Postsynaptic neuromuscular dysfunction in organophosphate induced intermediate syndrome.

Area of Science:

• Neurotoxicology
• Clinical Neurology
• Environmental Medicine

Background:

• Organophosphate (OP) compounds, like fenthion, are widely used pesticides.
• Acute cholinergic crisis from OP poisoning can lead to delayed neurological syndromes.
• Intermediate syndrome is a rare, distinct neurological complication following OP exposure.

Observation:

• A 65-year-old female experienced an intermediate syndrome 7 days post-fenthion ingestion and acute cholinergic crisis.
• Electromyography (EMG) demonstrated neuromuscular transmission abnormalities, specifically fade on tetanic stimulation.
• Muscle biopsy revealed mild rhabdomyolysis with weak cholinesterase staining.

Findings:

• Cholinesterase activity and serum fenthion levels were monitored serially.
• EMG findings of neuromuscular junction transmission defects were transient, resolving by day 19.
• The observed EMG pattern shares similarities with myasthenia gravis, indicating a postsynaptic defect.

Implications:

• The intermediate syndrome pathophysiology may involve postsynaptic desensitization and a restoring acetylcholine/acetylcholinesterase ratio.
• This case highlights the potential for delayed neurological complications from fenthion exposure.
• Understanding these mechanisms is crucial for managing OP pesticide poisoning and related neurological disorders.