CIDP Masquerading as Mononeuritis Multiplex: The Value of MR Neurography

Abstract

Background: We present two patients with the Lewis-Sumner variant of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), charting the diagnostic challenge posed by their clinical presentation and electrodiagnostic findings. The learning points center on the use of magnetic resonance imaging (MRI) in establishing a definitive diagnosis when clinical and neurophysiology data do not otherwise add up. Cases: The first patient presented with slowly progressive asymmetric distal weakness of the lower limbs with wasting, weakness, areflexia and numbness on examination. The second patient experienced stepwise asymmetric hand/forearm weakness with deformity and areflexia, plus mild distal sensory impairment. Neurophysiological studies for both patients were initially most suggestive of mononeuritis multiplex, with no evidence of demyelination. Conclusion: The possibility of asymmetric or multifocal CIDP, the Lewis-Sumner variant, should not be forgotten in suspected mononeuritis multiplex and the value of MRI in such cases is discussed.