if vertigo occurs in flight , it may lead to sudden incapacitation , thus impairing a pilot and possibly resulting in an accident . .benign paroxysmal positional vertigo ( bppv ) is the most common cause of peripheral vertigo . it is considered to result from free - floating canaliths ( canalithiasis theory ) or from adherent particles in the cupula ( cupulithiasis theory ) . bppv presents vertigo of sudden onset that is provoked by certain changes in head position and is characterized by intense , positional provoked vertigo . although the condition is termed  benign ,  the clinical presentation can be severe and incapacitating in certain situations . bppv is thought to occur due to canalithiasis of the posterior semicircular canal and this hypothesis has been supported by many clinicians and researchers . recently , a new entity of bppv , differing from that mentioned above , has been recognized . this new entity is known as horizontal canal ( hc)-bppv . although only 3 to 8% of bppv is due to horizontal canal involvement , hc - bppv is not rare . we present a case of a fighter pilot who had an incident of hc - bppv on the ground . a previously healthy 42-year - old male , chinese naval command pilot with close to 2 000 flying hours , presented with potional vertigo accompanied with nausea and vomiting . the patient indicated that lying on his left side provoked his vertiginous symptoms , although he reported less intense symptoms when lying on his right side . the symptoms had started five days earlier as p vertigo episodes with mean duration ranging from a few seconds to two minutes , his symptoms were fairly mild or moderate in intensity . clinical examination showed bp , 120/80 mmhg and heart rate , 76 beats / min . no spontaneous nystagmus in darkness and no pathological findings by standard clinical neurological examination were found . horizontal head impulse test , headshaking test , and vibration - induced nystagmus test and subjective visual horizontal were normal . standard static positional testing revealed a persistent , geotropic nystagmus of 18 degrees per second in left lateral and 7 degrees per second in right lateral positions . the patient reported experiencing moderate , subjective vertigo with the left ear positioned downward and much less intense vertigo with the right ear downward . following vestibular evaluation , it was demonstrated that the patient did not have posterior or anterior canal bppv ( negative dix - hallpike to either side ) . furthermore , the persistent geotropic nystagmus was consistent with a typical nystagmus that is observed with most cases of hc - bppv , due to canalithiasis . the patient was temporarily grounded and treatment with the use of hc - bppv liberatory maneuvers , which was introduced by appiani et al . was recommended . for the appiani maneuver , the patient is then moved into a lateral side - lying position with the unaffected ear down and kept in this position for two minutes . this duration allows the relatively heavy otolith debris to travel through the endolymphatic fluid in the canal . he responded favorably to treatment with the appiani maneuver and continued habituation exercises during the following week . he was evaluated with side - lying test immediately and on days 3 , 5 , and 14 after the treatment . we repeated the maneuver until the patient is asymptomatic , and bppv could not be provoked . on follow - up at three months later , his symptoms had disappeared completely . he was recommended for waiver for return to flying status in two - seat aircraft . this waiver recommendation was approved , and he was returned to flying status to fly with copilot six months after his episode of acute vertigo . a follow - up vestibular function evaluation 1 year later showed no change in his condition , and he was continued on flying status with a follow - up period of 2 years . the incidence may range from 10 to 107 cases per 100 000 individuals per year . schuknecht suggested the term  cupolithiasis  in 1969 , which explains bppv as resulting from adherent basophilic particles in the cupula making it unstable , hence causing the vertiginous feeling . the canalithiasis theory explains bppv as resulting from free - floating debris ( canaliths ) in the posterior semicircular canal(scc ) , causing abnormal endolymph circulation . of the two theories , canalithiasis is most generally accepted as the cause of classic bppv . although bppv can theoretically affect each of the three sccs , the majority of all cases are of the posterior scc.[1416 ] hc - bppv is a recently proposed new entity of the positional vertigo syndrome . a diagnosis of hc - bppv is made based on the symptoms and finding of positional nystagmus . in hc - bppv patients , turning one 's head or body to either side in the supine position provokes vertigo , which usually lasts for several minutes . based on these symptoms and on the presence of nystagmus , the origin of the disease in these patients is thought to be located in the horizontal canal . however , there is no definite evidence concerning the pathological localization of this new entity of disease . hc - bppv is generally self - limited and the rate of spontaneous remission is high , but in some patients , it may persist for several months . medications that were historically prescribed for symptomatic relief are largely ineffective ; many , if not all , are disqualifying for use by pilots while flying . the primary management for bppv includes maneuvers to reposition the debris into the utricle of the inner ear . hc - bppv is easily treated using the methods of appiani et al . or casani et al . the appiani maneuver is preferred for patients with geotropic nystagmus , while the casani maneuver has been used for patients with apogeotropic nystagmus . the casani maneuver is quite similar to the appiani with one key exception ; the patient is moved from the initial seated position to a lateral side - lying position with the affected ear down . the casani maneuver was developed to attempt to free any otoconial debris that may be adherent to the cupula of the horizontal semicircular canal . there is much concern regarding vertigo occurring while performing aviation duties.[2023 ] a pilot 's spatial orientation in flight is crucial , and any compromise of this orientation may easily result in a fatal accident . in addition to the unpleasant feeling associated with it , vertigo causes incapacitation and impairs any job requiring psychomotor skills . generally speaking , vertigo is considered as disqualifying for aviators unless it is treated successfully . u.s . air force regulations state that  recurrent episodes of vertigo with or without nausea , vomiting , tinnitus , and hearing loss  are disqualifying . however , an airman with a history of bppv can be considered for return to flying duties after a period of observation , usually several months . the u.s . navy waiver guide states that   vertigo  causes which are self - limiting and non - recurrent may well be waiverable once symptoms have abated .  as mentioned above , for hc - bppv , spontaneous remission is possible , and the treatment of hc - bppv is usually very simple and effective . since the condition is not associated with any sequelae , one might well consider a rapid return to flight after a successful treatment . however , the high recurrence rate in bppv poses the question ,  is it safe to fly yet ?  for the airman presented herein , the appiani maneuver treatment is highly efficacious and the symptoms of this patient were completely resolved . appiani et al . also reported successful treatment of 100% of their patients with hc - bppv who presented with geotropic nystagmus . since the recurrence of this type of vertigo is unlikely , it is our opinion that the patient should be cleared to resume flying duties . considering that military pilots of high - performance aircraft may face the high - acceleration forces and vibration stimulation , it is anticipated that a vertigo attack of hc - bppv would occur during military flight . in 1990 , martin - saint - laurent et al . reviewed the causes of in - flight incapacitation in a commercial aviation setting . between 1968 and 1988 , of 1 800 aircrew flying on average 600 hours a year , 10 episodes of in - flight incapacitation occurred , one of which was from vertigo . in addition , the military aircrew 's ability to complete an assigned mission could be seriously degraded by a recrudescent vertiginous episode from hc - bppv , placing the aviator at risk . so , this concern has lead to the restriction of pilots with hc - bppv to fly in dual - controlled aircraft , although u.s . the incidence may range from 10 to 107 cases per 100 000 individuals per year . schuknecht suggested the term  cupolithiasis  in 1969 , which explains bppv as resulting from adherent basophilic particles in the cupula making it unstable , hence causing the vertiginous feeling . the canalithiasis theory explains bppv as resulting from free - floating debris ( canaliths ) in the posterior semicircular canal(scc ) , causing abnormal endolymph circulation . of the two theories , canalithiasis is most generally accepted as the cause of classic bppv . although bppv can theoretically affect each of the three sccs , the majority of all cases are of the posterior scc.[1416 ] hc - bppv is a recently proposed new entity of the positional vertigo syndrome . a diagnosis of hc - bppv is made based on the symptoms and finding of positional nystagmus . in hc - bppv patients , turning one 's head or body to either side in the supine position provokes vertigo , which usually lasts for several minutes . based on these symptoms and on the presence of nystagmus , the origin of the disease in these patients is thought to be located in the horizontal canal . however , there is no definite evidence concerning the pathological localization of this new entity of disease . hc - bppv is generally self - limited and the rate of spontaneous remission is high , but in some patients , it may persist for several months . medications that were historically prescribed for symptomatic relief are largely ineffective ; many , if not all , are disqualifying for use by pilots while flying . the primary management for bppv includes maneuvers to reposition the debris into the utricle of the inner ear . hc - bppv is easily treated using the methods of appiani et al . or casani et al . the appiani maneuver is preferred for patients with geotropic nystagmus , while the casani maneuver has been used for patients with apogeotropic nystagmus . the casani maneuver is quite similar to the appiani with one key exception ; the patient is moved from the initial seated position to a lateral side - lying position with the affected ear down . the casani maneuver was developed to attempt to free any otoconial debris that may be adherent to the cupula of the horizontal semicircular canal . there is much concern regarding vertigo occurring while performing aviation duties.[2023 ] a pilot 's spatial orientation in flight is crucial , and any compromise of this orientation may easily result in a fatal accident . in addition to the unpleasant feeling associated with it , vertigo causes incapacitation and impairs any job requiring psychomotor skills . generally speaking , u.s . air force regulations state that  recurrent episodes of vertigo with or without nausea , vomiting , tinnitus , and hearing loss  are disqualifying . however , an airman with a history of bppv can be considered for return to flying duties after a period of observation , usually several months . the u.s . vertigo  causes which are self - limiting and non - recurrent may well be waiverable once symptoms have abated .  as mentioned above , for hc - bppv , spontaneous remission is possible , and the treatment of hc - bppv is usually very simple and effective . since the condition is not associated with any sequelae , one might well consider a rapid return to flight after a successful treatment . however , the high recurrence rate in bppv poses the question ,  is it safe to fly yet ?  for the airman presented herein , the appiani maneuver treatment is highly efficacious and the symptoms of this patient were completely resolved . appiani et al . also reported successful treatment of 100% of their patients with hc - bppv who presented with geotropic nystagmus . since the recurrence of this type of vertigo is unlikely , it is our opinion that the patient should be cleared to resume flying duties . considering that military pilots of high - performance aircraft may face the high - acceleration forces and vibration stimulation , it is anticipated that a vertigo attack of hc - bppv would occur during military flight . in 1990 , martin - saint - laurent et al . between 1968 and 1988 , of 1 800 aircrew flying on average 600 hours a year , 10 episodes of in - flight incapacitation occurred , one of which was from vertigo . in addition , the military aircrew 's ability to complete an assigned mission could be seriously degraded by a recrudescent vertiginous episode from hc - bppv , placing the aviator at risk . so , this concern has lead to the restriction of pilots with hc - bppv to fly in dual - controlled aircraft , although u.s . navy waiver guide the pilots with hc - bppv could not be consider to return to flight unless they were treated successfully and their symptoms were fully resolved with the addition of no recrudesce under several months ' observation . however , considering the complexities of military flight environment and out of concern for the safety of the aircrew , we suggested that waivers to return to limited flight duties ( dual control pilot ) are considered and granted in the pilots with hc - bppv .
benign paroxysmal positional vertigo ( bppv ) is the most common disorder of the peripheral vestibular system , characterized by intense , positional provoked vertigo . 
 bppv is thought to occur due to canalithiasis of the posterior semicircular canal . 
 recently , a new entity of bppv , known as horizontal canal ( hc)-bppv , has been recognized . 
 although only 3 to 8% of bppv is due to horizontal canal involvement , hc - bppv is not rare . 
 we present a case of a naval fighter pilot who had an incident of hc - bppv on the ground . 
 the pilot aeromedical evaluation and considerations are discussed .