The pituitary is a gland that hangs down from the base of the brain, into the sphenoid sinus that lies behind the nose. It makes many hormones, including thyroid hormone, cortisol, growth hormone, prolactin, oxytocin, anti-diuretic hormone and the sex hormones (FSH/LH & testosterone).
Pituitary tumours comprise about 15% of adult brain tumours. Many are found incidentally, when someone has a brain scan for unrelated problems such as headaches. Otherwise, they can produce too much of one type of hormone, destroy the normal production of the other hormones or grow upwards to compress the optic nerves and give rise to blurred vision. Rarely, there can be sudden blindness due to bleeding into the tumour, a neurosurgical emergency.
Pituitary tumours are diagnosed using blood tests (if they produce excessive hormone) and MRI brain scan.
There are many ways of looking after pituitary tumours :
- If they are not causing any problems and are small, observation can be considered. But if they grow on successive MRI scans, they should be treated.
- Surgical excision offers the chance of cure, provided the tumour has not spread sideways into the cavernous sinuses. It also allows us to examine the tissue to confirm the diagnosis. Most pituitary tumours are soft and can be resected through the nose (transsphenoidal surgery). Others may require an approach through the skull (craniotomy).
- Radiation therapy. Radiosurgery (Gamma Knife?, X-knife?, Brainlab? etc) involves treating the tumour in a single outpatient session, to kill the tumour cells and stop its growth. This can be considered if the optic nerves are not too close to the tumour. Otherwise, some form of fractionation may be required (stereotactic radiosurgery, conformal radiotherapy), where the tumour is treated with small doses of focused radiation over several weeks. Radiation is used to treat residual tumours or as the first treatment when the patient is not fit for an operation.
- Medical therapy. The treatment of choice for prolactin-secreting pituitary tumours is medicine (bromocriptine, cabergoline). Surgery is then offered if the side effects cannot be tolerated or the medicine does not work.
Endoscopic transsphenoidal surgery via bilateral sphenoidotomies. Since 1997, Dr Alvin Hong has been resecting pituitary tumours using endoscopes, together with Dr Sethi, an ENT surgeon who specialises in surgery of the nasal sinuses. In this minimally invasive approach, the pituitary tumour is approached directly via the back of the nose, avoiding the more traditional approach of a cut in the gum above the teeth or in the nasal septum in the front of the nose. The scopes allow one to look around the corner, to inspect the sphenoid sinus and also the cavity in the pituitary gland after the tumour has been resected. He has done more than 200 of such operations.
The pituitary team. Patients with pituitary problems are managed by a team of specialists including the surgeons (neurosurgeon & ENT surgeon), hormone specialist (endocrinologist), eye specialist (ophthalmologist) and radiation specialist (radiotherapist).