Consensus Paper: Ataxic Gait.

The aim of this consensus paper is to discuss the roles of the cerebellum in human gait, as well as its assessment and therapy. Cerebellar vermis is critical for postural control. The cerebellum ensures the mapping of sensory information into temporally relevant motor commands. Mental imagery of gait involves intrinsically connected fronto-parietal networks comprising the cerebellum. Muscular activities in cerebellar patients show impaired timing of discharges, affecting the patterning of the synergies subserving locomotion. Ataxia of stance/gait is amongst the first cerebellar deficits in cerebellar disorders such as degenerative ataxias and is a disabling symptom with a high risk of falls. Prolonged discharges and increased muscle coactivation may be related to compensatory mechanisms and enhanced body sway, respectively. Essential tremor is frequently associated with mild gait ataxia. There is growing evidence for an important role of the cerebellar cortex in the pathogenesis of essential tremor. In multiple sclerosis, balance and gait are affected due to cerebellar and spinal cord involvement, as a result of disseminated demyelination and neurodegeneration impairing proprioception. In orthostatic tremor, patients often show mild-to-moderate limb and gait ataxia. The tremor generator is likely located in the posterior fossa. Tandem gait is impaired in the early stages of cerebellar disorders and may be particularly useful in the evaluation of pre-ataxic stages of progressive ataxias. Impaired inter-joint coordination and enhanced variability of gait temporal and kinetic parameters can be grasped by wearable devices such as accelerometers. Kinect is a promising low cost technology to obtain reliable measurements and remote assessments of gait. Deep learning methods are being developed in order to help clinicians in the diagnosis and decision-making process. Locomotor adaptation is impaired in cerebellar patients. Coordinative training aims to improve the coordinative strategy and foot placements across strides, cerebellar patients benefiting from intense rehabilitation therapies. Robotic training is a promising approach to complement conventional rehabilitation and neuromodulation of the cerebellum. Wearable dynamic orthoses represent a potential aid to assist gait. The panel of experts agree that the understanding of the cerebellar contribution to gait control will lead to a better management of cerebellar ataxias in general and will likely contribute to use gait parameters as robust biomarkers of future clinical trials.

Time-dependent and lesion-dependent HMGB1-selective localization in brains of patients with cerebrovascular diseases.

High mobility group box 1 protein (HMGB1) has multiple functions, including the maintenance of nucleosomes and the regulation of gene transcription. HMGB1 is released from activated macrophages, resulting in the induction of inflammatory cytokines. Recently, much research about the role of HMGB1 in cerebrovascular disease (CVD) has been reported. In an animal model, HMGB1 neutralization ameliorates brain infarction, there is an early release of HMGB1 from neurons, and HMGB1 antibody attenuates delayed cerebral vasospasm in experimental subarachnoid hemorrhage. It was also reported that elevation of HMGB1 in serum correlates with severity of acute intracerebral hemorrhage. However, the evidence of HMGB1 localization in brains of patients with CVD is very limited. Therefore, we investigated at autopsy the immunolocalization of HMGB1 in brains of patients with CVD (acute and chronic cerebral infarction, acute cerebral hemorrhage, subarachnoid hemorrhage). In 3 out of 10 acute cerebral infarction cases, the cytoplasm of neurons located around the ischemic core (i.e., penumbra) was positive for HMGB1. In the chronic stage of cerebral infarction, macrophages located in some ischemic regions were positive for HMGB1. Around the hematoma in the basal ganglia, HMGB1-like immunoreactivity (IR) was intense in macrophages. However, around the subarachnoid hematoma, HMGB1-like IR was not seen in the cortex. In arteries surrounded by subarachnoid hematoma, HMGB1-like IR was located in the cytoplasm of vascular smooth muscle cells. These findings, which partially differ from animal model results, may provide translational research and a basis for understanding the role of HMGB1 in brains of patients with CVD.