Seizure-like activity caused

Patients with epilepsy may have completely normal findings in these assessments. Many of the tests are done to rule out other causes of seizures (e.g., infection or electrolyte imbalance). Often the EEG appears normal between seizures.20 Several manipulations can be done in an attempt to capture seizure or seizure-like activity on the EEG. These include sleep deprivation, photic stimulation, prolonged (greater than 20 minutes) EEG recording, and 24-hour EEG monitoring with video correlation. 

Onset of anaesthesia is as rapid though not as smooth as after thiopentone administration, but recovery is more rapid with methohexitone and occurs within 2-5 minutes through redistribution. Drowsiness persists for much longer as the drug is slowly metabolised in the liver. While methohexitone has been reported to cause occasional EEG seizure-like activity in epileptics the drug also possesses anticonvulsant properties. 

C. Baclofen overdose causes coma, respiratory depression, occasional bradycardia, and paradoxical seizure-like activity. Onset is rapid but may last 12-48... 

In the 1960s GHB was developed as an anesthetic s ent. Like PGP, it had serious side effects (seizure-like activity) and its use y/as discontinued. In the 1980s GHB was sold in the health food industry as a growth hormone stimulator and was supposed to help body builders gain muscle mass. It was also sold as a sleep aid. It became a popular recreational drug because in low doses it can have an aphrodisiac effect as well as cause relaxation and euphoria. However, at higher doses it causes coma and amnesia. These effects made it effective as a date rape ... 

Fenvalerate has low toxicity in mammals due to its rapid metabolic breakdown. It acts directly on nerve axons by prolonging sodium channel opening in cell membranes. Insects exposed to fenvalerate are quickly paralyzed exposure causes quick insect knockdown. In small animals, type II pyrethroids cause salivation, chewing, burrowing, choreoathetosis, and seizures. They also cause lower action potential amplitude, marked membrane depolarization, and eventual total neural activity blockade. Fenvalerate is likely to act both on peripheral and central nervous system. It is also a potent inhibitor of calcineurin (protein phosphatase 2B). 

Meropenem (Merrem IV) is a dimethylcarbamoyl pyro-lidinyl derivative of thienamycin. It does not require coadministration with cilastatin because it is not sensitive to renal dipeptidase. Its toxicity is similar to that of imipenem except that it may be less likely to cause seizures (0.5% of meropenem- and 1.5% of imipenem-treated patients seized). Its in vitro activity is similar to that of imipenem, with activity against some imipenem-resistant P. aeruginosa but less activity against Gram-positive cocci. Chnical experience with meropenem demonstrates therapeutic equivalence with imipenem. 

The tricyclics also have antimuscarinic (sometimes referred to as anticholinergic or atropine-like) activity and can cause dry mouth, blurred vision, constipation, urinary retention and an increase in ocular pressure. Postural hypotension and cardiotoxic effects may also occur, but they are less frequent. CNS adverse effects include sedation, the precipitation of seizures in certain individuals, and extrapyramidal reactions. 

All such animal procedures suffer from the obvious and basic problem that laboratory animals do not behave like humans and that humans cannot reliably interpret their reactions and behaviour. Thus we know that Parkinson s disease is caused by a degeneration of the dopaminergic nigrostriatal tract but its lesion in animals does not produce any condition which resembles human Parkinsonism, except in primates, even though there are functional tests (e.g. rotational movements) which readily establish that loss of dopamine function and also respond to its augmentation (Chapter 15). By contrast, there are many ways, e.g. electrical stimulation and the administration of certain chemicals, to induce convulsions in animals and a number of effective antiepileptic drugs have been introduced as a result of their ability to control such activity. Indeed there are some tests, as well as animals with varied spontaneous seizures, that are even predictive of particular forms of epilepsy. But then convulsions are a very basic form of activity common to most species and epileptic seizures that are characterised by behavioural rather than motor symptoms are more difficult to reproduce in animals. 

Tricyclic antidepressants resemble the phenothiazine antipsychotics such as chlorpromazine in structure and function. Like the phenothiazine derivatives (e.g., chlorpromazine), tricyclic antidepressants (e.g., amitriptyline) may reduce the seizure threshold and precipitate seizures in epileptic patients, cause cholestatic jaundice, movement disorders, and hematologic side effects. Unlike the phenothiazine derivatives, the tricyclic antidepressants may increase motor activity, have a very slow onset and long duration of action, a relatively narrow margin of safety, and a strong anticholinergic effect. In fact, dry mouth is the most common side effect, and other anticholinergic effects such as tachycardia, loss of accommodation, constipation, urinary retention, and paralytic ileus have been reported following amitriptyline. 

Overdosage with trimipramine causes CNS stimulation followed by CNS depression. The first 12 hours after acute ingestion are a stimulatory phase characterized by excessive anticholinergic activity (agitation, irritation, confusion, hallucinations, parkinsonian symptoms, seizure, urinary retention, dry mucous membranes, pupillary dilatation, constipation, and ileus). This is followed by CNS depressant effects, including hypothermia, decreased or absent reflexes, sedation, hypotension, cyanosis, and cardiac irregularities (including tachycardia, conduction disturbances, and quinidine-like effects on the ECG). 

Physostigmine has the potential for induction of seizure activity. In addition, the increase in cholinergic activity does not significantly affect the bradycardia caused by the quinidine-like effects of tricyclics. 

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