Lesioning involves deliberate, selective damage (creating a lesion) within a particular part of the brain. Computer imaging is used to locate the target site precisely while the patient’s head is kept in place with a stereotactic frame. The lesion is created by inserting an electrode with its tip at the optimum point and then passing an electric current through the tip.
There are currently three target areas for lesioning:
- pallidotomy – this is the most common lesioning technique in which a lesion is made in the Gpi area of the brain. A few bilateral pallidotomies are performed for maximum symptom control but the risks are greater and so it is generally carried out only on one side
- thalamotomy – a lesion is made in the thalamus, usually only on one side as treating both sides is thought to be too risky
- subthalamotomy – a lesion is made in the STN area of the brain but this is used less commonly because it carries with it higher risks and its long term effects are unclear.
Because lesioning is irreversible and cannot be modified without further surgery, it is not ideal and is unlikely to be a treatment option in the long term.
