ABSTRACT
Twitching is a non-specific term used to describe fine dyskinetic or abnormal involuntary movements. Tics, tremors and myoclonic jerks are included in the term 'twitching.' Twitching should be distinguished from the normal fasciculations of wasted muscles. Tics are repetitive stereotyped movements that can be held in check voluntarily, but the concentration required exhausts and stresses the patient. Myoclonic jerks are rapid shock-like muscle jerks, which are often repetitive and sometimes rhythmic. Opioids may cause myoclonic jerks. This normally only occurs for two reasons: the dose of opioid has been rapidly increased, or the patient's previously normal renal function has deteriorated, resulting in an accumulation of the metabolic products of opioids. A tremor is a rhythmic movement of a body part, caused by regular muscle contractions. Tremors can be of three types: intention tremor, postural tremor and resting tremor.
