Entrapment Neuropathies in Chronic Stroke Patients

ExoMechHand prototype development and testing with EMG signals for hand rehabilitation

Rehabilitation is a major requirement to improve the quality of life and mobility of patients with disabilities. The use of rehabilitative devices without continuous supervision of medical experts is increasing manifold, mainly due to prolonged therapy costs and advancements in robotics. Due to ExoMechHand's inexpensive cost, high robustness, and efficacy for participants with median and ulnar neuropathies, we have recommended it as a rehabilitation tool in this study. ExoMechHand is coupled with three different resistive plates for hand impairment. For efficacy, ten unhealthy subjects with median or ulnar nerve neuropathies are considered. After twenty days of continuous exercise, three subjects showed improvement in their hand grip, range of motion of the wrist, or range of motion of metacarpophalangeal joints. The condition of the hand is assessed by features of surface-electromyography signals. A Machine-learning model based on these features of fifteen subjects is used for staging the condition of the hand. Machine-learning algorithms are trained to indicate the type of resistive plate to be used by the subject without the need for examination by the therapist. The extra-trees classifier came out to be the most effective algorithm with 98% accuracy on test data for indicating the type of resistive plate, followed by random-forest and gradient-boosting with accuracies of 95% and 93%, respectively. Results showed that the staging of hand condition could be analyzed by sEMG signal obtained from the flexor-carpi-ulnaris and flexor-carpi-radialis muscles in subjects with median and ulnar neuropathies.

Ultrasound measurements of the median nerve at the carpal tunnel in ambulant chronic stroke patients: comparison between paretic and non-paretic sides

[Purpose] The purpose of this study was to examine the cross-sectional area (CSA) and longitudinal sliding length (LSL) of the median nerve bilaterally in patients with ambulant chronic hemiplegia and to compare these measurements with those in healthy controls using ultrasound. [Participants and Methods] Forty patients with hemiplegia who developed a non-functional hand on the paretic side after one year or more of stroke and 25 asymptomatic controls were included. To obtain the CSA of the median nerve at the wrist in the neutral position and the LSL of the median nerve during wrist extension, the participants underwent bilateral ultrasound examination. [Results] The non-paretic side of stroke patients had the largest median nerve CSA, followed by the paretic side and then the controls; the median nerve CSA in the non-paretic side and the controls differed significantly. The CSA of the median nerve was significantly larger in the non-paretic sides of patients, evaluated at more than 5.5 years post-stroke relative to those evaluated at less than 5.5 years. The LSL of the paretic side was significantly shorter than the non-paretic side and the controls. [Conclusion] Compared to the controls, the CSA of the median nerve was enlarged in the non-paretic hand of ambulant chronic stroke patients and the LSL were identical. As such, entrapment neuropathy of the median nerve may follow long-term chronic stroke due to overuse. This study indicates the usefulness of ultrasound in the potential identification of such cases.

Alterations in the spinal cord and ventral root after cerebral infarction in non-human primates

BACKGROUNDS

Cerebral infarction does not only cause focal injury in the ischemic site, but also secondary non-ischemic damage at the remote areas of nervous system associated with the primary focus.

OBJECTIVE

This study investigated the changes in the spinal cord and ventral root after middle cerebral artery occlusion (MCAO) in cynomolgus monkeys (Macaca fascicularis).

METHODS

Adult male cynonolgus monkeys (4-5 years, 5.5-7.5 kg) were subjected to MCAO (n = 6) or sham surgery (n = 4). After 12 weeks, spinal cords and the ventral roots were harvested. Morphometric alterations in the spinal cord were detected at C5 and L5 levels via immunofluorescence. The profiles of C5 and L5 ventral roots were displayed by toluidine blue staining and transmission electron microscopic examination.

RESULTS

Significant axonal loss in the contralateral corticospinal tract and abnormally enlarged axons in the ipsilateral were observed in monkeys with MCAO. The number of neurons in the contralateral ventral horn got declined while that in the ipsilateral was almost unaffected after MCAO compared with sham controls. Glial activation post-MCAO was observed in the bilateral corticospinal tract and the ventral horn. Aberrant nerve fibers appeared frequently in the contralateral ventral roots of MCAO monkey but rarely in the ipsilateral.

CONCLUSIONS

These results indicate that focal cerebral infarction leads to pathological alterations in the spinal cord and ventral roots in non-human primates.

Electrodiagnostic and nerve ultrasonographic features in upper limb spasticity: an observational study

To better understand the effects of spasticity on peripheral nerves, we evaluated the electrodiagnostic and nerve ultrasonographic features of the median and ulnar nerves in adults with upper limb spasticity. Twenty chronic stroke patients with spastic hemiparesis underwent nerve conduction study and nerve ultrasonography of the median and ulnar nerves at both upper limbs. Affected versus unaffected upper limb comparisons showed significant differences in the median and ulnar nerve distal motor latencies, compound muscle action potentials and F-wave minimal latencies. Furthermore, we observed a significantly greater median nerve crosssectional area at the elbow of the affected upper limb compared with the unaffected one. Our findings confirmed electrodiagnostic asymmetries and nerve ultrasonographic abnormalities in the affected versus the unaffected upper limb after stroke. Slight changes in lower motor neuron activity and spasticity might contribute to these alterations.

Ulnar Neuropathy at the Elbow in Chronic Alcohol-Dependent Subjects

OBJECTIVES

To evaluate the occurrence of Ulnar neuropathy at the elbow (UNE) among alcohol dependent subjects.

METHOD

The study sample comprised 99 consecutive alcohol dependent subjects treated for detoxification voluntarily in the specialized unit of the Athens University Psychiatric Clinic in an inpatient basis.

RESULTS

UNE was found in 51 subjects (51.5%): in 40.4% on the right side, in 44.6% on the left and in 20.1% on both. Polyneuropathy was diagnosed in 41.4% of the total sample. Statistical analysis showed UNE significantly associated with age of the subjects, age at alcohol dependence onset and duration of alcohol dependence. Was more frequent in men and the probability of UNE was lower in obese subjects.

CONCLUSIONS

UNE is frequent among alcohol dependent subjects and they must be instructed to avoid abnormal postures and to protect their elbow while working with the elbows flexed and resting on a hard object.

Neuroprotective coordination of cell mitophagy by the ATPase Inhibitory Factor 1

The mitochondrial ATPase Inhibitory Factor 1 (hereafter referred to as IF1) blocks the reversal of the F1Fo-ATPsynthase to prevent detrimental consumption of cellular ATP and associated demise. Herein, we infer further its molecular physiology by assessing its protective function in neurons during conditions of challenged homeostatic respiration. By adopting in vitro and in vivo protocols of hypoxia/ischemia and re-oxygenation, we show that a shift in the IF1:F1Fo-ATPsynthase expression ratio occurs in neurons. This increased IF1 level is essential to induce accumulation of the PTEN-induced putative kinase 1 (PINK-1) and recruitment of the mitophagic ubiquitin ligase PARK-2 to promote autophagic "control" of the mitochondrial population. In IF1 overexpressing neurons ATP depletion is reduced during hypoxia/ischemia and the mitochondrial membrane potential (ΔYm) resilient to re-oxygenation as well as resistant to electrogenic, Ca(2+) dependent depolarization. These data suggest that in mammalian neurons mitochondria adapt to respiratory stress by upregulating IF1, which exerts a protective role by coordinating pro-survival cell mitophagy and bioenergetics resilience.