My mother has developed neuroleptic malignant syndrome. what is it exactly?

A serious issue: This is a rare but serious problem which is usually related to taking medications for psychiatric treatment, or sometimes for Parkinson's disease. It causes fever, muscle rigidity, unstable blood pressure and other problems. The medication causing nms must be identified and discontinued. If you ever need anesthesia, be sure to tell the anesthesiologist if you've had this problem.

Dangerous reaction: Nms-a reaction by the body to certain drugs(anti-psych, typically) that may manifest as shivering, increased temperature, swings in blood pressure. The underlying theme appears to be blockade of Dopamine function, a naturally occurring substance. Mainstay of treatment-remove offending medication, hsopitaliztion if severe, future avoidance of this class of drugs.