Lateral medullary syndrome in a boy with hereditary dysfibrinogenemia.

A 9-year-old boy presented with sudden onset of nausea, vomiting and unsteady gait after a bread-eating game, which possibly caused neck hyperextension. Neurological examination revealed hemisensory loss of pain and temperature sensation in the right trunk and limbs along with left Horner's syndrome, suggesting lateral medullary syndrome (LMS). Magnetic resonance (MR) imaging of the brain revealed infarction at the left lateral medulla. MR angiography showed no sign of arterial dissection and no occlusion or stenosis of the intracranial, basilar or vertebral arteries or their branches. No evidence of cardioemboli or systemic inflammation was apparent. Repeated blood examination revealed low activity of fibrinogen. Genetic testing confirmed the presence of hereditary dysfibrinogenemia with a mutation in the FGB gene (BβGly15Cys). This fibrinogen variant has previously been found in Japanese patients with atherosclerosis obliterans or no symptoms. Under conservative treatment without anticoagulation and aspirin, the patient made a good recovery within a few months. We presume that microthrombosis may have been deposited within the vertebral system as a result of extension and rotation of the neck during sports activity, with a contribution from hereditary dysfibrinogenemia.