[Hypoxic cerebral lesions. X-ray computed tomography and MRI aspects. Apropos of 20 cases. Selective vulnerability of the striatopallidum].

Brain lesions following hypoxic-ischaemic injuries are known from autopsy studies, but their appearance in live patients has been only occasionally described, and only sporadic reports have been published on their CT and MRI images. Over a 2-year period (1991-93) we studied the clinical, MRI and CT features in 20 patients shortly after a severe hypoxia. Clinical examination showed motor extrapyramidal signs in 13 cases and coma in 7 cases. MR with inversion recovery (IR) and T2-weighted spin echo (SE) sequences was performed in 17 patients and CT in 15. Bilateral lesions were found in 11 cases, but in 13 of them CT was normal. Radiological lesions were always symmetrical and bilateral, located in the pallidum in 10 cases, the striatum in 4 cases and the thalamus in 2 cases. Additional white matter lesions were present in only 4 MRI examinations. No relationship was found between the mechanism of hypoxia and the severity of clinical signs. The course of the clinical signs was correlated with the presence of radiological lesions. In comatous patients there was a relation between parkinsonism and abnormalities of basal ganglia. None of the patients who had perinatal asphyxia had radiological lesions. The presence of pallidal or striatal confirmed the hypoxic origin of neurological symptoms, especially in patients with parkinsonism. MRI, particularly in IR sequences, makes it possible to detect small lesions in basal ganglia after hypoxic injuries.