Spinal Nerve Root Hypertrophy as Etiology of Back Pain in CIDP (P1.072)

OBJECTIVE: To report a case of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with severe radicular pain due to spinal root enlargement and to distinguish enlarged nerve roots from neurofibromata. BACKGROUND: Spinal nerve root enlargement is an uncommon development in longstanding CIDP. Nerve root hypertrophy can contribute to radicular pain and can be mistaken for neurofibromata. DESIGN/METHODS: We report a case of a 59 year old man with 22 year history of CIDP with associated IgG lambda gammopathy and negative skeletal survey who was admitted for plasmapheresis due to CIDP exacerbation and worsening pain of the flank, mid back, and left upper extremity. Motor examination showed 3/5 hand intrinsics, 5-/5 quadriceps, 4/5 hamstrings, 4/5 gastrocnemius, and 0/5 anterior tibialis with atrophy of the hand intrinsics and distal lower extremities. Reflexes were absent, plantar response was equivocal. There was a high frequency action tremor of the upper extremities, head, and voice. Sensory examination showed impaired vibration, proprioception, pin prick, and temperature to the knees with decreased vibration in the fingers. RESULTS: MRI of the cervical, thoracic, and lumbar spine revealed what were initially thought to be neurofibromata extending through neural foramina and compressing the spinal cord from C5 to T1. MRI brain, internal auditory canal protocol, did not show acoustic neuromas. Electrodiagnostic studies showed demyelinating range slowing in the motor nerves of the arm with absent potentials in the sensory nerves of the arm and all potentials in the legs. Sural nerve biopsy showed severe loss of myelinated fibers and extensive onion bulb formation on remaining fibers. The patient’s back pain improved after plasmapheresis. CONCLUSIONS: While the MRI report suggested the possibility of neurofibromata as the etiology of enlarged roots, the patient’s back pain resolved with plasmapheresis. His severely enlarged nerve roots were thus contributed to his onion bulb formation from his CIDP. Disclosure: Dr. Shaefer has nothing to disclose. Dr. Alsharabati has nothing to disclose. Dr. Claussen has nothing to disclose. Dr. Oh has nothing to disclose.