Michael E. Hoffer

Oculomotor, Vestibular, and Reaction Time Tests in Mild Traumatic Brain Injury.

Objective Mild traumatic brain injury is a major public health issue and is a particular concern in sports. One of the most difficult issues with respect to mild traumatic brain injury involves the diagnosis of the disorder. Typically, diagnosis is made by a constellation of physical exam findings. However, in order to best manage mild traumatic brain injury, it is critically important to develop objective tests that substantiate the diagnosis. With objective tests the disorder can be better characterized, more accurately diagnosed, and studied more effectively. In addition, prevention and treatments can be applied where necessary. Methods Two cohorts each of fifty subjects with mild traumatic brain injury and one hundred controls were evaluated with a battery of oculomotor, vestibular and reaction time related tests applied to a population of individuals with mild traumatic brain injury as compared to controls. Results We demonstrated pattern differences between the two groups and showed how three of these tests yield an 89% sensitivity and 95% specificity for confirming a current diagnosis of mild traumatic brain injury. Interpretation These results help better characterize the oculomotor, vestibular, and reaction time differences between those the mild traumatic brain injury and non-affected individuals. This characterization will allow for the development of more effective point of care neurologic diagnostic techniques and allow for more targeted treatment which may allow for quicker return to normal activity.

Neurosensory Symptom Complexes after Acute Mild Traumatic Brain Injury

Mild Traumatic Brain Injury (mTBI) is a prominent public health issue. To date, subjective symptom complaints primarily dictate diagnostic and treatment approaches. As such, the description and qualification of these symptoms in the mTBI patient population is of great value. This manuscript describes the symptoms of mTBI patients as compared to controls in a larger study designed to examine the use of vestibular testing to diagnose mTBI. Five symptom clusters were identified: Post-Traumatic Headache/Migraine, Nausea, Emotional/Affective, Fatigue/Malaise, and Dizziness/Mild Cognitive Impairment. Our analysis indicates that individuals with mTBI have headache, dizziness, and cognitive dysfunction far out of proportion to those without mTBI. In addition, sleep disorders and emotional issues were significantly more common amongst mTBI patients than non-injured individuals. A simple set of questions inquiring about dizziness, headache, and cognitive issues may provide diagnostic accuracy. The consideration of other symptoms may be critical for providing prognostic value and treatment for best short-term outcomes or prevention of long-term complications.

Clinical trials in mild traumatic brain injury.

BACKGROUND Traumatic brain injury is an increasingly prevalent injury seen in both civilian and military populations. Regardless of the mechanisms of injury, the most common sub-type of injury continues to be mild traumatic brain injury. Within the last decade, there has been tremendous growth in the literature regarding this disease entity. PURPOSE To describe the obstacles necessary to overcome in performing a rigorous and sound clinical research study investigating mild traumatic brain injury. This examination begins by a consideration of changing standards for good faith open and total reporting of any and all conflicts of interest or commitment. This issue is particularly critical in mTBI research. We next examine obstacles that include but are not limited to diagnostic criteria, inclusion/exclusion criteria, source of injury, previous history of injury, presence of comorbid conditions and proper informed consent of participants. Frequently, multi-center studies are necessary for adequate subject accrual with the added challenges of site coordination, data core management and site specific study conduct. We propose a total reversal to the traditional translational research approach where clinical studies drive new concepts for future basic science studies. CONCLUSIONS There have been few mild traumatic brain injury clinical trials in the literature with treatments/interventions that have been able to overcome many of these described obstacles. We look forward to the results of current and ongoing clinical mild traumatic brain injury studies providing the tools necessary for the next generation of basic science projects.

The use of oculomotor, vestibular, and reaction time tests to assess mild traumatic brain injury (mTBI) over time: OVRT Test to Assess mTBI

The objective of this work is to examine the outcomes of a set of objective measures for evaluating individuals with minor traumatic brain injury (mTBI) over the sub‐acute time period. These methods involve tests of oculomotor, vestibular, and reaction time functions. This work expands upon published work examining these test results at the time of presentation.

Preventing Episodic Migraine With Caloric Vestibular Stimulation: A Randomized Controlled Trial

To evaluate the safety and efficacy of a novel solid‐state, caloric vestibular stimulation (CVS) device to provide adjuvant therapy for the prevention of episodic migraine in adult migraineurs.

Posttraumatic dizziness and vertigo

Traumatic brain injury is an increasingly common public health issue, with the mild variant most clinically relevant for this chapter. Common causes of mild traumatic brain injury (mTBI) include motor vehicle accidents, athletics, and military training/deployment. Despite a range of clinically available testing platforms, diagnosis of mTBI remains challenging. Symptoms are primarily neurosensory, and include dizziness, hearing problems, headaches, cognitive, and sleep disturbances. Dizziness is nearly universally present in all mTBI patients, and is the easiest symptom to objectify for diagnosis. Aside from a thorough history and physical exam, in the near future specialized vestibular function tests will be key to mTBI diagnosis. A battery of oculomotor (antisaccade, predictive saccade) and vestibular tasks (head impulse test) has been demonstrated to sensitively and specifically identify individuals with acute mTBI. Vestibular therapy and rehabilitation have shown improvements for mTBI patients in cognitive function, ability to return to activities of daily living, and ability to return to work. Dizziness, as a contributor to short- and long-term disability following mTBI, is ultimately crucial not only for diagnosis but also for treatment.

Effectiveness in Rehabilitation of Current Wireless CROS Technology in Experienced Bone-Anchored Implant Users

OBJECTIVE To compare the effectiveness of current contralateral routing of signal technology (CROS) to bone-anchored implants in experienced bone-anchored implant users with unilateral severe-profound sensorineural hearing loss. DESIGN Prospective, within-subject repeated-measures comparison study. SETTING Tertiary referral center. PATIENTS Adult, English-speaking patients (n = 12) with severe-profound unilateral sensorineural hearing loss implanted with a bone-anchored implant for the indication of single-sided deafness. INTERVENTION Subjects were fitted with contralateral routing of signal amplification and tested for speech in noise performance and localization error. OUTCOME MEASURES Speech perception in noise was assessed using the BKB-SIN test materials. Localization was assessed using narrow band noises centered at 500 and 4000 Hz, as well as a broadband speech stimulus presented at random to the front hemifield by 19 speakers spatially separated by 10 degrees. RESULTS There was no improvement in localization ability in the aided condition and no significant difference in performance with CROS versus bone-anchored implants (BAI). There was a significant improvement in speech in noise performance for monaural listeners in the aided condition for speech poorer ear/noise better ear, speech front/noise front, and speech front/noise back. No significant difference was observed on performance with CROS versus BAI subjects. CONCLUSION Contrary to earlier studies suggesting improved performance of BAIs over CROS, the current study found no difference in performance in BAI over CROS devices. Both CROS and BAI provide significant benefit for monaural listeners. The results suggest that noninvasive CROS solutions can successfully rehabilitate certain monaural listening deficits, provide improved hearing outcomes, and expand the reach of treatment in this population.

Does Combat Hearing Preservation Equipment Affect Balance

OBJECTIVES (1) To investigate whether the occlusion effect and hearing attenuation produced by 3M Combat Arms Ear Plugs (CAEP) affects balance when compared to no hearing protection and (2) to investigate whether the occlusion effect and noise-canceling capabilities of the Nacre QuietPro system affects balance when compared to no hearing protection. METHODS This prospective study collected pilot data for investigation of mechanisms of balance. 20 subjects with normal hearing and no vestibular dysfunction were tested with blackened goggles in three conditions-no hearing protection, CAEP, and with the Nacre QuietPro. RESULTS A static posturogrpahy forceplate was used to measure center of gravity angular acceleration for a period of 20 seconds. The order of the conditions tested was randomized for each individual. Mean angular acceleration and standard deviation (degrees/second) of the three conditions were: (1) no hearing protection (control), 0.65 + 0.19, (2) CAEP, 0.69 + 0.23, and (3) QuietPro, 0.70 + 0.20 (one-way analysis of variance [ANOVA], df = 2, F = 0.38, p = 0.706). CONCLUSIONS The components of an intact balance system include a variety of neural inputs, to include vesitbuloocular, vestibulospinal, and labyrinthine afferents. Both the CAEP and Nacre QuietPro are hearing preservation devices utilized during Operation Iraqi Freedom and Operation Enduring Freedom in Afghanistan. Our pilot data show no decrement in balance with utilization of these combat hearing preservation devices.

Intracranial venous injury, thrombosis and repair as hallmarks of mild blast traumatic brain injury in rats: Lessons from histological and immunohistochemical studies of decalcified sectioned heads and correlative microarray analysis.

BACKGROUND Many previous experimental studies of blast wave effects have reported vascular and parenchymal injury in brains extracted from the skulls prior to histopathological assessment. Brain removal disrupts vasculature and structural features of the meninges that may be sources of signs and symptoms of mild traumatic brain injury, particular at lower blast overpressures (<5psi peak). NEW METHOD Immunohistochemical and histopathological studies have been conducted in sections from decalcified, paraffin embedded, histologically sectioned whole rat heads. These sections preserve the entire cranial contents in situ, and permit evaluation of the inner ear, central nervous system and associated vasculature. The findings could also be correlated with mRNA expression patterns from whole brains subjected to similar treatment. RESULTS Lower levels of blast wave exposure produce primarily vascular effects in rats. Messenger RNA profiles of the whole brains showed evidence of both blast intensity and time dependent effects on vascular wound healing markers. The rats exposed to 10-11psi overpressure tended to show a similar pattern of mRNA expression changes in these vascular repair and inflammatory pathways as rats exposed to approximately 5psi overpressure, but the changes were greater. The changes in mRNA expression after a 14-15psi exposure were different and suggestive of more severe injury, particularly for DNA repair, lymphocyte activation and lymphocyte migration pathways. Histopathological examination of decalcified heads revealed that even 2.5-7.9psi blast exposures produced a high prevalence of mild venous hemorrhage and thrombosis (accompanied by inflammatory markers) in the inner ear, vertebrobasilar circulation, hippocampal choroidal fissure and the veins associated with velum interpositum. COMPARISON WITH EXISTING METHOD(S) The sites of vascular injury would not have been included in specimens extracted from the skull prior to processing. CONCLUSIONS The isolated regions of intravascular coagulation in small veins and the isolated, very small venous hemorrhages in the subarachnoid space are worthy of consideration as factors in both healing and chronic sequelae of mild blast concussion. Although small, remnants persisted in the subarachnoid space even 42 days after a single blast exposure. The high prevalence of very mild subdural and subarachnoid hemorrhage may be a target for clinical management.