Upper Extremity Skills, Trunk Control, and Body Awareness in Parkinson's Disease

Investigation of Upper Extremity Skills, Trunk Control, and Body Awareness in Individuals With Parkinson's Disease

Parkinson's disease is associated with impairments in upper extremity function, postural control, and sensory-motor processing that may negatively affect daily activities and quality of life. While upper extremity dysfunction has been extensively investigated, the potential contributions of trunk control and body awareness have received less attention. This cross-sectional observational study aims to compare upper extremity skills, trunk control, and body awareness between individuals with Parkinson's disease and healthy adults, and to examine the relationships among these variables within the Parkinson's disease group. The findings may improve understanding of factors associated with upper extremity performance and support the development of more comprehensive rehabilitation approaches for individuals with Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by degeneration of dopaminergic neurons and the presence of both motor and non-motor symptoms. In addition to the cardinal motor features of tremor, rigidity, bradykinesia, and postural instability, individuals with PD commonly experience impairments in upper extremity function that negatively affect daily activities and participation. Difficulties in hand strength, manual dexterity, reaction time, movement speed, and upper limb coordination may interfere with reaching, grasping, object manipulation, and fine motor tasks.

Upper extremity performance in PD is influenced by several factors beyond the primary motor symptoms. Trunk control provides proximal stability required for efficient upper limb movement and functional task performance. Deficits in postural control, trunk mobility, and postural alignment may therefore contribute to upper extremity limitations. In addition, body awareness, defined as the perception and interpretation of bodily sensations, movements, and physical changes, has received increasing attention in neurological rehabilitation. Altered sensory integration, impaired kinesthetic processing, and movement-related difficulties observed in PD may affect body awareness and subsequently influence motor performance.

Although upper extremity dysfunction has been widely investigated in Parkinson's disease, the combined examination of upper extremity skills, trunk control, and body awareness remains limited. Furthermore, studies investigating body awareness in individuals with PD are scarce, and the relationship between body awareness and upper extremity performance has not been sufficiently explored.

The primary aim of this study is to investigate upper extremity skills, trunk control, and body awareness in individuals with Parkinson's disease and compare these characteristics with those of healthy adults. The secondary aim is to examine the relationships among upper extremity performance, trunk control, and body awareness within the Parkinson's disease group.

This study is designed as a cross-sectional observational study and does not include any intervention. A total of 118 participants will be recruited, including 59 individuals diagnosed with idiopathic Parkinson's disease and 59 age- and sex-matched healthy adults. Participants with Parkinson's disease will be evaluated during their medication "on" period. All assessments will be completed in a single session.

Data collection will include demographic and clinical characteristics, cognitive screening, disease staging, assessment of hand grip and pinch strength, upper extremity reaction time and movement speed, manual dexterity, self-reported upper extremity function, trunk control, and body awareness. Comparisons will be performed between the Parkinson's disease and healthy control groups, and associations among upper extremity skills, trunk control, and body awareness will be analyzed within the Parkinson's disease group.

The findings of this study are expected to provide a better understanding of the factors associated with upper extremity performance in Parkinson's disease and to clarify the potential contributions of trunk control and body awareness. Improved knowledge of these relationships may support the development of more comprehensive physiotherapy assessment and rehabilitation strategies for individuals with Parkinson's disease.

Inclusion Criteria:

• Diagnosis of idiopathic Parkinson's disease
• Age between 50 and 80 years
• Montreal Cognitive Assessment (MoCA) score ≥21
• Modified Hoehn and Yahr Stage 2-3
• Stable medication regimen with no medication or dosage changes within the previous month
• Ability to understand and follow instructions
• Voluntary agreement to participate

Exclusion Criteria:

• Presence of another chronic neurological disorder
• Orthopedic or rheumatologic conditions limiting upper extremity movement
• Previous upper extremity or trunk surgery
• Severe tremor or dyskinesia preventing participation in assessments
• Significant visual or communication impairments interfering with testing