Hypokinetic-rigid gait disorders with balance impairment - A walk through clinical and pathophysiological definitions.

Hypokinetic-rigid gait disorders with balance impairment are a common clinical phenotype of different syndromes and diseases. However, multiple designations are used across the literature with unclear definitions, which brings heterogeneity and subjectivity to the discussion of such gait disorders. Therefore, there is a need for clear concepts to increase accuracy in clinical diagnosis and allow consistent comparisons and reasoning within research data. We performed a review of concepts, including lower body parkinsonism (LBP), higher level gait disorders, frontal gait disorders, gait apraxia, senile gait and cautious gait. Additionally, we reviewed the basic pathophysiological mechanisms underlying these gait disorders. LBP was found to be mainly associated with dysfunction of the motor thalamocortical circuit and of the mesencephalic locomotor region. We propose that for research purposes, concepts with greater specificity, such as LBP, should be preferentially used to improve the accuracy of studies involving this population. Considering the significant phenotypic and pathophysiological overlap between hypokinetic-rigid gait disorders, a multi-modal approach would be more pertinent to optimize the differential diagnosis in both clinical and research settings.