"Intermediate" syndrome with loss of muscle power is associated with poisoning due to?

Intermediate Syndrome * Intermediate syndrome is a neurotoxic effect that appears after acute cholinergic crisis but before the expected onset of delayed neuropathy. * The cardinal feature of the syndrome is muscular weakness, affecting predominantly the proximal limb muscles and the neck flexors. Cranial nerve palsies are common. (The intermediate syndrome predominantly affect muscles innervated by the cranial nerves -- neck flexors, proximal muscles of the limb and the muscles of respiration). * This syndrome carries a risk of death because of the associated respiratory depression. * The muscle weakness had an acute onset, noticed within 24 to 96 hours after poisoning. REF;THE SYNOPSIS OF FORENSIC MEDICINE:KS NARAYANA REDDY;28th EDITION;PAGE NO 292