Seminars in neurology
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Seminars in neurology · Oct 2015
ReviewThe Concussion Toolbox: The Role of Vision in the Assessment of Concussion.
Concussion may lead to subtle changes in brain function, and tests involving the visual system probe higher cortical functioning and increase our sensitivity in detecting these changes. Concussions are acutely and sometimes more persistently associated with abnormalities in balance, cognition, and vision. The visual system involves roughly half of the brain's circuits, including many regions susceptible to head impacts. ⋯ The King-Devick (K-D) test is a visual performance measure that may increase the sensitivity of detecting concussions on the sideline when used in combination with tests of cognition and balance that are part of the Sports Concussion Assessment Tool (3rd ed.; SCAT3). Portable eye movement trackers and pupillometry may in the future improve our neuro-ophthalmic assessment after concussions. Combining visual tasks with neuroimaging and neurophysiology has allowed subtle changes to be detected, may refine our ability to make appropriate return-to-play decisions, and could potentially determine susceptibility to long-term sequelae of concussion.
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Seminars in neurology · Oct 2015
Comparative StudyNonmydriatic Ocular Fundus Photography in the Emergency Department: How It Can Benefit Neurologists.
Examination of the ocular fundus is a critical aspect of the neurologic examination. For example, in patients with headache the ocular fundus examination is needed to uncover "red flags" suggestive of secondary etiologies. However, ocular fundus examination is infrequently and poorly performed in clinical practice. ⋯ In headache patients, not only optic disc edema and optic disc pallor were observed as would be expected, but also a large number of abnormalities associated with hypertension. Based upon subjects with focal neurologic deficits, the FOTO-ED study suggests that the ocular fundus examination may assist with the triage of patients presenting with suspected transient ischemic attack. Continued advances in the ease and portability of nonmydriatic fundus photography will hopefully help to restore ocular fundus examination as a routinely performed component of all neurologic examinations.
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The United Kingdom (UK) has incorporated a brainstem formulation into its brain death criteria since the first guidelines were published in 1976. A clinical diagnosis incorporating three sequential but interdependent steps is sufficient for the determination of brain death in the UK. There must be no doubt that the patient's comatose condition is due to irreversible brain damage of known etiology, and potentially reversible causes of coma and apnea, such as drug effects, metabolic or endocrine disturbances, or hypothermia, must be excluded. ⋯ Confirmatory tests are not required in the UK, but may be useful to reduce any element of uncertainty or minimize the period of observation prior to the diagnosis of brainstem death if the preconditions for clinical testing are not met, or if a comprehensive neurologic examination is not possible. Brainstem death must be diagnosed by two doctors who must be present at each of the two sets of clinical tests that are required to determine death. Although death is not confirmed until the second test has been completed, the legal time of death is when the first test confirms the absence of brainstem reflexes.
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Asia is the largest and most populous continent in the world with people from many diverse ethnic groups, religions and government systems. The authors surveyed 14 countries accounting for the majority of Asia's population and found that, although the concept of brain death is widely accepted, there is wide variability in the criteria for certification. ⋯ Despite this difference, most countries require only neurologic testing of irreversible coma and absent brainstem reflexes as criteria for certification of brain death. Variability exists in the number of personnel required, qualifications of certifying doctors, need for repeat examination, minimum time interval between examinations, and requirement for and choice of confirmatory tests.
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Clinical guidelines for the determination of brain death in children were first published in 1987. These guidelines were revised in 2011 under the auspices of the Society of Critical Care Medicine, the American Academy of Pediatrics, and the Child Neurology Society, and provide the minimum standards that must be satisfied before brain death can be declared in infants and children. After achieving physiologic stability and exclusion of confounders, two examinations including apnea testing separated by an observation period (24 hours for term newborns up to 30 days of age, and 12 hours for infants and children from 31 days up to 18 years) are required to establish brain death. ⋯ Ancillary studies (electroencephalogram and radionuclide cerebral blood flow) are not required to establish brain death and are not a substitute for the neurologic examination. The committee concluded that ancillary studies may be used (1) when components of the examination or apnea testing cannot be completed, (2) if uncertainty about components of the neurologic examination exists, (3) if a medication effect may be present, or (4) to reduce the interexamination observation period. When ancillary studies are used, a second clinical examination and apnea test should still be performed and components that can be completed must remain consistent with brain death.