Use of
Gamma Knife technology for pituitary adenoma

The pituitary gland produces hormones and is located in the middle of the skull base.

Most pituitary tumors are adenomas (pituitary adenoma). An adenoma is a benign tumor – in this case affecting the pituitary gland. 70% of these are hormone inactive pituitary adenomas and around 30% produce their own hormones, known as hormone active pituitary adenomas. Like other benign tumors they normally do not metastasize.

Growth of tumors causes problems

Symptoms include:

• Headache
• Hormonal imbalances
• Tiredness
• Restricted field of vision
• Impaired vision up to blindness
• Hydrocephalus (water on the brain)

Pituitary gland dysfunction or hormone deficiency

A tumor can also impair the function of the pituitary gland itself. An incipient hormone deficiency is detected in 85% of patients. This involves pituitary insufficiency that can produce the following symptoms:

• Feeling of weakness
• Tiredness
• Weight loss
• Anemia (insufficient red blood cells)
• Menstrual disorders in women or loss of libido in men

Hormone overproduction

A pituitary adenoma may cause overproduction of certain hormones. This may also lead to acromegalia (uncontrolled secretion of growth hormones), Cushing syndrome (overproduction of cortisol), or prolactinoma (overproduction of prolactin). Possible symptoms include:

• Weight gain
• Growth of hands and feet
• Enlarged head circumference
• Menstrual disorders in women or loss of libido in men
• Psychological symptoms

Diagnosis

It is first important to clarify exactly what symptoms your existing physician has already diagnosed. Often an endocrinologist will first measure your hormone levels. An MRI scan should also be performed.

During the subsequent diagnosis, the adenoma is classified according to size: A macroadenoma is a tumor larger than 1 cm in diameter. Around half of macroadenomas lead to vision impairment. An opthalmologic examination is a must with a macroadenoma. Macroadenomas pushed up against the optic tract will impair vision and can even result in blindness if left untreated.

Treatments

Displacing tumors normally require surgery to relieve the pressure from the surrounding structures. Only in very rare instances does drug therapy cause tumors to shrink. Where the patient’s vision is affected, it constitutes a medical emergency that can cause blindness if left untreated. An experienced neurosurgery department is always the first port of call whenever vision is impaired. In all other cases, an endocrinologist diagnoses and treats pituitary adenomas wherever possible.

Asymptomatic pituitary tumors that do not produce hormones or damage surrounding structures can be initially monitored. Where tumor growth is detected, surgery is the method of choice. The tumor is usually removed with transsphenoidal surgery, i.e. through the nose. Neuronavigation, a computer-assisted surgical procedure makes this kind of operation safer.

Even though the pituitary tumor has already been surgically removed, you are diagnosed with a recurrent tumor – meaning the pituitary adenoma has returned? Or a follow-up examination found that you still have a residual tumor after the operation?

In both cases radiosurgical treatment with the Gamma Knife is the best solution for you. The therapy offers numerous advantages over conventional surgery for you as a patient:

Aim of treatment with the Gamma Knife

The aim of any radiosurgery with the Gamma Knife is to prevent the tumor from growing further. This goal is achieved in over 90% of cases with a single treatment.

With hormone active pituitary adenomas a secondary aim is to normalize raised hormone production. Statistically this is achieved in almost 70% of cases with Cushing syndrome patients. For patients with prolactinoma in approx. 60% of cases and for patients with acromegalia in around half of all cases. Side effects (impaired vision, double vision, etc.) are reported in less than 3–5% of cases. Around 10% of cases see hormonal levels worsen.

Radiosurgery is always possible if the remaining or recurrent tumor is far enough away from the optic system, is well delineated from the surrounding structures, and does not exceed a certain size. If a tumor extends into the optic system (optic nerve), you can also treat it with the Gamma Knife with a hypofractionated (several doses spread over 5–7 days) regimen.

Necessary aftercare following radiosurgery includes MRI checkups every six to 12 months initially. Every three months an endocrinologist should check your hormone levels. An ophthalmologist should check your visual acuity and visual field every six months. Aftercare following radiosurgery and following surgery aims to detect a potential tumor recurrence or a hormonal impairment early on. Subsequent side effects should be ruled out after radiosurgery and also after conventional radiotherapy. This will require lifelong aftercare. There is no need for rehabilitation after radiosurgery.