<unk>  or<unk> , from Greek roots, opistho meaning "behind" and tonos meaning "tension", is a state of a severe hyperextension and spasticity in which an individual's head, neck and spinal column enter into a complete "bridging" or "arching" position.  This abnormal posturing is an extrapyramidal effect and is caused by spasm of the axial muscles along the spinal column. It is seen in some cases of severe cerebral palsy and traumatic brain injury or as a result of the severe muscular spasms associated with tetanus.
Opisthotonus
Myoclonus
Lenticonus
Chorea
Dystonia
Hypotonia
Pseudoathetosis
Catatonia