P-PN023. Childhood-onset demyelinating polyneuropathy: Challenges in differentiating acquired from genetic disease

Introduction. Childhood chronic inflammatory demyelinating polyneuropathy (CIDP) can be misdiagnosed for the more common genetic neuropathies such as Charcot-Marie-Tooth (CMT) disease. We present a case of childhood-onset demyelinating polyneuropathy who was initially diagnosed as CMT before a revised diagnosis of CIDP was made. Results. A 14-year-old boy with bilateral pes cavus presented with progressive history of ataxic gait, generalized areflexia and proprioceptive sensory loss. Nerve conduction studies showed demyelinating features including markedly slow motor conduction velocities and prolonged distal motor latencies resembling CMT1. Despite the absence of a family history of genetic neuropathies, a diagnosis of CMT1 was considered most likely. The patient represented two years later with an acute onset of worsening instability and muscle weakness. A detailed history revealed functional improvement following the last presentation along with two separate episodes of exacerbations suggesting a relapsing-remitting form of neuropathy. Cerebrospinal fluid analysis showed cytoalbuminergic dissociation. Nerve ultrasound demonstrated enlarged peripheral nerves, particularly in the proximal and non-entrapment sites. Genetic testing was negative for known mutations in common CMT genes. A course of intravenous immunoglobulin resulted in clinically significant improvement. Conclusion. This report highlights the diagnostic challenges in childhood-onset demyelinating neuropathies and the importance of not missing a potentially treatable immune-mediated neuropathy.