Elderly Patients with low Energy Blunt Trauma: Head CT?

Aug 12, 2024

Here’s a patient presentation, I have residents and registrars discuss with me frequently. An elderly patient who had a mechanical fall at home is brought into the ED by ambulance. The patient may or may not remember a head strike. I am asked the question, "They seem well, no headache and no loss of consciousness and not on anticoagulants, do I need to do a CT head?" (20 minutes read)

How would you answer? What do all the head injury scores say?
This new study gives us a glimpse into the rate of injury from fall from standing height trauma. It also gives us a very concerning picture of how many of the elderly with significant injuries, have little to find in the history and clinical examination.

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We know that older age is an independent predictor of intracranial injury. In these elderly patients our clinical judgement has been found to be unreliable in identifying those patients with serious intracranial injury. It is for that reason that elderly patients are excluded from low risk head injury scores. Both the NEXUS Head CT Instrument and the Canadian Head CT Injury Rule, only require a patient to be > 65 years old, to be called a high risk case requiring a CT scan.

In this review we look at a secondary analysis of data from the National Emergency X-Radiography Utilization Study (NEXUS) Head Computed Tomography (CT) validation study.

What They Did

They performed a secondary analysis of patients > 65 years enrolled in the NEXUS Head CT decision instrument validation study, whose main aim had been to validate the performance of the previously derived NEXUS head CT decision instrument.

The original study had been performed in 4 emergency departments.

Consecutive blunt trauma patients who underwent head CT imaging were included. The decision to image was left to the treating physicians.

Patients were excluded if they had:

penetrating trauma
delayed presentations (>24 hours after their injury)
were receiving imaging for indications other than blunt trauma
had known injuries transferred from an outside hospital.

The CT results were divided into:

No intracranial injury

Intracranial injury: These were divided into significant and non-significant injuries

significant injury:
- defined as all injuries found on head CT imaging except:
- solitary small contusions
- localized subarachnoid hemorrhages < 1 millimeter thick
- subdural hematoma < 4 millimeters thick
- isolated pneumocephaly
- closed or depressed skull fractures that do not violate the inner table
Significant Injuries were further divided into:
- Significant Injury requiring neurosurgical intervention: defined as the need within 7 days:
  - need for craniotomy
  - elevation of skull fracture
  - intubation related to head injury
  - intracranial pressure monitoring.
- Significant injury not requiring neurosurgical intervention

What They Found

Total numbers of patients in the study were 11770

3659 (31.1%) patients were > 65 years old. Of these patients 325 (8.9% of all elderly patients) had significant intracranial injuries. These injuries included:

Subarachnoid Haemorrhage
Subdural Haematoma
Ventricular bleed
Contusions

The injury mechanisms reported included:

Automobile vs Pedestrian: N = 149 (4.7%)
Motor vehicle accident: N=229 (7.2%)
Bicycle Injuries: N=77 (2.4%)
Falls: These were divided into:
- Ground Level fall: N = 2211 (69.6%)
  - Of the 323 total patients with a significant injury 180 (55.7%) were in this group
  - Of the 176 patients requiring neurosurgical intervention, 94 (53.4%) patients were in this group.
  - Of the total mortality (N=81), this group comprised 46.9% (38 patients)
- Fall from Height: N=37 (1.2%)
- Fall down stairs: N=148 (4.7%)
- Fall from ladder: N=34 (1.1%)

In this study, elderly patients comprised less than one-third of all patients, with most injuries being the result of low-energy mechanisms and ground-level falls accounting for two-thirds of all injuries and over half of the elderly injuries that required intervention.

1 in every 6 elderly patients with intracranial injuries lacked historical or physical evidence of serious injury.

Over half of the patients with intracranial injuries and two-thirds of the patients who died from their injuries had subdural and subarachnoid hemorrhages.

Cervical spine imaging was ordered in 54.7% (1,738/3,178) of all elderly head injury patients, and 80.8% (143/177) of patients with head injuries requiring intervention.

Cervical spine injuries were identified in 77 patients (2.4%), of which 22 (6.8%) patients were requiring neurosurgical intervention
In those patients with ground-level falls cervical spine injuries were identified in 31 patients (1.4%). The NEXUS c-spine decision instrument assigned a high-risk in all patients requiring spine interventions.

My Take on This

The elderly patient is at high risk of an intracranial injury, from seemingly low energy mechanisms, such as falls. This study showed that ground level falls accounted for nearly 70% of all injuries, however over 50% of patients requiring neurosurgical intervention and nearly 50% of all deaths were in this group.

Elderly patients had a significant mortality and a more prolonged requirement for care. A higher percentage of elderly who required an intervention for their subdural hematoma died, when compared to the general population.

This was a pragmatic approach to looking at the question of blunt head trauma in the elderly. The results may be affected by variation in clinical practice not only of the emergency physicians, but also of the neurological units.

The study doesn't identify which are trivial injuries and if there is a need to image all elderly head trauma patients. What it does show is that it can be difficult to identify injury in older patients. More importantly it shows that low energy falls, such as from a standing position can result in significant head injury and that only a small proportion (<20%) of these patients with intracranial injuries had physical or historical evidence of such injuries.

This study only enrolled patients that had undergone CT head imaging and not all patients involved in blunt head trauma. This raises the potential for verification bias and missed head injuries, although followup at 3 months of a subgroup of blunt trauma patients, who had not received a CT brain, revealed no missed injuries.

What I take away from this is that we need to take care and use good judgement when ordering tests. The potential for cervical injury, can be handled by NEXUS criteria. Given however that falls from a standing height are associated with such morbidity and mortality and that patients present looking well, also that radiation risk, does not play such a major role in these elderly patients, I will be ordering CTs on these patients. This doesn't really change my practice much. Does that mean I image every elderly patient with a fall? No. Even though trivial injury isn't defined in this study, most of us have our own gestalt about what is trivial.

References

Mower WR, et al. Validation of the sensitivity of the National Emergency X-Radiography Utilization Study (NEXUS) head computed tomographic (CT) decision instrument for selective imaging of blunt head injury patients: an observational study. PLOS Med. 2017;14:e1002313.
Stiell IG, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357: 1391-1396.
Haydel MJ, et al. Indications for computed tomography in patients with minor head injury. N Engl J Med. 2000;343:100-105.
Rathlev NK, Medzon R, Lowery D, et al. Intracranial pathology in elders with blunt head trauma. Acad Emerg Med. 2006;13:302-307.
Sartin R, et al. Discussion of “Is routine head CT indicated in awake stable older patients after a ground level fall?”. Am J Surg. 2017;214:1055-1560.
Mower WR, et al. Developing a decision instrument to guide computed tomographic imaging of blunt head injury patients. J Trauma. 2005;59:954-959.
Smits M, et al. Predicting intracranial traumatic findings on computed tomography in patients with minor head injury: the CHIP prediction rule. Ann Intern Med. 2007;146:397-405.