A CIA doctor dispatched to investigate the so-called Havana syndrome opened up about his own illness.
The anonymous doctor told CNN he started experiencing symptoms of the syndrome himself while in Cuba.
Experts aren't sure what causes the syndrome, but the leading theory involves electromagnetic waves.
A doctor has opened up about getting the symptoms of the very syndrome he was investigating: the so-called "Havana syndrome."
The Central Intelligence Agency doctor, who used the pseudonym Dr. Paul Andrews for the purposes of an interview with CNN, was one of the first experts to be dispatched to Havana, Cuba, to study the mysterious syndrome which has impacted US officials overseas.
Five years later, he still struggles with debilitating symptoms that match those of the mystery illness, he told CNN's Dr. Sanjay Gupta as part of a CNN special report released Sunday.
Reports of this syndrome, nicknamed "Havana syndrome" because of where it was first reported in late 2016, are officially referred to as "anomalous health incidents" (AHIs).
Since 2017, hundreds of cases of AHIs have been reported among US agency personnel, diplomats, and officials.
The exact cause for the syndrome remains unknown, but experts have now ruled out early-leading hypotheses like mass psychosis, loud crickets, and sonic attacks.
Andrews was awakened by a sudden loud noise
Andrews told CNN that he was in "disbelief" when he started experiencing the symptoms himself.
While on mission, he recalls being awakened at around 5:00 a.m. one night by a sharp pain in his right ear, accompanied by nausea and a severe headache.
He also reports hearing a clicking, a telltale noise reported by previous patients of the syndrome.
At the time, the leading theory was that the symptoms could be linked to some kind of sonic weapon, so Andrews said he first wore headphones for 45 minutes in an attempt to counteract the impacts.
An hour later, as the symptoms were not getting better, he decided to leave his room. He said he felt very confused, so much so that he struggled to pack his bags and open doors, he said. His balance was also affected.
Five years later, Andrews says he still has problems with his balance and vision. Hiking and jogging make him feel nauseated and he feels dizzy when he turns his head left and right, per CNN.
Doctors have found damage in his vestibular structures, the part of the inner ear that is involved in balance and that tells the body where it is in space.
"It's very frustrating that all those things you want to do, you can't," he said.
The so-called Havana syndrome has come under intense scrutiny in recent years, as more and more US cases have been reported.
In 2021, President Joe Biden tasked two panels to investigate the syndrome and allocated $30 million for the victims of the syndrome in the 2021 US defense-spending bill.
According to a 2020 report from the National Academies of Science and Medicine (NASEM), AHI symptoms include:
hearing a loud noise suddenly, mostly coming from one direction
feeling intense pressure of vibration in the head
pain in the ear or head
and for some patients: ringing in the ear, hearing loss, dizziness, trouble walking, and issues with eyesight.
In the long run, some patients may experience symptoms like brain fog, insomnia, and headaches.
Experts are still seeking a plausible cause, but so far it remains a mystery what causes the syndrome.
The leading theory, espoused by the NASEM report as well as a February report from the Office of the Director of National Intelligence, is that pulsed electromagnetic energy or microwaves may cause the syndrome.
Not all experts agree with this theory.
"The evidence would be on the outside of their body," Cheryl Rofer, a retired chemist from Los Alamos National Laboratory, previously told Insider.
"It would be like a thermal burn, if you want to get really grisly."