# Effects of subthalamic nucleus deep brain stimulation on the speech of Spanish-speaking Parkinson’s disease patients during the first year of treatment

## TL;DR

This study examines how deep brain stimulation affects speech in Spanish-speaking Parkinson's patients over one year, finding significant individual variation.

## Contribution

The study provides new insights into the variable effects of STN-DBS on speech in Spanish-speaking Parkinson's patients.

## Key findings

- No significant group-level changes in speech measures after STN-DBS or medication state.
- Individual speech measures varied inconsistently or consistently based on pre-surgery variation intervals.
- Speech outcomes were highly variable across participants, suggesting no shared post-surgery pattern.

## Abstract

To describe the effects of subthalamic nucleus deep brain stimulation (STN-DBS) on the speech of Spanish-speaking Parkinson's disease (PD) patients during the first year of treatment.

The speech measures (SMs): maximum phonation time, acoustic voice measures, speech rate, speech intelligibility measures, and oral diadochokinesis rates of nine Colombian idiopathic PD patients (four females and five males; age = 63 ± 7 years; years of PD = 10 ± 7 years; UPDRS-III = 57 ± 6; H&Y = 2 ± 0.3) were studied in OFF and ON medication states before and every three months during the first year after STN-DBS surgery. Praat software and healthy native listeners’ ratings were used for speech analysis. Statistical analysis tried to find significant differences in the SMs during follow-up (Friedman test) and between medication states (Wilcoxon paired test). Also, a pre-surgery variation interval (PSVI) of reference for every participant and SM was calculated to make an individual analysis of post-surgery variation.

Non-significative post-surgery or medication state-related differences in the SMs were found. Nevertheless, individually, based on PSVIs, the SMs exhibited: no variation, inconsistent or consistent variation during post-surgery follow-up in different combinations, depending on the medication state.

As a group, participants did not have a shared post-surgery pattern of change in any SM. Instead, based on PSVIs, the SMs varied differently in every participant, which suggests that in Spanish-speaking PD patients, the effects of STN-DBS on speech during the first year of treatment could be highly variable.