We sought to determine the changes in urinary symptoms and urodynamic parameters of patients with neurologic disease after deep brain stimulation (DBS). Our hypothesis is that DBS can improve objective and subjective outcomes of lower urinary tract function in patients with Parkinson disease and essential tremor. Although studies have evaluated outcomes with questionnaires, this is the first study performing objective pre- and post- DBS urodynamic evaluations.

We prospectively recruited patients with a neurologic diagnosis amenable to treatment with DBS surgery. These patients had exhausted more conservative treatment options for their neurologic disease. Patients had DBS electrodes implanted in the ventral intermediate nucleus of the thalamus on both the left and right sides by a single neurosurgeon. Only patients with moderate urinary symptoms (AUA symptom score > 8) were enrolled in the study. Before and 2 months after surgery, demographic data, validated questionnaires and urodynamic studies (UDS) were obtained and performed. Patients were followed 12 months after surgery.

A total of eight patients (four men and four women) were enrolled in the study. Five of the eight patients (63%) had Parkinson disease and three patients (47%) had essential tremor as the underlying reason for seeking DBS surgery. All patients had urinary incontinence as their main urologic complaint. One of the 8 patients was taking medication for treatment of urge urinary incontinence and no patients were on alpha-blockers. 

Four of eight patients (50%) completed the post-DBS surgery American Urological Association (AUA) symptom questionnaire and AUA symptom score (AUA-SS) was calculated for these patients. Having enrolled patients with moderate symptoms at minimum, patients with mild urinary symptoms were screened out and excluded from the study. The mean pre-surgical AUA-SS for this subgroup was 18 with mean quality of life (QoL) score 4.5 (between "mostly dissatisfed" and "unhappy"). Pre-DBS, storage symptoms were worse (mean score 9.25) than the voiding symptoms (mean score 7.875). Mean AUA-SS after surgery was 18.5 with mean QoL score of 3 (a rating of "mixed" QoL on the questionnaire).  

Four patients had urodynamic evaluation an average of 8 weeks post-DBS surgery. All patients had UDS performed once they achieved stable settings on DBS. Two of these 4 patients had detrusor overactivity both pre- and post-DBS surgery, and only 1 patient had detrusor overactivity with leak post-surgery with DLPP of 84. F-test of post-void residuals (PVR) showed significant less variance in PVR in post-surgical patients. The attached diagram outlines the differences in UDS parameters pre- and post-DBS.

Using the AUA symptom score as a metric for subjective evaluation of patient symptoms, although there was not a significant change in the overall AUA symptom score pre- and post-DBS, there was an improvement in the quality of life (QoL) metric from 4.5 which is a score between "mostly dissatisfied" and "unhappy." This QoL metric was improved to a score of 3 after DBS which is that the patient feels "mixed" about his or her urinary symptoms. 

Examining the urodynamic data pre- and post-DBS, there is an increase in bladder compliance and detrusor pressure at maximum flow (Pdet at Qmax) post-DBS surgery. Additionally, the volume of first sensation was delayed after DBS. There was a decrease in detrusor leak point pressure (DLPP) and post-void residual (PVR) after DBS. Undergoing DBS surgery did not demonstrate improvements in bladder capacity or urinary flow in this patient group.

Our study examined changes in urinary metrics in patients with neurologic disease who underwent DBS surgery. The study demonstrated favorable changes after deep brain stimulation surgery in both subjective and objective measures of lower urinary tract function. After DBS surgery, the patients experienced an improvement in the Quality of Life (QoL) metric of the AUA symptom score. Looking at the objective data with urodynamic parameters, there were improvements in ability to delay the first sensation, decreased detrusor leak point pressure and post-void residual, and increased overall compliance and detrusor pressure at maximum flow during the voiding phase of the study. A significant limitation of this study was low patient numbers. A possible explanation for this could be the late stages of the particular neurologic disease process that leads patients to seek DBS as a treatment option. Despite this limitation, this was the first study of its kind examining both subjective and objective data on lower urinary tract symptoms and function in patients with moderate to severe lower urinary tract symptoms pre- and post-DBS surgery.