Upgoing thumb sign: A sensitive indicator of brain involvement?

Area of Science:

• Neurology
• Clinical Neuroscience
• Diagnostic Medicine

Background:

• A subtle clinical finding, the upgoing thumb sign, was previously identified in patients experiencing transient ischemic attacks (TIAs) or minor stroke.
• The diagnostic utility and reliability of this sign require further investigation, particularly in differentiating stroke from stroke mimics.

Purpose of the Study:

• To determine the frequency of the upgoing thumb sign in patients with minor stroke and TIAs compared to those with stroke mimics.
• To evaluate the inter-rater reliability in detecting the upgoing thumb sign.
• To assess the agreement between the presence of the upgoing thumb sign and confirmed clinical findings.

Main Methods:

• Prospective study conducted at a Stroke Prevention Clinic involving independent examinations by blinded stroke faculty and fellows.
• Comparison of the upgoing thumb sign frequency between minor stroke/TIA patients and stroke mimic patients.
• Inter-rater reliability assessed using Cohen's kappa (κ) statistic, with agreement also evaluated against patient symptoms.

Main Results:

• The upgoing thumb sign was significantly more prevalent in patients with minor stroke or TIAs compared to stroke mimics (p=0.001).
• Substantial agreement was observed between examiners for detecting the sign on both the right (κ=0.71) and left (κ=0.78) sides.
• The upgoing thumb sign demonstrated substantial agreement with patient symptoms, as assessed by both examiners (κ=0.65 and κ=0.64, both p<0.01).

Conclusions:

• The upgoing thumb sign serves as a sensitive and reliable indicator of neurological involvement, specifically brain involvement.
• This non-invasive and easily performed clinical examination is highly compatible with and confirmatory of a patient's reported symptoms.
• The sign's reliability and agreement with clinical findings support its use in the diagnostic workup of suspected stroke or TIA.