Of 330 records, 8 articles met inclusion criteria, spanning 580 total patients undergoing PD-DBS with pre-operative MCI. Of the 4 studies reporting a difference in PD-DBS outcomes in MCI patients, the differing outcomes in the MCI group involved cognitive domains and the rate of progression to dementia. None of the studies included a matched control of non-operated patients, although 7 included a PD-NC cohort. Three (37.5%) studies included at least one QOL measure.

The precise role of preoperative MCI on post-DBS outcomes remains speculative given the paucity of existing literature. Definitions of MCI are variable between studies, further complicating methodological comparisons. Furthermore, the clinical relevance of outcomes beyond standardized scales, such as QOL outcomes and caregiver burden, are less definitive. Ultimately, understanding the role of preoperative baseline characteristics, such as MCI, in surgical outcomes among PD DBS candidates could strengthen patient selection and counseling.