Misdirection and guidance of regenerating axons after experimental nerve injury and repair

Abstract

Misdirection of regenerating axons is one of the factors that can explain the limited results often found after nerve injury and repair. In the repair of mixed nerves innervating different distal targets (skin and muscle), misdirection may, for example, lead to motor axons projecting toward skin, and vice versa-that is, sensory axons projecting toward muscle. In the repair of motor nerves innervating different distal targets, misdirection may result in reinnervation of the wrong target muscle, which might function antagonistically. In sensory nerve repair, misdirection might give an increased perceptual territory. After median nerve repair, for example, this might lead to a dysfunctional hand.Different factors may be involved in the misdirection of regenerating axons, and there may be various mechanisms that can later correct for misdirection. In this review the authors discuss these different factors and mechanisms that act along the pathway of the regenerating axon. The authors review recently developed evaluation methods that can be used to investigate the accuracy of regeneration after nerve injury and repair (including the use of transgenic fluorescent mice, retrograde tracing techniques, and motion analysis). In addition, the authors discuss new strategies that can improve in vivo guidance of regenerating axons (including physical guidance with multichannel nerve tubes and biological guidance accomplished using gene therapy). 493Abbreviations used in this paper: BDNF = brain-derived neurotrophic factor; DY = diamidino yellow; FB = fast blue; GC = growth cone; GDNF = glial cell line-derived neurotrophic factor; LV = lentiviral vector; NGF = nerve growth factor.

Convergent end‐to‐end neurorrhaphy: An alternative technique for dual innervation of the gastrocnemius muscle in rats

“…However, these assessment methods could lead to unreproducible and unreliable side‐to‐side measurements if variables are not standardized (Wood et al, ). Furthermore, the improper coaptation of the nerve stumps promotes dispersion and poor direction of the regenerating axons, and compromises muscle reinnervation (de Ruiter, Spinner, Verhaagen, et al, ). The use of a synthetic fibrin conduit in the shape of a funnel could be an alternative in cases where the combined thickness of the two proximal nerve stumps is far larger than the thickness of the distal nerve stump (Kalbermatten et al, ).…”

Extensive motor axonal misrouting after conservative treatment of obstetric brachial plexus lesions

“…5 Misrouting occurs when a regenerating axonal sprout grows into a distal basal lamina tube that is not the original one. 8 In misrouting, an outgrowing axon reinnervates muscle fibres in areas other than where they are intended. These fibres may lie in an agonist (e.g.…”

Nociceptive and Neuronal Evaluation of the Sciatic Nerve of Wistar Rats Subjected to Compression Injury and Treated with Resistive Exercise

“…Some neurotrophic factors are produced and released by Schwann cells and then cause a neurotropism effect, that is, guiding the nerve stump to its target organ. Different factors have been identified including nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) [8]. …”