Lyme disease is known for its numerous neurological manifestations. Cerebral ischemic lesions are more rarely reported. We describe the case of a 27 – year old man – presenting with a left-sided hemiparesis when waking up. We first thought of a stroke, due to the presence of a light right capsulo-thalamic hypodensity on C.T. scan and the spontaneous regression of the hemiparesis within a few days. However, the lumbar puncture performed on the patient due to a fever running 38 degrees C and some drowziness showed a lymphocytic pleocytosis with a very inflammatory face of the spinal fluid. The M. R.I. revealed a right capsular and thalamic image with edema of the front part of the thalamus showing either a vascular or an inflammatory origin. The
Lyme serodiagnosis in the blood and in the spinal fluid was positive, and we demonstrated an intrathecal Borrelia burgdorferi specific antibody synthesis. This case is interesting because it shows a central form of neuroborreliosis through cerebral infarct and its regressive evolution under treatment. The possible pathophysiology mechanisms have been discussed.