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Another Treatable Sensory Variant of CIDP?

These findings identify a new entity, chronic sensory demyelinating neuropathy, that appears to respond well to immunotherapy.

Chronic ataxic neuropathy (CAN) is most commonly due to sensory ganglionopathy, which can be identified by the classic sensory neuronopathy pattern in nerve conduction study (NCS): a marked sensory nerve conduction abnormality in the presence of normal motor nerve conduction. However, treatment of sensory ganglionopathy has been disappointing, so CAN is therefore considered untreatable.

Sinnreich and colleagues report data from 15 patients who clinically had CAN and what they term chronic immune sensory polyradiculopathy (CISP), which responded favorably to immunotherapy. All the patients had gait ataxia, paresthesias, and large-fiber sensory loss. All but 1 had reduced reflexes, and 9 had frequent falls. Motor and sensory nerve conduction findings were normal, including those in the sural nerve. The most remarkable laboratory finding was a high CSF protein level in almost all patients. Two helpful tests in lesion localization were somatosensory evoked potential (SSEP) measurement and MRI scan of the nerve root. SSEPs were abnormal in all 12 patients tested: In median SSEP, the most common abnormality indicated a lesion to the nerve root; and in tibial SSEP, the most common finding was a nonlocalizing abnormality in the cortical response. Lumbar MRI scan showed thickened roots in one third of cases. Lumbar sensory rootlet biopsies from 3 patients showed evidence of inflammatory demyelinating neuropathy. Six patients with severe symptoms received immunotherapy (intravenous immunoglobulin in 4 patients and IV steroids in 2). All improved noticeably.

Comment: Few causes of chronic sensory neuropathy are treatable. One of them is chronic sensory demyelinating neuropathy, a sensory variant of CIDP (chronic inflammatory demyelinating polyneuropathy) that responds to immunotherapy and is recognized by the demyelinating index of NCSs and by a high CSF protein level. As these results show, chronic immune sensory polyradiculopathy, another sensory variant of CIDP, can be identified by a high CSF protein level, SSEP abnormalities, and thickened nerve roots on MRI. It is important to recognize these entities because of their apparent remarkable response to immunotherapies.

— Shin J. Oh, MD, FAAN

Dr. Oh is Professor, Department of Neurology, University of Alabama at Birmingham.

Published in Journal Watch Neurology February 24, 2005

Citation(s):

Sinnreich M et al. Chronic immune sensory polyradiculopathy: A possibly treatable sensory ataxia. Neurology 2004 Nov 9; 63:1662-9.

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