Does Whiplash Result in Brain Injury?

Many of the symptoms that result from auto injuries are obviously related to the direct injury to the spine; neck pain after whiplash, for instance, is easy to understand. Some symptoms, however, are not so easy to diagnose. A significant percentage of patients with whiplash report symptoms such as tinnitus, problems with concentration, dizziness, or visual symptoms. These problems are difficult to describe in terms of injury to the neck, and many researchers over the years have speculated that some auto injury patients may actually have suffered a brain injury.

A new study from a group of Canadian and Swiss researchers has looked more closely at the relationship between whiplash and concussion. The authors studied sensory evoked potentials (SEPs) in whiplash patients, concussion patients, and healthy control subjects.

Sensory evoked potentials are a diagnostic test that measures the brain's response to an electrical stimulus. SEPs are used to diagnose brain injury or disease. In this case, the researchers used SEPs to determine if there were any similarities between whiplash and concussion; they did so by measuring the evoked potentials created by stimulation of the median nerve.

The authors actually conducted two studies in this one article. The first study compared 10 recent whiplash patients and 10 chronic patients to 83 healthy control subjects. In this part of the study, the researchers found that patients tested within one month of injury showed significantly increased SEP scores compared to the normal controls; the chronic patients did not show a difference.

The authors reported the following:

• The SEP scores were significantly increased in both the whiplash group and the concussion group, compared to the normal group. The concussion patients, however, had higher scores than the whiplash patients.
• At the 3-month follow-up, the whiplash and concussion patients still showed elevated SEP findings.
• Although the SEP scores decreased in both groups at the follow-up, the whiplash patients still reported significant, and sometimes increased, symptoms at the 3-month follow-up.

The authors state:

“From the results of both studies, it would appear that the changes in [SEP scores] normalize between three to six months post injury. It is thus evident that the acute increase in [SEP scores] is related to reversible traumatic functional abnormalities in the brain of patients post whiplash or concussion injury.”

“The SEP findings of our prospective study provide objective evidence that whiplash and concussion involve reversible pathophysiological changes affecting the same brain areas, providing support for the hypothesis that the overlapping clinical symptomatology post whiplash and concussion may reflect a similar underlying mechanism of rotational mild traumatic brain injury.”

One mystery from the study is easily understood: Why the whiplash patients reported an increase in some symptoms, even though the SEP scores improved. These results are not surprising, since the whiplash patients also suffered a cervical spine injury in addition to the concussion. The symptoms that did not improve (general impairment, neck pain, headache, vertigo, irritability, and depression) are also related to neck injury or chronic pain and it easy to see how these patients could continue to have these problems, even if a potential brain injury had improved at the follow-up.

In fact, this study makes it clear that brain injury symptoms can easily be overlooked in whiplash patients, as many of the symptoms of whiplash are similar to those of brain injury.

Zumsteg D, Wennberg R, Gutling E, Hess K. Whiplash and concussion: similar acute changes in middle latency SEPs. Canadian Journal of Neurological Sciences 2006;33:379-386.

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