Hypothesis / aims of study
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.
Study design, materials and methods
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.
Interpretation of results
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.