Monomelic Amyotrophy after Permethrin Poisoning: A Case Study

Monomelic amyotrophy (MMA) known as Hirayama disease (HD). The first report appeared in 1959 when Hirayama described 12 patients [1] then, a large group of patients was found from Japan [2,3]. MMA from South India was also reported in 1984 [4]. The disease accounted for males over 80% of cases, especially between 15 and 25 years of age. The disorder has been recognized as, unilateral or bilateral asymmetric atrophy of hand and forearm with sparing of brachioradialis giving the characteristic appearance of oblique amyotrophy. Symmetrically bilateral disease has also been recognized. It is believed to be a cervical flexion myelopathy [5].

Pyrethroids are used as insecticides due to their high potency. These are highly toxic to a wide range of insects but have low toxicity to humans. Pyrethroids are known to cause neurotoxicity in humans like seizures, tremors, and dizziness. Motor neuron damage has been reported in acute toxicity due to ingestion of pyrethroids and organochlorines [6] and MND (Motor neuron disease) like features after chronic exposure has been reported [7]. Here a case of monomelic amyotrophy following massive ingestion of permethrin, amytriptyline and benzodiazepine tablets is reported.