Chronic inflammatory demyelinating polyneuropathy associated with contactin-1 antibodies in a child

A previously healthy 2-year and 9-month old boy was brought to the emergency department for a 6-day history of weakness in the legs and frequent falls, rendering him unable to walk 1 day before admission. He did not have pain, dysphagia, bladder dysfunction, or sensory symptoms. There was no history of trauma, but he developed diarrhea 3 days before symptom onset. Family history was negative for consanguinity or neurologic diseases. At examination, he had bilateral leg weakness requiring substantial aid to walk a few steps and was unable to stand up from the floor. He had absent tendon reflexes in the lower extremities and flexor plantar responses. Strength and reflexes in upper extremities and the rest of the examination were normal. CSF showed a protein concentration of 125 mg/dL (NR: 15-45), with normal white blood cell count and glucose concentration. Blood cell count and chemistry were normal, and stool culture was negative. Nerve conduction studies (NCSs) and EMG showed decreased amplitudes in both peroneal nerves (table e-1, ). The patient was treated with IV immunoglobulins (IVIg) 2 g/kg administered in 3 days. During the next 2 weeks, there was mild improvement in motor strength as he was able to walk and stand up with support (the Guillain-Barre syndrome disability scale [GBSds](1) score remained 3), and he was discharged home. Two weeks later (4 weeks after symptom onset), he was brought back for worsening weakness in the legs and new onset weakness in the arms. This time, the examination revealed weakness in legs and arms, generalized areflexia, and impossibility to stand up from the floor (GBSds 4). Repeat CSF studies showed a protein concentration of 148 mg/dL and normal white blood cell count and glucose level. No toxic or infectious etiologies were identified, and serum was negative for ganglioside antibodies. NCSs showed prolonged distal motor latencies, conduction slowing, and decreased amplitude of compound muscle action potentials, along with EMG features of chronic denervation, fibrillation, and positive sharp waves (table e-1, ). Treatment with IVIg was ineffective, but IV methylprednisolone (30 mg/kg/d for 5 days) resulted in substantial improvement, leaving the patient with normal strength except for mild distal lower extremity weakness (GBSds 1).