Short-term effects of local microwave hyperthermia on pain and function in patients with mild to moderate carpal tunnel syndrome: a double blind randomized sham-controlled trial

Abstract

Objective: To determine the short-term effects of local microwave hyperthermia on pain and function in patients with mild to moderate idiopathic carpal tunnel syndrome. Design: Double-blind randomized sham-controlled trial. Setting: Outpatient clinic of the Department of Physical Medicine and Rehabilitation, University Hospital. Participants: Twenty-two patients with idiopathic carpal tunnel syndrome, 12 of whom had bilateral involvement, for a total of 34 wrists, divided into two groups: a hyperthermia active treatment group (number of wrists = 17) and a sham-controlled group (number of wrists = 17). Intervention: Six sessions, two per week, of either hyperthermia or sham treatment were provided over a period of three weeks. Main measures: Visual analogue scale, Levine–Boston Self-Assessment Questionnaire (part I: evaluation of pain intensity; part II: evaluation of functional status) and neurophysiological assessments, were determined at baseline and at the end of the treatment. Results: The hyperthermia group experienced a significant improvement in pain (visual analogue scale: P = 0.002; Levine–Boston part I: P < 0.0001) and functional status (Levine–Boston part II: P = 0.002) relative to baseline. No improvements in pain intensity or functionality were observed in the sham-treated group. Changes in pain severity between baseline and the end of treatment were larger in the hyperthermia group than in the sham-controlled group (Δ visual analogue scale P = 0.004; Δ Levine–Boston part I: P = 0.009). No differences either intra or between groups were observed for median nerve conduction velocity. Conclusion: Hyperthermia provides short-term improvements in pain and function in patients with mild to moderate carpal tunnel syndrome.