Strychnos nux vomica: A Fatal Convulsant
By Avik Basu1 and Saikat Kumar Basu2
Guyana Journal, February 2012
Keywords: convulsion, alkaloid, clonic, tonic, opisthotonus
Convulsion is a sudden excessive and prolonged involuntary spasmodic contraction of the skeletal muscles (Asimov et al., 1966). It may be clonic or tonic in nature (Asimov et al., 1966). It is found to occur in neurological diseases like epilepsy (Bruni, 2004), Wolf-Hirschhorn syndrome (Bird & Tapscott, 2004) and meningeal leukemia (Aminoff, 2004). It may also occur in case of overdose of oral hypoglycemic drugs like sulfonylurea (Gardner et al., 2007).
Strychnos nux vomica seeds (commonly known as poison nut, Quaker buttons, Snake-wood, strychnine tree) contain an important alkaloid, strychnine that blocks the post-ganglionic receptors for the motor neurons arising from the ventral horn of spinal cord segments. It also opposes the inhibitory effect of the neurotransmitter glycine at the level of the spinal cord segment. This leads to the convulsive episodes in case of strychnine poisoning (Reddy, 2009).
Though convulsion may occur in toxic effects of other agents as well, viz., castor seed (Ricinus communis), Indian liquorice (Abrus precatorius), organophosphorus compounds and mushrooms (Amanita phalloides), yet strychnine poisoning stands out as a prominent cause because in this case, it is the convulsion that acts as the sole reason for death of the person (Reddy, 2009).
Signs and Symptoms of Strychnine Poisoning
Ingestion of crushed seeds of Strychnos nux vomica leads to the characteristic clinical features of strychnine poisoning (Reddy, 2009). Initial prodromal symptoms like dysphagia, nausea and uneasiness are followed by muscle twitching and rigidity (Karmakar, 2007). This is almost immediately replaced by severe clonic-tonic convulsive attacks involving almost all the skeletal muscles of the body simultaneously (a contrasting feature from tetanic convulsions) (Reddy, 2009). The person assumes an opisthotonic posture owing to involvement of the anti-gravity muscles (Karmakar, 2007). Spasm of risorius muscle of the face leads to the characteristic Satan's face (Risus sardonicus) (Karmakar, 2007). The person is exhausted and shows cyanosis and labored breathing during the period of attack (Reddy, 2009). However, the convulsive phase may be paused for a while (differing from tetanic convulsions) when the person feels better but only to be resumed spontaneously or in response to mild stimulus, i.e., touching the person (Reddy, 2009). Death may result from respiratory failure due to paralysis of respiratory centre in the brain stem (Karmakar, 2007).
Treatment of Strychnine Poisoning
The treatment regimen is as follows:
1Medical College Kolkata, WB India
2School of Agriculture & Life Sciences, CAAS, Lethbridge College, Lethbridge, AB, Canada; Email