OBJECTIVE

To assess the change of speech disorders in patients with advanced stages of Parkinson’s disease (PD) during bilateral chronic deep stimulation of the subthalamic nucleus (DS STN).

MATERIAL AND METHODS

The study included 40 patients with PD (20 males and 20 females, mean age 53.5±9.1 years) who received DS STN. The patients had a clinical and neurological examination with an assessment of speech disorders in the week before surgery, as well as at 3, 6, and 12 months after surgery. The severity of dysarthria was assessed using the assessment scale developed by I.N. Balashova and N.P. Vanchakova.

RESULTS

DS STN led only to a transient decrease in dysarthria during the «off» period at 3 months of postoperative observation (p<0.05), with a relapse in the next 6 and 12 months of dysarthria during the «off» period to the preoperative level and an increase in its severity almost twice during the «on» period at month 12 of follow-up, compared to preoperative indicators (p<0.05). During the «off» period before surgery, mild dysarthria was detected in 30% of patients, and after 12 months of deep brain stimulation (DBS), only in 12.5%. During the «on» period, mild dysarthria before surgery was detected in 5% of patients, and after 12 months of DS STN, in 10% of patients. Therefore, neurostimulation increased the risk of dysarthria during the «on» period.

CONCLUSION

Bilateral DS STN can help reduce dysarthria without drug therapy, but can be a risk factor for dysarthria while taking antiparkinsonian drugs. Associations of dysarthria with postural and gait disorders have been reported, which indicates dysarthria in the «off» period as a marker of the patient’s postural instability.