It is a rare extrapyramidal side effect of phenothiazines, haloperidol, and metoclopramide.Opisthotonus with the presence of the risus sardonicus is also a symptom of strychnine poisoning and prussic acid (hydrogen cyanide) poisoning. Drowning and the "dinosaur death pose"
Opisthotonus is seen with drowning victims – called the "opisthotonic death pose". This pose is also common in complete dinosaur skeletal fossils and it has been suggested that this is due to the animal drowning or being immersed in water soon after death. Vivisection
Opisthotonus can be produced experimentally in animals by transection of the midbrain (between the superior colliculus and the inferior colliculus), which results in severing all the corticoreticular fibers.Severe "arching" (hyperextension) occurs due to stimulus by the anterior reticulospinal tract caused by the loss of the balancing inhibitory counter-stimulus of corticoreticular fibers, which normally act upon the pons reticular formation. Other causes
Opisthotonus is also described as a potential CNS symptom of heat stroke along with bizarre behavior, hallucinations, decerebrate rigidity, oculogyric crisis, and cerebellar dysfunction.Opisthotonus is a symptom of "lavender foal syndrome", a lethal genetic disorder in horses.Sir Rudolph Peters, in Oxford, introduced thiamine-deprived pigeons as a model for understanding how thiamine deficiency can lead to the pathological-physiological symptoms of beriberi. Indeed, feeding the pigeons upon polished rice leads to an easily recognizable behavior of head retraction, a condition called opisthotonos. If not treated, the animals died after a few days. Administration of thiamine at the stage of opisthotonos led to a complete cure within 30 minutes.
Triangular alopecia  is hair loss that may be congenital but usually appears in childhood as a focal patch of loss that may be complete or leaving fine vellus hairs behind. : 643  Affected individuals are typically entirely healthy. Hair restoration surgery using follicular unit transplantation has been a successful treatment modality for TTA

Presentation
Association with Other Conditions
TTA has been associated with several disorders, such as Phakomatosis pigmentovascularis. And a rare syndrome Setleis syndrome. It is inherited by the autosomal dominant trait and is characterized by cutis aplasia or atrophic skin at the temples, which is said to resemble forceps marks. There may also be a coarse facial appearance, anomalies of the eyelashes and eyebrows, and periorbital puffiness. Frequency
The suggested frequency for this condition in the general population is around 0.11%. The hair loss is non-progressive and does not expand beyond these areas. It is a non-inflammatory, non-scarring form of hair loss easily confused with alopecia areata. In one report, the condition was incorrectly believed by the parents to be induced by doctors inserting intravenous cannulas into scalp vessels during the neonatal period. The condition is permanent and the affected skin does not change later in life.Of the 53 reported cases of TTA, more than half (55.8%) were detected in childhood between the ages of 2 and 9 years, while 36.5% were detected at birth and only 3.8% (only two cases) in adulthood. See also
Alopecia
Skin lesion
List of cutaneous conditions


== References ==