Morphological Detection and Functional Assessment of Regenerated Nerve after Neural Prosthesis with a PGLA Nerve Conduit

Abstract

This study aimed to observe the morphological characteristics of a PGLA [poly(glycolide-co-L-lactide)] nerve conduit and regenerated nerve bundle in the human body using high-frequency ultrasound and examine functional recovery of the regenerated nerve using functional magnetic resonance imaging (fMRI) after neural prosthesis with a PGLA nerve conduit. Thirty-nine patients underwent high-frequency ultrasound, and one patient with superficial radial nerve injury (27-mm defect) underwent fMRI at one, three, and six postoperative months. The fMRI examination results were compared with sensory detection and high-frequency ultrasound results during the same follow-up window period. The normal and regenerated nerve bundles had similar ultrasonic imaging features. At one postoperative month, fMRI displayed activeness of the normal cortex in the brain region corresponding to the contralateral superficial radial nerve, while no activeness was observed on the ipsilateral side. From three to six postoperative months, fMRI revealed gradually increasing activeness in the brain region corresponding to the ipsilateral superficial radial nerve, but the activation area on the ipsilateral side was smaller than that on the contralateral side. Combining morphological detection of the regenerated nerve using high-frequency ultrasound and functional detection of the regenerated nerve using fMRI may be a valuable method for evaluating repair of peripheral nerve injury.

Ultrasound Appearance of In Vitro Nerve Allografts and Conduits for Peripheral Nerve Reconstruction

“…28 Preliminary studies showed that serial US can evaluate morphological variations of the regenerated nerve. 29 In particular, the changes to the PN in nerve wrapping and the possibility of following nerve regeneration could theoretically be followed by US, although the morphology of the regenerated PNs do not prove the recovery of nerve function. 29 One additional application could be serial following of the resorption of synthetic conduits.…”

“…29 In particular, the changes to the PN in nerve wrapping and the possibility of following nerve regeneration could theoretically be followed by US, although the morphology of the regenerated PNs do not prove the recovery of nerve function. 29 One additional application could be serial following of the resorption of synthetic conduits. In 1 patient, US showed failure of the human umbilical cord artery NC allograft (surgically proved), and the presence of 2 neuromas at the distal and proximal ends of the nerve.…”

“…Haug et al suggested that US may indicate complications such as tube collapse and kinking as well as the failure of tube resorption and neuroma formation 28 . Preliminary studies showed that serial US can evaluate morphological variations of the regenerated nerve 29 . In particular, the changes to the PN in nerve wrapping and the possibility of following nerve regeneration could theoretically be followed by US, although the morphology of the regenerated PNs do not prove the recovery of nerve function 29 .…”

Advances in biotechnology and clinical therapy in the field of peripheral nerve regeneration based on magnetism

“…A variety of materials have been used in the preparation of magnetic nanofibers, such as chitosan/poly (vinyl alcohol) (PVA), poly (ε-caprolactone) (PCL), hydroxyapatite (HA), magnetic poly (L-lactic acid) (PLLA), poly (D, L-lactic acid) (PDLLA), and poly (glycolide-co-L-lactide) (PGLA) (46)(47)(48)(49)(50). Due to the tunability, porosity, hydrophilicity, capacity for the incorporation of biological factors, and the polymeric nature of hydrogels, they are increasingly used in bone or nerve regeneration, cancer therapy, and tissue engineering (51).…”

In Vivo Cellular‐Level 3D Imaging of Peripheral Nerves Using a Dual‐Focusing Technique for Intra‐Neural Interface Implantation

“…Magnetic resonance imaging and ultrasonography, used in clinical practice, can help visualize the peripheral nerve structure in vivo; however, their spatial resolution of hundreds of micrometers is insufficient to visualize cellular structures such as myelinated axons with a diameter of 12–20 µm. [ 11 , 12 , 13 ] Recently, spectral confocal reflectance microscopy [ 14 ] and coherent anti‐Stokes Raman spectroscopy [ 15 ] were successfully applied to visualize the myelinated axons of rodent and rabbit sciatic nerves, respectively, in vivo. However, their narrow field of view (FOV) and nonvolumetric imaging properties provide information limited only to the nerve surface.…”