Segmental abdominal wall paresis caused by lateral low thoracic disc herniation.

STUDY DESIGN

Clinical, radiologic, and neurophysiologic description of 2 cases.

OBJECTIVE

To describe 2 cases with spontaneous deep unilateral abdominal pain as the first symptom of thoracic disc herniation at a low thoracic vertebral level, further manifested by unilateral partial paresis of the obliquus abdominis muscle.

SUMMARY OF BACKGROUND DATA

Clinical manifestation of lateral thoracic disc herniation with electrophysiologic results and conservative therapy as treatment of choice when spinal cord functions are preserved.

METHODS

Magnetic resonance imaging revealed bilateral paramedian disc protrusions at T12-L1 in Patient 1 and foraminal herniation at T10-T11 and paramedian herniation at T11-T12 in Patient 2. Electromyography (EMG) and evoked potentials were investigated in the acute stage and after 6 months.

RESULTS

Spontaneous activity on needle EMG confirmed axonal root impairment. Somatosensory and motor-evoked potentials were within normal limits and excluded spinal cord involvement. Nonsteroidal anti-inflammatory drugs and periradicular injection of steroids and local anesthetics rendered both patients pain-free. Normalization of muscle strength within 3 to 6 months was accompanied by EMG findings of reinnervation.

CONCLUSION

Lateral disc herniation causing compression of a thoracic root associated with unilateral segmental paresis of the abdominal wall is a rare condition. Despite EMG documentation of axonal root lesion, however, a purely conservative therapeutic approach may be considered treatment of choice in cases without spinal cord involvement.