Athletes With Vestibular Symptoms After Concussion at Risk

Nancy A. Melville

June 03, 2013

INDIANAPOLIS, Indiana — Athletes with vestibular symptoms after concussion may have slower reaction times, putting them at risk for new injury compared with those who have concussions without these symptoms, according to research presented here at the American College of Sports Medicine (ACSM) 60th Annual Meeting.

The study of 48 athletes, aged 9 to 23 years, with a diagnosed protracted concussion, showed that patients with vestibular dizziness had significantly lower scores in gauging reaction time compared with those without the impairment (P = .05), as did athletes with vestibule-ocular symptoms (P = .04).

"The vestibular system plays a role in movement and timing as it helps to regulate our body's movement through space and time and our awareness of that movement," said lead investigator Anthony Kontos, PhD, from the University of Pittsburgh Medical Center's Sports Medicine Concussion Program in Pennsylvania.

"Therefore, if this system is compromised in some way following concussion, it makes sense that a reaction time would be slowed. This is an important point, as athletes with this impaired reaction time may be at greater risk for subsequent injury until they are no longer impaired."

The participants in the study had sustained their injuries more than 21 days earlier and completed computerized neurocognitive tests and symptom reports at their initial clinical visits. They also received vestibular screening, which includes clinical interview and exams evaluating vestibular dizziness and vestibulo-spinal and vestibulo-ocular domains.

In addition to having slower reaction time, the athletes with vestibular dizziness and vestibulo-spinal and vestibule-ocular impairments reported more total symptoms (P = .009, P = .004, and P = .03), than those without the impairments.

 
Between 37% and 48% of patients experienced vestibular-related impairments, yet not all centers screen comprehensively for the impairments. Dr. Anthony Kontos
 

The 3 vestibular impairments were also associated with greater cognitive impairments (P = .01, P = .03, P = .05) and somatic symptoms (P =.001, P =.001, P =.002) compared with patients without the symptoms.

An abnormal (>6 cm) convergence distance was associated with a lower reaction time (P = .05), and a dose-response for vestibular impairments was indicated for total symptoms (P = .007), as well as cognitive (P = .03), somatic (P = .001), and sleep (P = .02) symptoms.

The findings support previous research by Dr. Kontos and his team indicating that dizziness was associated with a significant increase in risk for protracted outcome after concussion.

"Our clinicians see a lot of patients with vestibular impairment or symptoms that take longer to recover than other patients, so we really wanted to look at vestibular impairment empirically to see if these patients do indeed have longer recovery and worse symptoms and to see if vestibular impairment was related to cognitive performance," he said.

Approximately 20% of athletes require more than 21 days to recover after sustaining a concussion, and in the current study, between 37% and 48% of patients experienced vestibular-related impairments, yet not all centers screen comprehensively for the impairments, Dr. Kontos noted.

"Our clinicians use a brief vestibular screening exam and interview and then follow-up with more comprehensive vestibular assessments as needed in conjunction with our vestibular therapist and physicians," he explained. "There are other clinics doing this too, but it is not yet common practice."

Once identified as having the impairments, patients are provided with various targeted therapies, Dr. Kontos said.

Targeted Therapy

"A patient who is identified as having a convergence insufficiency, for instance, may be prescribed in-office and home-based vision therapy designed to improve this visual deficit," Dr. Kontos explained.

"In contrast, another patient may be identified as having predominately dizziness-related vestibular impairment from post-traumatic migraine or cervicogenic factors that might be targeted with specific medications for migraine symptoms or physical therapy if it is neck-related," he said.

The key to providing appropriate treatment is to screen for vestibular impairment, Dr. Kontos emphasized. "Clinicians need to assess and identify vestibular impairment following concussion using brief screening tools to allow them to move patients into targeted treatment tracks that will provide more individualized therapies for their specific impairments."

Session moderator Kevin Guskiewicz, PhD, said that a key concept in understanding concussion outcomes is the fact that "concussions are like snowflakes — no two are alike."

He added in a separate talk that increasing evidence involving sophisticated imaging techniques is showing that concussion can be recognized as a structural injury when it has previously been described as a functional problem.

While vestibular deficits are among established symptoms of concussion, the findings in Dr. Kontos' research shed important new light on their manifestation, he told Medscape Medical News.

"We have long known that balance and vestibular deficits are common following concussion," said Dr. Guskiewicz, chair of the Department of Exercise and Sport Science at the University of North Carolina, Chapel Hill.

"There are also some symptoms, such as dizziness and visual disturbances that are associated with balance problems in concussed athletes with protracted recovery," he said. "These recent findings are interesting and suggest that other important symptoms may also be associated with these deficits."

This study was supported by the Albert B. Ferguson, Jr. MD Orthopaedic Fund of the Pittsburgh Foundation Research Grant. Dr. Kontos and Guskiewicz have disclosed no relevant financial relationships.

American College of Sports Medicine (ACSM) 60th Annual Meeting: Abstract 1816. Presented May 30, 2013.

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