Severe Head Injury in an Army Pilot

Transcription

1 Severe Head Injury in an Army Pilot Royal Aeronautical Society Aerospace Medicine Symposium Lt Col C Goldie RAMC 12 Dec 17 Joint Helicopter Command

2 Scope Case History Literature review Aeromedical policy review Considerations Aeromedical disposal Questions 2

3 Case History (1) 28 year old Army (Apache) pilot Jun 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

4 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 1 st year ~ 3% risk in year 1-2 ~ 0.6% deemed fit to handle live weapons 4

5 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

6 A Population-Based Study of Seizures after Traumatic Brain Injuries JF Annegers et al cases of TBI evaluated aged 15 to 64 Risk of developing epilepsy in general population 0.06% * Brain contusion, intra-cranial haematoma, LOC or PTA > 24 hrs 6

7 Cumulative probability of unprovoked seizure in 4541 patients with TBI - Annegers 7

8 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

9 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 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

10 Long-term risk of epilepsy after traumatic brain injury in children and young adults: a population-based cohort study J Christensen et al. Time since severe TBI Pts with epilepsy New cases/1000 person years RR 95% CI > No injury

11 Relative Risk of epilepsy after brain injury - Christensen 11

12 Risk of epilepsy after TBI: a retrospective population-based cohort study - Chun-Chieh Yeh et al. J Neurol Neurosurg Psychiatry 2013 Study of TBI and non-tbi patients Aged > 15 years, de novo TBI Followed up to 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 # 12

13 Risk of epilepsy after TBI: a retrospective population-based cohort study - Chun-Chieh Yeh et al. HRs for risk of epilepsy after TBI, adjusting for covariates Risk of epilepsy in various subtypes of TBI and skull # Latent interval for epilepsy after TBI 13

14 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< ) Risk of epilepsy: Skull # > Severe TBI > Mild TBI * Mental disorder, migraine, liver cirrhosis, end-stage renal disease 14

15 Risk of epilepsy with various severities of TBI Chun-Chieh Yeh Type of TBI n Epilepsy Cases HR 95% CI HR * (Adj) 95% CI * (Adj) No TBI Reference 1.00 Reference Skull Fracture Severe TBI Mild TBI

16 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< ) 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 ( ) Risk increases with increasing age at time of TBI (before adjustment) * EDH: HR 3.3 ( ) 16

17 Latency for developing epilepsy skull fracture Chun-Chieh Yeh Onset time, years Incidence HR 95% CI > No TBI Reference 17

18 Latency for developing epilepsy severe TBI Chun-Chieh Yeh Onset time, years Incidence HR 95% CI > No TBI Reference 18

19 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

20 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

21 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

22 Considerations Apache - tandem seat aircraft, BUCS system, collapsible front cyclic, confined cockpit, supportive seat and harness 22

23 23 Crown Copyright

24 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

25 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

26 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 Return must be preceded by occupational performance report and DH SQEP panel 26

27 Questions? 27