Head Injuries and Concussion: Pathophysiology, Assessment and Red Flags
Updated: 18 hours ago
Head injuries range from a brief knock that resolves in minutes to a rapidly deteriorating bleed that needs urgent intervention, and the tricky part is that early presentations can look deceptively similar. Knowing what separates the two is one of the most important assessment skills a student can build.
Mechanism Matters, But It Isn't Everything
A high-energy mechanism raises suspicion, but a seemingly minor knock can still cause a significant injury, particularly in the very young, the elderly, or anyone on blood-thinning medication. Mechanism informs your index of suspicion, it doesn't rule anything out on its own.
The Red Flags That Change Everything
Deteriorating conscious state, repeated vomiting, worsening headache, seizure activity, unequal pupils, or any focal neurological deficit all suggest a more serious underlying process and warrant urgent escalation. A patient who initially looks fine can still deteriorate, which is why reassessment matters as much as the initial assessment.
In practice: a patient who was talking normally at the scene but becomes drowsy and vomits twice on the way to hospital is a deterioration, not a coincidence, it needs to change your management, not just get noted in the handover.
Concussion Is Often Underestimated
Concussion doesn't require loss of consciousness to be significant, and symptoms like poor concentration, light sensitivity, and irritability can persist for days to weeks. Because there's no visible injury on imaging in most cases, it's easy for the patient (and sometimes the clinician) to underestimate how much recovery time is genuinely needed.
Reassessment Is the Skill, Not Just the First Look
A single conscious-state score at one point in time tells you far less than a trend over several assessments. Building the habit of reassessing and comparing against your own earlier findings, not just the notes is what catches early deterioration before it becomes obvious.
A patient who looks fine now is not the same as a patient who will still look fine in twenty minutes.
Protect the Brain From Secondary Injury
The initial impact causes the primary brain injury, and prehospital care can't undo it. What you can influence is secondary injury: further damage caused by hypoxia, hypotension and raised intracranial pressure in the minutes and hours afterwards. Even a single episode of low oxygen levels or low blood pressure is associated with worse outcomes, so supporting oxygenation and ventilation, and maintaining adequate blood pressure, are priorities from the moment you arrive. The Queensland Ambulance Service guideline, for example, targets a systolic blood pressure of 100 to 120 mmHg when fluids are given, and aims for normal carbon dioxide levels by avoiding both hyperventilation and hypoventilation.
Positioning and Simple Measures
Simple measures make a real difference. Where spinal precautions allow, position the patient head-up at around 30 degrees, and loosen anything tight around the neck, such as clothing or a poorly fitted collar, which can impair venous drainage from the head and raise intracranial pressure. Managing pain, nausea and agitation also matters, as each can contribute to rising pressure inside the skull.
The Signs of Rising Intracranial Pressure
A falling conscious state is usually the earliest and most sensitive sign that intracranial pressure is rising. Later signs include a unilateral dilated or sluggish pupil, and Cushing's reflex: hypertension with a widening pulse pressure, bradycardia and an irregular breathing pattern. Cushing's reflex is a late and ominous sign of impending herniation, so don't wait for it before escalating care.
Using the GCS Well
The Glasgow Coma Scale is only useful if it's scored consistently. Record each component (eyes, verbal and motor) rather than just the total, because a drop in the motor score carries more weight than losing a single verbal point. Note the time with every score, and compare each new result against your own earlier findings.
Conclusion
Head injury assessment rewards vigilance over a single snapshot judgement. Know the red flags, reassess rather than assume stability, and take concussion symptoms seriously even without a dramatic initial presentation.
References
Queensland Ambulance Service. Clinical Practice Guidelines: Trauma/Traumatic brain injury. https://www.ambulance.qld.gov.au/__data/assets/pdf_file/0024/219147/cpg_traumatic-brain-injury.pdf
Traumatic Brain Injury. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK557861/
Concussion. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK537017/
Patricios JS, Schneider KJ, Dvorak J, et al. Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport – Amsterdam, October 2022. Br J Sports Med. 2023;57(11):695–711. https://doi.org/10.1136/bjsports-2023-106898
Teasdale G, Jennett B. Assessment of coma and impaired consciousness: a practical scale. Lancet. 1974;2(7872):81–4. https://doi.org/10.1016/S0140-6736(74)91639-0
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Disclaimer: This article is general education for students. It is not medical advice, and it does not replace your service's clinical practice guidelines, your educators or your local protocols.
