Letter to the Editor
To the Editor:
A 50-year-old man presented with 10 years of progressive gait unsteadiness and limb weakness. Examination showed mild symmetric proximal weakness of the lower limbs, severe weakness and atrophy of the hands, hypoesthesia below the knees, vibratory sensation loss in the lower limbs and hands, and absent tendon reflexes. Cerebrospinal fluid contained 2.20 g/L protein (normal, less than 0.45 g/L) and 3 lymphocytes/mm3 (normal, less than 5 lymphocytes/mm3). Serologic tests for neurotropic viruses and syphilis in cerebrospinal fluid were negative. Gammaglobulin ratio in cerebrospinal fluid, performed by electrophoresis, was normal, and the search for oligoclonal bands was negative. Nerve conduction studies revealed an acquired demyelinating polyneuropathy (Tables 1 and 2), and electromyographic examination gave evidence of active denervation, ie, fibrillation potentials and positive sharp waves in left and right first dorsal interosseous, abductor digiti minimi, flexor carpi ulnaris, and abductor pollicis brevis muscles. Electromyographic examination of left and right deltoid, biceps brachialis, triceps brachialis, and cervical paraspinal muscles was normal. Biochemical, hematologic, virologic, and renal function investigations were normal. Chest radiography showed no abnormality. The search for antiganglioside antibodies (including anti-GQ1b, GT1a, GT1b, GD1a, GD1b, GM1, GM2, GM3, asialo-GM1, and sulfatides) using an enzyme-linked immunosorbent assay was negative. The search for anti-MAG antibodies and antineuronal antibodies was also negative. Autoantibody screen was negative as was rheumatoid factor. Serum complement concentrations were normal, and there was no monoclonal gammapathy. There was no Borrelia burgdorferi infection (Lyme disease), and the testing of PMP22 and Connexin 32 genes was normal. The patient was eventually diagnosed with definite chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) using the European Federation of Neurological Societies/Peripheral Nerve Society guidelines and treated with corticosteroids and intravenous immune globulin for 13 years.1 Ataxia and strength gradually improved, but severe weakness of hands and severe denervation in hand muscles remained. Coronal short tau inversion recovery (STIR) magnetic resonance imaging (MRI) assessment of brachial plexus was then performed in this 63-year-old patient with long-duration CIDP and demonstrated severe bilateral brachial plexus atrophy (Fig. 1).
MRI assessment of brachial plexus in CIDP usually demonstrates diffuse enlargement and abnormally high signals on STIR.2–4 More rarely, slightly high signal on T1-weighted images and high-intensity signal on diffusion-weighted images with high apparent diffusion coefficient values are also observed.2–4 It is generally considered there is no relationship between MRI and clinical findings in CIDP, because MRI abnormalities persist even when clinical symptoms improve.3,4 However, MRI follow-up of long-duration CIDP has not been performed until now.2–4
Here, brachial plexus STIR MRI was performed in a patient with severe weakness and atrophy of hands and with CIDP of very long duration, ie, 23 years, and demonstrated severe bilateral brachial plexus atrophy. To our knowledge, this is the first time brachial plexus atrophy is demonstrated in CIDP. It is known that CIDP of sufficient severity may be associated with secondary axonal degeneration, which may not respond to immunomodulating therapy, and the brachial plexus MRI showed here most likely reflects this secondary axonal degeneration.5 Imaging of patients with shorter duration CIDP who have secondary axonal degeneration would be of interest to test whether STIR MRI follow-up is useful to detect early axonal loss in CIDP.
1. Joint Task Force of the EFNS and the PNS. European Federation of Neurological Societies/Peripheral Nerve Society guideline on management of chronic inflammatory demyelinating polyradiculoneuropathy: report of a joint task force of the European Federation of Neurological Societies and the Peripheral Nerve Society–First Revision. Eur J Neurol. 2010;17:356–363.
2. Sureka J, Cherian RA, Alexander M, et al.. MRI of brachial plexopathies. Clin Radiol. 2009;64:208–218.
3. Adachi Y, Sato N, Okamoto T, et al.. Brachial and lumbar plexuses in chronic inflammatory demyelinating polyradiculoneuropathy: MRI assessment including apparent diffusion coefficient. Neuroradiology. 2010 Apr 20 [Epub ahead of print].
4. Duggins A, McLeod J, Pollard J, et al.. Spinal root and plexus hypertrophy in chronic inflammatory demyelinating polyradiculoneuropathy. Brain. 1999;122:1383–1390.
5. Vallat JM, Sommer C, Magy L. Chronic inflammatory demyelinating polyradiculoneuropathy: diagnostic and therapeutic challenges for a treatable condition. Lancet Neurol. 2010;9:402–412.