Severe Head Injury in an Army Pilot

Royal Aeronautical Society – Aerospace Medicine Symposium

Lt Col C Goldie RAMC

12 Dec 17

Joint Helicopter Command

Scope

Case History

Literature review

Aeromedical policy review

Considerations

Aeromedical disposal

Questions

2

Case History (1)

28 year old Army (Apache) pilot

Jun 2014 - Fell 15ft from side of a building

Found unconscious lying on his face with head trauma

MRI – EDH in middle cranial fossa

L → R uncal shift and pneumocephalus

Minimally depressed L parietal skull #

Multiple contrecoup parietal contusions with small SAH

EDH evacuated same day, remained in induced coma for several days

Good post-op recovery

Started on prophylactic Keppra, discharged 5 days post injury

3

Case History (2)

Post discharge: BPPV, fatigue, reduced concentration. No focal neuro.

Returned UK late Jul – referred to neuro rehab at DMRC.

Full cognitive and executive function - superior scores.

Some minor stuttering/ tripping over words – no SLT required.

Keppra stopped early Aug 14.

Neuro review Oct 14 – repeat MRI unremarkable.

Risk of PTS acknowledged. No flying for 3 years and then re-consider case.

Repeat review Mar 15 – PTS cumulative risk in 1st year ~ 3%

risk in year 1-2 ~ 0.6%

deemed fit to handle live weapons

4

Case History (3)

Successfully completed ground based phased RTW Jun 15

Mar 16 – private neuro opinion: risk of PTS at year 2 - 3 is 0.426%

Summary:

28 yr old pilot

Severe TBI

No PTS

No focal neuro

Normal cognitive functioning – high achieving

In full time ground based work

5

A Population-Based Study of Seizures after Traumatic Brain Injuries – JF Annegers et al.

4541 cases of TBI evaluated - 2546 aged 15 to 64

Risk of developing epilepsy in general population – 0.06%

* Brain contusion, intra-cranial haematoma, LOC or PTA > 24 hrs

6

Cumulative probability of unprovoked seizure in 4541 patients with TBI - Annegers

7

A Population-Based Study of Seizures after Traumatic Brain Injuries – JF Annegers et al.

Incidence of unprovoked PTS correlates strongly with severity of injury

Severity of injury correlates with the interval during which PTS risk is

increased

Brain contusion and SDH biggest risk factors for late seizures – effect

persists for 20 years

Skull fractures and prolonged LOC – significant but weaker predictors

In severe TBI seizures occurring >10 years can be attributed to the injury

8

Long-term risk of epilepsy after traumatic brain injury in children and young adults: a population-based cohort study – J Christensen et al.

1.6 m individuals followed up for 19.5 million person years, including

78 572 cases of TBI

Young children to mid-teens

Baseline population rate of epilepsy development 0.088% per annum

Risk of PTS after severe injury was highest during first years after injury

but remained elevated beyond 10yrs cf non-TBI individuals.

RR increased with increasing age at time of injury, especially for severe

HI > 15 years (ARR 12.24)

9

Long-term risk of epilepsy after traumatic brain injury in children and young adults: a population-based cohort study – J Christensen et al.

10

Time since

severe TBI

Pts with

epilepsy

New

cases/1000

person years

RR 95% CI

0.0 – 0.5 35 19.62 21.26 15.25 – 29.62

0.5 – 1.0 19 11.52 13.45 8.57 – 21.09

1.0 – 2.0 18 6.06 7.42 4.68 – 11.79

2.0 – 3.0 11 4.26 5.40 2.99 – 9.76

3.0 – 5.0 11 2.69 3.52 1.95 – 6.35

5.0 – 10.0 15 3.22 4.40 2.65 – 7.30

> 10.0 7 2.94 4.29 2.04 – 9.00

No injury 17354 0.89 1.00

Relative Risk of epilepsy after brain injury - Christensen

11

Risk of epilepsy after TBI: a retrospective population-based cohort

study - Chun-Chieh Yeh et al. J Neurol Neurosurg Psychiatry 2013

12

Study of 19 336 TBI and 540 322 non-TBI patients

Aged > 15 years, de novo TBI 2000 - 2003

Followed up to 2008. Time in person-years until diagnosis of epilepsy calculated for each person

Those with other risk factors for epilepsy excluded

Categorised into mild and severe TBI and skull #

Risk of epilepsy after TBI: a retrospective population-based cohort

study - Chun-Chieh Yeh et al.

13

HRs for risk of epilepsy after TBI, adjusting for co-variates

Risk of epilepsy in various subtypes of TBI and skull #

Latent interval for epilepsy after TBI

Results

Mean age of TBI group – 39.1 years

TBI group had higher percentage of co-variates*

Risk of epilepsy TBI vs non-TBI – 1.9% vs 0.3% (p< 0.0001)

Risk of epilepsy: Skull # > Severe TBI > Mild TBI

* Mental disorder, migraine, liver cirrhosis, end-stage renal disease

14

Risk of epilepsy with various severities of TBI – Chun-Chieh Yeh

15

Type of TBI n Epilepsy

Cases

HR 95% CI HR *

(Adj)

95% CI *

(Adj)

No TBI 540322 1553 1.00 Reference 1.00 Reference

Skull Fracture 522 25 17.2 11.6 – 25.5 10.6 7.14 – 15.8

Severe TBI 11371 254 7.78 6.82 – 8.89 5.05 4.40 – 5.79

Mild TBI 7443 83 3.88 3.12 – 4.84 3.02 2.42 – 3.77

Results

Mean age of TBI group – 39.1 years

TBI group had higher percentage of co-variates

Risk of epilepsy TBI vs non-TBI – 1.9% vs 0.3% (p< 0.0001)

Risk of epilepsy: Skull # > Severe TBI > Mild TBI

Risk of epilepsy: ICH > SDH > EDH* > SAH > brain contusion

No real difference in risk between skull vault # or basal #

Men at greater risk: HR 1.7 (1.3 – 2.1)

Risk increases with increasing age at time of TBI (before

adjustment)

* EDH: HR 3.3 (1.3 – 8.8)

16

Latency for developing epilepsy – skull fracture – Chun-Chieh Yeh

17

Onset time,

years

Incidence HR 95% CI

0 -1 25.3 38.2 21.7 – 67.0

1 - 2 7.8 12.3 4.59 – 33.1

2 - 3 3.9 6.03 1.50 – 24.3

3 - 4 3.9 6.17 1.53 – 24.8

>4 1.1 1.66 0.62 – 4.43

No TBI 0.4 1.00 Reference

Latency for developing epilepsy – severe TBI – Chun-Chieh Yeh

18

Onset time,

years

Incidence HR 95% CI

0 -1 9.3 14.8 11.7 – 18.8

1 - 2 2.4 4.23 2.82 – 6.35

2 - 3 2.8 5.12 3.51 – 7.48

3 - 4 2.3 4.05 2.69 – 6.12

>4 0.8 1.21 0.94 – 1.56

No TBI 0.4 1.00 Reference

Limitations

Insurance claims data lacks clinical risk scores (GCS), lesion

characteristics and biochemical markers that predict PTE.

Database search focused on survivors after TBI – fatalities

excluded – prevalence of epilepsy may be underestimated.

Study only included TBI patients who received inpatient care –

some with minor TBI may have been excluded.

Focuses on genetically different population.

Summary

Risk of epilepsy increased after TBI: skull # > severe TBI > mild TBI

After 4 years post TBI risk of epilepsy reaches that of non-TBI group.

19

Aeromedical Policy

AP1269A - Not normally returned to flying - permanently unfit aircrew.

Exceptional cases* may be considered for return to flying from 3 years

post-injury.

DCA Neurology and CA Avn Med opinions are mandatory.

Med cat on return to flying - shorter periods of grounding with the pilot

returning to flying in an ‘as or with co-pilot’ limitation are not

acceptable for any form of rotary wing flying, due to the potential

hazard presented by incapacitation in the air.

*No definition of exceptional – clinical or employment criteria?

20

Aeromedical Policy

CAA: Class 1 – unfit 3 years after resolution or stable, non-disabling

symptoms. OML long term.

Class 2 – unfit 1 year after resolution. OSL 2 years.

USAF: Severe HI (brain contusion) – 5 years observation time.

USN & US Army: Severe HI (skull # or bleed) – permanent

disqualification.

21

Considerations

Apache - tandem seat aircraft, BUCS system, collapsible front cyclic,

confined cockpit, supportive seat and harness

22

23• Crown Copyright

Considerations

Apache - tandem seat aircraft, BUCS system, collapsible front cyclic,

confined cockpit, supportive seat and harness

No cognitive deficit

Risk of PTS: skull vault fracture, EDH ↑

young age at time of injury ↓

Effects of military stressors: sleep deprivation, circadian disruption,

dehydration, missed meals, stress (low level flying, poor weather, high

workload, NVG, hostile action)

24

Considerations

1. Should this pilot be granted clearance to fly at 3 years?

2. Should this pilot be granted clearance at 4 years?

3. Clearance after 4 years?

4. If cleared what (if any) limitations should be imposed?

25

Army Avn Med decision

1. No return to flying at 3 years

2. Return to flying could be considered at 4 years – platform

mitigations – although reservations still persist

3. DH acceptance of risk, attributes of individual and requirements of

the service would need to be considered

4. Limitations – no solo flight (PSQOT), front seat only, no controlling

below 500’

5. Return must be preceded by occupational performance report and

DH SQEP panel

26

Questions?

27