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