The first detailed clinical picture of the cluster of hearing, vision, balance, and cognitive symptoms experienced recently by US diplomats working in Havana, Cuba, in what the State Department has called "health attacks," has been published in a report this week.
Most of the individuals reported that their symptoms started after hearing a novel, directional, intensely loud, high-pitched sound, often accompanied with feelings of vibration or changes in air pressure, in their homes and hotel rooms.
While the exact cause of these concussion-like symptoms remains unknown, these individuals appeared to have sustained injury to "widespread brain networks without an associated history of blunt head trauma," report clinicians from the University of Pennsylvania's Center for Brain Injury and Repair in Philadelphia, which was selected to coordinate evaluation, treatment, and rehabilitation of affected patients.
Importantly, note Randel L. Swanson II, DO, PhD, and colleagues, there is no evidence that the symptoms reported by US embassy personnel in Cuba can be attributed to mass psychogenic illness, as some skeptics have suggested.
Mass psychogenic illness typically involves uniform symptoms that are of short duration and are often benign in nature, with no consistent physical exam findings. This is completely opposite of what is seen in the Cuba cohort, they note. Although not systematically excluded, viruses or chemical exposures are unlikely, they say.
"While there are many open questions that remain, we are collectively convinced that these individuals, as a group, sustained a neurological injury. So, the constellation of signs and symptoms and their response to rehabilitation mirrors what we see in patients with mild traumatic brain injury, both in the civilian population and in our military population," Swanson said in a JAMA podcast.
The preliminary report was published online February 15 in JAMA.
Persistent Cognitive Difficulties
The team evaluated 21 of 24 diplomats (11 women and 10 men) an average of 203 days after exposure to the mysterious sounds and sensory phenomena, which happened in late 2016.
The most common patient-reported symptoms were persistent (>3 months after exposure) sleep disturbance (86%), visual symptoms (86%), cognitive difficulty (81%), headache (76%), balance problems (71%), and auditory symptoms (68%). Objective findings included cognitive symptoms (76%) and vestibular (81%) and oculomotor (71%) abnormalities. Moderate to severe sensorineural hearing loss was identified in 3 individuals (14%).
Cognitive symptoms, including difficulty remembering and feeling cognitively slowed, were the most problematic for affected individuals more than 3 months after exposure, the authors report.
Most patients had conventional MRI neuroimaging findings, which were within normal limits, at most showing a few small nonspecific white matter changes in 9 individuals (43%).
Individualized rehabilitation programs were developed for the patients. The most symptomatic patients (n = 14 [67%]), who required multiple therapies, have not returned to work.
No Definitive Answers
The University of Pennsylvania team is continuing to monitor each patient's progress and plans to do neuropsychological testing on the other 6 patients, which has also been recommended.
The similarities among the 21 patients who have undergone coordinated multidisciplinary evaluation thus far "merit consideration of a common medical, environmental, or psychological event as the potential cause," write the coauthors of an editorial in JAMA.
However, at this point, a unifying explanation for the symptoms experienced by the US diplomats in Cuba "remains elusive and the effect of possible exposure to audible phenomena is unclear," write Christopher C. Muth, MD, associate editor, JAMA, and Steven L. Lewis, MD, Lehigh Valley Health Network, Allentown, Pennsylvania.
"Going forward, it would be helpful for government employees traveling to Cuba to undergo baseline testing prior to deployment to allow for a more informed interpretation of abnormalities that might later be detected after a potential exposure," they note.
"Just as critical, especially for assessment of individuals without baseline information, will be comparison of data with age- and sex-matched controls, and blinding of assessors to both patients and controls if possible. Additional testing with advanced neuroimaging techniques (especially compared with an age- and sex-matched control group) may also help characterize any functional or structural brain changes," write Muth and Lewis.
Importantly, they say, additional evidence must be obtained and rigorously and objectively evaluated before any definitive conclusions can be reached.
Study coauthor Dr Green-McKenzie reported receiving grants from Health Resources and Services Administration and the National Institute for Occupational Safety and Health. Lewis reported serving as the editor-in-chief of Continuum: Lifelong Learning in Neurology and serving as a trustee of the World Federation of Neurology and editor of World Neurology. The other study authors and Dr Muth have disclosed no relevant financial relationships.
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Cite this: Mysterious Symptoms in US Diplomats Deemed Neurologic Injury - Medscape - Feb 16, 2018.