Objectives:
To determine the incidence and factors associated with median neuropathy at the wrist (MNW) in systemic sclerosis (SSc) patients using an electrodiagnostic (EDX) study.

Material and methods:
SSc patients who attended the scleroderma clinic, Srinagarind Hospital, were prospectively evaluated by questionnaire, physical examination, and EDX study. The questionnaire consisted of the baseline characteristics, type of scleroderma, clinical signs and symptoms associated with scleroderma, and the Boston questionnaire. The physical examinations were the Modified Rodnan Skin Score, motor power grading of bilateral abductor pollicis brevis muscle, and pinprick sensation of median nerve distribution of both hands. Moreover, the EDX study, which was composed of median and ulnar sensory and motor nerve conduction studies of both hands and electromyography of the abductor pollicis brevis muscles, was evaluated at baseline and following two years.

Results:
Out of 75 systemic sclerosis patients, 50 individuals participated in the study. Diffuse cutaneous type of SSc is the most common type (72%). The common SSc associated symptoms were Raynaud phenomenon, skin tightness and hand deformity. Incidence of MNW was 90 cases per 1000 person-years. Following a two-year interval, the percentages of mild, moderate and severe MNW were 28%, 22% and 6% respectively. Most of those with MNW were still particularly asymptomatic in a mild degree. Moreover, 12 out of 50 patients (24%) had a worse EDX result. There was no statistically significant association between MNW occurrence and studied factors.

Conclusions:
MNW commonly has high incidence in SSc patients. Therefore, SSc patients should be followed up in both clinical and EDX studies for MNW screening. SSc patients with asymptomatic MNW might need clinical follow-up for early diagnosis.