Neuroimaging in Mild Traumatic Brain Injury

Abstract

Neuroimaging in mild traumatic brain injury (mTBI) is reviewed. While computed tomography remains the acute standard for neuroimaging of mTBI, it is only sensitive to gross abnormalities and is typically performed as a measure to rule out more serious and life-threatening injury. Magnetic resonance imaging (MRI), especially at field strength of 3.0 T, is the follow-up neuroimaging standard for assessing potential underlying structural injury to the brain. Several MRI sequences are particularly sensitive to subtle hemorrhagic lesions and signal abnormalities in white matter, sensitive enough to detect pathology when present in mTBI. Clinical correlation of neuropsychological outcome with neuroimaging findings is discussed along with the future potential for functional neuroimaging in evaluating the mTBI patient.Keywords Mild traumatic brain injury (mTBI) . Neuroimaging . Neuropsychological outcome . White matter . Magnetic resonance imaging (MRI) . Computed tomography (CT) . Functional neuroimaging A history of positive neuroimaging findings provides important information that assists the clinician in understanding the sequelae and potential effects of a traumatic brain injury (TBI) on neuropsychological test performance. Much has been written about neuroimaging methods and findings in TBI, which are summarized elsewhere (Dubroff and Newberg 2008; Le and Gean 2009). The focus of this article is just on neuroimaging findings in mild traumatic brain injury (mTBI) and how such findings provide additional context about the likely neuropathology of mTBI and its relationship to neurocognitive and neurobehavioral sequelae. This review will be brief and primarily focused on the clinical information that exists in standard radiological reports of mTBI patients and its relevance to neurobehavioral and neurocognitive sequelae. Obviously, psychological and neuropsychological assessments of the mTBI patient typically occur weeks or months post-injury. This circumstance requires that any clinician who sees the patient on follow-up must rely on the medical information, including clinical neuroimaging that has already been performed. This also means that the clinician needs to understand the decision making that takes place in the emergency department (ED) for how a mTBI is triaged and when radiological procedures are performed that typically follow established guidelines (Davis 2007;Jagoda et al. 2008). As such, this review begins with an examination of the literature on acute neuroimaging and what is typically performed in the mTBI patient. Acute Neuroimaging in mTBIA review of the medical literature on acute neuroimaging of TBI shows that, when medically indicated, computed tomography (CT) is typically the first scan performed in any patient who sustains a TBI, including those who meet

Traumatic Brain Injury Across the Lifespan: A Neuropsychological Tutorial for Attorneys

“…However, neuroimaging studies of MTBI have only recently been published (reviewed by Belanger et al 2007). Since the Belanger et al (2007) review, Bigler (2008) and Bigler et al (2010; in this topical issue) have further advanced our understanding of the neuroscience of MTBI in an attempt to capture the brain-based etiology of MTBI. For example, Wilde et al (2008) found abnormal findings in Diffusion Tensor Imaging (DTI) from conventional MRI in 90% of MTBI adolescents vs none in a control group.…”

“…In cases of MTBI, neurodiagnostics, such as computed tomography (CT), EEG, and the neurologic exam, as well as conventional MRI, are often normal. However, as reported in this topical issue (Bigler 2010; also see Bigler 2008;Lewine et al 2007), new generation MRI techniques (Diffusion Tensor Imaging) are sensitive in documenting white matter injury in acute cases of MTBI.…”

“…With the advent of sophisticated neuroimaging measures and enhanced computerized techniques (see Bigler 2010, in this topical issue); neuropsychological testing is no longer used to localize the part of the brain that has a lesion and is responsible for the pattern of deficits on testing. Instead, neuropsychological testing now serves as an important way for evaluating and documenting cognitive/functional complaints and determining appropriate treatment interventions.…”

“…Fourth, the neuroimaging techniques developed to document TBI are often negative. This conundrum would seem to leave the onus of objective documentation of an MTBI with newer generation MRI techniques (see Bigler 2010, in this topical issue) and Table 3 Premorbid and comorbid conditions that can adversely affect neuropsychological functioning Previous TBI/concussion with or without loss of consciousness Sleep disorders (e.g., apnea, insomnia) Heart attack with hypoxia/anoxia Metabolic/endocrine disorders (e.g., hypothyroidism, diabetes, liver disease) Vascular disorders (e.g., migraine, hypertension, stroke) Other cerebrovascular accident (e.g., aneurysm, TIA) Brain infection (e.g., meningitis, encephalitis)/brain tumor Chronic pain Major depressive disorder Anxiety disorder Bipolar disorder (formerly referred to as manic depressive illness) Schizophrenia and other psychotic disorders Substance abuse/dependence (prescription and street/recreational drugs, alcoholism) Cortical (Alzheimer's) and subcortical (Parkinson's disease) dementia Epilepsy Lupus Infectious processes (e.g., HIV infection, AIDS, chronic fatigue syndrome) Other neurologic disorders (e.g., normal pressure hydrocephalus, multiple sclerosis) with neuropsychological testing. However, if a patient fails symptom validity testing, test scores are invalid and not reflective of true functioning.…”

Feasibility of using normobaric hypoxic stress in mTBI research

“…This may be due to the lack of identifiable abnormalities on standard neurological imaging [66][67][68][69][70] and/or the potential for both psychological and physiological etiologies of subjective symptoms [62][63][64][65][66]71,72]. Furthermore, as suggested by Marshall and Ruff, conventional assessment of mTBI may lack sensitivity because patients can compensate for difficulties by expending greater cerebral effort to achieve normal performance:…”