Isolated weakness of the extensor hallucis longus in a patient with hereditary spherocytosis

A 24-year-old woman with a history of hereditary spherocytosis and oral contraceptive use presented with a spontaneous, isolated loss of great toe extension. She had clinical and electrodiagnostic evidence of a localized lesion affecting the nerve supply to the extensor hallucis longus (EHL). Full clinical recovery was apparent within 6 months with nonoperative therapy. Isolated EHL weakness may occur as a rare neurologic complication of procedures such as high tibial osteotomies, but, to our knowledge, this has not been reported in the absence of trauma or surgery. While the coexistence of hereditary spherocytosis and a peripheral neuropathy may have been purely coincidental, it is plausible that the isolated lesion in this patient was due to ischemic changes from underlying rheologic conditions, possibly in association with a variation in the neural or nutrient vessel supply to the EHL.