Human and behavioral factors contibuting to spine-based neurological cockpit injuries in pilots of high-performance aircraft: Recommendations for management and prevention

Military Medicine, Jan 2000 by Jones, Jeffrey A

The incidence and prevalence of cervical pain with or without radiculopathy has been increasing with each report in the literature, and the occurrence of pain in this report is the highest yet. We feel that this is attributable to several factors:

(1) More pilots are experiencing pain as they accumulate more hours in the aircraft, There seems to be a bimodal peak of incidence of injury. One small peak is found early in the fighter pilot's career, before learning techniques for avoidance but while the support structures are still vigorous, because of youth. The other peak occurs later in the pilot's career (> 1,000 flight hours logged), when the accumulated effect of many load-bearing events takes its toll on the cervical disks,"15; as the pilot ages, the supporting ligaments, muscles, and disc structure itself are less resistant to injury.

(2) The index of suspicion is higher among flight surgeons because these principles are taught in flight surgeon training programs.

(3) Anonymous survey reporting mechanisms allow pilots to reveal injury occurrences without significant concern for adverse effects on their career.

Because of the limited number of responses from F- 15 pilots, the results of this survey do not allow a comparison of injuries based on the turning capabilities of the various fighter aircraft. We postulated that the injuries would be greater in the F- 16 compared with the F- 15 or F- 14 because of the fly-by-wire computer flight control system that automatically g-limits the turn rate and allows the pilot to maximally input stick controls. The cockpit of the aircraft differ in several important ways. First, the F- 16 seat is reclined 30 degrees relative to the more upright seats of the other aircraft (a feature designed to improve the pilot's Gz tolerance and to decrease g-induced loss of consciousness episodes). Second, the location of handrails on the side of the cockpit is different among the aircraft. Finally, the F- 16 control stick is fixed in position on the right side of the cockpit, versus the center, floor-mounted sticks of the other fighters. Although most pilots constantly maintain center stick aircraft control with the right hand, the option exists, during a turn, to release the throttle and use the left hand to brace the upper body when looking left (Fig. 2). When turning right, however, the pilot of the center-seat aircraft (Fig. 3) could switch stick control hands and brace himself on the handrail with the right hand (Fig. 4). This option does not exist for the F- 16 pilot and could be one mechanism to account for the differential rate of injury between the F-16 and F/A-18 pilots and the disproportionate distribution of injuries in the right neck and associated rightsided paresthesias. Injuries seem to occur more often when pilots turn while looking right, but there is inconsistency in pilot use of the "switch-flight-control-hand" technique.

The inclination of the seat, as pointed out in earlier reports,7 may also make the F- 16 pilot more vulnerable to injury because of the natural neck flexion prompted by the backrest position before attempted head rotation. However, this mechanism does not account for the right-sided symptom predilection.

Treatment of significant aviation-related cervical injuries should be individualized based on the symptoms and pathology found on diagnostic evaluation. However, because of the unique mechanism of injury, we recommend, in the absence of cord impingement by the disc or fragments, that a conservative therapeutic option be used initially. This consists of rest, motion limitation with a cervical collar, anti-inflammatory with or without antispasmodic/muscle-relaing medications, and physical therapy, including transcutaneous electrical nerve stimulation and ultrasound treatment to facilitate early pain relief. This therapy should be conducted for several weeks to 2 months. After completion of this program and with resolution of symptoms, we recommend a rehabilitation program designed to reduce the risk of further injury. Should surgical intervention be required, we recommend a more conservative diskectomy, using microscopic techniques, before advancing to spinal fusion.