- Importance Adults with apparently minor head trauma (Glasgow Coma Scale [GCS] scores ≥13 who appear well on examination) may have severe intracranial injuries requiring prompt intervention. Findings from clinical examination can aid in determining which adults with minor trauma have severe intracranial injuries visible on computed tomography (CT). Objective To assess systematically the accuracy of symptoms and signs in adults with minor head trauma in order to identify those with severe intracranial injuries. Data Sources We performed a systematic search of MEDLINE (1966-2015) and the Cochrane Library to identify studies assessing the diagnosis of intracranial injuries. Study Selection Studies were included that measured the performance of findings for identifying intracranial injury with a reference standard of neuroimaging or follow-up evaluation. Fourteen studies (range, 431-7955 patients) met inclusion criteria with patients having GCS scores between 13 and 15 and 50% or more older than 18 years. Data Extraction and Synthesis Three authors independently performed critical appraisal and data extraction. Results The prevalence of severe intracranial injury (requiring prompt intervention) among the 23 079 patients with minor head trauma was 7.1% (95% CI, 6.8%-7.4%) and the prevalence of injuries leading to death or requiring neurosurgical intervention was 0.9% (95% CI, 0.78%-1.0%). The presence of physical examination findings suggestive of skull fracture (likelihood ratio [LR], 16; 95% CI, 3.1-59; specificity, 99%), GCS score of 13 (LR, 4.9; 95% CI, 2.8-8.5; specificity, 97%), 2 or more vomiting episodes (LR, 3.6; 95% CI, 3.1-4.1; specificity, 92%), any decline in GCS score (LR range, 3.4-16; specificity range, 91%-99%;), and pedestrians struck by motor vehicles (LR range, 3.0-4.3; specificity range, 96%-97%) were associated with severe intracranial injury on CT. Among patients with apparent minor head trauma, the absence of any of the features of the Canadian CT Head Rule (≥65 years; ≥2 vomiting episodes, amnesia >30 minutes, pedestrian struck, ejected from vehicle, fall >1 m, suspected skull fracture, or GCS score 60 years, intoxication, headache, vomiting, amnesia, seizure, or trauma above the clavicle) had an LR of 0.08 (95% CI, 0.01-0.84), lowering the probability of severe intracranial injury to 0.61% (95% CI, 0.08%-6.0%). Conclusions and Relevance Combinations of history and physical examination features in clinical decision rules can identify patients with minor head trauma at low risk of severe intracranial injuries. Certain findings, including signs of skull fracture, GCS score of 13, 2 or more vomiting episodes, decrease in GCS score, and pedestrians struck by motor vehicles, may help identify patients at increased risk of severe intracranial injuries.