Autonomic impairment in painful neuropathy

Objectives: 1) To determine the degree and distribution and quantitate the severity of autonomic impairment in painful neuropathy (PN). 2) To assess t he role of autonomic testing in evaluating PN. Methods: The authors studied 92 patients with PN (60 women and 32 men, age 56.9 +/- 12.4 years) using: 1) autonomic reflex testing (ART), Quantitative Sudomotor Axon Reflex Test (QSART), cardiac-vagal, head-up tilt, and surface skin temperature; 2) auto nomic symptoms questionnaire; 3) nerve conduction (NCS) and laboratory stud ies; 4) quantitative sensory testing; 5) skin biopsy; and 6) Composite Auto nomic Symptoms Score (CASS) scale to grade ART results from 0 (normal) to 1 0 (autonomic failure). Results: Autonomic involvement in PN had characteris tic features. Main symptoms were pain, secretory and skin vasomotor signs, hypertension, and impotence. ART results were abnormal in 86 (93.5%) (CASS < 4), QSART in 67 (72.8%), cardiac-vagal index in 58 (63%), skin temperatur e in 51 (55.4%), orthostatic hypertension in 39 (42.3%), and family history of PN in 26 (21%) of patients. Group 1 (abnormal NCS) (n = 45) had more se vere ART and sensory abnormalities than the Group 2 (normal NCS) (n = 47): 1) CASS 2.0 <plus/minus> 0.96 vs 1.55 +/- 0.88 (p < 0.01), cardiac-vagal in dex (p < 0.02), skin temperature (p < 0.02), hypertension (p < 0.03), cooli ng (p < 0.002), and vibration (p < 0.0005) thresholds. Conclusions: Autonom ic symptoms in painful neuropathy are predominantly cholinergic and form a unique constellation of features that are distinct from other autonomic neu ropathies.