Cavernous angiomas of the internal auditory canal A case report and review of literature

Summary Cavernous angiomas of the internal auditory canal (IAC) are rare. They are angiographically occult; and because the clinical symptoms are similar both in intracanalicular cavernous angiomas and acoustic tumors it had been difficult to differentiate pre-operatively both of these pathologies until the advent of magnetic resonance imaging (MRI). Even nowadays the correct diagnosis may be missed if the patient is imaged only with gadolinium enhanced MRI without prior obtaining a non-contrast MRI. These diagnostic difficulties are illustrated by the report of a related case. The importance of thorough neuroradiological investigations stressed and MRI features, surgical management and relevant literature concerning the cavernous angiomas of the internal auditory canal are discussed.     

Cavernous hemangiomas of the internal auditory canal

Cavernous hemangiomas are vascular malformations that are seldom found in the central nervous system. Four cavernous hemangiomas of the internal auditory canal and one of the cerebellopontine angle have been reported previously. We present a series of seven (six of which have never been reported) cavernous hemangiomas limited primarily to the internal auditory canal. Whereas all cases but one had marked unilateral sensorineural hearing loss, only two had preoperative facial nerve dysfunction. There are no specific symptoms or physical or audiometric findings to differentiate cavernous hemangiomas from acoustic neuromas. However, a hemangioma should be suspected when facial paralysis is present in conjunction with a small intracanalicular tumor as demonstrated by computed tomography or magnetic resonance imaging. The former reveals calcium stippling in the lesions, whereas magnetic resonance imaging reveals a high signal intensity on both T1- and T2-weighted images.     

Cavernous malformation of the internal auditory canal

Summary Cavernous malformations of the internal auditory canal are a rare clinical entity that, however, should be considered in the differential diagnosis of intracanalicular masses. Even though this type of malformation is usually associated with an evident gadolinium enhancement at MR examination, in some patients, like in this case, the signal characteristics may be not sufficiently specific to allow the correct preoperative diagnosis. Nevertheless, the clinical history, in particular, a rapid onset of cranial nerve deficits, lead to the suspicion of a vascular malformation.     

Cavernous angiomas of the brain

Summary Fourteen cases of cerebral cavernous angiomas are reported and the literature pertaining to the subject is reviewed. Some of these rare malformations remain asymptomatic throughout life, some give rise to symptoms (epileptic seizures with or without haemorrhage or slowly evolving focal nervous deficits) which usually appear in adult life. Precise pre-operative diagnosis is difficult, as at angiography they most often appear as avascular space-occupying lesions. Surgical removal is easy in most cases, and the operative outcome is good.     

Meningiomas of the internal auditory canal

OBJECTIVE: Meningiomas arising primarily within the internal auditory canal (IAC) are notably rare. By far the most common tumors that are encountered in this region are neuromas. We report a series of eight patients with meningiomas of the IAC, analyzing the clinical presentations, surgical management strategies, and clinical outcomes. METHODS: The charts of the patients, including histories and audiograms, imaging studies, surgical records, discharge letters, histological records, and follow-up records, were reviewed. RESULTS: One thousand eight hundred meningiomas were operated on between 1978 and 2002 at the Neurosurgical Department of Nordstadt Hospital. Among them, there were 421 cerebellopontine angle meningiomas; 7 of these (1.7% of cerebellopontine angle meningiomas) were limited to the IAC. One additional patient underwent surgery at the Neurosurgical Department of the International Neuroscience Institute, where a total of 21 cerebellopontine angle meningiomas were treated surgically from 2001 to 2003. As a comparison, the incidence of intrameatal vestibular schwannomas during the same period, 1978 to 2002, was 168 of 2400 (7%). There were five women and three men, and the mean age was 49.3 years (range, 27-59 yr). Most patients had signs and symptoms of vestibulocochlear nerve disturbance at presentation. One patient had sought treatment previously for total hearing loss before surgery. No patient had a facial paresis at presentation. The neuroradiological workup revealed a homogeneously contrast-enhancing tumor on magnetic resonance imaging in all patients with hypointense or isointense signal intensity on T1- and T2-weighted images. Some intrameatal meningiomas showed broad attachment, and some showed a dural tail at the porus. In all patients, the tumor was removed through the lateral suboccipital retrosigmoid approach with drilling of the posterior wall of the IAC. Total removal was achieved in all cases. Severe infiltration of the facial and vestibulocochlear nerve was encountered in two patients. There was no operative mortality. Hearing was preserved in five of seven patients; one patient was deaf before surgery. Postoperative facial weakness was encountered temporarily in one patient. CONCLUSION: Although intrameatal meningiomas are quite rare, they must be considered in the differential diagnosis of intrameatal mass lesions. The clinical symptoms are very similar to those of vestibular schwannomas. A radiological differentiation from vestibular schwannomas is not always possible. Surgical removal of intrameatal meningiomas should aim at wide excision, including involved dura and bone, to prevent recurrences. The variation in the anatomy of the faciocochlear nerve bundle in relation to the tumor has to be kept in mind, and preservation of these structures should be the goal in every case.     

Cavernous angiomas of the spinal cord

Five cases of histologically verified cavernous angiomas of the spinal cord are reported. Acute lower-extremity sensory disturbance was the initial symptom in four patients, and one presented with weakness of the hand. Progressive neurological deficit occurred in all patients, but the clinical course and outcome were extremely variable. Myelography revealed an intramedullary lesion in two cases but was completely normal in three; magnetic resonance imaging was diagnostic in these patients. Subtotal removal was accomplished in two cases, and myelotomy and biopsy were carried out in three. Four of the cavernous angiomas were located in the cervicothoracic region, whereas one was found in the thoracolumbar cord. All of the patients exhibited characteristic gross and microscopic features as well as hemosiderin-laden macrophages indicating remote hemorrhage. The diagnostic, therapeutic, and prognostic implications of this rare condition are discussed.     

Cavernous angiomas of the lateral ventricles

Background  Cavernous angiomas are vascular malformations which rarely involve the cavities of the lateral ventricles. Knowledge of the specific clinical and neuroradiological features displayed by these lesions is limited by the scarcity of patients included in the reported series. Objective and methods  The aim of this study was to compile and analyse the epidemiological, clinical, neuroradiological and surgical characteristics of these lesions as provided by the well-described examples reported in the scientific literature. A total of 49 were gathered, including three patients operated on recently in our Department. Findings and conclusions  Cavernomas developing within the ventricular cavities attain a larger size than parenchymal counterpart lesions, causing symptoms and signs derived mainly from the mass effect. The characteristic parenchymal hypointense rim is less frequently identified on T2-weighted echo-gradient MRI sequences. Total surgical excision is the treatment of choice for these lesions, yet the surgical routes employed may still be associated with a high rate of neurological complications.     

Vascular lesions of the internal auditory canal

We report here two cases of vascular tumors arising within the internal auditory canal, both of which presented with cerebellopontine angle symptoms and simulated acoustic neurinomas. The first case was an arteriovenous malformation that caused moderate sensorineural hearing loss, tinnitus, vertigo with lateropulsion, facial weakness, and trigeminal hypoesthesia on the same side. The second case was a venous angioma, to our knowledge the first ever reported in this location, which presented with sudden complete deafness and progressive hemifacial spasm. The latter subsided completely after successful total extirpation of this unique tumor. The literature on these extremely rare lesions is also reviewed.     

Infralabyrinthine approach to the internal auditory canal

Multiple surgical procedures have been developed to expose the contents of the internal auditory canal. These include the middle fossa approach, the posterior fossa approach, the retrolabyrinthine approach, and the retrosigmoid approach. Each has its own unique benefits, as well as disadvantages. A new posterior-inferior approach to the internal auditory canal (the infralabyrinthine approach) has been developed. This approach affords exposure of at least the medial half of the internal auditory canal while remaining extradural and extralabyrinthine. By dissecting below the posterior semicircular canal, and remaining extradural, hearing is preserved. The dissection can proceed far enough laterally in the internal auditory canal to separate the cochlear and vestibular nerve divisions. Further anatomic considerations, as well as clinical applicability, will be discussed.     

Postoperative MR findings in acoustic neuromas: nerve edema within the internal auditory canal

Postoperative MR findings of eleven acoustic neuromas were analyzed. MRI's were able to clearly visualize residual tumor around the 7th and 8th cranial nerves that were left to preserve cranial nerve function, although conventional X ray CT scans often failed to detect it due to artifacts in the parapetrous area. The facial nerves preserved during operations were also visualized from their brainstem portion to the internal auditory meatus. These findings indicate that MRI is excellent in delineating soft tissue in the CP angle that would be overlooked by conventional X ray CT scan. It was also found that the nerve bundles within the internal auditory canal gained increased signal intensity on the T1 and proton weighted images after surgical interventions and that this effect extended into the most distal end of the nerve bundles and even into the intracochlear portion of the cochlear nerve. The nerve bundles with increased signal intensity were conspicuously enhanced after intravenous administration of Gd-DTPA. This indicated that the blood nerve barrier of the nerves within the internal auditory canal were disrupted due to the surgical manipulations in excising tumors. Following such surgical manipulations, nerve edema ensued, although manipulations in the cerebello-pontine angle were done carefully and protectively under a surgical microscope. The clinical significance of disruption of the blood nerve barrier and following nerve edema were discussed from the standpoint of preservation of the 7th and 8th cranial nerve functions.     

Lipoma of internal auditory canal.

Lipoma of the internal auditory canal is a rare tumor. Clinically, it presents like an acoustic tumor. The diagnosis can be made with the use of a magnetic resonance imaging showing a high intensity on T1- and low intensity on T2-weighted image with no enhancement. Pathologically, this is a soft, smooth, yellow tumor with some fat in it that can resemble grossly any acoustic tumor. The lipoma is intermixed with the eighth nerve and can be adherent to adjacent structures. The growth of a lipoma can be slower than an acoustic tumor. A patient diagnosed with lipoma of the internal auditory canal can often have quite good hearing. As an alternative to surgical removal, another therapeutic option is to watch the growth of the lipoma with periodic magnetic resonance imaging, probably on a yearly basis initially.     

Cavernous angiomas of the central nervous system

The histopathological, epidemiological, clinical and neuroradiological findings of the cavernous angiomas of the central nervous system have been reviewed, based on an analysis of the literature. C.A. was considered a very rare lesion in the pre-CT era (5% of the vascular malformations). In the past mainly the cavernous angiomas operated on were responsible for a hemorrhagic syndrome or a space-occupying lesion syndrome and less frequently did they present with seizures. Since the introduction of the CT and moreover of MRI the reported cases of cavernous angiomas in the C.N.S. have increased considerably (25.1% of the vascular malformations). Familial cases, multiple localizations, association with tumors and other vascular malformations and extracerebral dural localizations have been documented. Angiographic examination can be negative, but in some cases a capillary blush in the late venous phase has been demonstrated. CT scan and MRI are the best procedures for the diagnosis of cavernous angiomas. MRI is able to demonstrate small and no recent traces of bleeding, but CT is more sensitive in distinguishing calcifications. Surgical results depending on the site of the angioma have been reported. Radical removal and good recovery have been documented in supratentorial cases, while partial removal and poor results have been reported in deeply sited cases (including spinal cord).     

Cavernous hemangioma of the internal auditory canal encasing the VII and VIII cranial nerve complex: case report and review of the literature

Cavernous angiomas originating in the internal auditory canal are very rare. In the available literature, only 65 cases of cavernomas in this location have been previously reported. We describe the case of a 22-year-old woman surgically treated for a cavernous hemangioma in the left internal auditory canal, mimicking on preoperative magnetic resonance imaging MRI an acoustic neuroma. Neurological symptoms were hypoacusia and dizziness. The cavernous angioma encased the seventh and, partially, the eighth cranial nerve complex. A “nearly total” removal was performed, leaving a thin residual of malformation adherent to the facial nerve. Postoperative period was uneventful; hearing was unchanged, but the patient had a moderate inferior left facial palsy (House-Brackmann grade II) slightly improved during the following weeks. On the basis of the observation of this uncommon case, we propose a revision of the literature and discuss clinical features, differential diagnosis, and treatment.     

Evaluation of the internal auditory canal with virtual endoscopy.

OBJECTIVE: Three-dimensional imaging can improve the understanding and comprehension of complex anatomy. Recent advances in software development allow the construction of a virtual endoscopic view of anatomic structures. This report applies virtual endoscopic capabilities to imaging of the internal auditory canal. STUDY DESIGN, SETTING, AND PATIENTS: We conducted a retrospective case review at a tertiary referral center of patients with abnormal internal auditory canal anatomy on computed tomography. INTERVENTIONS: Computed tomography images were obtained using conventional clinical algorithms involving multiple, 1-mm-thick slices through the temporal bone. Three-dimensional reconstructions were made using General Electric Advantage Windows Navigator software. The virtual endoscopic image-processing algorithm used selected image intensity threshold levels to visualize internal auditory canal anatomy from an endoscopic perspective. RESULTS: Eleven cases of abnormalities of the internal auditory canal were retrospectively identified. Clinical applications using the virtual endoscopic images are presented. The virtual endoscopic images supported prior clinical decision making in 6 of the 11 cases evaluated. CONCLUSION: This technique shows promise for the diagnosis, surgical planning, and teaching of temporal bone anatomy. Usefulness is dependent on acquisition parameters and clinical indications for examination.