Bilge Kocer

Aim: This study aimed to evaluate the early diagnostic potential of subthalamic nucleus (STN) radiomic features and machine learning algorithms to differentiate Parkinson's disease patients requiring Deep Brain Stimulation (DBS) from those managed solely with medical therapy. This approach seeks to provide a non-invasive imaging biomarker to assist in objective surgical decision-making. Methods: A retrospective analysis of 394 Parkinson’s disease patients (200 in the DBS surgical cohort and 194 in the medical treatment cohort) was conducted using preoperative MRI scans. Following meticulous manual segmentation of the STN, a comprehensive set of radiomic features—including shape, first-order statistics, and Gray Level Co-occurrence Matrix (GLCM) parameters—was extracted. A Random Forest classifier was trained on 70% of the dataset and validated on a 30% independent test set to classify the patients based on their microstructural STN signatures. Results: The Random Forest machine learning model achieved an exceptional overall classification accuracy of 93.10% on the test dataset. Receiver Operating Characteristic (ROC) analysis yielded an Area Under the Curve (AUC) of up to 0.938. The performance was perfectly unbiased, with precision, recall, and F1-scores reaching 0.93 for both the surgical and medical cohorts. Feature importance analysis revealed that morphological deformations, specifically STN flatness, and first-order signal intensity drops associated with iron deposition were the most highly discriminative biophysical biomarkers for identifying surgical candidates. Conclusion: The application of machine learning to STN radiomic features provides a highly accurate, non-invasive, and objective methodology to distinguish DBS candidates from medically managed Parkinson's patients. While these findings are promising, prospective and external validation is required before the model can be fully incorporated into routine clinical decision-making.

Objectives: Fear of falling is highly prevalent in Parkinson’s disease (PD) and contributes to reduced mobility, activity restriction, and diminished quality of life. The psychometric properties of the Turkish version of the Falls Efficacy Scale–International (FES-I) have not been specifically examined in individuals with PD. This study aimed to evaluate the reliability and construct validity of the Turkish FES-I in this population. Methods: A total of 131 patients with idiopathic PD were consecutively recruited from an outpatient rehabilitation clinic. The FES-I was administered twice with a 10–14-day interval. Internal consistency and test–retest reliability were assessed. Construct validity was examined using exploratory and confirmatory factor analyses, correlational analyses with clinical and functional measures, and known-groups comparisons across modified Hoehn and Yahr stages. Results: No missing data were observed. The mean FES-I total score was 34.0 ± 14.3, with minimal floor (2.3%) and ceiling (1.5%) effects. The scale demonstrated excellent internal consistency with Cronbach’s alpha = 0.976, and high test–retest reliability (ICC = 0.941–0.996). Sampling adequacy was confirmed (KMO = 0.962; Bartlett’s χ²(120) = 2443, p < 0.001). Factor analysis supported a single-factor structure explaining 74.1% of the variance. Higher FES-I scores were significantly associated with greater disease severity, freezing of gait, impaired balance and mobility, and poorer quality of life (p < 0.001). Conclusion: The Turkish FES-I demonstrates strong reliability and construct validity in patients with Parkinson’s disease and may serve as a clinically useful instrument for assessing fear of falling in this population. Keywords: Parkinson Disease, Accidental Falls, Psychometrics, Reproducibility of Results

The aim of the study was to examine the reliability and validity of the Groningen Meander Walk Test (GMWT). Forty-six people with Parkinson's disease (PwPD) and 32 controls were included. Reliability was determined using intraclass correlation coefficients (ICC) and the minimal detectable change (MDC). Correlations between the completion time (CT) and overstep score (OS) of the GMWT and the other balance and disease severity specific tools were used to assess validity. The CT and OS of the GMWT were also compared between fallers and non-fallers among PwPD. The GMWT times demonstrated excellent test-retest reliability (ICC = 0.964) while overstep scores had good test-retest reliability (ICC = 0.757). The MDC was 1.72 s for CT and 1.64 s for OS. The CT of the GMWT showed moderate to strong correlations with the other measures (correlation coefficients ranged from 0.530 to 0.847, p < 0.05 for all), while the OS showed fair to moderate correlations (correlation coefficients ranged from -0.361 to 0.660, p < 0.05 for all). Significant differences in the GMWT were found between PwPD and healthy controls and between fallers and non-fallers with PwPD (p < 0.05). The GMWT is a reliable and valid tool for quantifying the advanced walking skills of PwPD.Implications for RehabilitationThe Groningen Meander Walk Test is a reliable, valid, and easy-to-administer clinical assessment tool in people with Parkinson's disease.The Groningen Meander Walk Test can be used for assessing advanced walking ability in people with Parkinson's disease.The Groningen Meander Walk Test can detect fallers and freezers with Parkinson's disease.

Introduction It is important to identify the determinants of fall risk in people with Parkinson’s disease (PwPD), as they can play a critical role in planning appropriate treatment and interventions. The aim of this study was to discriminate the risk of falling in PwPD using the Trunk Impairment Scale (TIS). Methods This cross-sectional study included 181 PwPD. There were 95 patients in the faller group and 86 in the non-faller group among the study participants. Trunk control was evaluated using TIS, and fall history was documented by interviews. Results The mean ages of PwPD with and without a history of falls in the past year were 66.03 ± 7.47 and 64.65 ± 8.87, respectively. The median (IQR) values of the TIS of the faller group was 17.00 (14.00–19.00) while 20.00 (19.75-22.00) in non-faller group. For PwPD, the TIS cut-off value for fall risk was found to be 19.50 points. Conclusions Predicting the risk of falls in PwPD, a disease group in which falls are common and have devastating effects on patients, is very important for the success of rehabilitation practices, patient follow-up and patient safety. These results show that the TIS is a reliable and simple scale that can be used to identify patients at risk of falls for assesing trunk control in PwPD.

PurposeTo examine the effect of deep brain stimulation (DBS) on lower extremity dexterity in people with Parkinson's disease (PwPD) and to investigate the relationship between this effect and the effect of DBS on measures of different walking characteristics, and other features of Parkinson's disease.Materials and methodsThirty-six PwPD were included. Assessment was performed twice with DBS "on" and DBS "off" state.ResultsThe LEDT scores of both extremities, the Unified Parkinson Disease Rating Scale-motor section (UPDRS-III), the 10-Meter Walk Test (TMWT), the Timed Up and Go Test (TUG), the Figure-of-Eight Walk Test (FEWT), and the Three-Meter Backward Walk Test (TMBWT) scores were significantly better in "on" DBS condition than "off" DBS condition. The effect of DBS on lower extremity dexterity is related to age and levodopa equivalent daily dosage (LEDD). The effect of DBS on lower extremity dexterity and the effect of DBS on the bradykinesia, TUG, the FEWT, and the TMBWT were also related.ConclusionsDBS has a positive effect on lower extremity dexterity. Clinical characteristics such as age and LEDD and the effect of DBS on bradykinesia, walking with turning, curved walking, and backward walking is related with the effect of DBS on lower extremity dexterity. The age and levodopa equivalent daily dosage values of the patients should be considered when examining lower extremity dexterity in people with Parkinson's disease who have undergone deep brain stimulation (DBS).It may be beneficial to apply exercises to improve lower extremity dexterity for patients whose symptoms of bradykinesia do not progress as expected after DBS.Applying exercises to improve lower extremity dexterity may also be beneficial for patients who have complex walking deficits after DBS.

Background People with Parkinson’s disease (PwPD) lose the ability in backward walking which is an important part of mobility in daily life. The 3-m backward walk test (3MBWT) evaluates backward walking; however, its reliability and validity have not been examined in PwPD yet. Aims To examine (1) the test–retest reliability of the 3MBWT in PwPD; (2) the minimum detectable change in the 3MBWT times; (3) the concurrent and known-groups validity of the 3MBWT; and (4) the optimum cutoff time which best discriminates fallers from non-fallers with Parkinson’s disease (PD). Methods This cross-sectional study included 36 PwPD and 33 healthy people. The 3MBWT was conducted with the 10-m walk test, timed up and go test, Berg Balance Scale, four square step test, activity-specific balance confidence scale, Movement Disorders Society Sponsored Unified Parkinson’s Disease Rating Scale, and Hoehn and Yahr Scale. Results The 3MBWT demonstrated excellent test–retest reliability (ICC = 0.965). The MDC of 2.13 s was determined. The 3MBWT had moderate to high correlations with the other outcome measures (correlation coefficient ranged from −0.592 to 0.858). On the 3MBWT times, there were significant differences between PwPD and healthy people, and between fallers and non-fallers with PD (p < 0.001 and p < 0.001, respectively). A 3MBWT time of 10.31 s was found to best discriminate fallers from non-fallers with PD. Conclusions The 3MBWT is a reliable, valid, and easy to administer outcome measure to assess backward walking performance in PwPD, indicating it to be used in practice and research.

Introduction Many of the activities in daily living require different walking skills such as straight walking (SW), walking with turning (WwT), curved walking (CW) or backward walking (BW) in a dual-task condition. However, there is a lack of evidence regarding the dual task cost (DTC) during different types of walking. Therefore, this study was planned to compare the DTC during different types of walking in people with Parkinson’s disease (PwPD) and healthy controls. Methods Thirty-one PwPD and 31 healthy controls were included. Different types of walking were assessed using the 10-Meter Walk Test for SW, the Timed Up and Go Test for WwT, the Figure-of-Eight Walk Test for CW, and the Three-Meter Backward Walk Test for BW. Walking assessments were performed in a single-task and a dual-task condition. Results The DTC on SW was the lowest in both groups. The DTC on WwT, BW, and CW were similar in healthy controls, whereas the order of the DTC on remaining walking types from lowest to highest was; WwT, BW, and CW in PwPD. Also, the DTC on WwT, BW, and CW were higher in PwPD than healthy controls. However, the DTC on SW was similar in PwPD and healthy controls. Conclusion The DTC is different during SW, WwT, BW, and CW in PwPD. Therefore, walking type should be considered in studies investigating dual task walking in PwPD. Also, dual task exercises consisting of different types of walking should be included in rehabilitation programs of PwPD.