Some movement disorders involve increased movement and are termed hyperkinetic movement disorders. Tics and tremors fit this category, as do akathisia, chorea, and myoclonus. Akathisia is an inner sense of restlessness, like an “ants in the pants” feeling. It may complicate levodopa treatment of PD or treatment of some psychiatric disorders by selective serotonin reuptake inhibitors (SSRIs), anti-seizure drugs, or neuroleptic drugs.
Chorea, or dyskinesia, is a slow (one or two beats per second), moderate amplitude, non-rhythmical, chaotic, dance-like, flowing movement involving the head and neck (separately or together), tongue, arms and legs. Chorea can occur in Huntington disease (an inherited disorder of the brain), in PD treatment with levodopa, during psychiatric treatment with neuroleptic drugs, during pregnancy, during treatment with phenytoin or
Dilantin (anti-seizure drugs), after strokes of the basal ganglia, in hypoglycemia (low blood sugar), hypothyroidism (overactive thyroid), liver failure, and in Wilson disease. Myoclonus is a contraction of a muscle or group of muscles lasting less than 0.3 seconds. Myoclonus can be of moderate to high amplitude, can involve a single part of the body (an arm or leg) called focal myoclonus, or can be a coordinated, synchronized rhythmical movement of an arm and a leg, both arms, both legs (called segmental myoclonus), or both arms and legs and the trunk (called generalized myoclonus). It can also result from a sudden relaxation of a group of muscles which causes the limb to suddenly jerk. This relaxation is called asterixis and may complicate liver failure.
Myoclonus can arise from an electrical discharge in the cortex (as part of an epileptic seizure), in the basal ganglia, and in the spinal cord. It can occur as a normal phenomenon as when you are falling asleep, waking up, or when you are startled. Hiccoughs are myoclonus of your diaphragm. Myoclonus may be triggered by a variety of stimuli including light, sound, and sudden fright. Like chorea, myoclonus can be caused by a variety of disorders, including Alzheimer’s disease, AIDS, Creutzfeldt-Jakob disease, brain damage in utero, and circulatory failure as in cardiac arrest. Nocturnal myoclonus, which occurs while you fall asleep or awaken from sleep, may be aggravated by levodopa in PD patients.