Opisthotonos

Definition:

An abnormal posturing characterized by rigidity and severe arching of the back, with the head thrown backwards such that if a person were laid on his or her back only the back of the head and the heels would touch the supporting surface.

Considerations:

Opisthotonos occurs frequently in meningitis in infants and is a sign of meningeal irritation. (The meninges are the membranes covering the brain and spinal cord.)

Opisthotonos is caused by spasm of the muscles along the spine. It is thought to be a protective reflex that reduces the pain of meningeal irritation by immobilizing the spine. it may also occur as a result of severe muscle spasm as seen in tetanus.

Opisthotonos is much more common in infants and children than in adults. It is also more exaggerated in infants and children. This is a reflection of the relative immaturity of their nervous system.

Common causes:

• meningitis (most common cause)
• Arnold-Chiari syndrome
• subarachnoid hemorrhage
• tetanus
• brain tumor
• severe head injury
• glutaric aciduria
• achondroplastic dwarfism (occasionally)

Drugs, particularly phenothiazines and other antipsychotic medications, can cause a side effect known as acute dystonic reaction; opisthotonos may be part of this reaction.

Note: There may be other causes of opisthotonos. This list is not all inclusive, and the causes are not presented in order of likelihood. Use the Symptom Analysis option to explore the possible explanations for opisthotonos, occurring alone or in combination with other problems.