Succinate dehydrogenase (SDH) deficiency is rare. Clinical manifestations can appear in infancy with a marked impairment of psychomotor development with pyramidal signs and extrapyramidal rigidity.
Case report: A 10-month-old boy developed severe neurological features, evoking a Leigh syndrome; magnetic resonance imaging showed features of leukodystrophy. A deficiency in the complex II respiratory chain (succinate dehydrogenase [SDH]) was shown. The course was remarkable by the regression of neurological impairment under treatment by riboflavin. The delay of psychomotor development, mainly involving language, was moderate at the age of 5 years.
Conclusion: The relatively good prognosis of this patient, despite severe initial neurological impairment, may be due to the partial enzyme deficiency and/or riboflavin administration.