Role of magnetic resonance imaging in the diagnosis of bilateral facial paralysis.

Bilateral facial paralysis (BFP) is a rare clinical finding that may be caused by Guillain-Barré syndrome, a medical emergency. The differential diagnosis of BFP is lengthy but can be narrowed to a limited group of disorders by the patient's history and physical examination. The most important diagnostic tests to obtain initially are the lumbar puncture and magnetic resonance imaging (MRI) scan with gadolinium contrast enhancement. Based on the MRI and lumbar puncture findings, additional tests may be appropriately ordered. The diagnosis of bilateral Bell's palsy is made by exclusion of other disorders. This report presents five cases of BFP (Guillain-Barré syndrome, herpes simplex polyneuritis, meningeal lymphoma, and two cases of bilateral Bell's palsy) in which MRI imaging helped in the diagnosis and subsequent management of the patient. The appropriate sequence of diagnostic studies for patients with BFP is discussed.

Magnetic resonance imaging of brain herniation into the middle ear.

Four patients with cholesteatoma were shown to have a large area of eroded tegmen tympani on computed tomography (CT). Magnetic resonance imaging (MRI) in the coronal and sagittal plane showed temporal lobe herniation in three cases and cholesteatoma with abscess elevating the dura in one case. In the patient with a cholesteatoma and an eroded tegmen tympani on CT, MRI is indicated to rule out brain herniation into the middle ear.

Computed tomography and differential diagnosis of the extruded lumbar disc.

Herniated lumbar discs may infrequently extrude through or around the posterior longitudinal ligament and migrate within the epidural space either as a contiguous mass with or as a free fragment of the parent nucleus pulposus. Recognition of this entity may obviate the use of chymopapain or may otherwise alter the surgeon's approach to the disc herniation. The CT scans of 40 surgically confirmed cases of lumbar disc extrusion were reviewed. In 36 cases CT identified the extruded disc material as a lobulated soft tissue mass of similar attenuation to the disc space, migrating either superiorly or inferiorly from the parent disc interspace. In 34 cases the extrusion was 6 mm or more from the center of the parent disc. Calcification of the disc extrusion occurred in five cases. In six cases an extruded free fragment of disc material was associated with a normal-appearing parent disc interspace at CT. In one such case gas bubbles occurred within a degenerating extruded fragment which had eroded through the dura. The differential diagnosis of lumbar disc extrusion is also discussed.

Positional variations of the common carotid artery bifurcation: implications for digital subtraction angiography.

A retrospective examination of the arteriograms of 200 common carotid artery bifurcations was undertaken to determine the number of instances in which, because of superimposition of the external carotid artery in relation to the internal carotid artery, a lateral view would be required to profile the bifurcation fully. Although oblique views did adequately demonstrate the bifurcation in the majority of instances (124/200, 62%), the lateral view was clearly required for a diagnostically adequate display of the bifurcation in 37% (74/200) of instances. Therefore, if digital radiographs do not profile the bifurcation, a lateral arteriogram should be included in the radiographic examination; some serious, treatable abnormalities will otherwise go undetected.

Radiological techniques for small acoustic tumors--a re-evaluation.

Small acoustic neuromas are not detected on conventional, computed tomography (CT) brain scans. Eighteen patients with proven acoustic tumors and negative CT brain scans were studied retrospectively to re-evaluate current radiological techniques. We found that the conventional mastoid plain film or thin section tomography is an accurate, cost effective, screening test for acoustic tumors. When these screening studies are positive and agree with the clinical and audiometric examinations, a CT brain scan should then be performed. If the latter is negative, Pantopaque myelography or air-CT should follow. The decision to proceed to invasive studies has been helped by such tests as brain stem audiometry. Since no single, noninvasive X-ray test currently exists to diagnose the small acoustic tumor, screening X-ray studies are indicated before the use of invasive, expensive studies. A protocol for the radiological work-up of small acoustic tumors is suggested.

Fistula between the middle ear and subarachnoid space as a cause of recurrent meningitis: detection by means of thin-section, complex-motion tomography.

Recurrent meningitis due to a fistula between the subarachnoid space and the middle ear or mastoid cavities has various causes, including congenital anomalies, trauma, and infection. Five cases are described in which thin-section, complex-motion tomograms showed bony abnormalities which suggested both the site and cause of the fistula. Accurate determination of the site of the fistula with this technique facilitated appropriate surgical correction in each patient. Meningitis has not recurred in any of the cases.

Cerebellar infarction--a presentation of vertigo.

The differential diagnosis of acute vertigo includes cerebellar infarction. In the past a mortality rate of 50% - 80% was reported with cerebellar infarction. This is no doubt related to an inability to accurately diagnose small lesions which carry a better prognosis. The advent of computerized tomography (CT) now permits accurate diagnosis of small cerebellar infarctions. Seven patients admitted with acute onset of vertigo which mimicked a peripheral labyrinthine disorder are presented. In all patients a cerebellar etiology was demonstrated by CT. One patient had been subjected to therapeutic labyrinthectomy; three of seven patients had associated unilateral hearing loss suggesting partial brain stem involvemtation. Computerized tomography should be included in the routine work-up of acute vertigo with any associated neurologic findings to aid in proper diagnosis and effect appropriate treatment.

Early x-ray diagnosis of occult infiltrating nasopharyngeal carcinoma.

The occult type of nasopharyngeal carcinoma (NPC) accounts for 30% of all nasopharyngeal carcinomas. The occult NPC is clinically difficult to visualize, because the tumor infiltrates and grows in the submucosa. It then metastasizes to the skull base or draining lymph nodes. When the NPC is finally diagnosed, the prognosis is poor. Three refined x-ray techniques are evaluated for their utilization in earlier diagnosis of the occult NPC: thin section tomography, nasopharyngography, and Eustachian tube function studies. In a consecutive series of 50 patients, these techniques detected 12 infiltrating carcinomas not visible on clinical examination. Five of these patients also had initially negative blind biopsies. Patients having diplopia, facial numbness, cervical adenopathy, and chronic serous otitis media are highly suspect for NPC. The described x-ray techniques, that are safe and noninvasive, can detect these occult infiltrative tumors earlier than clinical examination. Earlier detection and treatment of NPC has resulted in a significant increased cure rate.