Following brain injury, changes to endocrine function (the release of hormones and maintenance of appropriate levels of hormones within the body) may occur. This can arise as a result of damage to the pituitary gland which is situated at the base of the brain.
How does pituitary injury occur?
- Traumatic brain injury (TBI) typically results in shearing forces being applied to the brain arising from movement within the skull.
- Areas of the brain lying on the base of the skull are particularly vulnerable to traumatic injury, as bony ridges restrict movement, adding to the shearing effect.
- The pituitary gland lies within a bony cavity, the pituitary fossa, and thus is particularly vulnerable to injury.
- It has been estimated that up to 25% of patients with TBI have a deficit of at least one pituitary hormone, and that up to 5-10% of patients are deficient in more than one hormone.
- These estimations are based on patients with more severe patterns of injury. Prevalence across all severity groups is probably lower.
- Pituitary impairment may present relatively late after injury, and the recommended time for screening is at 3 months post injury, with some centres recommending screening at 12 months post injury also.
- Risk appears to be higher in patients with:
- Diffuse Axonal Injury.
- Basal skull fracture.
- Age over 40 years
- Subarachnoid haemorrhage, secondary to aneurysm rupture, is also associated with a risk of hypopituitarism. This appears to be related to proximity of Circle of Willis to the pituitary stalk. Screening blood tests are also recommended for this patient group.
What is the Pituitary Gland?
What are the Clinical Features of Pituitary Gland Injury?
Why Screen for Pituitary Deficiency?