Objective: To observe the correlation between referred pain distribution and acupoint sensitization in patients with intestinal diseases.
Methods: In clinical research, 443 patients from 8 hospitals were recruited, including the outpatients and inpatients of Crohn's disease (n=143), ulcerative colitis (n=108), chronic appendicitis (n=87) and other intestinal diseases (n=105). The site with tenderness on the body surface and the morphological changes of local skin were observed and recorded in the patients. Using a sensory tenderness instrument, the pain threshold at the sensitization point was measured in 60 patients with ulcerative colitis. In animal experiment, SD rats were used and divided into a enteritis group (n=8), in which the enteritis model were established, and a control group (n=3), in which no any intervention was given. After the injection of Evans blue (EB) at caudal vein, the blue exudation points on the body surface were observed and the distribution rule was analyzed statistically.
Results: The referred pain on the body surface in the patients with intestinal diseases was mainly located in the lower abdomen (93.9%, 416/443), the lumbar region (70.9%, 314/443) and the lower legs (33.0%, 146/443). The diameter of tenderness region was 1.5 to 2.5 cm. Compared with the region without sensitization, the pain threshold of the sensitization point in the patients with ulcerative colitis was reduced significantly (P<0.001). The referred pain on the body surface in the patients with appendicitis was located in the right lower abdomen (97.7%, 85/87), the waist and back (54.0%, 47/87) and the right lower limbs on the medial side (71.3%, 62/87). The tenderness region was 1 to 2 cm in diameter and was irregular in form. After modeling of enteritis in the rats, the EB exudation points were visible from T12 to L2.
Conclusion: Intestinal diseases induce referred pain on the body surface where is the same as or adjacent to the location of the spinal segment corresponding to the affected intestinal section. These sensitization regions are related to the locations of acupoints.
Keywords: acupoint sensitization; appendicitis; colitis; hemostasis; nature of acupoint; pain threshold.