Pathological evidence of demyelination in the recurrent laryngeal, phrenic, and oculomotor nerves in Charcot-Marie-Tooth disease 4F

A comparative analysis of laryngeal nerve damage in patients with idiopathic vocal cord paralysis exhibiting different paralytic sides

Objective

To assess the extent of recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) damage in patients with idiopathic vocal cord paralysis (IVCP) exhibiting different paralytic sides.

Methods

A total of 84 IVCP cases were evaluated using stroboscopic laryngoscopy, voice analysis, and laryngeal electromyography (LEMG). The results were compared between patients with left-sided paralysis and right-sided paralysis based on different disease courses (less than or more than 3 months).

Results

Initially, the average age and disease progression of IVCP patients were found to be similar regardless of the side of paralysis (p > .05). Additionally, there were no significant variations in voice indicators, such as MPT, DSI, and VHI, between IVCP patients with left and right vocal cord paralysis (p > .05). Furthermore, no disparities were detected in the latencies and amplitudes of the paralyzed RLN and SLN, as well as the durations and amplitudes of the action potentials in the paralyzed TM and PCM, among IVCP patients with left and right vocal cord paralysis (p > .05). Notably, the amplitudes of the left paralytic CM were significantly lower than those of the right paralytic CM (0.45 vs. 0.53, Z = -2.013, p = .044). In addition, no disparities were observed in APDs and amplitudes between the ipsilateral PCM and TM, either for patients with left or right vocal fold paralysis (p > .05). Finally, all the IVCP patients were subdivided into two subgroups according to different disease course (less than or more than 3 months), and in each subgroup, the comparison of voice indicators and LEMG results in IVCP patients with left or right vocal fold paralysis were similar with the above findings (p > .05).

Conclusion

Overall, the degree of RLN and SLN damage appeared to be similar in IVCP patients with left and right vocal cord paralysis, provided that the disease course was comparable.

Level of Evidence

4.

Screening for PRX mutations in a large Chinese Charcot-Marie-Tooth disease cohort and literature review

Background

Periaxins (encoded by PRX) play an important role in the stabilization of peripheral nerve myelin. Mutations in PRX can lead to Charcot-Marie-Tooth disease type 4F (CMT4F).

Methods

In this study, we screened for PRX mutations using next-generation sequencing and whole-exome sequencing in a large Chinese CMT cohort consisting of 465 unrelated index patients and 650 healthy controls. Sanger sequencing was used for the validation of all identified variants. We also reviewed all previously reported PRX-related CMT cases and summarized the clinical manifestations and genetic features of PRX-related CMTs.

Results

The hit rate for biallelic PRX variants in our cohort of Chinese CMT patients was 0.43% (2/465). One patient carried a previously unreported splice-site mutation (c.25_27 + 9del) compound heterozygous with a known nonsense variant. Compiling data on CMT4F cases and PRX variants from the medical literature confirmed that early-onset (95.2%), distal amyotrophy or weakness (94.0%), feet deformity (75.0%), sensory impairment or sensory ataxia (65.5%), delayed motor milestones (60.7%), and spinal deformity (59.5%) are typical features for CMT4F. Less frequent features were auditory impairments, respiratory symptoms, late onset, dysarthria or hoarseness, ophthalmic problems, and central nervous system involvement. The two cases with biallelic missense mutations have later onset age than those with nonsense or frameshift mutations. We did not note clear correlations between the type and site of mutations and clinical severity or distinct constellations of symptoms.

Conclusion

Consistent with observations in other countries and ethnic groups, PRX-related CMT is rare in China. The clinical spectrum is wider than previously anticipated.

Review of general and head and neck/oral and maxillofacial features of Charcot-Marie-Tooth disease and dental management considerations

Charcot-Marie-Tooth disease (CMTD) is an uncommon progressive neuromuscular disorder of the peripheral nervous system and primarily leads to distal extremity weakness and sensory deficits. Frequently, affected patients manifest pes cavus, drop foot, and digit contractures that may pose significant challenges in ambulation and grasping objects. Although there are numerous articles of this syndrome in the medical literature, there is a limited number of dental publications. The objective of this article is to review the general and head and neck/oral and maxillofacial features of CMTD. General guidelines for dental management are also provided.