Hypertrophic cardiomyopathy is a component of subacute necrotizing encephalomyelopathy.

Twelve patients, ranging from the neonatal period through adolescence, with subacute necrotizing encephalomyelopathy (Leigh disease) were studied. Autopsies of these patients demonstrated an associated hypertrophic cardiomyopathy in seven; of these, four had asymmetric septal hypertrophy. In two patients, the cardiac lesion was observed by premortem echocardiograms. The common occurrence of a cardiac lesion emphasizes the probable systemic nature of SNEM and may serve to segregate these patients into two groups. Because of the involvement of the two systems, we suggest that SNEM may have some relation to a variety of other cardioneurologic syndromes.