Pituitary adenoma and chiasmal syndrome is a benign tumour of the pituitary gland that, as it grows, begins to press on the optic chiasm — the crossing point of the visual nerves. Because of this, a person gradually loses the side (temporal) parts of the field of vision in both eyes. The condition develops slowly, so many people notice it late.
What is pituitary adenoma and chiasmal syndrome
The pituitary is a small gland at the base of the brain that controls the body’s hormones. An adenoma is a benign (non-cancerous) overgrowth of its tissue. The pituitary sits very close to the optic chiasm — the place where the visual nerves of both eyes partly cross over. When the adenoma enlarges, it presses on this crossing from below upwards. As a result, it damages exactly the fibres responsible for the temporal (side) halves of the visual field. This produces the “chiasmal syndrome” — the typical picture of losing side vision on both sides.
Causes
- Benign overgrowth of pituitary cells (adenoma) — the main cause.
- Hormonally active tumours that produce excess hormones (prolactin, growth hormone and others).
- Hormonally inactive tumours that grow unnoticed for a long time and are found only when already large.
- Sometimes other masses of the chiasmal-sellar region that press on the crossing.
- Inherited tendency to tumours of the endocrine glands (rarely).
Symptoms
- Loss of the side fields of vision in both eyes (bitemporal hemianopia) — the person says “I can’t see at the edges”, bumps into door frames, and does not notice objects to the side.
- Gradual decline in sharpness of vision — mild at first, then more noticeable.
- A feeling of “blinkers” or tunnel vision, when only the central part remains.
- Double vision when looking to the side (if the tumour affects nearby nerves).
- Headache, most often in the forehead area or behind the eyes.
- Hormonal disturbances: disrupted menstrual cycle, reduced libido, fatigue, weight changes, and in men reduced potency.
Why this is a neuro-ophthalmological condition
The problem does not arise in the eye itself, but in the fact that the tumour presses on the visual pathways in the brain. A routine eye examination may show that the fundus and retina look normal, while the field of vision is already dropping out. This is exactly why a consultation with a neuro-ophthalmologist is important — a doctor who understands both the eye and the link between vision and the brain. They assess the visual fields and the state of the optic nerve, arrange the necessary tests, and, if needed, refer you to a neurosurgeon and an endocrinologist.
Diagnosis
- Perimetry (visual field testing) — the key study, which reveals the characteristic loss of the temporal halves in both eyes.
- Optical coherence tomography (OCT) — measures the thickness of the optic nerve fibres and shows signs of their compression.
- MRI of the chiasmal-sellar region — the main examination, showing the tumour itself, its size and the degree of pressure on the crossing.
- Examination of the fundus and testing of visual acuity.
- Blood tests for pituitary hormones (together with an endocrinologist).
Treatment
The most important thing is to seek help as early as possible: the less time the tumour presses on the optic chiasm, the greater the chance of keeping or restoring vision. Treatment is always a team effort. The neuro-ophthalmologist monitors the state of vision and the visual fields. The neurosurgeon decides on removal of the tumour (often through a minimally invasive approach). The endocrinologist selects treatment for hormonal disturbances — some tumours (for example, prolactinomas) respond well to medication without surgery. After treatment it is important to check the visual fields regularly, to track recovery and notice any regrowth in time.
When to seek urgent help
Do not delay a visit if you notice that the side field of vision has gradually “narrowed” on both sides, that sharpness of vision is falling quickly, that double vision has appeared, or that you have a severe, unusual headache. A sudden, sharp worsening of vision together with a severe headache and nausea may be a sign of bleeding into the tumour — a condition that requires emergency medical care.
German Eye Clinic, phone 0 800 507 670, the service page “Neuro-ophthalmologist consultation”.
