A girl presenting at 6 years with familial spastic paraparesis and having deficiencies of respiratory chain enzyme complex I, III and IV is reported from the Departments of Pediatrics and Neurology, Loyola University Medical Center, Maywood, IL. Her gait was clumsy and her maternal grandmother had a spastic gait with onset at age 40. Deep tendon reflexes were brisk at the knees. Plantar responses were extensor bilaterally and ankle clonus was unsustained. The tone was increased in both lower extremities. The gait was wide based with hip circumduction. A 3 centimeter cyst in the left parietal region on MRI appeared to be coincidental. Efforts to treat the deficiencies of mitochondrial enzymes with various respiratory chain co-factors (coenzyme Q, vitamin K and C) and a mitochondrial substrate entry carrier (carnitine) were rewarded with no further progression of symptoms and some mild improvement clinically. The mitochondria were structurally normal by electron microscopy and ragged red fibers were absent on muscle biopsy. 
COMMENT. Familial spastic paraparesis or Stümpell’s disease is characterized by a progressive gait disturbance with lower extremity spasticity and weakness, without associated sensory, cerebellar or cranial nerve deficits. The age of onset ranges from 1-55 years and varies within specific kindreds. Heredity may be autosomal dominant, autosomal recessive or sex-linked. Involvement of the spinal cord is unique for a mitochondrial disorder.