Handbook of clinical neurology
-
Over the past 20 years or so, functional magnetic resonance imaging (fMRI) has proven to be an influential tool for measuring perceptual and cognitive processing non-invasively in the human brain. This article provides a brief yet comprehensive overview of this dominant method for human auditory neuroscience, providing the reader with knowledge about the practicalities of using this technique to assess central auditory coding. ⋯ The future utility of fMRI and anticipated technical developments is also briefly evaluated. Throughout the review, key concepts are illustrated using specific author examples, with particular emphasis on fMRI findings that address questions pertaining to basic sound coding (such as frequency and pitch).
-
In the past, direct physical evidence of mild traumatic brain injury (mTBI) from explosive blast has been difficult to obtain through conventional imaging modalities such as T1- and T2-weighted magnetic resonance imaging (MRI) and computed tomography (CT). Here, we review current progress in detecting evidence of brain injury from explosive blast using advanced imaging, including diffusion tensor imaging (DTI), functional MRI (fMRI), and the metabolic imaging methods such as positron emission tomography (PET) and magnetic resonance spectroscopic imaging (MRSI), where each targets different aspects of the pathology involved in mTBI. ⋯ Additionally, although used less frequently for conventional mTBI, PET has the potential to characterize a variety of neurotransmitter systems using target agents and will undoubtedly play a larger role, once the basic mechanisms of injury are better understood and techniques to identify the injury are more common. Finally, our MRSI imaging studies, although acquired at much lower spatial resolution, have demonstrated selectivity to different metabolic and physiologic processes, uncovering some of the most profound differences on an individual by individual basis, suggesting the potential for utility in the management of individual patients.
-
Complex regional pain syndrome (CRPS) is the current consensus-derived name for a syndrome usually triggered by limb trauma. Required elements include prolonged, disproportionate distal-limb pain and microvascular dysregulation (e.g., edema or color changes) or altered sweating. CRPS-II (formerly "causalgia") describes patients with identified nerve injuries. ⋯ Investigational treatments include ketamine, botulinum toxin, immunoglobulins, and transcranial neuromodulation. Nonrecovering patients should be re-evaluated for neurosurgically treatable causal lesions (nerve entrapment, impingement, infections, or tumors) and treatable potentiating medical conditions, including polyneuropathy and circulatory insufficiency. Earlier impressions that CRPS represents malingering or psychosomatic illness have been replaced by evidence that CRPS is a rare complication of limb injury in biologically susceptible individuals.
-
Each year close to 20000 Americans are involved in gunshot wounds to the head (GSWH). Over 90% of the victims of GSWH eventually fail to survive and only a meager 5% of the patients have a chance to continue with a useful life. One of the fundamental jobs of providers is to realize who the best candidate for the best possible management is. ⋯ In case of a positive study, these patients should have endovascular management of their vascular injuries in order to prevent catastrophic intracerebral hematomas and permanent deficit. Although supported by class III data, subjects of GSWH need to be on broad spectrum antibiotics for a period of 3-5 days. If cerebrospinal fluid (CSF) fistulas are observed at any time during the patient's hospital course, they should be taken very seriously and appropriate management is needed to prevent deep intracranial infections.
-
Developing insight into which factors determine prognosis after traumatic brain injury (TBI) is useful for clinical practice, research, and policy making. Several steps can be identified in prediction research: univariate analysis, multivariable analysis, and the development of prediction models. For each step, several methodological issues should be considered, such as selection/coding of predictors and dealing with missing data. "Traditional" predictors include demographic factors (age), type of injury, clinical severity, second insults, and the presence of structural abnormalities on neuroimaging. ⋯ Prognostic models can be used for providing information to relatives of individual patients, for resource allocation, and to support decisions on treatment. At the group level, prognostic models aid in the characterization of patient populations, are important to clinical trial design and analysis, and importantly, can serve as benchmarks for assessing quality of care. Continued development, refinement, and validation of prognostic models for TBI is required and this should become an ongoing process.