Ventral polyradiculopathy with pediatric acute lymphocytic leukemia

A 3-year-old girl with acute lymphocytic leukemia (ALL) in remission developed lower extremity paraparesis and areflexia 15 days after receiving intrathecal methotrexate, cytarabine, and hydrocortisone. Cerebrospinal fluid protein was 107 mg/dl. Compound muscle action potential amplitudes were reduced, F waves were absent, and sensory conduction studies were normal. Needle electromyography (EMG) revealed reduced motor unit potential recruitment. Magnetic resonance imaging (MRI) showed lumbosacral ventral root enhancement. She was treated with intravenous immunoglobulin and slowly recovered. Nerve conduction and EMG abnormalities correlated with MRI root enhancement, facilitated early diagnosis, and distinguished this from a myelopathy or distal polyneuropathy. These findings could represent selective ventral nerve root vulnerability to intrathecal chemotherapy. A selective autoimmune process cannot be excluded.