[Absence of anal reflex in patients with central nervous system diseases]

The anal reflex was examined electromyographically in 336 patients with central nervous system disease. The absence of anal reflex was found in a total of 78 patients. The incidence of the absence of anal reflex was 31 over 132 (23.7%) in the patients with pyramidal signs in lower extremities, 7 over 41 (17.0%) in patients with extrapyramidal signs in lower extremities, 12 over 50 (24.0%) in patients with both signs and 28 over 113 (24.8%) in patients without both signs. Further incidence of the absence of anal reflex was 6 over 26 (23.1%) in patients with unilateral pyramidal signs, 24 over 106 (22.6%) in patients with bilateral pyramidal signs, 3 over 13 (23.1%) in patients with unilateral extrapyramidal signs and 4 over 28 (14.3%) in patients with bilateral extrapyramidal signs. There was no statistical difference among the above groups, therefore the absence of anal reflex appeared to have no specific relationship to pyramidal or extrapyramidal signs. On the other hand, the incidence of the absence of anal reflex was 33 over 81 (40.7%) in patients with and 45 over 255 (17.6%) in patients without disturbance of light touch and/or pinprick in sacral area. The incidence of the former is statistically higher than that of the latter. Therefore we may conclude that the central afferent arch of the anal reflex has a strong relationship to superficial sensory tract, but the central efferent arch has almost no connection with pyramidal or extrapyramidal tracts.