[Nuclear magnetic resonance imaging of the brainstem: evaluation of the normal structures and small lesions].

Nuclear magnetic resonance (NMR) imaging of the brainstem region from 12 asymptomatic individuals were reviewed in addition to these of 12 patients with various symptoms of small brainstem lesions. Abnormalities consisted of 3 cases of multiple sclerosis, 1 case of neuro-Behçet disease, 5 cases of infarction and hematoma and 3 cases of degenerative disease. NMR transverse imaging using inversion recovery sequence was able to locate many of the normal intra-axial brainstem nuclei, such as the periaqueductal gray matter, the red nucleus, the substantia nigra, the pontine nuclei, the pontine reticular nuclei, the facial nerve nucleus and so on in an about half of 12 asymptomatic individuals. The remarkable gray-white matter differentiation was obtained on NMR imaging using inversion recovery sequence and enabled the internal structures to be visualized within the brainstem. In addition, the midsagittal imaging provided an excellent demonstration of anatomical relationships of the brainstem and surrounding structures. In the diencephalic region, the mamillary body, the anterior commissure and the optic chiasma were also demonstrated on the midsagittal imaging. The lesions within the brainstem were vaguely shown on X-ray computed tomography in 6 of 12 patients but NMR imaging using inversion recovery or spin echo sequence provided more detailed data and revealed clear small lesions, such as the demyelinated plaques of multiple sclerosis and lacunar infarcts in 9 of 12 patients. Especially, in 2 of 3 multiple sclerosis patients, the plaques of the brainstem were definitely identified on NMR imaging only and the accurate localized lesion which was responsible for the facial myokymia or the Foville syndrome was identified.(ABSTRACT TRUNCATED AT 250 WORDS)