Researchers have identified a new potential concussion marker—spontaneous headshake after a kinematic event—that shows a 91.9% predictive accuracy for concussion among football players, according to a recent study.
The study led by Christopher J. Nowinski, et al. from the Concussion Legacy Foundation examined the utility of a newly observed sign, the Spontaneous Headshake After a Kinematic Event (SHAAKE), in relation to concussion symptoms. SHAAKE is defined as a rapid, lateral headshake occurring at a rate of 2-8 Hz, typically within seconds to minutes following a kinematic event, potentially indicative of concussion.
In this cross-sectional study, published in Diagnostics, 347 athletes (median age 27; 47.6% female) were surveyed on SHAAKE occurrences and associations with self-reported concussions. The study, conducted primarily in North America (79.3%, with 64.6% from USA and 14.7% from Canada), found that 68.9% of participants reported at least one SHAAKE. Results showed a median frequency of five SHAAKEs per participant, with four SHAAKEs (IQR: 2-7) specifically associated with concussion symptoms.
Across all sports, SHAAKE demonstrated a sensitivity of 49.6% and a positive predictive value (PPV) of 72.4% for diagnosing concussions. Among football players, SHAAKE sensitivity was 52.3%, specificity was estimated at 99.9%, with a PPV of 91.9%, and a negative predictive value of 99.5%.
The majority of athletes (93.3%) who reported a SHAAKE associated it with concussion symptoms. The top three reported reasons for the movement were disorientation or confusion (71.7%), dizziness (54.0%), and a feeling like they needed to jumpstart their brain (52.3%). Notably, this is the first formal study of this sign, despite its previous appearances in popular media including movies, television shows, and cartoons.
While these findings suggest a possible link between SHAAKE and concussion indicators, the researchers acknowledge study limitations, including its reliance on self-reported data and retrospective recall. They recommend further validation through real-time video monitoring and prospective studies to confirm SHAAKE's diagnostic accuracy across various sports contexts.
Full disclosures can be found in the published study.
