LATE NEUROLOGICAL SEQUELS AFTER ACUTE POISONING WITH DIMETHOATE

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LATE NEUROLOGICAL SEQUELS AFTER ACUTE POISONING
WITH DIMETHOATE

• Niko Bekarovski, B. Pavlovski, N.Popovski,
  I.Jurukov
• Clinic of Toxicology and Urgent Internal Medicine
  Clinic Center - Skopje,
• Republic of Macedonia

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INTRODUCTION

• There are large number of studies describing
  acute neurological effects after acute
  organophosphate poisoning, but there are only a
  limited number of studies describing the chronic
  neurological effects, after acute organophosphate
  poisoning.

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AIM OF THE STUDY

• Aim of this study is to show a case with late
  neurological sequels, develop one year after
  acute poisoning with organophosphate pesticide
  Dimethoate
• ( Sistemin 40).

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CASE REPORT

• 63 year old male patient was admitted to the
  Clinic of Toxicology in Clinic Center Skopje,
  Republic of Macedonia, six hours after ingesting
  an unknown dose of the organophosphate Dimethoate
  in a suicide attempt. In the next few days
  developed bilateral hyporreflexia, positive
  Babinski, rigidity of all limbs, akinesia,
  tremor, that persisted even after total
  cardiopulmonary recovery (8th day) and
  normalization of plasma cholinesterase range
  (12th day).

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• Bradyphrenia, tremor and rigidity remained after
  two weeks of poisoning and therefore the
  diagnosis of Parkinsonism was suspected by
  neurologist, and treatment with Biperiden lactate
  (Akinetone) 2x5 mg. started I.V. After second
  injection, there was great improvement of all
  symptoms, especially on consciousness, mobility
  and speech. Four weeks latter, at 43rd day of
  poisoning, all signs disappeared and patient was
  discharge from the Clinic completely free of
  Parkinsonism. CT, EEG and EMG were normal.

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• One year later the patient was called to hospital
  and matched controls. We found a serious deficit
  in memory, decrease in vibrotactile sensitivity,
  as indicator for peripheral neuropathy, tremor
  and bilateral patellar hiporreflexia. EEG didn't
  show any pathological changes and EMG wasn't made
  because the patient didn't allow to make it.

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DISCUSSION

• Three large epidemiological studies have examined
  the chronic effects among patients poisoned by
  organophosphates. Savage et al studied 100
  patients, an average of nine years after
  poisoning. They found significant deficits among
  the cases on several cognitive tests of memory
  and abstraction but no differences on
  electroencephalography or neurological
  examination. Cases had worse reading ability than
  controls, and educational differences may have
  accounted for the results.

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• Rosenstock et al. and McConnell et al. studied 36
  men poisoned by organophosphates (mostly
  methamidaphos) who had been admitted two years
  earlier, as well as matched controls. They found
  several cognitive deficits in the poisoned
  subjects and a significant decrease in
  vibrotactile sensitivity, an indicator of
  peripheral neuropathy.

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• Finally, Steenland et al studied 128 men poisoned
  a mean of seven years earlier and 90 controls.
  Vibrotactile sensitivity and one cognitive test
  (sustained attention) were significantly worse in
  the poisoned men, and several tests showed
  deficits which increased with the severity of the
  poisoning. Nerve conduction tests and clinical
  neurological examination showed no differences

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• In summary, therefore, well-designed studies have
  shown chronic sub clinical damage to the central
  and peripheral nervous system among those
  previously poisoned by organophosphates. Studies
  of subjects with long-term low level exposures
  have been less consistent, but some have also
  shown sub clinical effects on the central and
  peripheral nervous system. Low response rates and
  possible selection biases have affected almost
  all studies but are unlikely to explain the
  observed effects indeed loss to follow up of
  more severely affected individuals may have
  caused some bias towards showing no effect

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• Differences between studies may be due to the
  different organophosphates. The observed
  peripheral effects are consistent with persistent
  delayed neuropathy induced by organophosphate.
  The mechanism by which chronic central nervous
  system effects might occur is unknown Duffy et
  al has observed persistent changes on
  electroencephalograms after high level exposure.

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• Clinical neurological examinations have given
  negative results in the subjects studied
  epidemiologically. The importance of the observed
  sub clinical effects on quality of life or day to
  day functioning may be minimal. The study
  subjects generally were not followed for long
  periods, and we do not know whether the observed
  sub clinical effects will diminish, persist, or
  get worse. This question is important in the
  light of the large number of people exposed and
  in the light of some case reports that suggest
  that more severe long term effects are possible.

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CONCLUSSION

• This case shown that all patients with acute
  organophosphate intoxication have to be
  monitoring few years after the poisoning,
  especially if there are any signs of neurological
  sequels during the acute phase.