Lateral ventricle volume is poor predictor of post unilateral DBS motor change for Parkinson's disease

Background: Deep Brain Stimulation (DBS) surgery can effectively treat many debilitating motor symptoms of Parkinson's disease (PD), but axial symptom improvement is variable. Predictors for post-DBS axial symptom performance have yet to be identified. Pre-surgery ventricle volume may be one predictor, for increasing ventricular size has been associated with worsening gait disturbance. In PD, ventricle size may also increase with the advancement of motor symptoms.

Objective: To examine the hypotheses that 1) lateral ventricular volumes would predict motor and axial motor symptom change from pre to four months post unilateral DBS, and 2) PD patients have larger ventricle volumes contralateral to side of symptom onset.

Methods: Idiopathic PD patients (n = 37) completed pre-surgery volumetric brain scans and UPDRS motor testing (off-medication), unilateral DBS (Globus Pallidus interna, n = 11; subthalamic nucleus, n = 26), and 4-month follow-up motor assessments (on-stimulation). Ventricle volumes were normalized using total intracranial volume.

Results: Total ventricular volume as well as measurements of contralateral/ipsilateral volumes to side of symptom onset or DBS lead placement did not predict outcome motor measures or correlate to axial motor change. Patients improving at least 2 standard errors of measurement (n = 6) did not have smaller ventricles relative to those without significant change. Post-operative hemorrhage (n = 1) had ventricle volumes similar to the group average. There was no asymmetry in ventricular volume by side of onset or side of lead placement.

Conclusion: Ventricular volume was a poor predictor of acute motor change following DBS. Asymmetrical ventricles may not be a consistent imaging marker for PD motor dysfunction.