Pallidotomy

Pallidotomy

In 1952, Dr. Lars Leksell performed Pallidotomy and showed that it was effective in relieving parkinsonian symptoms. At that time, the preferred surgical target for Parkinson’s disease surgery was thalamus. However, after the introduction of Levodopa, pallidotomy took the back seat. Uncontrolled dyskinesias appeared as a side effect of prolonged levodopa treatment. Alternative drugs provided only temporary relief for this disabling side effect. This forced the surgeons to rethink about the surgical treatment for Parkinson’s disease.

In 1985 Dr. Lauri Laitinen from Sweden demonstrated that the pallidotomy described by Dr. Leksell could be effective in treating advanced Parkinson’s disease patients. He modified the surgical target within the pallidum and achieved the better control of the symptoms. Many of his patients suffered from severe bradykinesia, rigidity, tremors and other unusual involuntary movements. These patients had long standing severe Parkinson’s disease and suffered from drug-induced dyskinesias.

He reported his first pallidotomy series of 38 patients in January 1992 and claimed that 80% to 90% of the patients had a long lasting relief of symptoms. This encouraging experience prompted other specialists to re-examine the role of pallidotomy in Parkinson’s disease. Pallidotomy has been found to be most effective in controlling drug induced dyskinesias, dystonia and other associated with off phase symptoms. During the same time Pallidotomy was offered for Dystonia and over period of time the GPi (Globus Pallidus internus) became the target of choice for treating dystonia.

Drawing showing the relationship of the pallidal target to the internal capsule and optic tract

The surgical target for pallidotomy is the most poster-ventro-medial part of the globus pallidum known as Globus pallidum internus (Gpi). This part of the Gpi is located in close relationship to the internal capsule and optic tract. Internal capsule carries nerve fibres that are responsible for motor function and any damage to these fibres can cause weakness on the opposite side of the body whereas the optic tract carries the fibres for the vision and any damage to these fibres can cause visual field defect. These side effects can be avoided by using the expertise and experience of a functional neurosurgeon.