Preliminary findings on patients who were victims of an alleged sonic attack is a case of mass hysteria or psychogenic illness, Robert Bartholomew, a medical sociologist, said. There was widespread belief that employees of the US embassy in Cuba experienced some symptoms after an acoustic instrument was used on them.

The initial symptoms included dizziness, nausea, and difficulty sleeping, according to the study published this week in the Journal of the American Medical Association, WGN Radio reported. The report confirmed the embassy staff has symptoms of mild traumatic brain injury.

Unknown cause

However, the cause of the injury remains not known. The symptoms of the 21 embassy workers are similar to a concussion. These include cognitive impairment, balance issues, hearing problems, sleep issues, and headaches. But the findings suggested that none of the proposed causes of mass brain symptoms really make sense, LiveScience reported.

Prior to experiencing the symptoms, the employees heard loud strange noises and felt movement in the air that surrounded them. But at the same time, other workers in the room sensed nothing was wrong. When the affected worker moved just a few feet, the noises would stop, but the serious symptoms of a concussion would emerge.

In rejecting the sonic weapon use allegation, the researchers pointed out that it is not likely because the 20 Hz to 20,000 Hz sound in the audible range is not known to cause persistent injury to the central nervous system.

But the case likewise does not fit the typical patterns of a mass delusion, the researchers said. In mass delusions, the benign symptoms are quickly resolved and it appears mostly in older people. The researchers noted that the symptoms were not benign and the embassy workers affected were of various ages. Despite high levels of effort and motivation to treat the patients, the symptoms did not disappear quickly.

Chemical agent?

The researchers, however, could not rule out chemical agents or viruses as the cause although there were no typical symptoms of viral infection such as fevers that came with the symptoms. A chemical agent could unlikely damage the neurological systems without the other organs being involved. If it was a chemical agent, it would cause symptoms within 24 hours of the embassy staff's arrival in Havana.

The symptoms of the patients also do not match exactly with typical concussions because the most unusual symptom recorded was damage to the inner ear which is not associated typically with concussions.

Big Think noted that the symptoms are still there almost 250 days after the attack. The report said that the longer the workers were exposed to the sound, the worse the symptoms are. The website said the source of the sound likely emanated from a vehicle parked outside the embassy and fired from the car.

Sonic attacks are real

While there are no clear answers to the source of the attack, sonic attacks are real. In 2010, to disperse the crowds at the Occupy Wall Street protest, authorities used the LRAD 500x. At the Dakota Pipeline protests, sound cannons similar to the LRAD 500x were used on the protestors.

Not all of the 21 embassy workers knew each other. What apparently happened was that some of them inside the embassy building heard the sound in August 2016, dealt with it at the moment, and reported it later after the initial symptoms developed.

After the incident, US officials accused Cuba of launching the sonic attack, but the Cuban government denied it was involved. The JAMA report came out 15 months after the first symptoms were reported.

The US federal government commissioned the study which found MRI brain scans of the patients were normal. The study debunked a previous report by the Associated Press that medical tests showed white matter in the brains of patients.

In January, Secretary of State Rex Tillerson said he would ask for an independent review board to investigate further. The federal government called the JAMA board to conduct further research.

Mitchell Valdes-Sosa, an auditory expert from the Cuban Neurosciences Center in Havana, said the argument for a new syndrome or a health attack is very weak. Valdes-Sosa pointed out that the abnormal audiograms were present in only very few of the cases and are inconsistent, and added that it is not possible to know if the results are because of pre-existing ailments or if the prevalence is larger than expected for any group or persons of the same age, Metro USA reported.

His theory is that behind the incident are people whom the US government listens to and who want to roll back the work that previous US President Barack Obama had achieved with Cuba which was to reestablish diplomatic ties and tourist trade.

Charles Liberman, a hearing loss researcher at Harvard Medical School and Massachusetts Eye and Ear in Boston, does not discount the possibility that the workers were exposed to low-frequency sound waves that are below the audible range. It is similar to the infrasound generated by windmills or wind generators, Live Science pointed out.

[researchpaper 리서치페이퍼= Vittorio Hernandez 기자]