Postoperative control in deep brain stimulation of the subthalamic region: the contact membership concept

Object

In deep brain stimulation, the anatomic positions of electrode contact centers are used as the basis for analysis. We propose a new semi-quantitative approach (contact membership concept) considering patient’s individual anatomy, contact size, and extent of involvement of STN and neighboring structures.

Materials and methods

In ten bilaterally operated and improved Parkinsonian patients, effective contact positions (contacts used for monopolar stimulation) were analyzed. The position of the contact center (classical binary approach: each center assigned, 1, or not, 0, to a given structure) and of the contact in its dimension (contact membership concept: membership degree, ordinal values from 0 to 1, assigned to each anatomic structure according to extent of involvement) were compared for the whole patient group and, individually, for each patient.

Results

The membership concept revealed that for 13 out of 20 contacts, more than one structure was involved, where the classical binary approach assigned only one structure. For both approaches lateral STN, zona incerta and H1 (Forel’s Field) were the main structures involved, but their frequencies of appearance differed.

Conclusion

The membership concept allows detailed analysis of the anatomic contact position. In the future this approach could assist in correlating anatomy and clinical results for all electrode contacts (effective ones and clinically less efficient ones).