The effects of head posture on nerve conduction studies in patients with ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory disease which effects cervical posture of patients. The aim of this study was to evaluate AS patients according to the degree of cervical disorder and was evaluate them electrophysiologically, functionality, and disease parameters. Our study comprised 64 AS patients and 30 healthy controls. The head posture of patients was evaluated by craniovertebral angle (CVA) measurement. Nerve conduction of bilateral median, radial, ulnar, and medial antebrachial cutaneous (MAC) nerves were studied in all patients. The most important nerve conduction differences in AS patients who have severe forward head posture (FHP) were decrease in sensory nerve action potential (SNAP) amplitude and compound muscle action potential amplitudes of median nerves, a decrease in the SNAP amplitude of ulnar nerves, a delay in the F response latency of ulnar nerves, and prolongation in the SNAP latency of the MAC nerve. The FHP disorder that develops in AS patients may have electro physiological effects, similar to those of thoracic outlet syndrome In addition, the functional status of these patients is worsened as severity of FHP increases.