Head Injury: The Evidence Behind the Pathway

It is eleven at night in a taluk hospital casualty. A 24-year-old man is brought in after his motorcycle skidded on the way back from a wedding. He was not wearing a helmet. He smells of alcohol. His friends say he was “out for a minute”. He has vomited once. He opens his eyes when you speak, is a little confused about where he is, and obeys commands: a Glasgow Coma Scale of 14. The nearest scanner is forty kilometres away. The intern asks whether he can simply be watched overnight, since he is “just drunk”. This is an illustrative case, not a real patient.

The Head Injury Pathway will help you with him: what is available where you are, the scan decision by three different rules, the coma scale read properly, the pressure thresholds, the drug doses and their disagreements, the surgical thresholds and the discharge. What it no longer carries is some of the background. The burden figures, the one Indian study of scanning in practice and the history of the mannitol recommendation sat in its Evidence tab and have moved here, so that the tool stays quick at the bedside. By the end of this article you will know which head injury numbers can be trusted, and why the tool is careful with the others.

1. The scale of it, and which numbers hold

India had an estimated 7.46 million traumatic brain injuries in 2019, uncertainty interval 6.38 to 8.67 million (India State-Level Disease Burden Initiative, 2021). Road injury killed 218,876 people in 2017 and was the leading cause of death in Indian males aged 15 to 39 (India State-Level Disease Burden Initiative, 2020). Our patient, at 24, sits in the middle of that age band.

“So how many of them die?” Here you need to be careful about what a paper actually says. The Global Burden of Disease paper prints no traumatic brain injury death count. It estimated the disability-adjusted life years for this condition as years lived with disability, and nothing else. So anybody citing it for mortality is citing something it does not contain.

The Indian national guideline’s own figures do not reconcile with any of that. It states nearly 500,000 deaths a year from traumatic brain injury and a minimum of 15 million moderate to severe injuries. Five hundred thousand is two to three times every road death from every other source, and road injury is the leading cause. This tool does not print that figure as established. The lesson is a general one: a large round number repeated often is not the same as a measured one.

Then alcohol. 16 per cent of head-injured patients were intoxicated at registration across seven Bangalore hospitals (Gururaj 2004). During the 2020 lockdown daily presentations at one centre fell from 29.4 to 19.5, and the authors attributed it to road decongestion and the regulation of alcohol sales. Alcohol and the road travel together, and our patient brought both.

That is exactly why the intern’s plan is the common mistake. It is easy to see why it tempts: the smell of alcohol explains the confusion, and the scanner is far. But intoxication does not excuse a low score. The British guideline is explicit: assume a depressed conscious level is due to alcohol only after an important brain injury has been excluded.

2. The scan, and what Indian practice actually does

The tool sets out three answers to the scan question: the national workflow’s seven items, the British one-hour and eight-hour lists, and the Canadian CT head rule. Our patient has a coma score below 15 and lost consciousness. On the workflow’s list either one is an indication, and if his score is still below 15 two hours after the injury, the British and Canadian rules ask for a scan too. He needs it, and the forty kilometres are part of the treatment.

“Has anyone tested the Canadian rule in India?” Once. In the only Indian validation, 101 patients with minor injury in Pune, the Canadian rule was 100 per cent sensitive and 45.8 per cent specific, and all 39 patients who did not meet it had a normal scan (Lamba 2021). That n is small for a claim of perfect sensitivity, and the tool says so: it prints these figures beside the rule for every patient.

The finding worth carrying from that study is not the sensitivity. It is the practice: the emergency physicians applied the rule in every case of mild injury, and the neurosurgeons scanned everybody on clinical gestalt. Two groups of doctors, one hospital, two habits.

And two gaps. There is no Indian study of the British criteria in an Indian population, and no Indian figure for how many scans in minor head injury were unnecessary. Both absences are stated rather than filled with a figure from elsewhere.

3. Mannitol has less behind it than its reputation

Mannitol is the drug every intern reaches for in head injury. It is worth knowing how thin the guideline support has become. The Brain Trauma Foundation’s fourth edition makes no recommendation at all on hyperosmolar therapy: not for it, not against it, and not for one agent over another (Carney 2017). The familiar 0.25 to 1 g/kg is third edition text that the fourth edition republished without re-endorsing, and the familiar ceiling of 320 mOsm/L is not in it either.

“Then why does the tool still give a mannitol dose?” Because the national workflow and the Indian national guideline both do, and the tool prints what they say, with their units. One gives a dose per bolus and the other a dose per day, and confusing them puts a resident out by a large factor. What survives is narrower: do not start it for everybody; before pressure monitoring is in place, keep it for signs of transtentorial herniation or deterioration not explained outside the head; and avoid hypotension.

Back to the casualty

Our patient was not watched overnight. He went for his scan with a nurse, a cervical collar and a written note of his coma score and pupils. If the scan is normal and he reaches a score of 15, he goes home only with a responsible adult for the first 24 hours and written advice on when to come straight back. Each of those steps is a line in the tool.

Try this

A 70-year-old woman on warfarin slips in her bathroom and bumps her head. She did not lose consciousness, has no amnesia and has a coma score of 15. Her son asks whether a scan is really needed. What do you say? Illustrative case.

Answer. Do not let the Canadian rule decide. It was never derived on anticoagulated patients, so it cannot be used to withhold her scan. The British guideline handles anticoagulants by a separate rule: with no other indication, consider a scan within 8 hours, or within the hour if she comes more than 8 hours after the fall. Notice the word: consider, which is weaker than the instruction for the other criteria, and the tool prints it that way. Check her INR, and if the scan shows bleeding, reverse the warfarin as the tool’s Drugs tab sets out.

Take-home points

• Never put a low coma score down to alcohol until a brain injury has been excluded.
• The national guideline’s 500,000 deaths a year does not reconcile with the road death figures; do not repeat it as fact.
• The Canadian rule’s one Indian validation was small; it cannot be used on anticoagulated patients at all.
• Mannitol has no recommendation in the current Brain Trauma Foundation edition; use it narrowly, and check the units.
• Discharge only at a score of 15, to a responsible adult, with advice in writing.

Read with this: Spinal Injury: The Evidence Behind the Pathway, for the neck that goes with every head injury, and Sadgati: Safe Passage on Roads.

Declaration: the author built and maintains the tool. It is free to use. The figures in this article are those the tool carried in its Evidence tab on 4 November 2026. Where a figure is attributed, the attribution is the tool’s own reference whose title matches; the lockdown figures were printed by the tool without a source and are reproduced as it printed them. The tool is in administrator preview, pending clinical review.

References

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