MR imaging of midbrain pathologies.

The spectrum of pathologic processes affecting the midbrain features some differences to other brain areas. The midbrain is exposed to traumatic alterations due to its position between the tentorial edges, and some neurodegenerative and metabolic-toxic diseases may typically involve the midbrain. Isolated midbrain ischemia is rare, whereas the midbrain is typically part of the "top of the basilar" syndrome. Primary midbrain tumors are also infrequent and often show a benign clinical course. Apart from multiple sclerosis other inflammatory autoimmune processes and some infectious agents predominantly affect the brainstem including the midbrain. This review discusses the different pathologic processes of the midbrain, i.e., infarction, hemorrhage and trauma, inflammation, toxic and metabolic diseases, neurodegeneration, neoplastic diseases, as well as pathologies typically involving the perimesencephalic cisterns.

[Corpus callosum. Landmark of the origin of cerebral diseases]. / Corpus callosum. Landmarke für die Genese zerebraler Erkrankungen.

Diseases of the corpus callosum include developmental disorders, immunomodulated CNS diseases, vascular malformations, disturbances of metabolism including the electrolyte homeostasis, secondary degenerations and mechanical injuries. This report provides information on the differential diagnosis of reversible and irreversible pathological changes of the corpus callosum with special focus on the localization, which often allows conclusions on the pathogenesis to be drawn.

[Perioperative lesions of the corticospinal tract. Etiology, neuroradiological features and clinical outcome]. / Perioperative Läsionen des Tractus corticospinalis. Atiologie, neuroradiologische Befunde und klinischer Verlauf.

BACKGROUND: The neurosurgical resection of mass lesions in the vicinity of the corticospinal tract (CST) may induce a postoperative impairment of motor function. The etiology and localisation of lesions causing postoperative motor deterioration were analysed by preoperative and postoperative magnetic resonance imaging (MRI). PATIENTS AND METHODS: In 32 patients with mass lesions near the CST and intraoperative deterioration of the motor-evoked potentials, preoperative and postoperative MRI was performed and evaluated for new lesions along the CST. These lesions were classified into edema, infarction and haemorrhage. All patients were examined for perioperative central motor function. RESULTS: New lesions along the CST were found in 19 of the 32 patients. Postoperatively new or deteriorated motor function was found in 13 of these 19 patients (edemas: 4 out of 6, haemorrhages: 4 out of 7; infarctions: 5 out of 6). Of the 13 patients without new MRI lesion along the CST one had a new motor deficit. CONCLUSION: The postoperative MRI in patients with mass lesions near the CST and postoperative central motor deterioration sensitively showed the etiology and localisation of the lesion. Apart from being due to infarctions and haemorrhages, a larger number of postoperative motor impairments may be caused by edema.