Review Question - QID 210404

A 4-year-old boy is brought by his mother to the emergency room for malaise, dizziness, and sleepiness. The mother owns a dry cleaning shop and found her son in the back room with an open canister of carbon tetrachloride, one of their cleaning fluids. The boy reports feeling nauseous and has a mild headache. He has a history of spastic hemiplegic cerebral palsy and is seen regularly by a pediatric neurologist. He is otherwise healthy and takes no medications. His temperature is 98.6°F (37°C), blood pressure is 105/55 mmHg, pulse is 105/min, and respirations are 22/min. On exam, he appears tired and drowsy but is able to answer questions. He has increased tone in his left upper and lower extremities. Which of the following is most likely to be affected by this patient's exposure to the dry cleaning fluid?