The Shoulder-Tapping Sign: A Highly Specific Indicator of Neurocognitive Disorders

Perseveration, an inappropriate continuation of a response, is a well-established clinical sign of neurological dysfunction. The shoulder-tapping sign (STS) is a newly described and easily identified motor perseveration.

Investigate the diagnostic utility of the STS for identifying neurocognitive disorders in patients referred for neuropsychological evaluation.

We administered a five-step verbal command from the Commands subtest of the Boston Diagnostic Aphasia Examination ("Tap each shoulder twice with two fingers keeping your eyes shut") to 400 consecutive patients ( MAGE = 67.3, SD = 10.9) with suspected cognitive decline. The STS sign was considered positive if the patient tapped either shoulder more than twice. The STS was analyzed as a measure of neurocognitive disorder and compared with the final diagnosis. Analysis included calculations of sensitivity, specificity, and positive and negative likelihood ratios with 95% confidence intervals.

The STS was positive in 23% of our sample, 96% of whom met criteria for a neurocognitive disorder. The STS was seen in 38% with dementia, 21% with mild neurocognitive disorder, and 4% with no neurocognitive diagnosis. As a diagnostic marker of neurocognitive disorders, the STS had a specificity of 0.96 and sensitivity of 0.28. Positive and negative likelihood ratios were 6.15 and 0.76, respectively.

The STS is a highly specific indicator of neurocognitive disorders. Despite low sensitivity, the brevity and potential diagnostic yield make it a valuable addition to the cognitive assessment toolkit. When positive, the STS can be a defining feature of neurocognitive disorders in brief mental status examinations.