[Lateral bulbar infarctions. Distribution, etiology and prognosis in 40 cases diagnosed by MRI].

Recent advances in lateral medullary syndrome have focused on otoneuro-ophthalmology and magnetic resonance imaging (MRI). To reevaluate lateral medullary infarcts, 40 non fatal cases (30 men and 10 women, mean age 57.5 years) accounting for 4.5 p. 100 of overall cerebral infarcts were consecutively included in a prospective study using MRI in all cases. Thirty three patients were investigated using transfemoral or magnetic resonance angiography. Besides classical symptomatology, visual disorders were usually noted: diplopia (n = 18), transient visual tilt of the surrounding (n = 4), skew deviation (= 4), esotropia (n = 2) or conjugate gaze deviation (n = 2). The middle part of the medulla was affected in 35 cases. When associated, ipsilateral peripheral facial palsy and/or deafness were linked to the involvement of the pontomedullary junction (n = 3) while ipsilateral hemiparesis (Opalski's syndrome, n = 4) was linked to the involvement of the lower medulla and the cervicomedullary junction. MRI showed an associated cerebellar infarct in 35 p. 100 of cases. Of 33 patients angiographically investigated, 27 (82 p. 100) had stenosis or occlusion of the ipsilateral vertebral artery, usually affecting the intracranial portion, when 3 had isolated posterior inferior cerebellar artery occlusion. Atherosclerosis was recognized as the main cause of lateral medullary infarcts (n = 25). Other miscellaneous etiologies were diagnosed: coagulopathy (n = 2), spontaneous arterial dissection (n = 2), dolichoectatic artery (n = 1), arteriolopathy (n = 1) or cardiogenic embolism (n = 1). At the term of follow-up (mean: 35 +/- 24 months), 33 patients were free of residual handicap, 8 had experienced recurrent vertebrobasilar infarcts, including 3 medullary infarcts (median ipsilateral, n = 1 or lateral contralateral, n = 2), and 3 were died of basilar artery thrombosis complicating extensive atherosclerosis of the intracranial vertebrobasilar system.