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

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 < -15 mm Hg defined ischemia.

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 < .05 and p < .001). The presence of ischemia was observed in one or both arms in 10 (31%) patients with proved TOS and was always associated to phone-induced pain. Three (20%) of the controls had phone-induced ischemia. All had asymptomatic TOS and remained asymptomatic during the phone test (p = .42 from suspected-TOS patients).

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 registrationClinicalTrials.govNCT03355274.