The use of continuous high frequency “deep brain” stimulation (DBS) was established in the early 90s and is widely used with great benefit (Benabid et al.
1994). The implanted electrodes can be adjusted by changing the voltage, the pulse width and the frequency to improve symptoms and/or reduce potential side effects. In PD patients, the stimulation of either the subthalamic nuclei (STN) or the internal global pallidum (GPi) is mainly performed. The duration of benefit following GPi DBS is, however, variable. After STN DBS, an improvement in all main cardinal features of PD as well as a reduction of the mean severity and duration of dyskinesia has been documented in several studies (Limousin et al.
1998; Krack et al.
2003; Weaver et al.
2012). The best predictor for a favourable result is a good Levodopa response (Charles et al.
2002). Ideal candidates for STN DBS are patients below the age of 70 years, with motor fluctuations and dyskinesia or tremor and without cognitive or behavioural deficits. Side effects of the DBS include intracranial haemorrhage and infarction. Postoperational complications involve confusion, pneumonia, infection and in older patients pulmonary embolism (Voges et al.
2007). Lead breakage, extension wire failure, impulse generator malfunctions—generally referred to as hardware-related complications—typically appear within the first 3 months after operation (Baizabal Carvallo et al.
2012; Lyons et al.
2004). Stimulation-induced side effects include dysarthria, hypophonia, dizziness, eyelid opening apraxia and oculomotor deficits (Deuschl et al.
2006). Neuropsychiatric changes like post surgery depression and especially a 13-fold increased risk for suicide within the first year after STN DBS have been the cause for concern (Voon et al.
2008). A recent study did not find a difference in functional health measured by time spent in “on” and “off”, behavioural side effects, cognition and mood in patients who received GPi DBS or STN DBS (Odekerken et al.
2013).