleinhirnbrückenwinkel-Syndroms”?

The seventh and eighth cranial nerves course toward the internal auditory canal within the cerebellopontine angle. Lesions in this region are usually related to malfunctions of these cranial nerves. Although an acoustic schwannoma is one of the main etiologies of cerebellopontine angle pathology, various inflammatory processes and vascular anomalies even though rare must be considered. We describe 5 cases with vascular loops of the basilar or vertebral arteries as a possible cause for hearing loss, vertigo and pulsatile tinnitus. In two cases the vascular lesion was confirmed at surgery, in which a decompression procedure was performed. The work-up for each patient included an auditory test battery and electronystagmography. Imaging studies included MRI and angiography in two cases. Our experiences show that while the cerebellopontine angle syndrome is mostly caused by benign tumors an abnormal vascular loop has to be considered in any differential diagnosis.

A petrous bone artefact on MRI: technical note.

We report an artefact seen on MRI in a patient with a cerebellopontine angle syndrome due to an epidermoid cyst. Even minute nonferromagnetic metallic particles such as gold can cause large artefacts.

Cystic cavernous malformation of the cerebellopontine angle

A 46 year old male presented with a cerebellopontine angle syndrome. CT scan and MRI revealed a cystic mass with a solid nodule in the cerebellopontine angle. At surgery, a vascular lesion was encountered which was totally excised in two stages. The histopathology was consistent with that of a cavernous malformation. Only four such cases have been reported so far in the English literature. The clinical and radiological features and the surgical management are discussed.

Isolated Trigeminal Sensory Loss Secondary to a Distal Anterior Inferior Cerebellar Artery Aneurysm: Case Report

Abstract A previously healthy 25-year-old woman suddenly developed right-sided facial numbness and a headache. The neurological examination was within normal limits with the exception of meningismus and right-sided facial sensory loss. A computed tomographic scan and a magnetic resonance imaging study demonstrated an acute hematoma in the right cerebellopontine angle. A 4-vessel cerebral angiogram revealed no abnormalities. Posterior fossa exploration disclosed a large, partially thrombosed, fusiform anterior inferior cerebellar artery aneurysm, which indented the pons at the trigeminal root entry zone. The aneurysm was excised, and the patient made an excellent recovery. She was left with a persistent trigeminal sensory deficit. Anterior inferior cerebellar artery aneurysms are rare lesions that generally present with a cerebellopontine angle syndrome: occasionally, facial sensory loss is also a feature. Isolated trigeminal sensorv findings, as illustrated in this case, are extremely unusual in posterior fossa vascular lesions.

Isolated trigeminal sensory loss secondary to a distal anterior inferior cerebellar artery aneurysm

A previously healthy 25-year-old woman suddenly developed right-sided facial numbness and a headache. The neurological examination was within normal limits with the exception of meningismus and right-sided facial sensory loss. A computed tomographic scan and a magnetic resonance imaging study demonstrated an acute hematoma in the right cerebellopontine angle. A 4-vessel cerebral angiogram revealed no abnormalities. Posterior fossa exploration disclosed a large, partially thrombosed, fusiform anterior inferior cerebellar artery aneurysm, which indented the pons at the trigeminal root entry zone. The aneurysm was excised, and the patient made an excellent recovery. She was left with a persistent trigeminal sensory deficit. Anterior inferior cerebellar artery aneurysms are rare lesions that generally present with a cerebellopontine angle syndrome; occasionally, facial sensory loss is also a feature. Isolated trigeminal sensory findings, as illustrated in this case, are extremely unusual in posterior fossa vascular lesions.

Gangliocytoma of the cerebellum

A 31-year-old man presenting with a cerebellopontine angle syndrome underwent subtotal resection of a gangliocytoma of the left middle cerebellar peduncle. The tumor was positive for 68-kD neurofilament protein and vasoactive intestinal peptide. No glial cells were identified on immunohistochemical or ultrastructural examination. Electron microscopic study of neoplastic ganglionic cells revealed the presence of dense core vesicles, synaptic junctions, Hirano bodies, and marked dystrophic changes in the neuritic processes. The nosology of this lesion is discussed. Similarities between the morphological changes shown by mature neoplastic ganglion cells and comparable structural alterations seen in the physiological senescence of nonneoplastic neurons are stressed. (Neurosurgery 22:576-581, 1988)

聴神経しゅようと類似の症状を呈した脳幹しゅよう３例

Three patients with brainstem neoplasms had cerebellopontine angle symptoms and unilateral cerebellopontine angle shadows on conventional CT scans. As there were involved facial, acoustic and trigeminal nerves in clinical symptoms, cerebellopontine angle syndrome was diagnosed and acoustic tumor was suspected. Otoneurological tests showed unilateral perceptive deafness with retrocochlear lesions, and the gaze test showed Bruns-Cushing type nystagmus.In 19 patients with brainstem lesions, the ABR test results were all abnormal: loss of each component in 74% and prolonged latency of wave V in 24%. Most of the ABR test results in cases of intramedullary lesions with space-occupying effects in the brainstem were abnormalities in the presence and latency of wave V. It is concluded that the ABR test is helpful in determining the sites of intrinsic brainstem lesions.

Investigation of patients presenting with cerebellopontine angle syndromes

Many neuroradiological procedures are available for the elucidation of lesions presenting with clinical evidence of a cerebellopontine angle syndrome. For 10 years we have favoured plain skull rays, sometimes supplemented by gamma encephalography, followed by angiography and have uncommonly needed further information from other contrast studies before operation. The innocuous value of computed tomography (C.T.) made it necessary to consider modification of this routine which had been found to be very satisfactory in routine practice. To obtain precise information on the diagnostic reliability and complications of the method we reviewed a large consecutive series of patients presenting with angle lesions. The radiological signs in such cases have been described many times and are well known, but our findings in a single comprehensive series emphasize the value of the method and are presented in a review. The modifications induced by CT are discussed.

Clinical significance of visual fixation upon caloric nystagmus-caloric pattern test- (author's transl)

The effect of opening of the eyes and of ocular fixation upon caloric nystagmus has been routinely tested in our neurotological assessment of patients since 1974. All cases who showed a sign of FFS (Failure of Fixation-Suppression of Caloric Nystagmus) were found to have central nervous 'system '.lesions, especially posterior fossa lesions. From an analysis of caloric nystagmus with the sign of FFS, patterns of FFS were classified into the following three types. Type I Visual fixation failed to suppress caloric nystagmus to both directions. In this type, diffuse involvement of the central nervous system such as cerebellar degeneration, organic mercurials intoxication and myoclonus epilepsy was included. Type II : Visual suppression of caloric nystagmus could not be observed on either side regard-less of water temperature applied as caloric' stimuli. In this type, cerebellopontine angle syndrome such as acoustic tumor, meningioma, epidermoid and arachnoiditis was included. Type III: Visual fixation failed to suppress caloric nystagmus to either direction depending upon caloric stimuli. In this type, vascular disorder, head trauma and unilaterally located tumor of the cerebellar hemisphere were included. On the basis of our clinical data classified above, underlying neuroanatomical mechanism was discussed.

Neurocysticercosis: infrequent clinical forms. II. Cerebellopontile angle forms

A localização de cisticercos no recesso lateral da cisterna pontina poderá levar à constituição de uma síndrome do ângulo pontocerebelar, simulando eventualmente um neurinoma do acústico. São revistos os casos dessa forma clínica de neurocisticercose descritos na literatura. O problema do diagnóstico diferencial com os tumores (neurinomas) do acústico é discutido sob os pontos de vista clínico e radiológico. Os autores apresentam 7 casos de cisticercose do ângulo pontocerebelar. O diagnóstico etiológico foi estabelecido pela positividade da reação de fixação do complemento para cisticercose no liqüido cefalorraqueano em 5 casos e, em 2, pela cirurgia e/ou necropsia. Em todos os pacientes havia sintomas de lesão coclear, bilaterais em 2; lesão vestibular foi comprovada em 4 casos. Em 6 pacientes ocorreram sinais indicativos de lesão unilateral do nervo trigêmeo. Comprometimento do nervo facial foi observado em 4 casos. Existia faringoplegia em 3 casos e estrabismo interno em 2. Em 3 casos não foram observados sinais cerebelares, o que faria com que o diagnóstico propendesse para o de tumor do acústico, não fôssem outras características clínicas e subsidiárias. A síndrome de hipertensão intracraniana era nítida em 5 pacientes. Convulsões ocorreram em 2 casos. A propósito do resultado dos exames radiológicos, os autores salientam que, num dos casos, foi verificada amputação da ponta do rochedo ipsolateral à síndrome do ângulo pontocerebelar; outros comemorativos do caso levaram, porém, a rejeitar a hipótese de tumor (neurinoma) do acústico, tendo a cirurgia comprovado o acêrto do diagnóstico clínico.