The first part of new evidence-based guidelines, published in the September 2014 issue of Neurosurgery, sought to identify which signs, symptoms, and neurologic and cognitive deficits have the highest and most consistent prevalence in samples of individuals sustaining a potentially concussive event.
The researchers, composed of a team led by Nancy Carney, PhD, Oregon Health & Science University, Portland, and Jamshid Ghajar, MD, Brain Trauma Foundation, New York, New York, sifted through over 5,000 studies and systematically narrowed the stack down to 26 that met their strict criteria.
According to the results, the four indicators of concussion, observed in alert individuals (defined as a Glasgow Coma Scale Score, 13 to 15) after a force to the head are the following:
1. Observed and documented disorientation or confusion immediately after the event
2. Impaired balance within 1 day after injury
3. Slower reaction time within 2 days after injury
4. Impaired verbal learning and memory within 2 days after injury
The main symptoms experienced by subjects with potential concussive events were headache (93%), blurred vision (75%), dizziness (64%), and nausea (61%). Other key findings from the review include:
* Decrements in cognitive function decreased from 58% on day 1 to 8% on day 7, indicating that in the majority of cases, cognitive deficits resolve within 1 week.
* Tests of reaction time, memory, and attention/processing speed/working memory most consistently showed deficits in cognitive function within the first week of injury.
* Individuals with a history of previous concussions had lower scores on tests from baseline to 5 days after injury, compared to those without previous concussions.
The research team hopes to publish the second step of the guidelines by the end of the year. The goal of that document will be to identify further symptoms and provide further verification of the four indicators described here.