Vestibular schwannoma: role of conservative management.

OBJECTIVE: To assess the outcome of conservative management of vestibular schwannoma. STUDY DESIGN: Observational study. SETTING: Tertiary referral centre. PATIENTS: Four hundred and thirty-six patients with vestibular schwannoma (490 tumours), including 327 sporadic tumours and 163 tumours in 109 patients with neurofibromatosis type two. MAIN OUTCOME MEASURES: The relationship of tumour growth to tumour size at presentation, and to certain demographic features. RESULTS: The initial tumour size was significantly larger in the neurofibromatosis type two group (11 mm) than in the sporadic vestibular schwannoma group (5.1 mm). In both groups, 68 per cent of tumours did not grow during follow up (mean 3.6 years; range one to 14 years). The mean growth rate was 1.1 mm/year (range 0-15 mm/year) for sporadic tumours and 1.7 mm/year (range 0-18 mm/year) for neurofibromatosis type two tumours. The tumour growth rate correlated positively with tumour size in the sporadic tumour group, and correlated negatively with age in the neurofibromatosis type two group. CONCLUSION: Two-thirds of vestibular schwannomas did not grow. Radiological surveillance is an acceptable approach in carefully selected patients. Once a sporadic vestibular schwannoma reaches 2 cm in intracranial diameter, it is likely to continue growing. We do not recommend conservative management for sporadic tumours with an intracranial diameter of 1.5 cm or more. Vestibular schwannoma management is more complex in patients with neurofibromatosis type two.

Imaging appearances of unusual conditions of the middle and inner ear.

Requests for imaging of patients complaining of deafness and other symptoms related to the petrous bone are becoming increasingly common. Although much of this work is related to the exclusion of vestibular schwannomas by MRI, high-resolution CT is available in most departments and is necessary for the evaluation of many conditions of the middle ear and bony labyrinth. In this pictorial review, some of the more unusual conditions that may be encountered in the middle and inner ear are presented, which might not be overly familiar to non-otological radiologists, illustrating the roles of CT and MRI.

Stenosis of the internal auditory meatus masquerading as bilateral vestibular schwannomas: a cautionary tale.

Stenotic malformations of the internal auditory meatus (IAM) are rare. They are known to symptomatically mimic vestibular schwannomas leading to potential diagnostic error. We present a case (along with literature review) where a stenotic IAM was clinically and radiologically misdiagnosed as a vestibular schwannoma.

Metastatic carcinoma mimicking a facial nerve schwannoma: the role of computerized tomography in diagnosis.

Secondary deposits in the temporal bone are uncommon but well recognized. Such tumours may involve the facial nerve by direct extension of the destructive process into the fallopian canal. We present a rare case of metastasis from a breast carcinoma in the facial nerve itself, involving the nerve in the internal acoustic meatus with extension into the labyrinthine segment, the first genu and into the middle-ear segment. The rest of the temporal bone was not involved. The lesion resembled a facial schwannoma on a routine magnetic resonance (MR) image. The diagnosis was confirmed after a post-operative computed tomography (CT) scan showed another separate secondary deposit in the basisphenoid. Histology was consistent with secondary tumour from a breast carcinoma. The case highlights the importance of keeping a high degree of suspicion for metastatic tumours in patients with a previous history of malignancy and the usefulness of CT scan in the evaluation of such cases.

Magnetic resonance imaging in the investigation of sensorineural hearing loss: is contrast enhancement still necessary?

High resolution T2-weighted magnetic resonance (MR) imaging has been proposed as a rapid, inexpensive means of investigating patients with sensorineural deafness, particularly to exclude vestibular schwannomas. Whether the accepted 'gold standard' of contrast-enhanced T1-weighted images can be omitted, however, remains controversial. Over a 22-month period the use of axial turbo-spin echo T2-weighted images (T2W) were prospectively compared with contrast-enhanced T1-weighted spin echo scans in the evaluation of 513 patients presenting with audiovestibular symptoms. A 2-D T2W turbo spin echo (TSE) sequence with 3 mm slices was used in 340 patients while a 3-D sequence with overlapping 1 mm slices was used in 173 patients. The T2-weighted image findings were documented and subsequently compared with contrast-enhanced images. With the 2-D sequence 24 patients (25 lesions) had internal auditory meatus (IAM)/cerebello-pontine angle (CPA) masses identified by contrast-enhanced T1-weighted images, all of which were seen on the T2-weighted TSE sequence; there was one false positive 'mass' on the T2-weighted scans and one false negative case of IAM dural enhancement on T1-weighted imaging; six were considered normal initially on the T2-weighted images although three were subtly abnormal in retrospect. With the 3-D sequence three acoustic neuromas were all identified correctly with no false positive and only one false negative result (labyrinthitis). The 2-D and 3-D images were judged technically inadequate for clinical assessment in 15 and nine per cent respectively. We conclude that mass lesions of the IAM/CPA can be reliably identified on T2W TSE imaging but labyrinthine lesions may be missed without contrast enhancement. This is of particular importance in planning the management of neurofibromatosis type 2. Non-neoplastic disorders of the inner ear are also likely to be missed.

Imaging of temporal bone brain hernias: atypical appearances on magnetic resonance imaging.

Brain tissue with or without its dural covering may protrude into the temporal bone through a defect in the tegmen tympani. Infection or granulation tissue, with or without cholesteatoma may make diagnosis difficult. While computed tomography (CT) may demonstrate a bony defect, it is difficult to distinguish between herniated brain, cholesteatoma or granulation tissue. Magnetic resonance imaging (MRI) clearly demonstrates healthy herniated brain tissue, but ischaemic or necrotic elements may mimic other lesions. We present a series of five patients with brain hernia, highlighting the spectrum of preoperative radiological appearances, and some of the difficulties encountered in interpreting these images. MRI demonstrated herniation of healthy brain in two patients but in three, showed irregular soft tissue with signal characteristics consistent with cholesteatoma. Surgery in these three patients demonstrated necrotic brain with coexisting cholesteatoma in two. Brain hernias are often necrotic and may have morphological and signal characteristics similar to cholesteatoma with which they may coexist.

Imaging in neurofibromatosis type 2: screening using magnetic resonance imaging.

NF2 is a distinct entity characterized by bilateral eighth-nerve schwannomas, other intracranial schwannomas and meningiomas, and multiple spinal canal schwannomas, meningiomas and gliomas. Screening of the entire neural axis is mandatory because of the incidence of asymptomatic lesions. MRI is the technique of choice, particularly employing contrast-enhanced, T1-weighted sequences in multiple image planes.

Primary tumours of the vestibule and inner ear.

Seven primary tumours of the vestibule and inner ear are described, six schwannomas and one traumatic fibroma. Schwannomas in this situation may occur as sporadic tumours, or may be a feature of neurofibromatosis type 2 (NF-2). In the latter condition they may occur in isolation or in association with, but separate from, schwannomas arising in the internal meatus. Direct extension into the vestibule of an intrameatal vestibular schwannoma is well reported, but extension of an intravestibular tumour into the internal meatus is not described. Traumatic fibromas of the vestibule are rare and the trigger could be an attack of labyrinthitis. Intravestibular tumours, although rare, are likely to be diagnosed with increasing frequency with the widespread use of MR imaging.

Transient global amnesia and cortical blindness after vertebral angiography: further evidence for the role of arterial spasm.

We describe a series of six patients who experienced severe retrograde amnesia (five cases) or cortical blindness (one case) during selective vertebral angiography. All angiograms were obtained with the same nonionic contrast medium. Analysis of the contrast batch demonstrated no abnormalities, but investigation of the angiographic suite revealed a faulty contrast warming cabinet resulting in injection of contrast material above body temperature. The warming cabinet was withdrawn, and the complication has not recurred. We believe that these symptoms reflect ischemia caused by vertebral arterial spasm.

Facial palsy after glomus tumour embolization.

A case is presented of a patient undergoing pre-operative embolization of a glomus tumour who developed a facial palsy one hour after embolization. At the time of surgery it was found to be due to the embolization material (polyvinyl alcohol foam) blocking the stylomastoid artery. The blood supply of glomus tumours and the variations in the blood supply of the facial nerve are discussed.

The callosal-septal interface lesion in multiple sclerosis: effect of sequence and imaging plane.

We examined the effect of imaging plane and sequence on the demonstration of lesions at the callosal-septal interface (CSI) by magnetic resonance imaging in 20 patients with known multiple sclerosis. Variable-echo-(VE) T2- and proton density (PD) weighted images were performed in coronal axial and sagittal planes. Sagittal gradient echo (GE) T2- and PD-weighted images were also performed. Lesions at the CSI were seen in all patients and were all demonstrated on both sagittal and coronal VE images. Sagittal PD-weighted GE images were slightly less sensitive but showed good overall agreement with sagittal VE. Axial VE and sagittal T2-weighted GE images demonstrated CSI lesions poorly.

Case report: diagnosis of metastatic leptomeningeal melanoma by contrast enhanced MRI.

A case of leptomeningeal melanoma metastases with a confusing clinical picture is presented. Despite repeated cytological examinations of the cerebrospinal fluid proving negative, the diagnosis was eventually made by magnetic resonance imaging with gadolinium DTPA enhancement.

The fate of tumour rests following removal of acoustic neuromas: an MRI Gd-DTPA study.

The fate of capsular fragments left attached to vital structures at the time of otherwise total tumour removal was studied in 14 of 21 such patients who underwent acoustic neuroma surgery. Imaging using magnetic resonance Gd-DTPA at post-operative intervals of 6 months-12 years (mean 70 months) showed evidence of persistent tumour in half the patients. None of the patients had developed new symptoms and computed tomography had failed to demonstrate tumour recurrence. Persistence of the tumour was more likely if the residual fragments were not cauterized at the time of operation. Four of the seven persisting tumour rests showed evidence of gradual enlargement. The implications for patient management, particularly if an attempt is made to preserve hearing, are discussed.

The role of epidural fibrosis and defective fibrinolysis in the persistence of postlaminectomy back pain.

Clinical features, contrast-enhanced lumbar tomographic findings, and biochemical plasma fibrinolytic parameters were critically assessed in 70 patients suffering severe, chronic postsurgical low-back and radicular pain to determine the cause of their persisting symptoms. Patients exhibited gross functional disability and significant impairment of plasma fibrinolytic activity, compared with 84 normal control subjects. This fibrinolytic defect appeared attributable to disproportionate increases in circulating plasminogen activator inhibitor-1 levels. Clinical features were slightly worse in patients with radiologic epidural fibrosis, whereas the frequency of radiologic abnormalities, including epidural fibrosis, was higher in patients with fibrinolytic abnormalities. The results, however, demonstrated no significant associations between patients' symptoms and signs and their biochemical and radiologic abnormalities.

Gas in a spinal extradural cyst. Case report.

This case report describes a patient with sciatica resulting from lumbar root compression by a gas-containing cyst in the extradural space. Removal of the cyst provided prompt relief. The origin and anatomic distribution of gas collections in the spine are considered based on a review of the literature.

Dynamic low-dose three-dimensional computed tomography: a preliminary study.

Three-dimensional (3D) computed tomographic reformations have been used successfully as an adjunct to standard axial computed tomography (CT) in the evaluation of disorders affecting areas of complex anatomy. The basic requirements for high-quality 3D reformations are an absence of patient movement and narrow-width transaxial sections. Speed of examination is an important factor in optimizing image quality. One hundred examinations were performed on an IGE CT 9800 scanner. For bone studies, 80 mAs and, for certain soft tissues, 140 or 200 mAs were employed with 120 kVp. The advantages of such a "low-dose" technique are significant reduction in patient skin dose and a faster examination. The main disadvantage is a reduction in signal-to-noise ratio. The image quality obtained in 3D presentations has nevertheless been sufficient to enable all bony abnormalities to be identified. Three-dimensional examinations are now being performed routinely using a dynamic mode and this "low-dose" technique.