What is Cushing’s Disease?
Cushing’s disease is a debilitating endocrine disorder that is the result of excessive levels of cortisol—a steroid hormone produced by the adrenal glands—in your blood. Abnormally high levels of cortisol in the blood can be caused by tumors of the pituitary gland, adrenal glands, or cancer arising elsewhere in the body (adrenocorticotropic hormone or ACTH-producing tumors). However, Cushing’s disease refers specifically to excessive ACTH secretion caused by a type of benign pituitary tumor called a pituitary adenoma.
Cushing’s Disease Symptoms
|Common Symptoms||Less Common Symptoms|
|High blood pressure||Recurrent infection|
|Poor short-term memory||Thin skin and stretch marks|
|Excess hair growth (women)||Depression|
|Red, ruddy face||Weak bones|
|Extra fat around neck||Acne|
|Round face||Balding (women)|
|Fatigue||Hip and shoulder weakness|
|Poor concentration||Swelling of feet/legs|
|Menstrual irregularity||Diabetes mellitus|
Cushing’s Disease Treatments
Surgery is the best form of Cushing’s Disease treatment and the only cure. Your surgeon will gain access to your pituitary gland using the transsphenoidal approach—so named because the route crosses, or transects, your sphenoid bone. This bone is located behind your nose mostly within your skull.
Using precise surgical instruments, your surgeon will make an incision through your nasal cavity to create an opening in your sphenoid bone. Once your surgeon gains access to your sphenoid sinus (the air-filled area behind the sphenoid bone), further incisions will be made until a hole is created in the sella turcica—the bone that cradles and protects your pituitary gland.
After your pituitary gland and its associated tumor are in the operative field, removal of the tumor can proceed. Your surgeon will use high magnification to readily distinguish normal pituitary tissue from the adenoma.
Once the tumor has been removed, your surgeon will clean and seal the tumor cavity. At Barrow Neurological institute at Dignity Health St. Joseph’s Hospital and Medical Center, our surgeons specialize in two types of surgery for pituitary tumors:
- Microsurgery uses a powerful operating microscope to help your surgeon distinguish between tiny structures in and around your pituitary gland.
- Endoscopic surgery uses small tubes and a tiny camera to help your surgeon remove your tumor in small pieces.
Both surgeries aim to minimize trauma to the tissue surrounding your pituitary gland while facilitating a speedy recovery with as little pain or discomfort as possible. Each technique has its own inherent advantages and disadvantages, and your surgeons will work with you to help determine which is the best fit for you.
Most patients are able to return home the day after surgery for removing a pituitary tumor, and nasal packing is seldom required.
Gamma Knife radiosurgery is a highly advanced form of radiotherapy that is used to achieve similar results to the traditional surgical techniques described above.
The ‘knife’ in this surgery is actually made up of many small beams of radiation focused on a single point. Each individual beam is too weak to damage healthy tissue, but at the point where the beams converge they deliver a dose of radiation that is lethal to the tumor.
Gamma Knife is an outpatient procedure, does not involve any incisions, and requires only brief sedation under general anesthetic.
Surgery does not always cure Cushing’s disease. In the event your disease does not go into remission after surgical removal of your pituitary adenoma, there are several medical options for controlling surgery-resistant Cushing’s disease.
- Ketoconazole is a prescription antifungal agent that has also shown the ability to lower cortisol levels in the blood.
- Mitotane is an anti-neoplastic agent, meaning it is used to shrink or slow the growth of tumors. It is also effective for lowering cortisol levels in the blood. Careful monitoring by your doctor will be necessary if you are prescribed mitotane because of the possiblity of serious side effects relating to the regulation of cortisol levels in your blood. If you take mitotane continuously for more than 2 years, your doctor will schedule regular neurological evaluations, because the drug can cause neurological damage when taken long term.
- Metyrapone inhibits the ability of your body to make cortisol. Each of these medications has different side effects and indications, and your pituitary specialists will determine which might work best for you.
Cushing’s Syndrome versus Cushing’s Disease
Cushing’s syndrome generally refers to increased cortisol levels in your blood. Cushing’s disease is more specific and describes increased blood cortisol levels caused by a pituitary adenoma.
How is Cushing’s disease diagnosed?
Diagnosis of Cushing’s disease usually involves three methods: hormonal diagnosis, inferior petrosal sinus sampling, and imaging studies.
- Hormonal diagnosis is used to confirm abnormally high levels of cortisol. It is noninvasive and usually involves urine collection or a blood test.
- Inferior petrosal sinus sampling uses angiography and endocrinological tests to determine if the excess cortisol in your blood is caused by pituitary adenoma (confirming a diagnosis of Cushing’s disease) or by an ACTH-producing tumor elsewhere in your body. This test is only performed after hormonal diagnosis has confirmed high levels of cortisol in your blood.
- A pituitary magnetic resonance imaging (MRI) study will be performed to confirm the diagnosis. MRI is preferred over computed tomography (CT) because it detects adenomas that CT can miss.
How common is Cushing’s disease?
Cushing’s disease is rare. Just five to 25 cases occur per million people per year. It is most prevalent in adults between the ages of 20 and 50. Women account for 70 percent of cases. Although rare, there have been cases reported in children.