Autonomic impairment in painful neuropathy. (Abstracts of Current Literature).

Novak V, Freimer ML, Kissel JT, et al (Department of Neurology, The Ohio State University, Columbus,Ohio), Neurology. 2001;56:861-868.

The purposes of this study were to examine the extent of autonomic nervous system impairment in people with painful neuropathy (PN) and to evaluate the usefulness of autonomic testing in the assessment of PN. A total of 92 subjects (60 women, 32 men; mean age=56.9 [+ or -] 12.4 years) with painful feet of unknown etiology received medical laboratory tests, nerve conduction studies (NCS), autonomic reflex testing, Quantitative Sudomotor Axon Reflex Test (QSART), cardiac-vagal index, an autonomic nervous system questionnaire, quantitative sensory testing, and skin biopsy.

The results of the NCS separated the subjects into 2 distinct groups. Group 1 consisted of 45 subjects (mean age = 59.6 [+ or -] 12.6 years) with abnormal NCS (sural nerve action potential amplitude=3.31 [+ or -] 4.1 [micro]V; peroneal motor nerve conduction velocity = 39.0 [+ or -] 5.9 m/s), which, according to the researchers, suggested the involvement of large myelinated nerve fibers. Group 2 consisted of 47 subjects (mean age = 54.6 [+ or-] 12.6 years) with normal NCS (mean sural nerve action potential amplitude = 20.6 [+ or -] 4.1 [micro]V) who displayed either decreased intra-epidermal nerve fiber density, abnormal autonomic nervous system testing, or abnormal qualitative sensory testing.

Autonomic nervous system and sensory abnormalities were present in both groups of patients but tended to be more severe in group 2. There were several distinct features of autonomic nervous system involvement in PN. The chief symptoms were pain, secretory and skin vasomotor signs, hypertension, and impotence. More than half of the total number of subjects had abnormal results for autonomic reflex testing (n=86; 93.5%), QSART (n=67; 72.8%), cardiac-vagal index (n=58; 63%) and skin temperature (n=51; 55.4%). A substantial proportion of subjects had orthostatic hypotension (n=39; 42.3%) and a family history of PN (n=26; 21%).

The authors concluded that the autonomic symptoms that are associated with PN are mainly cholinergic in nature and are different from the symptoms associated with other autonomic nerve disorders.

Sheila Schindler-Ivens, PT
University of Iowa
Iowa City, Iowa