**4. Future Direction**

Studies published to date have shown that the rationale and technology of STN DBS surgery performed under GA are accurate, and they presented similar clinical results compared to STN DBS under LA cohort. A large-scale prospective randomized controlled trial is in progress to assess the degree of the improvement of non-motor symptoms in PD patients [120].

Care should be taken when interpreting and applying the conclusion, since the STN DBS surgery under GA data reported to date have been published in large centers with considerable experiences. In general, STN DBS surgery should be performed in the most convenient way for the surgeons and center to provide the best results to the patients. Traditionally, factors, such as claustrophobia, severe off-medication symptoms, or nonspecific fear of waking during surgery, made patients choose GA. However, based on the increasingly cumulative data showing similar or better results compared to LA, a surgeon may choose STN DBS surgery under GA.

Adaptive DBS is a promising technology because it can provide more selective stimulation trigger/parameter and reduce stimulation-induced dyskinesia by suppressing beta activity when it exceeds a certain threshold level [121,122]. There is still little literature on adaptive DBS implemented under general anesthesia, and further studies for application of adaptive DBS under general anesthesia should be conducted.

There are patients who cannot undergo STN DBS surgery due to various reasons or may not benefit from STN DBS surgery. Non-invasive lesion-based therapies, such as focused ultrasound and Gamma Knife radiosurgery (GKRS), have been proposed as alternatives to DBS because of their effectiveness and safety [123–126]. The further innovative refinement of noninvasive methods of Gamma Knife radiosurgery (GKRS) and focused ultrasound may allow advanced PD patients to receive surgical treatment more conveniently and e fficiently in the near future.
