Three-Dimensional In vivo Magnetic Resonance Imaging (MRI) of Mouse Facial Nerve Regeneration

Repair and regeneration of peripheral nerve injuries that ablate branch points

The peripheral nervous system has an extensive branching organization, and peripheral nerve injuries that ablate branch points present a complex challenge for clinical repair. Ablations of linear segments of the PNS have been extensively studied and routinely treated with autografts, acellular nerve allografts, conduits, wraps, and nerve transfers. In contrast, segmental-loss peripheral nerve injuries, in which one or more branch points are ablated so that there are three or more nerve endings, present additional complications that have not been rigorously studied or documented. This review discusses: (1) the branched anatomy of the peripheral nervous system, (2) case reports describing how peripheral nerve injuries with branched ablations have been surgically managed, (3) factors known to influence regeneration through branched nerve structures, (4) techniques and models of branched peripheral nerve injuries in animal models, and (5) conclusions regarding outcome measures and studies needed to improve understanding of regeneration through ablated branched structures of the peripheral nervous system.

Neural tissue engineering: From bioactive scaffolds and in situ monitoring to regeneration

Peripheral nerve injury is a large-scale problem that annually affects more than several millions of people all over the world. It remains a great challenge to effectively repair nerve defects. Tissue engineered nerve guidance conduits (NGCs) provide a promising platform for peripheral nerve repair through the integration of bioactive scaffolds, biological effectors, and cellular components. Herein, we firstly describe the pathogenesis of peripheral nerve injuries at different orders of severity to clarify their microenvironments and discuss the clinical treatment methods and challenges. Then, we discuss the recent progress on the design and construction of NGCs in combination with biological effectors and cellular components for nerve repair. Afterward, we give perspectives on imaging the nerve and/or the conduit to allow for the in situ monitoring of the nerve regeneration process. We also cover the applications of different postoperative intervention treatments, such as electric field, magnetic field, light, and ultrasound, to the well-designed conduit and/or the nerve for improving the repair efficacy. Finally, we explore the prospects of multifunctional platforms to promote the repair of peripheral nerve injury.

Diagnostic value of dynamic contrast-enhanced magnetic resonance imaging in Bell's palsy

BACKGROUND

Bell's palsy (BP) is the most common form of acute facial nerve disorder and is characterized by rapid onset peripheral facial palsy of unknown etiology.

PURPOSE

To explore the diagnostic value of dynamic contrast-enhanced (DCE) magnetic resonance imagine (MRI) in patients with BP particularly in involved segments.

MATERIAL AND METHODS

A retrospective analysis was performed on the patients with BP who underwent routine MRI examinations and volumetric interpolated breath-hold examination (VIBE) sequence-based DCE-MRI before surgery in our department from January 2015 to July 2020. DCE-MRI data postprocessing was performed on Siemens Workstation Extended MR Work Space 2.6.3.5. Statistical analyses were performed using SPSS®v.19.0. The inter-observer reliability was evaluated with kappa identity test and McNemar's test.

RESULTS

Twenty-three patients were included. On conventional contrast-enhanced MRI, the two observers were inconsistent in their diagnosis of lesion segments of facial nerve (Kappa 0.426, P = 0.009). Compared to the results of the surgery, the diagnostic consistency of both observers was general (Kappa 0.476, P < 0.001 and Kappa 0.430, P < 0.001, respectively). The diagnostic results of DCE-MRI for lesion segments of the facial nerve were consistent between the two observers (Kappa 0.929, P < 0.001). Compared to the results of the surgery, the diagnostic consistency of both observers was good (Kappa 0.753, P < 0.001 and Kappa 0.731, P < 0.001, respectively).

CONCLUSION

Compared to conventional MRI, DCE-MRI has good stability and repeatability in the diagnosis of the lesion segments of the facial nerve as well as a good specificity and accuracy.

Diagnostic value of dynamic contrast-enhanced MRI in Bell's palsy: initial experience

AIM

To assess the ability of conventional magnetic resonance imaging (MRI) combined with dynamic contrast-enhanced (DCE)-MRI to accurately identify characteristic imaging findings of Bell's palsy particularly in involved segments.

MATERIALS AND METHODS

A retrospective analysis was performed on MRI images of patients with Bell's palsy in Shanghai Ninth People's Hospital from January 2015 to July 2019. DCE-MRI analysis was performed on a SIEMENS Workstation Extended MR Work Space 2.6.3.5 and by using the T1-weighted volumetric interpolated breath-hold examination (VIBE) sequence. Statistical analyses were performed by using SPSS v. 19.0. The chi-square test was used to compare the accuracy of conventional MRI versus DCE-MRI in imaging the involved segment of the facial nerve.

RESULTS

Combined with the results of the surgery, the accuracy of conventional MRI in imaging the involved segments of the affected facial nerves was 38.5% (5/13), but was 92.3% (12/13) for DCE-MRI. There was a statistically significant difference between the two groups (chi-square value is 8.327, p = 0.004).

CONCLUSION

DCE-MRI is useful to diagnose the involved segments of the affected facial nerve accurately compared to the conventional MRI. This approach has advantages both for the patient, in terms of safety, and for the physician, in terms of the accuracy of the diagnosis.