SELECTIVE AUTONOMIC AND SENSORY DEFICITS IN SLOW TRANSIT CONSTIPATION

Chronic idiopathic constipation is likely to be a heterogeneous condit ion. Our previous studies on the stimulated sweating response suggeste d that autonomic dysfunction may be a cause in a subset of patients. O ur aims were to test selectively the neural and sweat gland components of the sweat response and to test unmyelinated sensory fibres so as t o determine whether a small fibre neuropathy is present: Twelve female patients with proven slow transit constipation and nineteen age-match ed healthy volunteers took part in the study, The sensory tests includ ed thermal thresholds and axon reflex vasodilatation in response to in tradermal capsaicin, measured with a laser Doppler. Direct and axon re flex sweating was induced with intradermal methacholine and nicotine, respectively, and measured with ar; evaporimeter. Non-parametric tests were used for statistical comparison with a group of seven control su bjects. Results are expressed as medians and range. All four patients who reported constipation from childhood had a selective deficit of un myelinated afferent fibre function in the feet, with markedly elevated thresholds to warm sensation (controls 5.2; 4.3-10.6, patients 13.8; 11.8-16.1 partial derivative T (degrees C), P < 0.02) and heal pain (c ontrols 10.6; 8.2-14.7, patients 18.1; 13.9-22.6 partial derivative T (degrees C), P < 0.05) and a reduced response to capsaicin (controls 4 7.0; 24-117, patients 13.5; 12-30 partial derivative Flux (V), P < 0.0 05). In contrast, patients with adult onset constipation (n = 7) had a selective neural sweating deficit (controls 49.8; 32.0-61.8; patients 27.7; 7.3-44.3 g/m(2) h, P < 0.05), indicating dysfunction of post-ga nglionic sympathetic cholinergic fibres. Patients from both groups wer e shown to have normally functioning sweat glands in direct response t o methacholine. Our findings suggest that patients with severe chronic idiopathic constipation may have selective small fibre neuropathies, of which constipation is a manifestation. (C) 1997 Elsevier Science B. V.