Vertigo: A carousel in the cockpit
March 2015 column
Vertigo is common. When you were a kid I bet there was a time or two when you spun around and around until the whole world was topsy-turvy or you tossed your cookies! A variant of that happens in flight. When you’re in the clag and abruptly bend down, let’s say to pick up a pencil, suddenly it seems as if either you or the plane is in a spin.
Hold still, don’t do anything funny with the stick and it goes away. Accelerate rapidly and the aircraft seems to be pitching up. Slow down quickly and it seems to pitch down. In all of these instances you are fooling around with your balance or vestibular apparatus located in the inner ear. You may remember from your private pilot training that positional sense and movement are in part detected by the semicircular canals.
These fluid filled tubes are lined up in each of the three planes of movement. When your head changes position movement of fluid in the canals is sensed by nerve filaments that line the canals. At the bottom of these canals is another pair of sensors, the utricle and saccule. They are also lined with motion detecting filaments as well as small particles called otoliths.
They bump around in the utricle and saccule to increase the sensation of acceleration or deceleration. The signals generated by the vestibular apparatus are sent by the auditory nerve to the brain where movement is sensed. The brain correlates their input with that from the eyes. When you don’t have much eye input flying in IMC it is very easy for the vestibular apparatus to mislead you.
When eye input and vestibular input are at odds with each other, all heck breaks loose. The room seems to spin, the nausea centers in the midbrain get upset and your stomach feels like it did when you were a kid!
Vertigo can be caused by a number of things. The positional changes we just described are examples of what is called “Physiologic Vertigo.” Motion sickness and height vertigo are the most common more severe forms. Another very common type is “Benign Positional Vertigo.” If you’ve ever had it, you know it darn well is not “benign.” Severe sudden attacks of vertigo come on with change of head position, turning over in bed, getting in and out of bed, bending over or straightening up. It is caused by some of the otoliths in the saccule wandering out into the semicircular canals. Happily it often can be controlled with some simple positional movements of the head. So called “Vestibular Neuritis” or “Labyrinthitis” is caused by a viral infection of the vestibular nerve. It often follows a cold, can affect several family members and usually goes away in a week or two.
Some residual dizziness can hang on for months however. Head trauma or concussion as well as migraines are often associated with vertigo. Older folks with some hardening of the arteries can get it when blood supply to the brain is not what it should be. Occasionally some really nasty stuff like brain tumors or Meniere’s disease can cause vertigo. Bottom line — if the cause of dizziness is not obvious, it is something that you should have a physician evaluate.
So what does the FAA have to say about vertigo? Obviously if the world is spinning around for whatever reason you have no business in the cockpit. Therefore the cause of the vertigo and its likelihood to recur while flying determines the action the FAA will take.
The Aviation Medical Examiners Guide states that “transient processes, such as those associated with acute labyrinthitis or benign positional vertigo may not disqualify an applicant when fully recovered.” At the other end of the spectrum, stuff like a brain tumor is disqualifying and will require a special issuance (SI) after recovery from surgery. The same holds true for vertigo associated with migraines. You need to consult a neurologist and see if the attacks can be reliably controlled with medications that in themselves are not disqualifying. Again you are looking at an SI. This is also the case with just about any other cause of recurrent disturbance of equilibrium.
Understandably, the FAA wants to take a very close look at any of these conditions. You will need to work with you AME and your primary physician to get the information that they need to make a decision.
Fly wisely. See you next month!
As always, comments, questions and suggestions are welcome: firstname.lastname@example.org.