Somato-sensory Reflex Arch in Spinal Cord Injury - Effect on Clinical Outcome

Introduction:

Spinal cord injury has a profound impact on the lives of those affected. Quality of life is restricted not only by immobility but also by severe neurogenic bladder and bowel dysfunction. For example, 66% of SCI patients have to empty their rectum digitally, 75% suffer from faecal incontinence and 9% spend more than 60 minutes each time they defecate. Neurological impairment due to SCI is permanent and the average age at injury is only 28 years. The longevity of individuals with SCI is approaching that of the general population and, accordingly, most patients have to live for several decades with severe bladder and bowel symptoms. It is estimated that the number of individuals with SCI in Denmark is 3.000 and each year 10.000 persons in the European Union sustain a SCI. Even though clean intermittent catheterization has successfully reduced mortality due to urinary tract infections or reflux and though several new treatment modalities for neurogenic bowel dysfunction have been introduced, both bladder and bowel dysfunction still rank among the top three causes of impairment of quality of life after SCI.

Somato-sensory reflex arch:

The concept was pioneered by professor Xiao. Animal studies and basic clinical research were performed in the United States and later human clinical studies have been done in Wuhan, China. The surgical procedure principle can briefly be summarized as follows:

All spinal nerves have an anterior efferent root and a posterior afferent root. For the somato-sensory reflex arch (or "Xiao procedure") the posterior (afferent or sensory) root of the 5th lumbar nerve (L5) is kept while the anterior root is cut and anastomosed to the anterior root of a lower segment, usually the third sacral segment (S3). Thereby, a new reflex arch has been created from the skin of the leg through the sensory part of L5 to the spinal cord and further through the anastomosis via S2 or S3 to the bladder and bowel. Strong stimuli at the L5 dermatome, i.e. scratching or electrical stimulation, will then initiate voiding (6,7). Effects of the somato-sensory reflex arch on neurogenic bowel dysfunction have not been studied, but clinical experience indicates that bowel management is substantially facilitated.