Mitochondrial disease and stroke

Background and Purpose-It is well known that some mitochondrial disorders a re responsible for ischemic cerebral infarction in young patients. Our purp ose was to determine, in this prospective ongoing study, whether ischemic s troke is the only manifestation of a mitochondrial disorder in young patien ts. Methods-Patients aged ::less than or equal to 50 years, admitted to the Str oke Unit from January 1999 to May 2000 with a diagnosis of ischemic stroke of unknown origin, were included in the study. All of them had full biochem ical and hematologic tests, neuroimaging studies, transesophageal echocardi ography, and extracranial and transcranial Doppler sonography. Patent foram en ovale was ruled out. Lactic acid concentrations were measured after anae robic exercise of the forearm, and a morphological, biochemical, and molecu lar study after biceps muscle biopsy was performed. Results-Of the 18 patients so far included, 3 (17%) presented lactic acid h yperproduction after physical exercise, and 6 (33%) showed deficit of the m itochondrial respiratory chain complexes. The molecular analyses have confi rmed mitochondrial mutations at base pairs 3243 (characteristic of mitochon drial encephalomyopathy, lactic acidosis, and strokelike episodes [MELAS]), 4216, and 15 928. Conclusions-These results suggest that ischemic stroke may be the only mani festation or the initial manifestation of a mitochondrial disorder.