Two dozen U.S. diplomats and government employees who experienced dizziness and ear pain from a mysterious illness while assigned to Cuba were found to have suffered inner-ear damage, according to a new study by doctors who first treated them.

The report, released Wednesday, said the majority of the 25 individuals reported intense pain in one or both ears and experienced tinnitus, or a ringing in ears.

All of the individuals noticed "unsteadiness and features of cognitive impairment," according to the report.

The study by physicians at the University of Miami and the University of Pittsburgh was published Wednesday in Laryngoscope Investigative Otolaryngology journal.

The doctors found that the patients displayed "abnormalities in the otolithic organs," or damage to the inner ear that controls balance.

"We're not saying it's not an injury to the brain. It may be," Dr. Michael E. Hoffer, lead author of the report and professor at the University of Miami's School of Medicine, told reporters Wednesday. "We do know, for sure, that it's an injury to the ear and that the brain is affected."

Dr. Carey Balaban, a professor at the University of Pittsburgh who contributed to the study, said the doctors have "measurable, quantifiable evidence that something really did happen. It's not just hysteria."

At the same time, Balaban said he wanted to stress that "we don't know what they were exposed to and certainly can't make any inferences as to whether it was deliberate or inadvertent."

An investigation by the F.B.I. and other government agencies has not determined the cause of the illness.

"The evidence suggest they were targeted," Hoffer, a former military officer with security clearance, told the Miami Herald and el Nuevo Herald. "But we can't prove that."

The incidents, which began in the fall of 2016 and continued into 2017 and involved 26 victims, prompted the U.S. State Department to reduce permanently the number of personnel at the embassy in Havana to the bare minimum.

Although never formally accusing Cuba of perpetrating the incidents, the Trump administration expelled 15 personnel from the Cuban embassy in Washington in 2017.

Then-Secretary of State Rex Tillerson said he ordered the expulsions “due to Cuba’s failure to take appropriate steps to protect our diplomats.”

Canada reported 13 cases of mysterious health problems at its Cuban embassy since early 2017.

Cuba has expressed doubts that anything happened to the diplomats and other U.S. employees.

"There's no evidence that can prove that something occurred in Cuba that could have damaged the health situation of a few U.S. diplomats," Carlos Fernandez de Cossio, Cuba's director-general of U.S. affairs, said Wednesday, according to the Associated Press.

The new study found most of the affected individuals reported hearing an unexplained noise before the symptoms began. They characterized the sound as being loud, of high frequency, very localized and " capable of following them throughout a room."

"Others reported a sensation of pressure passing through their head and abdomen in certain parts of the room that could be relieved by moving a few feet away," according to the report.

Some reported feeling as if they were caught in a “force field,” but that noise stopped immediately if they went outside their front door.

At the same time, however, almost a dozen housemates of the individuals were not affected, the study said.

Within 24 hours of the incidents, the study said, the patients reported feelings of dizziness, problems with balance, disorientation, lack of mental clarity and difficulty sustaining attention within 18 hours, the report said.

Contributing: Associated Press