Brainstem infarctions with normal MRI.

Most studies on brainstem infarctions included only patients with lesions documented by CT or MRI. The aim of this study was to analyse the clinical symptomatology in patients with the classical signs of brainstem infarcts and normal MRI results. Frequencies of MR-positive and negative infarctions should be analysed according to their location. In a series of 30 consecutive patients with acute clinical symptoms of ischemic brainstem lesions and persistence of the symptomatology for more than 10 days, 8 patients had normal MRI. In these patients the location of the lesion was established by clinical and electrophysiological criteria. The lesions in the 8 patients with normal MRI were situated in medulla oblongata (n=3), in pons (n = 2), and in midbrain (n = 3). In each of these patients the clinical symptoms corresponded to one of the classical alternating syndromes, which are pathognomic for brainstem infarctions (1 Wallenberg, 1 Avellis, 1 Jackson, 2 Millard-Gubler, and 3 Weber). The clinical course of the infarctions with normal MRI was favourable, the symptoms disappeared within few weeks. Our study proved that the clinical diagnosis of brainstem infarction, particularly in lesions of midbrain and caudal tegmentum pontis, can not be excluded by normal MRI.