Objective: To clarify the relationships between the individual anatomical variations of the brainstem, the site in which the PPTg DBS is applied and the clinical outcome in a relatively large number of patients affected by Parkinson’s disease or Progressive Supranuclear Palsy.
Methods: Magnetic resonance images (MRI) have been used to evaluate brainstem anatomy, and the relationships between lead position and specific brainstem landmarks. All data were matched on atlas representations of the PPTg and were correlated with UPDRS III, sub-items 27-30 of UPDRS III and Hoehn and Yahr’s evaluations.
Results: A high variance of brainstem parameters was evident, affecting the relationships between the position of the nucleus and lead contacts. According to the contacts giving the best clinical outcome, patients could be distinguished between those who required the utilization of two adjacent contacts, and those who required stimulation through two non-adjacent contacts. Furthermore, in the former group the target coordinates were more lateral and deeper compared to the latter group.
Conclusion: Individual PPTg-DBS planning is required to overcome inconsistencies linked to the high variability in the brainstem anatomy of patients. The lack of correlations between lead position, contacts setup and clinical outcome indicate that the benefits of PPTg DBS may not be strictly linked to the site of stimulation within the PPTg area, and may not be dependent upon the neurons still surviving in this region in PD or PSP.
From: The Clinical Effects of Deep Brain Stimulation of the Pedunculopontine Tegmental Nucleus in Movement Disorders May Not be Related to the Anatomical Target, Leads Location and Setup of Electrical Stimulation by Mazzone et al.