Marieke van Rosmalen

MRI of the intraspinal nerve roots in chronic inflammatory neuropathies 77 5 INTRODUCTION Multifocal motor neuropathy (MMN) and chronic inflammatory demyelinating polyneuropathy (CIDP) are chronic inflammatory neuropathies that respond to treatment. CIDP is characterized by pure motor, pure sensory or, most often, mixed deficits in arms or legs, while MMN is characterized by weakness without sensory deficits. Nerve conduction studies (NCS) are the main diagnostic tool for both disorders. They show motor conduction blocks in MMN with normal sensory nerve conduction. NCS in CIDP can also show blocks or a multifocal pattern of conduction slowing. Imaging studies showed thickened peripheral nerves in both MMN and CIDP that is sometimes more widespread than NCS suggest. 1–5 Nerve ultrasound has become a flexible diagnostic tool that can be used to examine the entire nerve and brachial plexus in one session. Magnetic resonance imaging (MRI) of the brachial plexus is also used for diagnostic purposes. Ultrasound and MRI abnormalities correlate in the forearm and brachial plexus. 6 Imaging abnormalities do not correlate with phenotype or clinical characteristics. 7 The more recently developed advanced MRI techniques allow assessment of the morphology of the intraspinal roots (i.e. motor ventral roots and sensory dorsal roots) and provide the opportunity to correlate morphological with functional changes. 8 In this MRI study we therefore used a quantitative approach to systematically evaluate the sizes of intraspinal nerve roots of patients with chronic inflammatory neuropathies, disease controls and healthy controls. METHODS Study design We performed a cross-sectional MRI study to assess cervical intraspinal nerve root sizes in patients with CIDP and MMN, disease controls with lower motor neuron syndromes and healthy controls. We systematically measured and compared the cervical intraspinal nerve roots by manually measuring the nerve root diameter. Patients and clinical data We enrolled all prevalent and incident patients with an established diagnosis of CIDP or MMN according to the EFNS/PNS criteria who visited our neuromuscular outpatient clinic at the University Medical Center Utrecht (UMCU). 4,9 We enrolled a group of patients with motor neuron disease (MND) as disease controls, according to the Brooks criteria. 10 Healthy controls were eligible for inclusion if they had no history of neuromuscular disorders, neuropathy or spinal (nerve root) injuries. We excluded patients aged < 18 years, patients with MND with a bulbar onset of symptoms and who were physically unable to undergo MRI or with a contraindication to MRI.