A Thoracic Disc Herniation Presenting as an Abdominal Hernia

Abstract

Thoracic disc herniations (TDHs) occur infrequently, accounting for fewer than 1% of all spinal disc prolapses.1 Although most TDHs present initially with radicular pain, others may demonstrate only myelopathic signs and/or, even less often, ipsilateral abdominal muscle weakness.2,3 A 75-yr-old male who had been successfully treated with intermittent split-table pelvic traction for a T12–L1 disc herniation returned a year later with new, abrupt-onset, severe left-flank and abdominal pain. The physical examination revealed a large abdominal-wall hernia (Fig. 1) involving both the left upper- and lower-abdominal quadrants. The straight-leg raising test was unrestricted. Sensory and motor testing and the deep tendon reflexeswere all normal.FIGURE 1: Large abdominal-wall hernia (arrow) with thoracic disc herniation.However, there was a notable reduction in the motor units of the muscular abdominal wall. No long tract signs were observed, and the bowels and bladder were controlled. Electroneuromyography demonstrated 4+ fibrillationand positive waves in the left paraspinal muscle at the T10–T12 levels, without similar findings in the adjacent abdominal muscle. However, there was a notable reduction in motor units in the abdominal musculature. The peroneal motor nerve conductions were normal. Magnetic resonance imaging revealed a large, left T12–L1 disc herniation (Fig. 2). With persistent pain and associated difficulty in walking, the patient was referred to a spinal surgeon and was restarted on split-table intermittent pelvic traction after thermal therapy.FIGURE 2: Thoracic disc herniation (arrow) at T12–L1.With continuing conservative treatment, the patient’s pain slowly remitted. TDHs account for 0.24–0.75% of all disc herniations, with an overall incidence of 1/1,000,000 patients per year.1 This relative paucity of TDHs has been attributed to the stabilizing influence of the rib cage. When thoracic radicular pain is accompanied by myelopathic signs (i.e., hyperreflexia and Babinski reflexes), they mimic the presence of a spinal cord tumor. Although suggestive, an abdominal hernia in the presence of radicular thoracic pain is not pathognomonic evidence of a TDH. Other sources of thoracic root compromise include, among others, diabetes mellitus and/or viral exanthems (i.e., poliomyelitis), as well as herpes zoster.