The American government employees in Cuba who suffered mystifying symptoms — dizziness, insomnia, difficulty concentrating — after hearing a strange high-pitched sound all had one thing in common: damage to the part of the inner ear responsible for balance, according to the first doctors to examine them after the episodes.
Two years after Americans posted at the United States Embassy in Havana began experiencing the peculiar phenomenon, doctors at the University of Miami on Wednesday published a scientific paper that confirms what these patients have said all along: Their condition is real, not the result of mass hysteria, a response to intense news media coverage or a stress reaction to being evacuated, as doctors in Cuba had suggested.
“These people were injured,” said Dr. Michael E. Hoffer, the director of the university’s Vestibular and Balance Program and lead author of the study. “We’re not sure how. The injury resulted in ear damage and some trouble thinking.”
To some of the 26 people affected, the episode felt like something out of “Star Trek”: A few minutes of a high-pitched noise, often accompanied by a high-pressure sensation, described as a “force field,” felt in their homes and hotel rooms in Cuba over several months starting in late 2016, changed their lives and, in some cases, ended careers.
The dizziness and cognitive problems that followed — including severe insomnia and nausea when using a computer — were so intense that at least one State Department employee went into early retirement this year. Another person who experienced a similar phenomenon in China went on leave. The State Department would not say how many people had returned to work.
Identifying the specific nature of the damage means that the patients could potentially be treated with physical therapy, the doctors said. It isn’t clear yet whether the injury is permanent.
The study, which also included work by a professor from the University of Pittsburgh and was published in the journal Laryngoscope Investigative Otolaryngology, is the first to document the earliest symptoms of a medical mystery that started in Cuba, damaging relations between that country and the United States, and may have spread to China.
Doctors found that all of the people affected by what was initially — and inaccurately — thought to be an acoustic attack had damage to the otolith, the organ that manages balance and the sensation of gravity.
The doctors found that it was unlikely that the affected diplomats and C.I.A. officers had suffered traumatic brain injuries. An earlier study from the University of Pennsylvania suggested that the patients showed signs of traumatic brain injury without ever experiencing a concussion.
The authors of the University of Miami study said it was the only one to document the medical examinations that took place soon after the sounds were heard, before news media reports or workers’ compensation claims could have affected results. The study does not offer any theory as to what caused the injuries, but Dr. Hoffer, who specializes in concussions, said he now felt confident that doctors can screen for the condition — and treat it.
He said the patients had described a “force field” sensation that they could physically feel. Some prolonged their exposure by walking around in search of the source. When they opened their front doors, it was gone, they told him.