Can J Neurol Sci
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Continuous EEG monitoring (CEEG) in the ICU is increasingly recognized as valuable means of monitoring cerebral function, otherwise inaccessible in the comatose patient. The principal applications are: monitoring for seizures and ischemia, guiding therapy for seizures and ischemia (especially vasospasm), adjusting levels of sedation for paralyzed or delirious patients, charting trends in brain function and prognosis. Continuous EEG monitoring is faced with numerous challenges: electrode failures (better electrodes are needed to replace standard EEG electrodes), documentation in the absence of a technologist, artifacts peculiar to ICU, prompt interpretation and review of large amounts of data, resource allocation and establishing the technology as being useful in improving outcomes and shortening ICU and hospital length of stay.
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Imaging of central-nervous-system (CNS) abnormalities is important in patients with mitochondrial disorders (MCDs) since the CNS is the organ second most frequently affected in MCDs and some of them are potentially treatable. Clinically relevant imaging techniques for visualization of CNS abnormalities in MCDs are computed tomography, magnetic resonance imaging, and MR-spectroscopy. The CNS abnormalities in MCDs visualized by imaging techniques include stroke-like lesions with cytotoxic or vasogenic edema, laminar cortical necrosis, basal ganglia necrosis, focal or diffuse white matter lesions, focal or diffuse atrophy, intra-cerebral calcifications, cysts, lacunas, hypometabolisation, lactacidosis, hemorrhages, cerebral hypo- or hyperperfusion, intra-cerebral artery stenoses, or moyamoya syndrome. ⋯ Some of these lesions may remain unchanged for years, some may show contiguous spread and progression, but some may even disappear, spontaneously or in response to medication. Dynamics of Stroke-like lesions may be positively influenced by L-arginine, dichloracetate, steroids, edavarone, or antiepileptics. Symptomatic treatment of CNS abnormalities in MCD patients may positively influence their outcome.
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The neurological determination of death (NDD) is primarily considered to be clinical. However, situations may arise where confounding factors make this clinical assessment difficult or impossible. As a result, ancillary tests have been developed in order to aid in the confirmation of brain death. ⋯ When this is not available, or is equivocal, 4-vessel cerebral angiography can be used to determine the presence or absence of intracranial blood flow. However, as cerebral angiography has its own limitations, other techniques are sought by physicians in the Intensive Care and Neuro-intensive Care settings to replace cerebral angiography. In this article, we briefly review the history of diagnosis of brain death, pathophysiologic issues in making this determination, and currently available CBF imaging techniques, discussing each in turn with respect to their utility in the diagnosis of brain death.
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Dissection of the extracranial carotid and vertebral arteries is increasingly recognized as a cause of transient ischemic attacks and stroke. The annual incidence of spontaneous carotid artery dissection is 2.5 to 3 per 100,000, while the annual incidence of spontaneous vertebral artery dissection is 1 to 1.5 per 100,000. Traumatic dissection occurs in approximately 1% of all patients with blunt injury mechanisms, and is frequently initially unrecognized. ⋯ Resolution is more common in vertebral dissections than in carotid dissections. Aneurysm enlargement occurs rarely. The uncommon patient presenting with acute hemodynamic insufficiency should be managed with measures to increase cerebral blood flow, and in this setting emergency stent placement to restore cerebral perfusion may be considered, provided that irreversible infarction has not already occurred.
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The neurological determination of death (NDD, brain death) is principally a clinical evaluation. However, ancillary testing is required when there are factors confounding the clinical determination or when it is impossible to complete the minimum clinical criteria. At the time of the 2003 Canadian Forum clarifying the criteria for brain death, 4-vessel cerebral angiography or radionuclide angiography were the recommended tests and the electroencephalogram was no longer supported. ⋯ Magnetic resonance angiography or Xenon CT. In the absence of neuroimaging, an established cardiac arrest, as defined by the permanent loss of circulation, fulfills the ancillary criteria for the absence of brain blood flow. Acknowledging the existing limitations in this field, further research validating current or evolving techniques of brain blood flow imaging are recommended.