A 16-year-old girl with progressive weakness of the left leg

Abstract

The patient first noted problems in 1996, almost 3 years prior to evaluation. She had fallen and injured her right knee on a brick. The onset of her left lower extremity problems was uncertain, but she noticed gradual weakness of her left foot subsequent to the injury. In January 1999, the weakness of the left foot was noted to be definite. Her left foot would slap with walking, and her mother would encourage her to “pick up her foot” when she walked. Her grandmother noted that she would often scuff her left foot. The patient experienced no pain with the weakness, and she herself was only aware of it while trying to run. The patient felt she had been unable to run properly for the last 2 to 3 years. Approximately 4 months later, electromyography (EMG) was done at Mayo Clinic at the request of the referring physician (table 1). This showed absent left peroneal motor and sensory responses and absent left sural sensory response. The left tibial motor conduction was normal. Needle examination revealed fibrillation potentials in the tibialis anterior with markedly reduced recruitment in the left peroneal innervated muscles. She was fitted with an orthosis at the local institution to prevent foot drop. View this table: Table 1 Electromyography 1999 In June 1999 at age 12, she was assessed clinically at the Mayo Clinic. She was on no medications. She had no significant past medical history but was overweight. She was born weighing 8 lbs 8 oz at normal gestation without any complications. Development was otherwise normal. She had no known exposure to any toxins and had no history of exposure to alcohol, cigarette smoking, or illicit drug use. There was no known family history of neurologic disease. The patient’s maternal grandmother had “hammer toes.” Her sister had surgically corrected femoral …