A person displaying decorticate posturing in response to pain gets a score of three in the motor section of the Glasgow Coma Scale, caused by the flexion of muscles due to the neuro-muscular response to the trauma.There are two parts to decorticate posturing. The first is the disinhibition of the red nucleus with facilitation of the rubrospinal tract. The rubrospinal tract facilitates motor neurons in the cervical spinal cord supplying the flexor muscles of the upper extremities. The rubrospinal tract and medullary reticulospinal tract biased flexion outweighs the medial and lateral vestibulospinal and pontine reticulospinal tract biased extension in the upper extremities. The second component of decorticate posturing is the disruption of the lateral corticospinal tract which facilitates motor neurons in the lower spinal cord supplying flexor muscles of the lower extremities. Since the corticospinal tract is interrupted, the pontine reticulospinal and the medial and lateral vestibulospinal biased extension tracts greatly overwhelm the medullary reticulospinal biased flexion tract.The effects on these two tracts (corticospinal and rubrospinal) by lesions above the red nucleus is what leads to the characteristic flexion posturing of the upper extremities and extensor posturing of the lower extremities.Decorticate posturing indicates that there may be damage to areas including the cerebral hemispheres, the internal capsule, and the thalamus. It may also indicate damage to the midbrain.
This clinical situation is known as Nelsons syndrome. Epidemiology
Cushings syndrome caused by treatment with corticosteroids is the most common form. Cushings disease is rare; a Danish study found an incidence of less than one case per million people per year. However, asymptomatic microadenomas (less than 10 mm in size) of the pituitary are found in about one in six individuals.People with Cushings syndrome have increased morbidity and mortality as compared to the general population. The most common cause of mortality in Cushings syndrome is cardiovascular events. People with Cushings syndrome have nearly 4 times increased cardiovascular mortality as compared to the general population.About 0.9 to 1% of those with Cushings syndrome has tendency to develop venous thrombosis. Other factors such as surgery and obesity also increases the chance of getting thrombosis. Other animals
For more information on the form in horses, see pituitary pars intermedia dysfunction. See also
Addisons disease
Adrenal insufficiency (hypocortisolism)
Corticosteroid-induced lipodystrophy

References
External links
"Cushings Syndrome". MedlinePlus. U.S. National Library of Medicine.