Laterality in Parkinson’s disease: A neuropsychological review

Abstract

Laterality of motor symptom onset in Parkinson's disease is both well-known and underappreciated. Treatment of disorders that have asymmetric pathological features, such as stroke and epilepsy, demonstrate the importance of incorporating hemispheric lateralization and specialization into therapy and care planning. These practices could theoretically extend to Parkinson's disease, providing increased diagnostic accuracy and improved treatment outcomes; however, laterality in Parkinson's disease has been largely ignored both clinically and in research. Additionally, while motor symptoms have generally received the majority of attention, non-motor features (e.g., autonomic dysfunction) also decrease quality of life and are influenced by asymmetrical neurodegeneration. Due to the laterality of cognitive and behavioral processes in the two brain hemispheres, analysis of hemibody side of onset can potentially give insight into expected symptom profile of the patient and allow for increased predictive accuracy of disease progression and outcome, thus opening the door to personalized and improved therapy in treating Parkinson's disease patients. This review discusses motor and non-motor symptoms (namely autonomic, sensory, visuospatial, language, and emotional dysfunction) of Parkinson's disease in respect to hemispheric lateralization from a theoretical perspective in hopes of providing a framework for future research and personalized treatment.

Association between Severity of Freezing of Gait and Turning Characteristics in People with Parkinson’s Disease

“…The basal ganglia involved in automatic movement serve to transmit signals step by step to the supplementary motor area that regulates gait control, and damaged neural output from the basal ganglia to the supplementary motor area may degrade the ability to control both sides for gait, causing asymmetry [7]. Consequently, these characteristics may be exacerbated in the "Off" medication state, and gait characteristics such as shuffling and walking with a short step length while dragging the foot on the ground may increase [3]. In addition, freezers with already compromised dynamic stability exhibit more cautious movements during turning and may use more restricted postural strategies to promote effective turning from dopamine-depleted states that may affect the control of automatized movements [15].…”

“…These asymmetric characteristics of freezers affect inter-limb coordination and decrease the ability to posture during movement due to posture instability in daily life [3]. Considering the generalized turning characteristics, the increased double support phase of the outer lower limb during the turning may be a general result.…”

“…Freezing of gait (FOG) is defined as a symptomatic episodic absence of forward progression or marked reduction in step length, despite the intention to walk [1], and approximately 80% of people with Parkinson's disease (PD) experience FOG [1,2]. FOG symptoms are mainly caused by turning, changing directions, multi-tasking, passing through narrow passages, moving when pressed for time, and approaching destinations [3]. Thus, FOG symptoms not only affect the daily life and movements of people with PD but are also related to an increased risk of falls [2,3].…”

“…FOG symptoms are mainly caused by turning, changing directions, multi-tasking, passing through narrow passages, moving when pressed for time, and approaching destinations [3]. Thus, FOG symptoms not only affect the daily life and movements of people with PD but are also related to an increased risk of falls [2,3].…”

Study on the asymmetric distribution characteristics of striatal dopamine transporter in early Parkinson's disease

“…However, in the early stages of PD, these motor symptoms are often asymmetrical, and symptoms start on one side as a characteristic of the illness. Additionally, the side of onset appears to determine the prognosis of the disorder and other features [3][4][5]. For example, right side tremors have a better prognosis than left-side dominant bradykinesia-rigidity.…”