Long-term outcomes of surgical therapies for Parkinson's disease

The surgical lesion of different brain structures has been used as a treatment for Parkinson's disease (PD) for several decades. More recently, the favored therapeutic approach has involved the administration of levodopa and the use of DBS. These two major therapeutic advances have greatly modified both the clinical condition of patients and the history of the disease. With the introduction of L-dopa in 1967, patients could regain mobility, because their akinesia, tremor, and rigidity were greatly improved, with consequent significant improvement in quality of life and increased life expectancy. However, after the so-called "honeymoon" period in which the disease seemed to be controlled, motor fluctuations and L-dopa-induced dyskinesias mitigated the initial enthusiasm. In the 1990s, unilateral pallidotomy and DBS of the globus palllidus internus and STN reduced these motor fluctuations and dyskinesias remarkably, thereby inaugurating a new era in the surgical treatment of PD. Short- and medium-term follow-up studies of patients who underwent surgery have documented sustained, significant motor benefits. However, given the progressive nature of PD and the purely symptomatic effects of pallidotomy and DBS, the long-term clinical evolution of these surgical patients currently seems to be associated with a new PD phenotype, mainly characterized by axial motor problems and cognitive impairment. Here, we analyze the long-term clinical outcomes of surgical PD patients with at least 5-year follow-up, focusing on the long-term motor symptoms that were initially responsive to surgery.