A pilot study of forearm microvascular impairment and pain while using a telephone

Abstract Objective To determine if using a telephone can induce forearm pain and ischemia. Design Prospective case-control trial. Setting Vascular laboratory in the university hospital in Angers between September 2018 and March 2019. Participants Fifteen apparently healthy subjects (controls) and 32 patients with suspected thoracic outlet syndrome (TOS) of vascular or non-vascular origin. Intervention Hand-holding a cellular phone to answer a call from investigators. Main outcome measures Presence of forearm fatigue or pain (primary outcome), ability to hold the phone with each hand for 1 min (secondary outcome 1) and decrease in forearm transcutaneous oxygen pressure DROP index indicating forearm ischemia (secondary outcome 2). A DROP  Results Answering a phone call resulted in 25(78%) patients with forearm fatigue or pain and in 18 (56%) cases in the inability to hold the phone for 1 min, on one or both arms in patients with suspected TOS, but never occurred in healthy volunteers (p  Conclusion The phone conversation resulted in pain in many patients with suspected TOS. Transcutaneous oximetry can document the underlying ischemia. Forearm phone-call-induced pain may be indicative of TOS provided that no earplug or headset is used. Trial registration ClinicalTrials.gov NCT03355274