Anti-Hu Polyneuropathies
Abstract & Commentary
Source: Camdessanche JP, et al. Paraneoplastic peripheral neuropathy associated with anti-Hu antibodies: A clinical and electrophysiological study of 20 patients. Brain. 2002; 125:166-175.
Among 50 anti-Hu positive patients retrospectively reviewed, 27 exhibited a paraneoplastic neurological syndrome, 7 (25.9%) with encephalomyelitis, and 20 (74.1%) demonstrating symptoms and signs of polyneuropathy. Other causes for neuropathy were excluded, including diabetes, renal failure, paraproteinemia, drug toxicity, vitamin deficiency, and cachexia. Data reviewed from the 20 patients included cerebrospinal fluid analysis, nerve conduction studies, and immunohistochemistry for detection of anti-Hu, anti-amphiphysin, and anti-CV2 antibodies. Fisher’s exact test and chi-square tests provided statistical analysis.
Among the 17 men and 3 women, polyneuropathy was the presenting symptom in 19 (95%) and the sole manifestation in 6 (30%). Pain was a frequent accompaniment (80%) but atrophy or fasciculations were not. Onset was acute in 1 (5%), subacute in 11 (55%), and progressive in 8 (40%). Cancer was diagnosed in 17 (85%) within a mean of 7.7 months, and in 13 (76.5%) it was small cell lung cancer. Clinically, pure sensory neuropathy was present in 14 (70%), pure motor in 1 (5%), and mixed sensorimotor in 5 (25%). Electrophysiologic study, however, demonstrated motor involvement in 10 of the 14 "clinically pure" sensory neuropathies, with an axonal/neuronal pattern of abnormality in 46.9% of nerves studied, a demyelinating pattern in 4.9%, a mixed axonal-demyelinating pattern in 18.3%, and no abnormality in 29.9%. Anti-CV2 antibody positivity did not correlate with neuropathy in this patient population. Motor involvement is much more common than suspected in anti-Hu sensory neuronopathy, indicating that, although pathology beyond the dorsal root ganglion is present, it does not preclude the diagnosis.
Commentary
Patients with anti-CV2 antibodies may demonstrate a mixed axonal-demyelinating sensorimotor polyneuropathy which, in the presence of co-existent anti-Hu antibodies, may be superimposed over an underlying subacute sensory ganglionitis (Ann Neurol. 2001;49: 214-221). Anti-CV2 antibody, likely identical to recently described CRMP-5 antibody, reacts with adult rodent brain oligodendrocytes and recognizes a 66-kd protein of the Ulip/CRMP protein family (Ann Neurol. 2001;49:141-142). CRMP-5 antibodies recognize collapsin response mediator protein-5 (CRMP-5, also known as CRAM), which is important for nervous system development as a mediator of axonal guidance. It also appears to be a marker for lung cancer, usually small cell, which was found in 77% of 116 CRMP-5 antibody positive patients (Ann Neurol. 2001;49:146-154). —Michael Rubin.
Rubin, MD, Associate Professor of Clinical Neurology, New York Presbyterian Hospital-Cornell Campus, is Assistant Editor of Neurology Alert.
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