Amnesia

Ethanol is classified for medical purposes as a central nervous system (CNS) depressant. Its effects—that is, being drunk—resemble the human response to anesthetics. There is an initial excitability and increase in sociable behavior, but this results from depression of inhibition rather than from stimulation. At a blood alcohol concentration of 0.1% to 0.3%, motor coordination is affected, accompanied by loss of balance, slurred speech, and amnesia. When blood alcohol concentration rises to 0.3% to 0.4%, nausea and loss of consciousness occur. Above 0.6%, spontaneous respiration and cardiovascular regulation are affected, ultimately leading to death. The LD50 of ethanol is 10.6 g/kg (Chapter 1 Focus On). 

Often referred to as short-term memory loss , this form of amnesia results in the inability to transfer new events to long term memory. The sufferer will still be able to recall older memories but will not be able to remember recent events once attention has been switched to something else. 

The definition of desired therapeutic and side effects in the case of the benzodiazepines very much depends on the clinical problem in question. The sedative and hypnotic actions are desired effects in the treatment of insomnia, but undesired effects in the treatment of anxiety disorders. Effects that are usually undesired include daytime drowsiness, potentiation of the sedative effects of ethanol, and anterograde amnesia. They are mediated via the benzodiazepine site of GABAa receptors, since they can be antagonized with flumazenil. 

Dissociative anesthetic is a term applied to phencyclidine and ketamine which induce a peculiar subjective state of dissociation from the environment, together with sedation, immobility, amnesia, analgesia, and ultimately coma. 

Neurological signs nystagmus, miosis, blurred vision, tremor, slurred speech, dystonia, convulsion, amnesia, confusion, peripheral numbness... 

Miotto and colleagues (2001) surveyed 42 recreational users of GHB and found that 66% reported episodes of unpredictable loss of consciousness and 26% had overdosed. Forty-five percent of daily users had experienced frequent amnesia during or after use of the drug, suggestive of blackouts typically attributed to severe alcohol abuse. The rate of adverse events was greater... 

Although the evidence base for this relatively rare disorder is not well developed, patients who are dependent on GHB appear to benefit from cognitive and motivational psychosocial therapies and from support of recovery in a manner similar to alcohol-dependent patients. However, because of the high likelihood of amnesia and cognitive dysfunction during the acute and subacute phases of GHB withdrawal, psychosocial interventions should, when possible, include significant others who can review and reinforce with the patient the negative consequences of GHB dependence. 

At low doses, ketamine may result in impairment of attention, learning ability, and memory, and at high doses it has been associated with delirium, amnesia, impaired motor function, hypertension, depression, and respiratory depression (Krystal et al. 1994). Another mechanism of action appears to be a blocking of the reuptake of catecholamines. This effect leads to an increase in heart rate and blood pressure (Reich and Silvay 1989). 

FIGURE 31.15 Variation of percent heat shrinkage and amnesia rating with radiation doses of low-density polyethylene/ethylene-vinyl acetate (LDPE/EVA) film from 50 50 blend without ditrimethylol propane tetra-crylate (DTMPTA). (From Chattopadhyay, S., Chaki, T.K., and Bhowmick, A.K., Radiat. Phys. Chem., 59, 501, 2000. With permission.)... 

It has been known for many years that antimuscarinic drugs like hyoscine, which enter the brain, cause amnesia when used clinically, e.g. pre-operatively, to reduce bronchial secretions. In experimental studies in both humans and animals they disrupt both the acquisition and the performance of learned behaviour. Anti-cholinestrase drugs have the opposite effect. It is by no means certain, however, that the memory defects induced by antimuscarinics are identical to those seen in AzD. 

Lorazepam (Ativan) 0.5-2 mg prior to chemotherapy Most common Sedation, amnesia Rare Respiratory depression, ataxia, blurred vision, hallucinations, paradoxical reactions (weeping, emotional reactions)... 

Benzodiazepines, especially lorazepam, are used to prevent and treat CINV.5,10 Lorazepam is thought to prevent input from the cerebral cortex and limbic system from reaching the central vomiting center in the brain stem.10 Sedation and amnesia are common side effects. Respiratory depression can occur with high doses or when other central depressants such as alcohol are combined with benzodiazepines. 

At blood levels of 0.02 g%-0.09 g% (4.34 to 19.5 mmol/L) may see some prolonged reaction time and muscular incoordination At blood levels from 0.1 g%-0.2g% (21.7 to 43.4 mmol/L) may see obvious prolonged reaction time, obvious incoordination and ataxia, and mental impairment At blood levels from 0.2 g% to 0.3g% (43.4 to 65.1 mmol/L) marked ataxia, some dysarthria, and possible nausea and vomiting At blood levels from 0.3 g% to 0.4g% (61.5 to 86.8 mmol/L) severe dysarthria, amnesia, and hypothermia... 

Inquire about carryover sedation and anterograde amnesia from therapy. 

Anterograde amnesia A condition in which events that occurred after the onset of amnesia cannot be recalled and new memories cannot be formed. 

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