Gamma Knife Radiosurgery

Gamma Knife radiosurgery makes no cut at all. Roughly 192 fixed cobalt-60 sources each send a beam too weak to harm the tissue it passes through, and all of them converge on a single point. Where they meet, the combined dose is intense enough to damage the DNA of the target cells so that they can no longer divide; the lesion stops growing and shrinks over time. The tissue the individual beams crossed on the way in is largely spared. That geometry, not any cutting, is the whole idea.

What it treats

Small and medium brain lesions, generally under 3 cm: benign and malignant brain tumours, including those in places open surgery cannot safely reach, secondary deposits — ten or twenty metastases can be planned in a single treatment — acoustic neuromas, and arteriovenous malformations, which it causes to thicken and close. It is also used for trigeminal neuralgia, where it interrupts the transmission of pain signals, and in selected cases of tremor, epilepsy and Parkinson's disease. Because it is precise and involves no incision or systemic drug, it can be considered for young children and for pregnant women, where the teratogenic risk of medication limits the alternatives.

How the session runs

Consent and routine investigations come first, then an MRI to locate the lesion exactly, then a check of general fitness. The head is then immobilised, by one of two methods: a frame-based approach, in which a fitted metal band is secured with pins under four local anaesthetic injections, or a frameless approach using a moulded thermoplastic mesh mask fixed to the machine. A CT or MRI scan is taken with the fixation in place to provide the measurements, and the team builds the treatment plan — which regions to target, at what dose, from what angles. The patient is then positioned, the table slides into the machine, and staff monitor by camera and talk through an intercom throughout. Afterwards the frame or mask and the drip come off, and there is at least half an hour in recovery.

How long, and how many times

The delivery itself runs from about fifteen minutes to a few hours depending on the type and site of the lesion, with half an hour being typical, and the whole hospital visit usually takes one to two hours. One session is normally enough. Some conditions are treated over three to five daily sittings, in which case the frameless mask is used because it can be removed and replaced accurately each day. No hospital admission is needed and patients are generally discharged the same day; allow around three days in India outside hospital. Hair can be shampooed after 48 hours, keeping the pin sites clean until they heal.

Side effects, and the thing to be clear about

Fatigue is common for a few weeks. The scalp may be red, sore or sensitive at the pin sites, and hair may thin temporarily over the treated area. Swelling in the brain can cause headache, nausea and vomiting. Numbness, seizures, loss of balance and vision problems are recognised. Get medical attention for a severe headache that medication does not touch, for progressive weakness, numbness or visual change, for continued bleeding or discharge from a pin site, or for a seizure. The one thing to be clear about is timing: this is not an operation that removes something on the day. The lesion responds over months, and follow-up imaging — not how you feel next week — is what shows whether it has worked. Both sources quote success percentages; neither attributes them, and we do not repeat them.