Organophosphorus poisoning induced delayed neurotoxicity: a report of two cases

INTRODUCTION

Organophosphorus compounds (OPC) are one of the most commonly used pesticides worldwide and are often misused for suicidal poisoning due to their easy availability. Acute manifestations and management of organophosphorus (OP) poisoning have been reported several times. Organophosphorus-induced delayed neurotoxicity (OPIDN) is a rare delayed presentation of OP poisoning that involves central-peripheral distal axonopathy.

CASE PRESENTATION

In this study, we report two cases of OPIDN developed after a few weeks of OP poisoning. Clinical features, electrodiagnostic study findings, and rehabilitative measures adopted for the patients and their follow-up have been described in the report.

DISCUSSION

Organophosphorus (OP) poisoning may rarely produce features of delayed neurotoxicity, which may gradually appear after acute cholinergic symptoms. This report shows the importance of considering the delayed presentation of possible OPC toxicity in patients with neurological symptoms and a history of OPC exposure.

Delayed myelopathy in a child following organic phosphate poisoning

We report a rare manifestation of delayed organophosphate (OP) poisoning in a male patient in his early childhood. After initially presenting with a cholinergic crisis after OP exposure, the patient returned 3 weeks later with paraparesis and difficulty with bladder control. The results of the MRI of the spine and brain as well as the nerve conduction studies were normal. Myelopathy induced by OP poisoning should be considered in any patient with a history of OP exposure and a presentation of paraparesis. At most recent follow-up, the patient had full bladder control and could walk without assistance. However, he demonstrated circumduction while walking with upper motor neuron signs. Furthermore, he had mild Achilles tendon contractures on both sides. To enable early detection, neurologists and paediatricians should be aware of this uncommon complication of OP poisoning which may influence neurological outcome.

A Study of Organophosphorus Induced Delayed Myelopathy: Uncommon Sequelae of a Common Poisoning

Introduction

Organophosphorus (OP) compounds, with their lipophilicity, are responsible for a spectrum comprising of acute cholinergic symptoms, intermediate syndrome, as well as delayed neurological sequelae in the form of OP-induced delayed neuropathy and subsequently, myeloneuropathy with predominantly thoracic cord affection, manifested on partial recovery of the neuropathy. The pathogenesis of this myeloneuropathy in humans is still not well perceived.

Aim of Study

To determine the onset and course of development of delayed myeloneuropathy in patients of OP poisoning.

Materials and Methods

Twelve patients of OP ingestion presenting with delayed myeloneuropathy were evaluated with prior history, examination, MR imaging, nerve conduction and electromyography studies, and various evoked potentials to elicit the pattern of disease manifestation and progression.

Results

Among the included patients, a majority had consumed chlorpyrifos and permethrin composition, a majority had undergone gastric lavage. Five (41.7%) had experienced acute worsening and 8 (66.7%) patients had developed intermediate syndrome. OPIDN had appeared after a median of 4 (1-8) weeks after the poisoning. All patients had lower limb hypertonia with wasting and distal more than proximal weakness with pure motor or sensorimotor involvement. MRI showed thoracic cord atrophy in 3 (25%) patients. Motor-evoked potential with reduced amplitude was noted in lower limbs on lumbar stimulation but absent on cortical stimulation.

Conclusion

Various animal models have shown similar patterns of neurotoxicity in OP poisoning with predominant thoracic cord pathology. Further research in humans may be undertaken to elicit the pathogenesis, thereby improving the treatment modality.

Delayed myelopathy after organophosphate intoxication: A case report

Organophosphate-induced delayed neuropathy, a central-distal axonopathy, passes through latent, progressive, static and improvement phases. During the improvement phase, the peripheral nerves regenerate unmasking the spinal cord lesion with myelopathic features. We report a case of a 16-year-old male who developed myelopathy 6 weeks following chlorpyrifos poisoning. He had a motor weakness of 4/5 in bilateral hips and 3/5 in bilateral knees and ankles. Spasticity and exaggerated reflexes with ankle clonus were present in the lower limbs. Sensory and the upper limb motor examinations were all normal. Pertinent blood, cerebrospinal fluid and nerve conduction tests were normal. Magnetic resonance imaging of the spine showed features of cord atrophy. Three months following physiotherapy, his power improved to 5/5 in bilateral knee and hip joints and 4/5 in bilateral ankles with spasticity. Organophosphate-induced delayed neuropathy can present as earlier as 6 weeks with myelopathy. Previous history of organophosphorous exposure is important in myelopathy or peripheral neuropathy.