Upgoing thumb sign: A sensitive indicator of brain involvement?

Objective: To assess the frequency of this finding in patients with minor stroke and TIAs compared to those with stroke mimics and to evaluate the level of agreement between examiners to detect an upgoing thumb sign.

Methods: We previously reported an upgoing thumb sign as a subtle clinical finding in patients with transient ischemic attacks or minor stroke. In this study conducted between March 2016 and October 2016 at the Stroke Prevention Clinic at University Hospital, University of Western Ontario, London, Canada, participants were examined independently by stroke faculty and fellows who were blinded to each other's findings. The frequency of the upgoing thumb sign in patients with minor or threatened stroke was compared to that in patients with stroke mimics, and the level of agreement between examiners and clinical findings was assessed with the Cohen κ test.

Results: The upgoing thumb sign was observed more frequently in those with minor stroke/TIA than in those with stroke mimics ( = 0.001). A substantial level of agreement between examiners was recorded in the detection of the thumb sign (κ: right 0.71, left 0.78). In addition, an upgoing thumb sign showed a substantial level of agreement with the patient's symptoms (examiner 1: κ = 0.65, < 0.01; examiner 2: κ = 0.64; < 0.01).

Conclusions: An upgoing thumb sign is a sensitive and reliable indicator of brain involvement. This examination is noninvasive, easy, reliable, and highly compatible with and confirmatory of the patient's symptoms.