Vestibular Neuronitis in Pilots: Follow‐up Results and Implications for Flight Safety

Abstract

OBJECTIVES To report our experience over the past 12 years with the evaluation and follow-up of pilots with vestibular neuronitis and to discuss points relevant to flight safety and the resumption of flying duties. STUDY DESIGN A retrospective, consecutive case series.METHODS Eighteen military pilots with vestibular neuronitis were examined and followed up. A complete otoneurological workup was performed, including both physical examination and laboratory evaluation. The latter included electro-oculography (EOG) and a rotatory chair test using the smooth harmonic acceleration protocol. RESULTS The mean patient age was 35 +/- 6 years (range, 23 to 42 y), and the average follow-up period was 20.5 +/- 12.8 months (mean +/- standard deviation [SD]; (range, 11 to 48 mo). Electro-oculography caloric test on presentation documented significant unilateral hypofunction in all patients. Thirteen of the 18 patients (72%) had abnormal smooth harmonic acceleration test results. None of the pilots reported any symptoms on follow-up. However, five (28%) had positive otoneurological examination findings, and eight (44%) still had significant caloric lateralization (>25%). The average caloric hypofunction was reduced from 67.8% +/- 29.3% at onset to 40% +/- 16% (mean +/- SD, <.05, paired test). Seven of the patients (39%) had additional electro-oculography findings beyond caloric hypofunction. These included spontaneous, positional, and positioning nystagmus. Smooth harmonic acceleration disease on follow-up was documented in eight patients (44%), five of whom had canal paresis. Eleven patients (61%) demonstrated residual vestibular damage on follow-up. In 6 of these 11 cases (55%), the laboratory evaluation revealed vestibular deficits otherwise undiagnosed by the bedside test battery. CONCLUSIONS The vestibular system plays a central role in orientation awareness and is often challenged by flying conditions. The finding that approximately 60% of pilots who have had vestibular neuronitis continue to show signs of vestibular malfunction, despite apparent clinical recovery, emphasizes the need for a complete vestibular evaluation, including specific bedside testing and laboratory examinations, before flying duties can be resumed.

Inferior vestibular neuritis: 3 cases with clinical features of acute vestibular neuritis, normal calorics but indications of saccular failure

“…Although rarely mentioned in the literature, positional nystagmus is sometimes seen after ordinary VN [18]. The cause of head position dependent nystagmus in our patients is unknown.…”

Prednisone Treatment for Vestibular Neuritis

“…This stimulus does not reflect the daily accelerations to which the semicircular canals respond that are in the range of 0.5 to 8 Hz (37). Thus, pathologic dynamic nystagmus and significant handicap might persist despite normal ENG caloric response to low-frequency accelerations (6,14,15,20,21). The ENG battery mainly tests the functioning of the horizontal semicircular canal, which is only 1 of the 5 end-organs residing in the vestibular labyrinth (3 semicircular canals and 2 otolith organs).…”

“…The rate of positive finding on vestibular evaluation may reach 60% (11Y14). However, vestibular impairment as reflected by positive bedside testing and vestibular laboratory evaluation is not necessarily accompanied by subjective complaints and does not always reflect the level of incapacity (15).…”

Ocular Vestibular-Evoked Myogenic Potentials in Healthy Pilots and Student Pilots

“…P ILOT SPATIAL disorientation is a leading factor contributing to many fatal fl ying accidents ( 10 ). Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems.…”

“…Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems. The normal function of all organs involved in orientation is emphasized in the aviation medical literature as being a prerequisite for fl ying ( 10 ). Normal and effective vestibular system function is especially an absolute precondition for high performance fi ghter pilots.…”