Following a mild head injury (MHI), a person may report a variety of symptoms such as headache, memory disturbance, dizziness, and concentration difficulties. For most persons the symptoms are transient, but some suffer persistent symptoms that can have a major impact on everyday life. It remains poorly understood why some but not others have full recovery after MHI. The aim of this thesis was to investigate outcomes after MHI, with particular focus on neuropsychological functioning, fatigue, and risk of dementia. A related objective was to examine the potential association of a genetic factor, Apolipoprotein (APOE), with MHI outcome. The APOE є4 allele has been associated with unfavorable outcomes after moderate or severe head injury, but little is known about its influence on outcome after MHI. In Study I and II, data from a population-based longitudinal study were used to compare neuropsychological functioning and fatigue before and after MHI. The results from Study I showed a post-injury decline in neuropsychological performance for є4-carriers, whereas the performance remained unchanged for non-carriers. Study II showed an increase in self-reported fatigue after MHI for both є4-carriers and non-carriers, with a more pronounced increase for є4-carriers. In Study III, a case-control study was conducted to examine whether a history of MHI increased the risk of developing dementia later in life. It was found that MHI alone did not increase the risk, but the combination of MHI and APOE є4 was associated with increased risk of dementia. Taken together, the studies generally indicate a positive outcome after MHI, but in combination with APOE є4 even mild head injury may lead to long-lasting negative outcomes. Consideration of pre-injury level of functioning and genetic factors seems critical for a complete understanding of the impact of MHI.

Background: Case reports are presented on four Veterans, aged 29–46 years, who complained of chronic dizziness and/or postural instability following blast exposures. Two of the four individuals were diagnosed with mild traumatic brain injury and three of the four were exposed to multiple blasts. Comprehensive vestibular, balance, gait, audiometry and neuroimaging procedures were used to characterize their injuries.Case report: Vestibular assessment included videonystagmography, rotary chair and cervical and ocular vestibular evoked myogenic potentials. Balance and gait testing included the sensory organization test, preferred gait speed and the dynamic gait index. Audiometric studies included pure tone audiometry and middle-ear measurements. Neuroimaging procedures included high resolution structural magnetic resonance imaging, susceptibility-weighted imaging and diffusion-tensor imaging.Findings: Based on the neuroimaging and vestibular and balance test results, it was found that all individuals had diffuse axonal injuries and all had one or more micro-hemorrhages or vascular anomalies. Three of the four individuals had abnormal vestibular function, all had abnormally slow walking speeds and two had abnormal gait and balance dysfunction.Conclusion: The use of contemporary neuroimaging studies in conjunction with comprehensive vestibular and balance assessment provided a better understanding of the pathophysiology and pathoanatomy of dizziness following blast exposures than standard vestibular and balance testing alone.

Background: There is currently no standard method of diagnosing the presence or severity of concussion in acute primary care settings. This pilot project is part of a larger study to develop a Computerized Concussion Assessment Tool (CCAT). Methods: A prospective observational clinical study was conducted to explore the validity of the CCAT among patients presenting to the Emergency Department at Kingston General Hospital and at Hotel Dieu Hospital (Kingston, Ontario) with minor head injury. Twenty-two patients with concussion and eighteen patients with head injury (but not diagnosed with concussion) were recruited to the study. All participants completed a background questionnaire, several neurocognitive tests and the CCAT assessment. Performance on the CCAT was compared between these two groups. Data collected during the development phase of the CCAT from a Normal Volunteers group (n=68) were used in an additional comparison. CCAT Scores for Selective Attention, Divided Attention and Memory were compared with standard neurocognitive tests through correlational analyses. In addition, the validity and clinical yield of the CCAT were investigated relative to gold standard measures. Results: After adjustment for covariates, no statistically significant differences were found between the three participant groups for any of the three primary CCAT Scores (Selective Attention, Divided Attention and Memory). Correlational analyses showed that the CCAT Selective Attention Score and the CCAT Memory Score are moderately correlated with standard neurocognitive tests. There was no correlation observed for the CCAT Divided Attention Score and its associated neurocognitive test. Conclusion: The CCAT was unable to discriminate between concussed patients and non-concussed individuals. However, moderate correlations observed between the CCAT Scores for Memory and Selective Attention and their respective neurocognitive tests support a view that there should be optimism for the future development of the CCAT. Issues related to the feasibility of the study and its administration in the emergency department setting are discussed. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2008-09-23 10:40:20.199

Disputats, Umeå universitet, 2006. / Härtill 3 uppsatser.

The purpose of this article is to review relevant literature on the effect of mild traumatic brain injury (mTBI) and blast injury on the vestibular system. Dizziness and imbalance are common sequelae associated with mTBI, and in some individuals, these symptoms may last for six months or longer. In war-related injuries, mTBI is often associated with blast exposure. The causes of dizziness or imbalance following mTBI and blast injuries have been linked to white matter abnormalities, diffuse axonal injury in the brain, and central and peripheral vestibular system damage. There is some evidence that the otolith organs may be more vulnerable to damage from blast exposure or mTBI than the horizontal semicircular canals. In addition, benign paroxysmal positional vertigo (BPPV) is a common vestibular disorder following head injury that is treated effectively with canalith repositioning therapy. Treatment for (non-BPPV) mTBI-related vestibular dysfunction has focused on the use of vestibular rehabilitation (VR) augmented with additional rehabilitation methods and medication. New treatment approaches may be necessary for effective otolith organ pathway recovery in addition to traditional VR for horizontal semicircular canal (vestibulo-ocular reflex) recovery.