Alison Leston, MD, PhD, didn't intentionally specialize in aviation neurology. It happened naturally from hanging around pilot friends and learning their jargon, she told Neurology Today.
Through deciphering what happens in the “sim”—the flight simulation program pilots use to train—and decoding the exact language needed in the routine medical certification required to fly, Dr. Leston became one of a very small handful of neurologists sought after by pilots and the aviation industry.
She serves on a Federal Aviation Administration (FAA) panel that reviews pilot fitness from a neurologic standpoint, and on the medical advisory board for the Texas department of public safety, where she plays a similar role for Texas drivers licenses. She is also active on the education committee of the Civil Aviation Medical Association, where she will help organize its annual meeting, and has written for the Flight Physician newsletter. That's all on top of her work as section head of general neurology at University of Texas-Southwestern.
Dr. Leston was initially torn between pursuing clinical medicine and basic neuroscience research. As an undergraduate at the University of Illinois, she majored in biochemistry and was accepted to both medical school and graduate school. She chose to focus first on neuropharmacology research, obtaining her PhD in neurobiology from the University of Chicago.
Her dissertation focused on the structure of nicotinic acetylcholine receptors, which are located at the neuromuscular junction. This receptor is the target that is attacked in the autoimmune disease myasthenia gravis.
Although she enjoyed research, she wanted to work with patients, and eventually went to medical school at Washington University in St. Louis. Thinking like a neuroscientist, she wrote her medical school application in the form of a signal transduction cascade. After residency and an EMG clinical neurophysiology fellowship in St. Louis, Dr. Leston went into private practice as a general neurologist, eventually making partner.
During her time in St. Louis, Dr. Leston started dating a pilot, and they moved to the Dallas-Fort Worth area to be near an American Airlines hub and for her to return to her academic roots by taking a faculty position at UT Southwestern.
Because many of her friends were pilots, she heard about some of the challenges they faced. Some were easily handled, such as their need for non-drowsy medications for allergies—Benadryl is the most common substance found in the toxicology results of airplane fatalities, she said.
At first most of her referrals came from American Airlines since she was near that hub. But as word got around through the union nurses, who “are really knowledgeable on what it's going to take to get a grounded pilot back in the back in the air,” she started getting referrals from pilots from other airlines who needed to be assessed.
“When they learned that I speak the pilot language, they started telling others that whenever they needed a neurologist that I was the one that they should see,” she said. Now Dr. Leston sees professional and private pilots from all over the country. She currently carves out a half-day specifically for pilots during her neurology clinic.
The Role of the Aviation Neurologist
Airline pilots need annual flight physicals until age 40, and then every six months, performed by an aviation medical examiner, Dr. Leston explained. They have to disclose any medical issue or doctor's appointment since their last flight physical.
“If there's any question of a neurologic dysfunction in a pilot, the aviation medical examiner will not be able to issue their medical certificate and will defer to the FAA to make that decision,” said Dr. Leston.
“Most of my patients in aviation neurology clinic are pilots who disclosed a neurologic condition to their aviation medical examiner or their union medical advisor. Those people may refer the patient to me, or the pilot may seek me out after receiving a letter from the FAA requiring a neurological evaluation.”
Less frequently, a pilot may be referred from the airline. For example, to be promoted to fly a larger aircraft, pilots have to clock many hours using the simulator. If they weren't able to catch on to the new controls or technology and were not able to learn new skills, there may be a question of whether that is a sign of early dementia. Their boss, the chief pilot, might be concerned that they need medical help.
“Those pilots would probably be referred to me for an evaluation,” said Dr. Leston. “We have picked up neurodegenerative disease that way, earlier than it would have been diagnosed without such stringent medical requirements.”
Some referrals come in related to activities pilot engage in their off time, she said, noting that pilots tend to be adrenaline junkies when they're not in the air. When a pilot hits their head, the consequences can be very different from a non-pilot, Dr. Leston noted, adding that it might be interesting to conduct research on whether head injuries are overrepresented in the pilot population.
“If you or I fell and hit our head, and maybe there was a moment of loss of consciousness, we'd probably return to work pretty quickly. But for a pilot, even if they feel back to baseline pretty quickly, they have to disclose that they had the injury and that starts the whole process that moves at the pace you would expect for a government agency,” she said.
“That pilot is likely to be grounded for six months and up to five years for a more severe head injury.
An aviation neurologist may be asked to focus specifically on conditions associated with sudden incapacitation. “I am most concerned about strokes and seizures, because those disorders can incapacitate [a pilot]fast enough to affect a flight,” she said.
A pilot may be grounded for five years after severe head injury, to get them past the time of highest risk of developing post-traumatic seizures. “This is frustrating for the pilot if they feel fully recovered from their injury and have never had a seizure,” she said.
An unfortunate aspect of airline life is that work takes pilots away from home and family, Dr. Leston said. “I've seen a number of pilots hospitalized during a layover far from home. And many come from out of state to see me, so I'm often collecting medical records from all over the world—usually from the layover city where they first sought care and their hometown hospital where they had follow-up. I will put the whole story together into a report the FAA will use to make sense of the case. That's why they come to me.”
Once the case comes to the attention of the FAA, physicians employed by the FAA will review the case. The FAA just hired their second neurologist.
“The FAA physicians may decide to issue or deny medical certification or request additional records or additional testing'” said Dr. Leston. “Sometimes they send the pilot a letter asking them to resubmit their application with a report from a neurologist. Their local neurologist may be uncomfortable with this, or the pilot may prefer someone with aviation experience, and come to me.”
For the most complicated cases, the FAA will bring in a panel of outside neurologists to discuss cases. Dr. Leston is a member of that panel but will recuse herself if she has seen the pilot as a patient. “We will review the medical records, especially the neurology consult report. Decisions are evidence-based whenever possible, referring to published data on things like risk of seizure or stroke recurrence in certain situations. Much of the discussion involves how the available data applies to the specific aviator whose medical certificate is at stake.”
”Everything hangs on that medical certification. If pilots lose their certification, their careers are over, and they don't have a lot of transferable skills,” Dr. Leston said. “Can you imagine finishing medical school and residency training for all that time and suddenly being told you can't practice medicine again? It's devastating.”
The State of Aviation Neurology
Aviation neurology is an area that's evolving, whether it's working with the FAA to accept new migraine medications that don't cause sleepiness or determining whether newer anticoagulants lower the stroke risk from atrial fibrillation enough to put a pilot back in the air. It's a controversial issue, she said.
Dr. Leston isn't alone in her subspecialty interest. There are currently 76 members of the International Aerospace Neuroscience Consortium, of which Dr. Leston is vice president. “This is a group of neurologists, neuropsychologists, and related professionals working in aerospace medicine who meet to discuss things like research, policies, and interesting cases. Many of them are in military medicine or are outside of the United States, so there are only a handful of us civilian neurologists in the U.S. with whom a U.S. pilot could actually schedule a neurology consultation,” said Dr. Leston.
She said the most important thing that neurologists need to know about aviation neurology is that the “fitness to fly decision,” does not rest solely on their shoulders.
“Although they are not authorized to make that decision, they need to be the eyes and ears for the FAA, because the FAA does not get to see the pilot themselves,” Dr. Leston said.
“The FAA depends on the neurologist who actually examined the patient, and that physician should make sure to take a good history and document the exam, so the FAA can use that to make a decision. It doesn't have to be as intimidating as neurologists sometimes fear, because they are not the ones making the decision themselves.