Hoover's sign is a sign of functional weakness: or is it more?

Abstract

Hoover's sign has long been used to support a clinical diagnosis of functional weakness. However, it also occurs in people with pain, other functional disorders and functional neurological disorder without weakness. Some of its clinical characteristics, such as being more prominent with visual attention, suggest it might be reframed as a sign of agency. The experience, reflections and awareness of people with an abnormal Hoover's sign can be seen in this context. Reframing Hoover's sign by linking it to agency, and extending it to other clinical scenarios, could help clinicians and, most importantly, patients.Hoover's sign has long been used to support a clinical diagnosis of functional weakness. This does not explain why it can be found in pain, other functional disorders and functional neurological disorder without weakness. It can be reframed as a sign of agency by looking at clinical nuggets like Hoover's in structural changes in the brain and other disorders and clinical characteristics, like it being more prominent with visual attention. The clinical experience of people with an abnormal Hoover's sign and their reflections and awareness can be seen in this context.A recently discovered clinical technique of inducing it briefly in healthy people with pressure on the patella or tonic vibration is discussed. This illustrates the importance of sensory processing (especially sensory attenuation and proprioception) and learning/habituation to stimuli, which is known to be altered in functional neurological disorder and other functional disorders.Reframing Hoover's sign by linking it to agency and extending it to other clinical scenarios could help clinicians, neuroscience and, most importantly, patients.