The Role of Physical Exercise and Rehabilitative Implications in the Process of Nerve Repair in Peripheral Neuropathies: A Systematic Review

Abstract

Background: The various mechanisms involved in peripheral nerve regeneration, induced by exercise and electrical nerve stimulation, are still unclear. Objective: The aim of this review was to summarize the influence of physical exercise and/or electrical stimulation on peripheral nerve repair and regeneration and the variatio nerve stimulationn of impact of intervention depending on timing, as well as kind and dosage of the intervention. A literature survey was conducted on PubMed, Scopus, and Web of Science, between February 2021 to July 2021, with an update in September 2022. Methodology: The literature search identified 101,386 articles with the keywords: “peripheral nerve” OR “neuropathy” AND “sprouting” OR “neuroapraxia” OR “axonotmesis” OR “neurotmesis” OR “muscle denervation” OR “denervated muscle” AND “rehabilitation” OR “physical activity” OR “physical exercise” OR “activity” OR “electrical stimulation”. A total of 60 publications were included. Eligible studies were focused on evaluating the process of nerve repair (biopsy, electromyographic parameters or biomarker outcomes) after electrical stimulation or physical exercise interventions on humans or animals with peripheral sensory or motor nerve injury. Synthesis: This study shows that the literature, especially regarding preclinical research, is mainly in agreement that an early physical program with active exercise and/or electrical stimulation promotes axonal regenerative responses and prevents maladaptive response. This was evaluated by means of changes in electrophysiological recordings of CMAPs for latency amplitude, and the sciatic functional index (SFI). Furthermore, this type of activity can cause an increase in weight and in muscle fiber diameter. Nevertheless, some detrimental effects of exercising and electrical stimulation too early after nerve repair were recorded. Conclusion: In most preclinical studies, peripheral neuropathy function was associated with improvements after physical exercise and electrical stimulation. For humans, too little research has been conducted on this topic to reach a complete conclusion. This research supports the need for future studies to test the validity of a possible rehabilitation treatment in humans in cases of peripheral neuropathy to help nerve sprouting.

Early Intensive Neurorehabilitation in Traumatic Peripheral Nerve Injury—State of the Art

“…Regeneration is estimated to a rate of nearly about 1 mm/day [ 30 , 32 ] and different nerve conduction studies (NCS) have been used [ 33 , 34 , 35 , 36 , 37 , 38 ], essentially, for the analysis of nerve conduction velocity [ 33 , 39 ] and electromyography (EMG), to record the compound muscle action potentials (CMAPs) [ 33 , 40 , 41 , 42 ], which is considered the best diagnosis to evaluate neuropathies and myopathies [ 43 ].…”

“…Electrodiagnostic testing in the clinical setting of a physiotherapy and rehabilitation center is not realistically easy to apply. However, it is possible to evaluate the nociceptive withdrawal reflex as an outcome measure [ 33 , 47 , 48 ] and also to document weight [ 36 , 49 , 50 , 51 , 52 ] and muscle mass as a sign of an increase in fiber diameter [ 38 , 53 , 54 , 55 , 56 , 57 ]. Assessments of functional recovery may be possible by video-based motion analysis that makes a precise evaluation of muscle function during locomotion [ 41 , 58 ].…”

“…Additionally, systemic biomarker measurements, such as the levels of neurotrophins and neurotrophic factors, could be used as nerve repair parameters [ 33 ]. The expression of brain-derived neurotrophic factor (BDNF) and its signal transduction receptor (TrkB) [ 33 , 47 , 65 , 66 , 67 , 68 , 69 ], as well as the nerve growth factor (NGF) and growth-associated protein 43 (GAP-43) levels, could be interesting parameters for this type of analysis [ 48 , 70 ]. After one week of intensive voluntary exercise, there should be an increase in the neurotrophic factor, BDNF [ 65 , 69 , 71 ].…”

“…Immobilization promotes detrimental effects on the number of fibers of the muscles compared to the contralateral limb [ 33 , 53 ] and can delay recovery, most likely due to a reduction in muscle regeneration rate [ 33 ].…”

Patient Outcomes After Peripheral Nerve Injury Depend on Bimanual Dexterity and Preserved Use of the Affected Hand

“…Physiologically, patients with traumatic nerve injury often do not benefit from physical therapy, 10 but success may be possible, since animal models have shown that exercise interventions can promote nerve and muscle regrowth. 11 Occupational therapy or related biopsychosocial interventions are recommended for rehabilitation after small fiber neuropathy, 12 and quality of life after peripheral nerve injury may depend on therapists' ability to help patients engage in meaningful work and household roles. 4,13 However, little of this research has explored specific consequences of unilateral impairment, because many clinical assessments were not designed to consider which hand was impaired.…”