Clinical Assessment and Diagnosis of Brain Injury
Core concepts
Master the Glasgow Coma Scale (GCS) - eye, verbal, motor - and its severity bands (mild 13–15, moderate 9–12, severe ≤8). Know that the motor component is the strongest prognostic subscale. Understand the acute neurologic exam: pupillary reactivity (brainstem), corneal and gag reflexes, oculocephalic/oculovestibular responses, and posturing (decorticate vs decerebrate). Understand concussion assessment: loss of consciousness is neither necessary nor sufficient; use symptom scales and vestibular/oculomotor screening. Know the role of CT rules (e.g., Canadian CT Head Rule) to identify who needs imaging after minor head injury, and that MRI is superior for subtle injury. Cognitive screening (MoCA, MMSE) informs but does not diagnose.
Traps
Questions exploit GCS scoring errors: score the best response, not the worst; intubated patients cannot be scored on verbal (record "T"). Do not equate a normal CT with absence of concussion. Remember that pupillary dilation in herniation is ipsilateral (CN III compression) before contralateral. Distinguish decorticate (flexor arms, cortical damage) from decerebrate (extensor, brainstem damage).
Rule of thumb
GCS ≤8 → consider airway protection. Any decline in GCS or new focal deficit after head injury → immediate imaging.
Worked example
A patient opens eyes to pain, speaks confused words, and withdraws from pain: E2 + V4 + M4 = 10, moderate TBI.