BY DR. DANIEL L. JOHNSON

Vertigo:The Basics, for Pilots

(All prior columns are at http://www.tinyurl.com/drdanscolumns)

The letter said:Dear Dr. Dan,I've had an attack of vertigo that lasted

6 -weeks. I've decided to give up soaring. Isthere any hope for me?

Sincerely,Dizzy Dave

This is an intelligent and wise ques-tion, and there are no glib answers.

This is an intelligent question becausethis pilot recognizes that vertigo inter-feres with accurate perception of thein-motion aviation environment, whichhinders accurate movements that de-pend on perception.

This is a wise question because it re-flects sound judgment: a willingness togive up soaring if that's appropriate, andopenness to expert advice.

This note reveals that the pilot hashad vertigo for quite a long time, andhe's feeling understandably discour-aged about recovery. It's right to askbasic questions, and it's normal to beanxious about the future (prognosis, inthe jargon).

Vertigo Versus Pilot in CommandThere are two important issues with

vertigo:First, it's not possible to fly safely with

vertigo. As one of my pilots said abouthis vertigo, "Fly!?! Jeez, I couldn't stand!"Even if we've recovered well enoughto sit in a cockpit, the head movementnecessary to see, avoid, and navigatemay precipitate an attack of vertigo untilcomplete recovery. The landing pattern

is not a good place to have our worldsuddenly start spinning.

Second, vertigo, even if long lastingsuch as this, even if not permanent, mayresult in some loss of fine coordination.In this regard, the important thing is tounderstand why the vertigo exists.

Understanding the cause reveals prog-nosis - the usual future course of thecondition (now called the disease trajec-tory, especially by cancer specialists).

Who Can Best Sort This Out?I don't want to dis general physicians

like myself, as many can indeed guidethis pilot to a proper investigation anddiagnosis. Yet only certain specialists areobligated to maintain current expertise inthe complete evaluation of vertigo.

The diagnostic specialty is otoneurol-ogy - the neurology of the inner ear. Goto vestibular.org to find a specialist. Ifyou have problematic vertigo troublewith equilibrium, seek out one of theseexperts. (The surgical specialty is neu-rotology, with similarly refined training.)

This ends the "what to do" section -now we'll go ahead with the "how thisworks" section.

OK, What /*" Vertigo?"We can skip the classic movie, a

convoluted tragedy that happened toinvolve chronic vertigo. It was not amedical story.

"Vertigo"is also applied to that feelingwe get when we lean past the edge ofa tall structure and look down. This is alittle closer to the medical meaning, butis neither abnormal nor disabling.

"Dizzy" is a vague word that meansmany things. When someone tells me

she's dizzy during a medical visit, it'snecessary to explore all the differentmeanings before we can surmise whatphysical process might be creating thissense. It might be vertigo. (Or it mightbe the emotions of the 84-year-oldmother, whose daughter and son-in-law invite themselves for a late dinnernearly every night, feed their dog withtheir fork from their plates, watch TVuntil bedtime, and then decamp with-out helping with the dishes. That'dmake me woozy with high blood pres-sure, too!)

In medicine, vertigo specifically de-notes a false sensation of rotation, eitherof self or the world. The spinning wesense while on the playground merry-go-round is not vertigo; the spinning wesense after it stops is vertigo.

We say that the vertigo is subjectivewhen the person feels as though he'sspinning, and objective when the worldseems to spin around us. This differenceis medically trivial, though maybe it re-flects personality. Do owners of single-seat ships have more objective vertigo?

I don't know why vertigo usuallyseems to be horizontal - around the yawaxis - less often, a sense of tumbling.When that's the case, it's really hard notto fall down.

Why Might We Get Vertigo?The basic reason is this: Any complex

instrument, when damaged, may simplygive wrong readings if damaged short ofdestruction. This is true for the vestibu-lar system, which is a highly complex in-strument that senses and analyzes soundand acceleration, with separate organsfor rotary and linear acceleration.

An important factor in vertigo is thatthere are two sets of accelerometers,one within each ear, and balanced func-tion is crucial to correct perception ofchanges of motion. Asymmetrical in-jury or inflammation is a very impor-tant cause of vertigo.

Vertigo resolves when either thedamage is repaired (or the imbalanc-ing cause is removed) or when the brainrecalibrates the instrument. If the causecan be removed quickly, such as whena canalith from the utricle or saccule iscaused to drift out the semicircular canal

Soaring • June 201 www.ssa.ort

that it's entered, the vertigo resolvesdramatically.

If the injury is permanent, so is theimbalance, and the brain does recalibrateslowly over a period of weeks. After thisrecalibration, one's equilibrium will beless precise to the extent that damagehas been done.

I include these details so that you canunderstand what to expect when you dohave vertigo, and so you can help yourdoctors give sound advice, especiallyabout piloting.

Pilots generally are willing to fly even ifthey're suffering, and a pilot who's neverhad vertigo might be mystified why weaeromedical physicians absolutely pro-hibit pilot duties until the vertigo is com-pletely resolved (and hopefully its causeunderstood). Each time I care for a pi-lot who has had vertigo, I ask, "Whenyou were dizzy, did you feel OK to fly?"Always, they say, "NO!!" emphatically.

I mean, what's going to be the out-come if you're on short final in a light,gusty crosswind, anticipating maybe tenknots of wind shear in the friction layer,you turn you head to the left to look atthe aircraft on base, and suddenly theairport starts spinning rapidly? Re-member the old joke about the guy withdouble vision, who crashed his car: "Icouldn't decide which road to take, so Idrove between them."

Why Does Vertigo Occur?As we've noted in prior columns, the

inner ear comprises 3 components: thecochlea, which parses sound; the semi-circular canals, which detect changesin circular motion; and the otolith ap-paratus, which detects accelerations(changes in linear motion). There aresome nice anatomical illustrations athttp ://tinyurl. com/otolith.

The otolith apparatus and the semi-circular canals together provide equi-librium and the cochlea provides sound.The sensations from each of these com-ponents are digitized and sent along asingle cable, the acoustic nerve or, moreaccurately, the vestibulocochlear nerve.

Perception is the conscious end re-sult of all the neurologic processing ofthe entire system from the inner earto the brain. Perception is a cartoon of

reality, the accuracy of which dependssuccessful integration of all theon

body's sensory faculties. Any malfunc-tion degrades this accuracy. Inaccurateperception, whether we're aware of aproblem or not, creates awkwardness inaircraft handling and leads to accidents.

Stages of AbnormalityVertigo does occur when the system

is normal: For example, spinning on a

turntable such as a merry-go-round, andthen stopping. But there are no lazy-susan cockpits.

Vertigo will occur abnormally whenany part of this system is asymmetricallyimpaired or damaged. (If we think aboutthis for a moment, it would be rare fordamage to be symmetric, so most abnor-malities of the vestibular system lead tosome flavor of vertigo.)

I say "some flavor of vertigo" because

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www.ssa.org • June 2015 • Soaring 41

dysfunctions of equilibrium do not al-ways involve a simple spinning sensa-tion, even when the abnormality is inthe semicircular canals.

Because one function of the system isto detect rotation, a defect may result insome sort of turning or tumbling sensa-tion, or a combination of these.

Because the other equilibrium functionof the inner ear is to detect linear accel-eration, a defect of that part of the systemresults in a mysterious sense of move-ment. When I talk to patients about theirexperiences, they agree that it's similar towalking on the deck of a moving ship.

Types of VertigoBroadly, causes of vertigo are divided

into central, related to defects of thebrain, brainstem, or acoustic nerve (thesignal-processing system) and periph-eral, related to defects of the inner ear(the sensors).

Central vertigo is relatively rare. Ittends to develop slowly and to be long-lasting. Tumors and multiple sclerosisare typical causes. For example, the pilotwith a tumor on the acoustic nerve onone side (the signal path from the sen-sor to the CPU) is prone to vertigo, im-balance, and hearing loss. The vertigois usually mild, and the pilot of my ac-quaintance with an acoustic neuroma isreported by colleagues at his field to flypatterns a bit awkwardly.

(The FAA required him to returnhis medical certificate, but gliders don'trequire medicals, do they?) Given thechange in performance from ATP-levelprecision to new-student imprecision,we wonder if the pilot has also devel-oped poor judgment for some reason.It's my experience that loss of judgmentis the most dangerous and disruptivedisease on the field.

Central causes of vertigo are relatedto the acoustic nerve, the brainstem, orthe brain.

We don't need to make a catalog of thespecific abnormalities. What you want tounderstand, when you do get vertigo, iswhether this will ever end, and whetheryou'll actually get back to normal whenit's all over. None of us wants to pilot anaircraft while having trouble knowingwhich way is up.

Soaring • June 2015

Central and peripheral vertigo behavedifferently. Because peripheral causesinvolve abnormality of the inner ear, andbecause the fluids of the inner ear alwaysrespond to motion, peripheral vertigo isalways affected by movement.

Central vertigo involves structuresthat are not sensitive to movement,so vertigo that does not change withhead movement is usually due to anabnormality of the acoustic nerve,midbrain, or brain. Of course, theremay be a relationship to movement ifthe abnormality distorts signals fromthe inner ear.

Peripheral causes of vertigo are mostlydue to degeneration, habituation ("thewobblies" in acrobatic pilots), abnormalinner-ear pressure (Meniere's Disease),injury, or infection. Most such infec-tions are viral (no pus seen behind theeardrum and a bad cold).

We doctors will usually tell the dizzypatient with a cold, "It's just a virus.You'll be fine in a couple of weeks,"with-out any real proof, and without actuallyspending hundreds or thousands of yoursoaring dollars on tests that would moreprecisely sniff out the cause of a diseasewithout treatment that will resolve soon.

If movement makes the dizzinessworse, we doctors usually say, "Youhave benign paroxysmal positional ver-tigo - BPPV" and may recommend a"canalith repositioning procedure" suchas the Epley Maneuver. This is the easydiagnosis because it's commonest, mostpeople have heard about it, and there'ssomething to do for it, so it gets you outthe door.

If head movement makes you spin(not just feel mildly dizzy), keep track ofwhich head-turning direction causes theturning. Then, in a clear moment, searchfor videos of "Epley maneuver" andfor written instructions. It's a simple,s-l-o-w procedure. It takes less than fiveminutes. Some doctors have bothered tolearn how to do it, which can save time,money, and suffering.

You don't really need to have five ses-sions of canalith re-positioning at $2007session at your local physical therapyshop to fix BPPV. The point here is notto deride my colleagues, but to point outthat misdiagnosis does occur, even with

us brilliant diagnosticians: been wrongbefore, will be again.

See, we tend to label as BPPV anyvertigo made worse by movement. Andit's really, really difficult to coax a dizzypatient into a carefully-observed de-scription of the experience. So there'soften doubt. And since the most treat-able cause of vertigo is BPPV, and thetreatment is straightforward, canalithrepositioning is the thing to do whenthe cause is unclear.

On the other hand, most vertigo, re-gardless of cause, is made somewhatworse with head motion because, afterall, the sensory instrument is malfunc-tioning and possibly rather twitchy insome modes and configurations.

Because the fluids of the inner ear areviscous, they settle down quickly if we'restill, so bouts of peripheral vertigo tendto be severe but brief, lasting minutes.

Because the lesions causing centralvertigo are static or slowly changing, thevertigo tends to be milder but more en-during, lasting hours, days, or longer.

Causes of Peripheral VertigoYou may have noticed that as we age,

the elastic parts get stiff and the firmparts get floppy. Also, stuff like cartilagegets brittle. The otolith apparatus - theutricle and saccule (http://tinyurl.com/otolith) consists of two little moundsof jelly, surmounted by tiny rocks, intowhich penetrate fibers that are rate-sen-sitive to bending.

After whacks to the head or with age,a rock or two might fall off. If one driftsinto a semicircular canal, it will moveback and forth with head movement,excessively stimulating the sensory hairsthat line these canals. The signal to thebrain is "turning!!" so we perceive rota-tion. This is pretty disorienting when themessage from the other inner ear andthe eyes is "not!" A short description isat http://tinyurl.com/equilibrium-gone.

This is called BPV (benign positionalvertigo), and bouts of spinning last untilthe crystals migrate to a better position.(Or BPPV, "benign paroxysmal posi-tional vertigo" because there are suddenepisodes.)

Other causes of peripheral vertigoare caused by what amounts to static

on the telephone wire: false signalsfrom inflamed sensors or nerves. Thisis called vestibular neuronitis (presumedto be a viral infection) and typicallylasts 2-3 weeks.

Typically, the lesion involves perma-nent damage to the affected inner ear,the vertigo is caused by unbalanced sen-sory signals to the brain, and it takesabout that long for the brain to recali-brate itself.

TheWobbliesSometimes, on returning to ground

after a bout of vigorous aerobatics, thepilot has trouble maintaining a sense ofequilibrium. This is not due to damageof the inner ear, but is probably causedby the sudden cessation of continuousoverstimulation. It is probably analo-gous to the "sea legs" of a sailor who'sbeen on a small ship for a long while.

The wobblies seldom last for morethan a few hours. Obviously, weshouldn't fly until it's completely quiet(though I've heard of competition pilotswho disregarded this and survived).

The wobblies shouldn't affect gliderpilots because our ships simply can'tperform the sudden high-g rotationsthat can be done in a short-wing pow-ered aircraft.

Dread Meniere's DiseaseMeniere's disease is possibly caused

by abnormal pressure in the inner ear. Itinvolves dysfunction of all componentsof the inner ear, and thus causes bothhearing loss and vertigo with or withoutdisequilibrium.

A person with Meniere's disease wrotea vivid description of the experience -Jane Gross, in the NY Times, 8/29/14,http://tinyurl.com/dizzying-times. Shesaid," 'Rotational'vertigo is the medical-ly and colloquially accurate description:the room spins. The walls aren't wherethe walls are supposed to be. The flooris only an idea, not a reality. One min-ute I was lying in bed, feeling perfectlynormal, and the next minute, trying toget to my feet, I was stumbling, grasp-ing at furniture to hold myself upright.... Along with the vertigo came nausea

and diarrhea ... I couldn't walk... [gettingto the bathroom was difficult]. Dehydra-tion made the vertigo worse.... I had dif-ficulty hearing people on the telephonewhen the receiver was at my left, but notmy right, ear.

"The only thing that everyone agreesis effective is lying perfectly still un-til the vertigo passes. ... the attacks lastfrom 20 minutes to 24 hours and comein clusters." I can't imagine going to theairport, never mind flying, with suchsuffering.

Central VertigoCentral vertigo is caused by any ab-

normality downstream of the inner ear- the auditory nerve, the brainstem, orbrain. The sensors are fine, but signalprocessing is distorted. Causes includeconcussion, closed head injury, mul-tiple sclerosis, migraine, brain tumor,or stroke. For example, the pilot whoflipped his motorcycle in his neighbor'smuddy back yard and KO'd himself hadvertigo for 8 weeks and couldn't fly thefriendly skies for 6 months (the manda-

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