Predicting outcomes in thoracic outlet syndrome

Objective To test the hypothesis that somatosensory evoked potentials (SEP) and results of arterial photoplethysmography (PPG) predict outcome after surgery for thoracic outlet syndrome. Design A retrospective case series which correlated surgical outcome with preoperative SEP and PPG results using Fisher's exact test. PPG results were considered abnormal when there was complete loss of arterial pulsation, and SEP results when amplitudes were reduced and latencies delayed. Setting Royal Prince Alfred Hospital, between March 1984 and February 1992. Patients Forty-six consecutive patients with clinically diagnosed thoracic outlet syndrome were admitted for surgery; sixteen underwent bilateral operations (total of 63 limbs). Interventions After SEP and PPG tests, all patients underwent thoracic outlet decompressive surgery--excision of the first rib, of the cervical rib (where present), and of other congenital anomalies associated with thoracic outlet syndrome--by the axillary approach. Main outcome measures Surgical outcome was graded as good when symptoms improved and the patient returned to work or pre-illness activities. It was graded as poor when symptoms remained unchanged or worsened, or when there was continued inability to work or engage in usual activities. Results The follow-up period ranged from 1.9-9.8 years (mean, 5.7 years). Significantly more limbs with abnormal SEP or PPG results had a good outcome (49 of 53 limbs; 93%) than limbs with normal SEP and PPG results (six of 10 limbs; 60%) (P = 0.02). Conclusions Abnormal SEP and PPG results correlated with a better postsurgical outcome. These tests may therefore aid in determining prognosis of surgery for thoracic outlet syndrome.