Treatment Benefits for Mild Traumatic Brain Injury

Mild traumatic brain injury (TBI) is the second most common neurological disorder with an incidence of 180 for 100,000. The symptoms of mild TBI include fatigue, headaches, dizziness, concentration, memory disorders, and irritability.

An axon is a single process of a nerve cell that under normal conditions conducts nervous impulses away from the cell body and its remaining processes (dendrites). Diffuse axonal injury (DAI) is the medical cause of TBI, a shearing of forces in the brain occurring after sudden deceleration.

DAI is characterized by axonal loss and degenerative changes the distal segment of a peripheral nerve fiber (axon and myelin), focal edema from small vessel disruption, and the release of excitatory neurotransmitters many of which may be active in apoptotic pathways. The duration of these symptoms in TBI patients is unclear. While some investigators believe that symptoms only last weeks to months, many investigators believe that symptoms can persist for years or may never completely resolve.

Complicating the study of TBI symptoms is the fact that there is not one accepted objective test that characterizes initial and persistent symptoms of TBI. In addition to the difficulty in characterizing the severity and duration of mild TBI and its associated symptoms, there is difficulty in characterizing the symptoms themselves. Many of the signs and symptoms of the disorder are subtle and other symptoms can be confused with each other making it difficult to determine when any particular symptom started or stopped. In particular, little evidence is available characterizing dizziness after mild TBI.

The goal of a new research effort was to examine the patterns of dizziness after mild TBI and to provide some treatment strategies and prognostic data for this common disorder. The authors of "Characterizing and Treating Dizziness after Mild Head Trauma" are Commander Michael E. Hoffer, CDR MC USN, Colonel Kim R. Gottshall, AMSC USA, Robert Moore PhD, and Derin Wester, PhD, CCC-A, all from The Department of Defense Spatial Orientation Center, Department of Otolaryngology, Naval Medical Center San Diego, CA. Their findings are to be presented at the annual meeting of the American Neurotology Society http://itsa.ucsf.edu/~ajo/ANS/ANS.html being held May 3, 2003, at the Opryland Hotel, Nashville, TN.

Methodology: Over a two-year period, 58 patients with post-mild traumatic brain injury dizziness were examined. All of the patients were diagnosed with mild TBI no loss of consciousness. All patients had vestibular symptoms of imbalance, true vertigo, dizziness, and/or unsteadiness. All of the individuals had a work up that included a detailed otolaryngologic history and physical exam, standard neurotological exam, and a magnetic resonance scan (MRI) to rule out a CPA lesion or other pathology. To be included in the study, patients were required to have no prior pathology or history of dizziness or severe headaches.

The patients were divided into three groups based on their history, physical exam, and results of the testing. The three groups were post-traumatic positional vertigo, post-traumatic migraine associated dizziness (PTMAD), and post-traumatic spatial disorientation. All groups (except for the positional group) underwent a 6-8 week standard vestibular rehabilitation program and then underwent repeat testing. The groups were compared on three criteria as follows: 1) Improvement of objective physical exam and testing results abnormalities after therapy, 2) Average time to return to work, and 3) Average time to return to the perception of normal balance function based on the DHI and ABC tests.

Results: Fifty-one of the 58 patients were classified into one of the three groups. The post-traumatic positional vertigo group was composed of 16 patients (28 percent, 12 males and four females), the PTMAD group was composed of 24 individuals (41 percent, 22 males and two females), and the post-traumatic spatial disorientation group was composed of 11 individuals (19 percent) (eight males and three females). The average age in the migraine group and the disorientation group was 30 and 32 years of age respectively, whereas the average age of the positional dizziness group was 42 years of age.

Despite this apparent difference statistical analysis demonstrated that the average age and male/female ratio among the three groups was not statistically different. Both the PTMAD and post-traumatic spatial disorientation groups had objective findings of altered vestibule-ocular reflex (VOR) function on testing. These disorders were typically a mid frequency (0.32 and 0.64 Hz) phase shift on sinusoidal rotation chair testing. In addition, several individuals, from both groups, displayed an abnormally low gain in the mid-frequencies on the same test. After six to eight weeks of rehabilitation therapy 84 percent of the migraine group demonstrated an improvement in VOR tests as compared to 27 percent of the disorientation group. This difference was significant (p<0.01)

The length of the disability for the disorientation group was significantly longer then for the other two groups. It should be noted that the disorientation data is for patients that returned to work and those whose symptoms resolved.

Conclusion: This was one of larger series examining dizziness after mild head trauma. The findings show that, depending on the type of balance disorder, treatment can improve the rate of recovery significantly. The majority of the patients (in the positional or PTMAD groups) show improvement in one to eight weeks. It was the disorientation group (19 percent of our total population) that had a more protracted course and on average did not have resolution of symptoms until 39 weeks

Approximately four percent of the study population was not better at the one year mark. It appears, than, at least for the migraine and positional group of patients, rehabilitation may have a positive impact by shortening disability time and speeding return to work.

This study looked at a cohort of patients with mild head trauma and categorized them into three different dizziness diagnoses. Diagnostic criteria and outcome results were provided. In time and with more study the diagnostic criteria and specific treatment modalities for each disorder could be refined resulting in improved patient outcomes and shorter disability times.