MRI was used to investigate 100 patients with hemifacial spasm, using 3D-FT T2-weighted (CISS) and contrast-enhanced 3D-FT T1-weighted (turbo-FLASH) sequences in all cases. MR angiography was performed in 54 patients, using 3D-MT FISP images. Decompression of the facial nerve through a retromastoid craniotomy was performed in all patients. Hemifacial spasm caused by tumours in the cerebellopontine angle was not included. Vascular contact with the facial nerve root-exit zone or at the internal auditory canal was present in 96 of 100 patients with hemifacial spasm. The vessel responsible was the vertebral artery (VA) in 18 cases, the posterior inferior cerebellar artery (PICA) in 23, the anterior inferior cerebellar artery (AICA) in 22, the VA and PICA in 24, VA and AICA in 3, PICA and AICA in 1, VA, PICA and AICA in 4, and a vein in 1 case. CISS images showed compressive vascular loops better than contrast-enhanced turbo-FLASH images alone. The sensitivity of MRI was high, since only one false-negative case was found among the 100 patients who underwent surgery.
Contrast-enhanced 3D-FT MRI of the intrapetrous facial nerve was obtained in 38 patients with facial nerve disease, using a 1.0 T magnet and fast gradient-echo acquisition sequences. Contiguous millimetric sections were obtained, which could be reformatted in any desired plane. Acutely ill patients, were examined within the first 2 months, included: 24 with Bell's palsy and 6 with other acute disorders (Herpes zoster, trauma, neuroma, meningeal metastasis, middle ear granuloma). Six patients investigated more than a year after the onset of symptoms included 3 with congenital cholesteatoma, 2 with neuromas and one with a chronic Bell's palsy. The lesion was found incidentally in two cases (a suspected neurofibroma and a presumed drop metastasis from an astrocytoma). Patients with tumours had nodular, focally-enhancing lesions, except for the leptomeningeal metastasis in which the enhancement was linear. Linear, diffuse contrast enhancement of the facial nerve was found in trauma, and in the patient with a middle ear granuloma. Of the 24 patients with an acute Bell's palsy 15 exhibited linear contrast enhancement of the facial nerve. Three of these were lost to follow-up, but correlation of clinical outcome and contrast enhancement showed that only 4 of the 11 patients who made a complete recovery and all 10 patients with incomplete recovery demonstrated enhancement. Possible explanations for these findings are suggested by pathological data from the literature. 3D-FT imaging of the facial nerve thus yields direct information about the of the nerve condition and defines the morphological abnormalities. It can also demonstrate contrast enhancement which seems to have some prognostic value in acute idiopathic Bell's palsy.
Forced laughter generally occurs in bilateral or diffuse lesions of the brain and is generally associated with pathologic crying. We report the cases of 3 patients in whom temporary forced laughter occurred after unilateral supratentorial infarction demonstrated by CT scan or MRI. In all cases, the lesion was exclusively subcortical and involved the striatocapsular region. For all patients the laughter occurred during the revovery phase of motor deficit and was ‘pure’ without associated weeping or other clinical features of pseudobulbar palsy. In all cases, the laughter attacks had become much less frequent or had totally disappeared 1 or 2 months after the stroke. According to a ‘motor’ hypothesis, a unilateral striatocapsular lesion may lead to temporary deregulation of the expression mechanisms.
We studied 76 patients with endocrinological features of prolactin-secreting microadenoma by MRI, using three dimensional (3D) gradient echo acquisition (FLASH) sequences. MRI revealed a focal signal abnormality in the pituitary in all 37 patients who had not previously taken bromocriptine. However, focal abnormality was shown in only half the patients had been on dopamine agonist therapy; the MRI findings in these 39 patients were not affected by the duration and dosage bromocriptine, nor by the time elapsed since its discontinuation. The microadenoma gave spontaneous high signal on the unenhanced T1-weighted images in 8 cases; it was not seen on unenhanced images in 25 cases. It appeared as low signal within the enhancing gland in 51 cases but enhanced in 7 cases. The 3D technique gives thin (1 mm) slices and therefore facilitates detection of small focal abnormalities in the pituitary gland (2 x 2 mm). In the 19 previously treated patients in whom MRI did not demonstrate a focal abnormality, it showed localised atrophy of the gland in 3, a large, round gland with homogeneous signal in 1, and a heterogeneous appearance in 11; it was normal in 4 cases.
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