A case of probable chronic inflammatory demyelinating polyradiculoneuropathy presenting as unilateral lumbosacral plexopathy

Abstract

Focal chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is rare but should be considered in the differential diagnosis of chronic progressive neuropathy affecting a single limb. We report here a 66-year-old male presented with progressive right lower limb weakness and sensory deficits in keeping with a lower right lumbosacral plexopathy. His electrophysiological studies, whilst the distal motor latency and conduction velocities were within normal limits, showed marked asymmetry of right tibial and peroneal nerves with minimum F wave latency significantly prolonged on the right (greater than 120% upper limit of normal and also compared to the opposite side). This raised possibility of proximal demyelination. MRI with contrast revealed a diffused thickening of the right lumbosacral plexus and proximal right sciatic nerve. A lumbosacral plexus biopsy would have been helpful but was not undertaken due to patient’s preference. No alternative cause was detectable upon extensive investigation. Patient was initiated on intravenous immunoglobulin for probable focal CIPD and has remained stable over a short period of follow up. In conclusion, even though lower limb involvement has rarely been described in literature, focal CIDP should be considered as a differential diagnosis of patients with focal neuropathies including unilateral lumbosacral plexopathy.