Systems involved include the cerebellodentatorubral, pyramidal, extrapyramidal, optic, auditory, posterior columns and gracile and cuneate nuclei, spinocerebellar tracts, motor neurons of cranial nerves and anterior horns, and muscle fibers. Palatal myoclonus is a regular, rhythmic contraction of one or both sides of the rear of the roof of the mouth, called the soft palate. These contractions may be accompanied by myoclonus in other muscles, including those in the face, tongue, throat, and diaphragm. The contractions are very rapid, occurring as often as 150 times a minute, and may persist during sleep. The condition usually appears in adults and can last indefinitely. People with palatal myoclonus usually regard it as a minor problem; some complain of an occasional "clicking" sound, a noise made as the soft palate muscles contract. Middle ear myoclonus occurs in the muscles of the middle ear. These muscles may include the tensor tympani and stapedius muscles. It can involve the muscles surrounding the Eustachian tube, which include the tensor veli palatini, levator veli palatini, and salpingopharyngeus. Those affected describe it as a thumping sound or sensation in the ear. Spinal myoclonus is myoclonus originating in the spinal cord, including segmental and propriospinal myoclonus. The latter is usually due to a thoracic generator producing truncal flexion jerk. It is often stimulus-induced with a delay due to the slow conducting propriospinal nerve fibers. Stimulus-sensitive myoclonus is triggered by a variety of external events, including noise, movement, and light. Surprise may increase the sensitivity of the patient.
Stimulant psychosis is a mental disorder characterized by psychotic symptoms (such as hallucinations, paranoid ideation, delusions, disorganized thinking, grossly disorganized behaviour) which involves and typically occurs following an overdose or several day binge on psychostimulants; however, it has also been reported to occur in approximately 0.1% of individuals, within the first several weeks after starting amphetamine or methylphenidate therapy. Methamphetamine psychosis, or long-term effects of stimulant use in the brain (at the molecular level), depend upon genetics and may persist for some time.The most common causative agents are substituted amphetamines, including substituted cathinones, as well as certain dopamine reuptake inhibitors such as cocaine and phenidates. Signs and symptoms
The symptoms of stimulant psychosis vary depending on the drug ingested, but generally involve the symptoms of organic psychosis such as hallucinations, delusions, or paranoia. Other symptoms may include mania, erratic behavior, agitation and/or aggression. Cause
Substituted amphetamines
Drugs in the class of amphetamines, or substituted amphetamines, are known to induce "amphetamine psychosis" typically when chronically abused or used in high doses. In an Australian study of 309 active methamphetamine users, 18% had experienced a clinical level psychosis in the past year. Commonly abused amphetamines include methamphetamine, MDMA, 4-FA, as well as substituted cathinones like a-PVP, MDPV, and mephedrone, though a large number of other closely related compounds have been recently synthesized. Methylphenidate is sometimes incorrectly included in this class, although it is nonetheless still capable of producing stimulant psychosis.