PITUITARY GLAND TUMOURS AND SURGERY:
What is “the pituitary”?
“The pituitary” is a gland that produces several different types of hormones that have a major impact in our bodies. The pituitary gland is also referred to as the “master gland” because its hormones control the production and release of other hormones in different parts of our body that influences growth, metabolism, thyroid function, stress responses, pain relief, brain development, blood pressure, water and salt regulation by the kidneys, temperature control, reproduction, lactation (milk production) and aspects of child birth.
The pituitary gland is found at the base of the brain, known as the skull base, within a bony fossa that protrudes into the sphenoid sinus. Hence, the sphenoid sinus provides a direct route to surgically access the pituitary gland. The normal gland is small, about the size of a pea, and is connected to the base of the brain via the pituitary stalk. The gland has an extremely rich blood supply through delicate and minute blood vessels, whose patency is essential to the normal functioning gland.
Critical structures adjacent to the pituitary gland include the optic nerves and optic chiasm (provide vision) and the cavernous sinuses, which are blood-filled chambers on either side of the pituitary. The cavernous sinuses contain a few cranial nerves (3rd, 4th and 6th which control eye movement) and the major blood vessel supplying the brain, the internal carotid artery (ICA).
I have a pituitary tumour, what does that mean?
A pituitary tumor is a form of brain tumor, and generally refers to an abnormal growth within the pituitary gland.
In most instances, this growth represents abnormal pituitary gland tissue. Most pituitary tumours are benign (non-cancerous), also known as a pituitary adenoma. However, tumours from nearby structures or uncommonly, other parts of the body can spread to the pituitary gland.
Craniopharyngioma occurs less commonly and is another form of brain tumour that is derived from embryonic pituitary gland tissue. Craniopharyngiomas usually originate from the region of the pituitary stalk, hence, above the pituitary gland proper.
What symptoms and problems can I expect if I have a pituitary adenoma?
Not all pituitary adenomas cause symptoms. Some pituitary adenomas are found incidentally, for instance, if sinus and brain scans are done for other reasons. In this situation, a consultation with an endocrinologist and neurosurgeon will still be needed as well as baseline blood tests. If these findings are normal, then a “wait and see” approach may be undertaken.
The symptoms depend on the size and nature of the tumour. Several of these symptoms are non-specific (such as headache, fatigue and lethargy) and an initial consultation with your GP is vital to determine the underlying cause.
Larger tumours can cause pressure-associated symptoms as they impinge on adjacent structures. Small tumours can still cause significant and troublesome symptoms if they are hyperfunctioning and releasing too much of a particular hormone.
1. Pressure on surrounding structures. If the tumour is large (greater than 10 mm), referred to as a pituitary macroadenoma, then it can compress adjacent structures such as optic nerves, and less commonly, nerves that control eye movements. This can lead to varying degrees of visual loss, double vision and headache.
2. Pressure on the pituitary gland. Macroadenomas can compress the adjacent normal pituitary gland tissue and cause it to produce too little of one or more hormones. Less commonly, a near complete reduction of pituitary hormones can occur (panhypopituitarism). Some of the symptoms include growth problems, weak bones, lethargy, fatigue, weight gain, cold sensitivity, low blood pressure, infertility, irregular menstrual cycles, impotence, blood pressure and blood sugar problems.
3. Too much production of a particular hormone. If the tumour is “functioning”, that is, producing hormones, then the symptoms depend on the type of hormone being produced. The following is a guide with a few examples of functioning tumours and expected symptoms. A thorough work up is needed to determine the underlying problem.
What treatment options are there for my pituitary tumour?
Not every pituitary tumour requires treatment. The main options include:
In many patients, medical treatment is successful in controlling their symptoms due to either excessive or lack absence of hormones released by the pituitary gland.
Surgery is indicated for some patients. Our patients are assessed by a multidisciplinary team of specialists, with expertise in the management of pituitary tumors. The patient’s symptoms, tumour size and functionality are taken into account, along with other co-morbidities and patient wishes when discussing the best treatment options.
When is surgery required for pituitary adenoma?
Not every pituitary tumour requires surgical treatment. In most situations, for instance hyperfunctioning tumors, surgical intervention is considered when medical treatment fails to control patient symptoms. This may take weeks, months or may occur after some years of starting medical therapy.
Surgery may be indicated earlier if pressure-related symptoms predominate, especially with a macroadenoma that presses on the optic nerves and causes problems with vision. Rarely, emergency surgical intervention may be considered if a sudden bleed into the tumour occurs, a condition known as pituitary apoplexy.
The abnormal tumour tissue removed during surgery is sent off to the pathology department for histology (using special dyes to examine the tissues under high magnification) to confirm the diagnosis.
How is the surgery performed? What do the terms “open”, “endoscopic”, “trans-sphenoidal microscopic” pituitary surgery mean?
There are two main ways to surgically access the pituitary gland:
1. Trans-cranial, from above, via an incision in the skull (“open”).
2. “Through the nose” or “trans-nasal” or “trans-sphenoid”, from below, by opening up the bony partition between the sphenoid sinus and the pituitary gland. The trans-nasal surgery may be performed by using:
For the majority of pituitary adenomas (micro and macroadenomas), the trans-nasal approach offers excellent patient outcomes without the morbidity associated with a skull incision and brain retraction with the open approach. However, for some patient’s pituitary tumours, the trans-cranial approach may be suited to achieve the best outcome, especially if the tumour extends beyond the limits of the trans-nasal approach.
Our surgical team has experience with all of these approaches and the decision to select a particular approach depends on an individual patient’s condition and treatment goals.
Trans-nasal microscopic pituitary surgery, or trans-sphenoid microscopic approach, has been used traditionally to remove pituitary tumours. Typically, this approach involves an incision in the gums under the upper lip and removal of the nasal septum to access the sphenoid sinus and pituitary gland.
More recently, with the advent of endoscopic surgical techniques, the endoscopic endonasal approach for removal of pituitary tumours offers:
This is our preferred surgical approach to treat pituitary tumours. This technique requires two surgeons, an ENT surgeon and neurosurgeon, to perform.
In some situations, tumour removal carries a risk of fluid surrounding brain tissue, cerebrospinal fluid (CSF), to leak. This is often anticipated prior to surgery based on specific risk factors. If a CSF leak occurs, this is repaired at the same time of tumour removal surgery using tissues from within the nose. Sometimes fascia and fat tissues may be obtained via an incision in the thigh or abdomen.
How does “through the nose” endoscopic endonasal pituitary surgery affect my quality of life?
With the endoscopic endonasal approach, recovery times following surgery are faster, there is no external wound and side-effects associated with the nasal approach are few.
In the absence of a CSF leak repair and nasal flaps, the nasal congestion and crusting symptoms settle after a month, and in the majority of patients, the sinonasal symptom scores tend to return to baseline between 1 and 3 months after surgery.
You will be followed up regularly by our endoscopic surgical and medical team, who work collaboratively to ensure a high standard of care for your pituitary and sinonasal related issues.
ABOUT THE AUTHOR, DR HARSHITA PANT:
Dr Pant undertook post graduate fellowship training at the University of Pittsburgh Medical Centre in the USA as a fellow and clinical instructor in minimally invasive skull base surgery, rhinology and allergy. She has a unique understanding of the influence of microbes (bacteria, fungi and viruses) and the patient’s immune system in chronic sinusitis and has extensive training in the medical and surgical treatment of nose and sinus problems. Dr Pant specialises in advanced endoscopic sinus surgery and skull base surgery in both adult and paediatric patients, using minimally invasive endonasal (through the nose) approaches. Dr Pant is a staff specialist consultant at the Queen Elizabeth Hospital and a senior lecturer at the University of Adelaide. She has an active teaching and research career at the University of Adelaide.