The gait disorder in primary orthostatic tremor

Abstract

Objective To uncover possible impairments of walking and dynamic postural stability in patients with primary orthostatic tremor (OT). Methods Spatiotemporal gait characteristics were quantified in 18 patients with primary OT (mean age 70.5 ± 5.9 years, 10 females) and 18 age-matched healthy controls. One-third of patients reported disease-related fall events. Walking performance was assessed on a pressure-sensitive carpet under seven conditions: walking at preferred, slow, and maximal speed, with head reclination or eyes closed, and while performing a cognitive or motor dual-task paradigm. Results Patients exhibited a significant gait impairment characterized by a broadened base of support (p = 0.018) with increased spatiotemporal gait variability (p = 0.010). Walking speed was moderately reduced (p = 0.026) with shortened stride length (p = 0.001) and increased periods of double support (p = 0.001). Gait dysfunction became more pronounced during slow walking (p < 0.001); this was not present during fast walking. Walking with eyes closed aggravated gait disability as did walking during cognitive dual task (p < 0.001). Conclusion OT is associated with a specific gait disorder with a staggering wide-based walking pattern indicative of a sensory and/or a cerebellar ataxic gait. The aggravation of gait instability during visual withdrawal and the normalization of walking with faster speeds further suggest a proprioceptive or vestibulo-cerebellar deficit as the primary source of gait disturbance in OT. In addition, the gait decline during cognitive dual task may imply cognitive processing deficits. In the end, OT is presumably a complex network disorder resulting in a specific spino-cerebello-frontocortical gait disorder that goes beyond mere tremor networks.

An exploratory investigation on spatiotemporal parameters, margins of stability, and their interaction in bilateral vestibulopathy

“…We aimed to determine the effect of a loss of peripheral vestibular function by comparing the spatiotemporal gait parameters and their step-to-step variability between BVP-patients and healthy controls during overground walking at preferred walking speed. We hypothesize that, in accordance with previous studies 24 , 26 , 27 , 33 , 34 , BVP-patients will show an increased gait variability during walking. Additionally, we also examined the interaction between the spatiotemporal gait parameters and MoS in BVP as compared to the healthy controls.…”

“…This could indicate a shift from a sensory feedback-driven control of balance to a more feedforward control of balance, as has been suggested before 22 , 35 – 37 . In addition, it has been shown that during slow walking speeds, the variability of most parameters is highest in BVP-patients 24 , 26 , 27 , 34 , 38 . The reason for this could be an increased need for sensory feedback at slower walking speeds in general, as passive dynamics play a smaller role in stabilising the body during this condition.…”

“…Additionally, HCs were only excluded based on self-reported visual, neurological or orthopaedic disorders and were thus not screened on any cognitive, mental or cardiovascular disorders which could coincidentally affect gait 52 , 53 . BVP-patients were currently only included when they were able to walk without assistance, which might place the current investigated patient population at a higher functional level as the populations investigated in previous studies 24 , 26 , 27 , 34 , 38 . Thus the current results might not be generalisable to patients that are less mobile.…”

“…Another way to quantify the stability of walking is by investigating spatiotemporal gait parameters and their step-to-step repeatability or variability 20 , 21 . Due to the impaired vestibular information processing in BVP, and vestibular feedback being essential in maintaining dynamic stability through the fine-tuning of timing and magnitudes of foot displacements, the gait disorder in BVP is primarily characterized by an increased gait variability and a higher risk of falls 22 – 26 . Additionally, BVP-patients with a history of falls exhibited a lower preferred walking speed with an increased step width and prolonged double support phase 27 .…”

The Phenomenology of Primary Orthostatic Tremor

“…Whereas initial reports describe the absence of ataxia and bradykinesia in POT, several recent reports indicate the potential presence of cerebellar ataxia. 10 , 11 , 12 , 13 , 14 , 15 These mainly comprise of features of gait such as reduced step length and increased step width, but also a certain degree of appendicular ataxia has been suggested. These observations are contradicted by case series demonstrating only very rare occurrence of ataxia.…”