Identifying posttraumatic amnesia in individuals with a Glasgow Coma Scale of 15 after mild traumatic brain injury.

Objective: To examine the utility of the Abbreviated Westmead Post-traumatic Amnesia Scale, which includes the Glasgow Coma Scale (GCS) and 3 picture cards used to measure amnesia, in identifying the presence or absence of posttraumatic amnesia in individuals with mild traumatic brain injury (mTBI).

Design: Prospective study using data from the Abbreviated Westmead Post-traumatic Amnesia Scale.

Setting: Trauma hospital.

Participants: Individuals with possible mTBI who presented between April and September 2011 (N=252; age range, 18-65y; mean age, 37.4±13.9y; 77% men).

Intervention: Administration of the Abbreviated Westmead Post-traumatic Amnesia Scale.

Main Outcome Measures: GCS and Abbreviated Westmead Post-traumatic Amnesia Scale pass/fail rates.

Results: Of the individuals, 169 (mean age, 35.1±13.6y; 77% men) received the scale. A pass/fail performance was achieved a median 121 minutes (interquartile range, 89-205min) after triage. Of the 45 who failed, 31 (69%) had a GCS score of 15. The likelihood of failing was associated with being older (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.02-1.06; P<.05), having consumed alcohol (OR, 3.09; 95% CI, 1.42-6.74; P<.01), and the scale being administered closer to the time of the injury (OR, 0.99; 95% CI, 0.99-1.00; P<.05). Nineteen (42%) of those who failed had consumed alcohol, 11 had a GCS score of 15, and 8 had a GCS score of 14.

Conclusions: A GCS score of 15 does not always signify return to normative cognitive function. Individuals with a GCS score of 15 who are acutely cognitively impaired are at risk of not being accurately identified. The addition of an amnesia score to the GCS in the Abbreviated Westmead Post-traumatic Amnesia Scale will assist in making a diagnosis of mTBI.