Electroencephalogram Theta

Convulsions occurred within two hours following occupational exposure to aldrin, dieldrin and endrin (Hoogendam et al. 1962, 1965). After removal from exposure, seizures subsided and complete recovery was achieved in 1-3 days. Abnormal electroencephalograms (EEGs) were usually observed in endrin-poisoned workers, and sometimes occurred without any clinical symptoms. Predominately bilateral synchronous theta waves, and synchronous spike and wave complexes were seen (Hoogendam et al. 

The electroencephalographic effects of phencyclidine intoxication have been reported in a patient who was comatose, with nystagmus and waxy rigidity of the limbs (11). The electroencephalogram showed widespread sinusoidal theta rhythm, interrupted every few seconds by periodic slow-wave complexes, similar to that seen in deep ketamine anesthesia. 

Headache, drowsiness, and dizziness are common with niridazole (2,4,5). More severe neuropsychiatric symptoms are more frequent in patients with liver disease, especially those with portosystemic shunts, in whom the drug bypasses the liver (6). Symptoms in these cases include insomnia, anxiety, depression, confusion, hallucinations, and convulsions the reactions may prove fatal. The electroencephalogram can show slowed alpha rhythms, beta waves, and theta waves, as well as sharp wave and spike forms with niridazole (7). A single case of acute cortical necrosis was recorded in the much older literature, but was probably coincidental (SED-8, 691) (8). Agitation can occur in patients with abnormal liver function. 

Epileptiform convulsions and abnormal electroencep-halographic patterns have been found in studies of insecticide manufacturing workers suffering from intoxication by isodrin. Fourteen patients with convulsions caused by the insecticide all showed specific anomalies in the electroencephalogram, consisting of bilateral synchronous theta wave activity and occasional bilateral synchronous spike and wave complexes believed to be associated with brain stem injury. 

Basal forebrain innervation appears prominent in maintaining theta rhythm in the hippocampus, contributing to arousal-associated cortical electroencephalogram (EEG) activity. The muscarinic antagonist scopolamine can block the cortical P-300 EEG arousal response elicited by novel stimuli. Ch5 and Ch6 also modulate behavioral arousal (Moruiai and Magoun, 1995 Kayamaef ai, 1992 Kayama and Koyama, 2003). 

One promising psychophysiological measure is electrical brain activity as measured by electroencephalogram (EEG). The EEG represents fluctuations in voltage recorded from the scalp that fall between 1 and 40 Hz. This frequency range is often subdivided into narrower bands named delta (1-3 Hz), theta (4-7 HzX alpha (8-13 Hz), and beta (13-20 Hz). 

Valproate may contribute to hyperammonemia by inhibiting carbamoylphosphate synthetase-I, the enzyme that begins the urea cycle. Phenobarbital may potentiate the toxic effect of valproate. The electroencephalogram in severe hyperammonemic encephalopathy exhibits continuous generalized slowing, a predominance of theta and delta waves, bursts of frontal intermittent rhythmic delta activity, and triphasic waves (Segura-Bruna et al., 2006). 

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