Change in fatigue after bilateral subthalamic nucleus deep brain stimulation for Parkinson's disease

Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) improves motor function in patients with medically intractable Parkinson's disease (PD), but the effects of STN DBS on fatigue are unknown. The purpose of this study was to examine the effects of STN DBS on fatigue scores in patients with PD.

Twenty PD patients underwent bilateral STN DBS surgery at our institution from 2007 to 2009. Only data from the 17 patients who completed the Parkinson Fatigue Scale (PFS) and Unified PD Rating Scale (UPDRS) before and approximately 6 months after surgery were analyzed. Other evaluations included the Geriatric Depression Scale (GDS), Apathy Evaluation Scale (AES), and Epworth Sleepiness Scale (ESS).

When the cohort was analyzed as a whole, there was no significant change in the mean or binary PFS score from baseline to the 6 month evaluation. However, the fatigue response of individual subjects was variable. Six of 12 subjects with fatigue before surgery were not fatigued post-operatively, while 3/5 subjects without fatigue before surgery became fatigued after DBS surgery. Fatigue in 8 subjects remained unchanged. Change in fatigue scores correlated significantly with change in the motor UPDRS, GDS and AES. Improvement in PFS also correlated with a higher PFS baseline score and higher baseline UPDRS motor off score.

Changes in fatigue severity were not observed in our cohort as a whole, but there were changes in fatigue on an individual level. These changes appear to be related to the effects of STN DBS on motor improvement and mood.