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Oct 06 2015

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Focus on Vision and Balance Deficits Following Youth Concussion

Recognizing a concussion oftentimes is not crystal clear for clinicians. A young patient with a head injury may report experiencing common concussion symptoms, and yet results from a standard physical exam seem normal. Findings from two new research studies suggest that additional assessments of a patient’s visual oculomotor system and balance system may help to bring a concussion diagnosis into better focus.

About 250,000 children were treated in U.S. emergency departments for sports and recreation-related injuries that included a diagnosis of concussion or traumatic brain injury (TBI), according to 2009 estimates from the Centers for Disease Control and Prevention. A concussion is a mild TBI from a blow or jolt that causes the brain to bounce around or twist in the skull. The shaking can disrupt brain functions, which can result in headaches, dizziness, nausea, balance problems, fatigue, blurred vision, motion sickness, and light and noise sensitivity.

A research study published in the journal Clinical Pediatrics showed that vision diagnoses are common after concussion and that visual oculomotor deficits likely are contributing to those symptoms. The research team examined 100 study participants 11 to 17 years old who received clinical care as part of the Concussion Care for Kids: Minds Matter program at The Children’s Hospital of Philadelphia. Overall, 69 percent had at least one vision diagnosis after concussion.

“It appears that what your brain does in terms of integrating all your visual function can be affected by concussion,” said Christina Master, MD, CAQSM, a sports medicine pediatrician in the divisions of orthopedics and general pediatrics at CHOP, who led the study. “That finely tuned coordination seems to be injured in concussion.”

For example, half the study participants had convergence insufficiency, which is when the eyes are not able to work together to keep an object in focus as a single image at near distance. In the general population, the prevalence of convergence insufficiency is between 2 and 8 percent, but among the study participants, almost 50 percent had convergence insufficiency. Other visual oculomotor function disturbances that the study participants often had were related to eye-tracking which is important for reading.

Typical visual acuity tests may not identify the eye coordination, eye tracking, and eye focusing problems that the researchers associated with concussions. “If you don’t do particular visual assessments, you may miss these visual deficits,” Dr. Master said. “These are not part of the standard visual evaluation, so I think they have been missed for a long time.”

Dr. Master also explained that young patients with concussions often do not realize that they are having vision problems, which can make diagnosis even more challenging. Clinicians often use the Post Concussion Symptom Scale as a screening tool to identify concussion symptoms, but Dr. Master pointed out that it has only one broad, generic question about vision problems. A more specific visual symptom questionnaire called the Convergence Insufficiency Symptom Survey that the research team used in the study could be an additional way to pinpoint vision diagnoses after injury.

Recognizing and treating vision problems after concussion is increasingly important, the investigators emphasized, because children are living in a highly connected electronic environment at home and school with a heavy visual workload. Looking closely at computer monitors, tablets, and smart phones is visually demanding, and children with concussions may find it difficult to read and interact with those electronic interfaces during recovery.

“All that ‘near work’ adds to the visual workload and somewhat amplifies the symptoms of the disrupted physiology after concussion,” Dr. Master said.

The vestibular system, which controls body balance, also is not usually part of a standard physical or neurological exam. Yet Dr. Master and her colleagues showed in another study published in The Journal of Pediatrics that a high prevalence of vestibular deficits appear after concussion. Eight-one percent of 247 study participants ages 5 to 18 with a history of concussion showed a vestibular abnormality, which was associated with extended recovery times and poorer performance on neurocognitive testing.

“Again, we need to make sure our vestibular assessments are challenging enough,” Dr. Master said. “Balance deficits following a mild traumatic brain injury may be subtle and require us to be more astute as clinicians in terms of picking them up.”

Clinicians throughout The Children’s Hospital of Philadelphia system — from Minds Matter concussion experts to emergency room physicians to primary care pediatricians — received training to perform dynamic assessments to find potential disturbances in patients’ vestibular system, including the vestibulo-ocular reflex (VOR), after concussion. The VOR is like a “steady cam” feature in the brain that allows you to look at a fixed object and keep the picture stable, even when your head is moving up and down or side to side.

Each part of the vestibular balance assessment becomes a little more demanding for patients who may be concussed. First, they walk forward in a tandem gait, as if on a balance beam, with their eyes open and then with their eyes closed. Next, they walk in tandem backwards with eyes open and closed, which can be tough to do if your vestibular system is damaged.

“When your brain balance function is disrupted by a concussion, you need to rely more heavily on your visual input to compensate in order to maintain your balance,” Dr. Master said. “It is like a pilot flying with just the instruments as opposed to being able to see the horizon, as well.”

As more clinicians learn how to identify balance and vision problems that are common after concussions, they will be able to refer patients to specialists who can provide oculomotor interventions and vestibular rehabilitative therapies. These approaches especially may be useful for patients who have prolonged symptoms and are not bouncing back after a few days of rest, and getting back to their full activities in a few weeks, Dr. Master said.

“I think active rehab is important to look at as a therapeutic, and it needs further study, but it appears to have a huge impact in terms of helping kids with prolonged concussion symptoms have better function and improved symptoms in both of these systems,” Dr. Master said.

Permanent link to this article: http://blog.research.chop.edu/focus-on-vision-and-balance-deficits-following-youth-concussion/