Re-examining death: against a higher brain criterion.
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While there is increasing pressure on scarce health care resources, advances in medical science have blurred the boundary between life and death. Individuals can survive for decades without consciousness and individuals whose whole brains are dead can be supported for extended periods. One suggested response is to redefine death, justifying a higher brain criterion for death. This argument fails because it conflates two distinct notions about the demise of human beings--the one, biological and the other, ontological. Death is a biological phenomenon. This view entails the rejection of a higher brain criterion of death. Moreover, I claim that the justification of the whole brain (or brain stem) criterion of death is also cast into doubt by these advances in medical science. I proceed to argue that there is no need to redefine death in order to identify which treatments ought to be provided for the permanently and irreversibly unconscious. There are already clear treatment guidelines. (+info)
Effects of sibutramine alone and with alcohol on cognitive function in healthy volunteers.
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AIMS: To investigate the effects of sibutramine in combination with alcohol in a double-blind, randomised, placebo-controlled, four-way crossover study in 20 healthy volunteers. METHODS: On each study day each volunteer received either: sibutramine 20 mg+0.5 g kg-1 alcohol; sibutramine 20 mg+placebo alcohol; placebo capsules+0.5 g kg-1 alcohol; or placebo capsules+placebo alcohol. Alcohol was administered 2 h following ingestion of the study capsules. During each study day, assessments of cognitive performance were made prior to dosing, and at 3, 4.5, 6 and 10 h post dosing. Blood alcohol concentration was estimated using a breath alcometer immediately prior to each cognitive performance test session. Each study day was followed by a minimum 7 day washout period. RESULTS: Alcohol was found to produce statistically significant impairments in tests of attention (maximum impairment to speed of digit vigilance=49 ms) and episodic memory (maximum impairment to speed of word recognition=74 ms). Alcohol also increased body sway (maximum increase 17.4 units) and lowered self rated alertness (maximum decrease 13.6 mm). These effects were produced by an inferred blood alcohol level of 53.2 mg dl-1. Sibutramine was not found to potentiate any of the effects of alcohol. There was a small, yet statistically significant, interaction effect observed on the sensitivity index of the picture recognition task. In this test, the combined effects of sibutramine and alcohol were smaller than the impairments produced by alcohol alone. Sibutramine, when dosed alone, was associated with improved performance on several tasks. Sibutramine improved attention (mean speed of digit vigilance improved by 21 ms), picture recognition speed (improvement at 3=81) and motor control (tracking error at 3 h reduced by 1.58 mm). Also sibutramine improved postural stability (reducing body sway at 3 h by 14.2 units). Adverse events reported were unremarkable and consistent with the known pharmacology of sibutramine and alcohol. CONCLUSIONS: There was little evidence of a clinically relevant interaction of sibutramine with the impairment of cognitive function produced by alcohol in healthy volunteers. The single statistically significant interaction indicated a reduction, rather than a worsening, of alcohol-induced impairment when sibutramine is taken concomitantly. Sibutramine when administered alone is associated with improved performance on several tasks. (+info)
Prolonged coma due to cerebral fat embolism: report of two cases.
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Fat embolism syndrome remains a rare, but potentially life threatening complication of long bone fractures. The true incidence is difficult to assess as many cases remain undiagnosed. Cerebral involvement varies from confusion to encephalopathy with coma and seizures. Clinical symptoms and computed tomography are not always diagnostic, while magnetic resonance imaging is more sensitive in the detection of a suspected brain embolism. Two cases of post-traumatic cerebral fat embolism, manifested by prolonged coma and diffuse cerebral oedema, are presented. The clinical course of the disease as well as the intensive care unit management are discussed. (+info)
Auditory evoked potentials to spectro-temporal modulation of complex tones in normal subjects and patients with severe brain injury.
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In order to assess higher auditory processing capabilities, long-latency auditory evoked potentials (AEPs) were recorded to synthesized musical instrument tones in 22 post-comatose patients with severe brain injury causing variably attenuated behavioural responsiveness. On the basis of normative studies, three different types of spectro-temporal modulation were employed. When a continuous 'clarinet' tone changes pitch once every few seconds, N1/P2 potentials are evoked at latencies of approximately 90 and 180 ms, respectively. Their distribution in the fronto-central region is consistent with generators in the supratemporal cortex of both hemispheres. When the pitch is modulated at a much faster rate ( approximately 16 changes/s), responses to each change are virtually abolished but potentials with similar distribution are still elicited by changing the timbre (e.g. 'clarinet' to 'oboe') every few seconds. These responses appear to represent the cortical processes concerned with spectral pattern analysis and the grouping of frequency components to form sound 'objects'. Following a period of 16/s oscillation between two pitches, a more anteriorly distributed negativity is evoked on resumption of a steady pitch. Various lines of evidence suggest that this is probably equivalent to the 'mismatch negativity' (MMN), reflecting a pre-perceptual, memory-based process for detection of change in spectro-temporal sound patterns. This method requires no off-line subtraction of AEPs evoked by the onset of a tone, and the MMN is produced rapidly and robustly with considerably larger amplitude (usually >5 microV) than that to discontinuous pure tones. In the brain-injured patients, the presence of AEPs to two or more complex tone stimuli (in the combined assessment of two authors who were 'blind' to the clinical and behavioural data) was significantly associated with the demonstrable possession of discriminative hearing (the ability to respond differentially to verbal commands, in the assessment of a further author who was blind to the AEP findings). Behavioural and electrophysiological findings were in accordance in 18/22 patients, but no AEPs could be recorded in two patients who had clear behavioural evidence of discriminative hearing. The absence of long-latency AEPs should not, therefore, be considered indicative of complete functional deafness. Conversely, AEPs were substantially preserved in two patients without behavioural evidence of discriminative hearing. Although not necessarily indicative of conscious 'awareness', such AEP preservation might help to identify sentient patients who are prevented by severe motor disability from communicating their perception. (+info)
Immediate surgery reduces mortality in deeply comatose patients with spontaneous cerebellar hemorrhage.
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Cerebellar hemorrhage is regarded as a neurosurgical emergency. However, patients with deteriorating consciousness are very likely to die irrespective of the choice of therapy, and it is not clear if surgical intervention can benefit patients in a deeply comatose state. We reviewed 20 patients with a Glasgow Coma Scale score of 3 at admission to ascertain the salvage rate and determine the prognostic factors. Four patients who were managed conservatively died within 2 days. Sixteen patients underwent decompressive suboccipital craniectomy and hematoma evacuation. At discharge, three patients were moderately disabled, three were severely disabled, four were persistently vegetative, and six had died. The overall mortality was 50%. The mean interval between the onset of symptoms and the operation was 1.67 +/- 0.29 hours in patients with favorable outcome, and significantly longer at 2.42 +/- 0.49 hours in patients with an unfavorable outcome (p = 0.025). Immediate evacuation of the hematoma reduces morbidity and mortality even in deeply comatose patients, especially if the time interval between the onset and surgery is within 2 hours. (+info)
A case of post-anoxic encephalopathy with initial massive myoclonic status followed by alternating Jacksonian seizures.
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To contrast stimulus-sensitive generalized myoclonus with ensuing multifocal localized myoclonus in a patient with post-anoxic coma, we stressed the clinical as well as electroencephalographical differences between his initial generalized and subsequent focal myoclonus. While generalized myoclonus was presumably of extracortical origin and responsive to valproic acid, alternating Jacksonian seizures were definitely cortical and suppressed with phenytoin. These two different types of myoclonus should not be confused in post-anoxic coma. (+info)
Quantitative analysis of the loss of distinction between gray and white matter in comatose patients after cardiac arrest.
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BACKGROUND AND PURPOSE: Anecdotal reports suggest that a loss of distinction between gray (GM) and white matter (WM) as adjudged by CT scan predicts poor outcome in comatose patients after cardiac arrest. To address this, we quantitatively assessed GM and WM intensities at various brain levels in comatose patients after cardiac arrest. METHODS: Patients for whom consultation was requested within 24 hours of a cardiac arrest were identified with the use of a computerized database that tracks neurological consultations at our institution. Twenty-five comatose patients were identified for whom complete medical records and CT scans were available for review. Twenty-five consecutive patients for whom a CT scan was interpreted as normal served as controls. Hounsfield units (HUs) were measured in small defined areas obtained from axial images at the levels of the basal ganglia, centrum semiovale, and high convexity area. RESULTS: At each level tested, lower GM intensity and higher WM intensity were noted in comatose patients compared with normal controls. The GM/WM ratio was significantly lower among comatose patients compared with controls (P:<0.0001, rank sum test). There was essentially no overlap in GM/WM ratios between control and study patients. The difference was greatest at the basal ganglia level. We also observed a marginally significant difference in the GM/WM ratio at the basal ganglia level between those patients who died and those who survived cardiac arrest (P:=0. 035, 1-tailed t test). Using receiver operating characteristic curve analysis, we determined that a difference in GM/WM ratio of <1.18 at the basal ganglia level was 100% predictive of death. At the basal ganglia level, none of 12 patients below this threshold survived, whereas the survival rate was 46% among patients in whom the ratio was >1.18. The empirical risk of death was 21.67 for comatose patients with a value below threshold. CONCLUSIONS: The ratio in HUs of GM to WM provides a reproducible measure of the distinction between gray and white matter. A lower GM/WM ratio is observed in comatose patients immediately after cardiac arrest. The basal ganglia level seems to be the most sensitive location on CT for measuring this relationship. Although a GM/WM ratio <1.18 at this level predicted death in this retrospective study, the difference in this study is not robust enough to recommend that management decisions be dictated by CT results. The results, however, do warrant consideration of a prospective study to determine the reliability of CT scanning in predicting outcome for comatose patients after cardiac arrest. (+info)
Therapy against brain swelling in stroke patients. A retrospective clinical study on 227 patients.
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The effectiveness of cerebral antiedema agents in stroke has been questioned. Animal and clinical work is inconclusive about steroids and osmotic drugs. A retrospective study of a continuous series of 227 stroke patients treated in the acute stage (some with dexamethasone alone, some with dexamethasone plus hyperosmotic mannitol infusions, and some without antiedema therapy) showed no significant difference in the ten-day survival rate. On this criterion, there is no ground for the systematic use of such agents against this type of brain swelling. (+info)