Pituitary apoplexy

Definitions & Key takeaways

Pituitary apoplexy is a rare but serious condition that occurs when there is either severe bleeding or loss of blood flow to the pituitary gland, leading to acute dysfunction of the pituitary gland. It is a medical emergency and requires prompt diagnosis and treatment.

Symptoms of pituitary apoplexy include sudden onset of severe headache, vision changes, nausea and vomiting, loss of consciousness, and neurological symptoms such as weakness or numbness on one side of the body. Treatment involves medications to control the bleeding or inflammation, and surgery to remove the pituitary tumor, or in some cases, a portion of the skull to relieve pressure.

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Introduction0:00–0:23

With pituitary apoplexy, pituitary refers to a tiny gland at the base of the brain, and apoplexy refers to bleeding or loss of blood flow to an organ.
So, pituitary apoplexy is a disorder where there is either severe bleeding, or loss of blood flow to the pituitary gland, resulting in cell death and sudden loss of function.

Physiology0:23–2:46

Normally, the pituitary is a pea-sized gland, hanging by a stalk from the base of the brain. It sits just behind the eyes near the optic chiasm, which is where the optic nerves cross.
The anterior pituitary, which is the front of the pituitary gland, contains a few different types of cells, each of which secretes a different hormone.
The largest group of cells are the somatotropes which secrete growth hormone, which goes on to promote tissue and organ growth.
The second largest cell group are the corticotrophs which secrete adrenocorticotropic hormone, or ACTH, which stimulates the adrenal glands to secrete cortisol, a hormone that controls the stress response, blood pressure, and metabolic regulation.
A smaller cell group are the lactotrophs which secrete prolactin. Prolactin stimulates breast milk production, and also inhibits ovulation, which is when an egg cell is released from the ovary, and inhibits spermatogenesis, which is the development of sperm cells.
There are also thyrotrophs which are cells that secrete thyroid stimulating hormone, or TSH, that stimulate the thyroid gland.
And finally, there are the gonadotrophs which secrete two gonadotropic hormones - luteinizing hormone, or LH, and follicle-stimulating hormone, or FSH, both of which go on to stimulate the ovaries or testes.
The posterior pituitary, which is the back of the pituitary gland releases the antidiuretic hormone, or ADH, which is made by a part of the brain called hypothalamus.
ADH acts on the kidneys to decrease the amount of water lost in the urine. The pituitary gland gets blood through two arteries - the superior hypophyseal artery, which forms a part of the hypophyseal portal system, a web of capillaries linking the hypothalamus to the anterior pituitary, and the inferior hypophyseal artery, which supplies the posterior pituitary.
After delivering oxygen, the blood collects in small pituitary veins and eventually drain into the nearby venous sinuses, or spaces, of the brain.

Pituitary apoplexy caused by hemorrhage2:46–4:15

Pituitary apoplexy can develop as a result of hemorrhage or infarction. The more common way is a hemorrhage, or profuse bleeding, into the pituitary gland.
The hemorrhage is most often due to a pituitary adenoma, which is a benign tumor of the anterior pituitary gland. Larger tumors demand more blood, and increased blood flow means increased pressure in the vessels, eventually causing them to rupture.
The blood collects in the interstitium, or the space between the cells, which makes the pituitary gland swell up. An enlarged pituitary gland can compress surrounding structures like the meninges, which is the protective layer overlying the brain and that typically causes pain when it’s stretched.
Also, an enlarged pituitary gland can compress the optic nerves as they cross at the optic chiasm. This can affect a person’s ability to view things that are in the temporal, or the outermost portion, of the visual field in both eyes, also called “bitemporal hemianopia”.
Another name for this is tunnel vision because the center of your vision is clear but everything in the periphery is dark, kind of like looking through a tunnel.
Finally, the pool of blood can also put pressure on nearby blood vessels and pinch them shut, leaving the pituitary cells without oxygen.
Other causes of pituitary hemorrhage include brain surgery and trauma to the head. The second, and less common, way that pituitary apoplexy can develop is when there’s infarction of the pituitary gland.

Pituitary apoplexy caused by infarction4:15–4:57

An example would be Sheehan’s syndrome which is commonly associated with pregnant women. During pregnancy, there’s an increased demand for blood by the pituitary cells and coupled with excessive blood loss during childbirth, it leaves pituitary cells without adequate blood flow and they start to die.
If the blood flow isn't restored soon enough, more and more tissue dies, and over time, the pituitary gland shrinks and becomes scarred.
Irrespective of the underlying cause, pituitary apoplexy results in hypopituitarism, which is a deficiency of pituitary hormones.

Symptoms4:57–5:47

Immediate symptoms of pituitary apoplexy are usually due to the lack of adrenocorticotropic hormone and the deficiency of cortisol that cause symptoms like hypoglycemia, or low blood glucose, low blood pressure, and a loss of consciousness, which is a medical emergency.
Symptoms of deficiency of the other hormones have a more gradual onset. Deficiency of thyroid hormone causes weight gain and cold intolerance.
Deficiency of gonadotropin hormones can cause menstrual problem, low libido, and infertility. Low growth hormone can lead to fatigue and loss of muscle mass.
Finally, low prolactin level generally only causes symptoms in breastfeeding women who can have agalactorrhea, which is a decrease in breastmilk production.

Diagnosis5:47–6:11

Diagnosis of pituitary apoplexy involves imaging using a CT scan or MRI, which shows an enlarged pituitary gland with a hyperintense blood filled center.
Blood tests can be done to look for low levels of adrenocorticotropic hormone, thyroid stimulating hormone, luteinizing hormone, follicle-stimulating hormone, growth hormone, and prolactin.

Treatment6:11–6:36

Treatment for pituitary apoplexy requires emergency replacement of glucocorticoids to help maintain a person’s blood pressure and glucose levels.
Typically the person needs replacement of the deficient hormones for the rest of his life. Pituitary tumors with apoplexy may require a transsphenoidal surgical resection, which is when the tumor is removed through the nose and the sphenoidal sinus.
All right, as a quick recap, in pituitary apoplexy, cells in the pituitary gland die due to a hemorrhage, where the pituitary swells, or an infarction, where the pituitary shrinks.

Review6:36–6:58

Both cause hypopituitarism but a swelling pituitary can also cause a sudden headache, nausea, vomiting, and finally loss of consciousness.