Identify patients with dynamic neurological exams in the first 48 hours after traumatic brain injury (TBI) based on the Glasgow Coma Scale (GCS) score variability and determine factors that are associated with high variability.

The Predictors of Low-risk Phenotypes after TBI Incorporating Proteomic Biomarker Signatures (PROTIPS) was a prospective, observational study of individuals aged 15 years and older who presented to the emergency department with TBI; GCS 3-12 confirmed by the presence of hemorrhage on head CT scan (n=126). 

Patients were characterized into two groups: low or high variability based on their hourly GCS during the first 48 hours after TBI. Patients with GCS scores that did not fluctuate more than 1 point were classified as low variability and the rest as high variability. Demographics and injury characteristics were compared between the variability groups. Then, principal component analyses (PCA) were run independently for each group and identified variables associated with low and high variability. 

Subjects in the high variability group (n=80) were significantly younger (40 ±19.5 v. 56 ±19.6 years, P= 0.001) and had lower admission GCS scores (Median 8 [IQR 5] v. Median 9 [IQR 4], P=0.011) than the low variability group (n=46). The groups had similar proportions of male subjects and severity of injury on imaging as measured by Marshall score. In the high variability group, PC1 explained 10.6% of the variance (correlation 0.99, P=0.001). Variables with high loadings in PC1 (>|0.45|) included death in hospital, presence of neurological deterioration events, presence of paroxysmal sympathetic hyperactivity, midline shift >5 mm, basal cistern compression and hypertonic saline administered.

PCA indicates that cerebral edema, both clinical and radiographical, among other factors, is associated with high variability of GCS scores over the first 48 hours after injury.