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In the acute phase of organophosphate poisoning, low serum acetylcholinesterase (> 50% of minimum normal value) supports the diagnosis of organophosphate poisoning but it does not show a significant relationship to the severity of poisoning (NS). The serum acetylcholinesterase activity may be a useful parameter in following the acute prognosis of organophosphate poisoning.

Essential tremor (ET) is classified as a pure motor system disease. It has been previously reported that impairments in cognitive functions can be associated with ET. The authors assessed cognitive functions in a relatively young patient group with ET and comparison subjects. Correlations between tremor severity and regional cerebral blood flow (rCBF) and neuropsychological test performances of ET patients and comparison subjects were investigated. Sixteen patients with ET and 16 comparison subjects were assessed by a comprehensive neuropsychological test battery designed to assess global attention, language, memory, visuospatial functions, and executive functions. In 11 of 16 patients and in nine of 16 comparison subjects, rCBF was measured by technetium-99m-hexamethyl propylene amine oxime single photon emission computed tomography (technetium-99m-HMPAO SPECT). The tremor severity was quantified using the Clinical Rating Scale for Tremor (CRST). Findings revealed that ET patients differed significantly from comparison subjects on tests assessing visuospatial functions and verbal memory, whereas differences in other tests did not reach statistical significance. There was no significant difference between the rCBF of ET patients and comparison subjects. There were statistically significant inverse correlations between tremor severity and executive functions. Tremor severity was inversely correlated with bilateral frontal blood flow by technetium-99m-HMPAO SPECT. Conclusions suggest that the subclinical cognitive deficits characterized by visuospatial and verbal memory impairments and executive dysfunction may be a clinical feature of ET, and the cerebello-thalamo-frontal network may play a role in the pathophysiology of this disorder.

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The aim of this study was to determine the effects of haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) on P300 cognitive potentials in patients with chronic renal failure (CRF) and to find out if P300 potential is a valuable marker for following subclinical cognitive disorder.This study was performed in 42 patients with chronic uraemia, of whom 25 were on HD and 17 on CAPD, and in 25 healthy subjects. All the subjects were investigated in terms of P300 cognitive potential obtained from auditory stimuli with the oddball paradigm and the Mini-Mental State (MMS) examination. Patients undergoing HD were evaluated before (pre-dialysis) and after (post-dialysis) standard HD treatment. P300 latency was longer in HD patients than in the control group and CAPD patients. The MMS score was greater and P300 latency was shorter after a standard HD session when compared to pre-dialysis values in HD patients (p < 0.001 for both values). There was a negative correlation between P300 latency and MMS scores, and a positive correlation between P300 amplitude and MMS scores.In conclusion, P300 is useful for evaluating cognitive function in uraemia, even in asymptomatic patients, and CAPD is superior to HD in the management of cognitive impairment.