Abdominal Clonus as a Rare Visceromotor Manifestation in Spinal Cord Injury: A Case Report.

Spinal cord injury can lead to reorganization of spinal reflex circuits and loss of supraspinal modulation of autonomic and somatic functions. Although bladder distension is a well-recognized trigger of autonomic dysreflexia, associated somatic motor manifestations are rarely described. We report the case of a 69-year-old man with a long-standing traumatic complete C6 spinal cord injury and chronic neurogenic bladder. Neurological classification according to the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) was American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade A. He experienced daily episodes of involuntary rhythmic abdominal contractions that reproducibly occurred in temporal association with bladder filling and ceased promptly after bladder emptying. In the absence of conscious sensation below the level of injury, the patient recognized these contractions as a sign of bladder fullness. When abdominal clonus occurred, he reclined his wheelchair to a near-supine position, facilitating reflex voiding into an external urinary collection device, with immediate cessation of the contractions following bladder emptying. His medical history included previous episodes of autonomic dysreflexia associated with bladder distension and marked structural changes related to chronic neurogenic bladder. This phenomenon may reflect aberrant recruitment of somatic motor circuits by visceral bladder afferents in the setting of chronic spinal hyperexcitability. In this case, abdominal clonus acquired an adaptive functional role, providing a clinically useful warning sign of bladder fullness in a patient at risk of autonomic dysreflexia. Abdominal clonus may represent a rare visceromotor manifestation of bladder distension after complete spinal cord injury. Recognition of such reflex motor responses may have clinical relevance for neurogenic bladder monitoring and the prevention of autonomic complications.