rhizotomy: surgical procedure in which spinal nerve roots are cut; done (anterior roots) to relieve intractable pain or (posterior roots) to stop severe muscle spasms
operation: a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body
hydrogen cyanide: a highly poisonous gas or volatile liquid that smells like bitter almonds; becomes a gas at around 90 degree Fahrenheit and is most dangerous when inhaled; the anhydride of hydrocyanic acid; used in manufacturing