Effectiveness of Radiofrequency Ablation for Treatment of Glossopharyngeal Neuralgia: A Systematic Review of the Current Literature.

BACKGROUND: Glossopharyngeal neuralgia (GPN) is a rare cause of facial pain that has an incidence of less than one per 100,000 people. The excruciating stabbing pain experienced by patients with GPN can be debilitating, leading to difficulties in activities of daily living, such as eating and speaking. As a result, there has been a recent increase in research on the effectiveness of radiofrequency ablation (RFA) for treating GPN. OBJECTIVE: The objective of our study was to evaluate the effectiveness of (RFA for treating GPN while examining its impact on patients' quality of life and assesses for any associated side effects. STUDY DESIGN: The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) model was employed to identify articles from 2 comprehensive medical databases. The patient outcomes and numbers from each article were aggregated and calculated in order to determine the percent efficacy of RFA for treating pain associated with GPN. METHODS: In this systematic review, the PRISMA review model was utilized to search through the PubMed and EMBASE databases. A comprehensive literature review was conducted. Of the initial 1,580 articles identified, 18 articles were included for analysis. Studies included in this systematic review encompassed idiopathic cases and secondary causes, such as an elongated styloid process, oropharyngeal cancers, and postsurgical/traumatic pain. RESULTS: Of the 288 patients treated with RFA, 231 experienced relief or complete resolution of pain, yielding an efficacy rate of 80.2%. Most of the patients experienced immediate pain relief after RFA; however, some patients reported numbness, dysphagia, and changes in taste. Our study examines the potential use of RFA as a minimally invasive and effective treatment for GPN. LIMITATIONS: Limitations of our study include the absence of comparisons between different types, modes, and settings of RFA procedures. The use of only 2 medical databases is another limitation. Finally, our systematic review does not include any randomized controlled trials. CONCLUSION: RFA is efficacious in treating GPN with over 80% of patients experiencing postprocedure pain relief. However, further research in the form of clinical and controlled trials is needed to contribute to a better understanding of RFA's long-term outcomes for patients with GPN.

Human imprinted chromosomal regions are historical hot-spots of recombination.

Human recombination rates vary along the chromosomes as well as between the two sexes. There is growing evidence that epigenetic factors may have an important influence on recombination rates, as well as on crossover position. Using both public database analysis and wet-bench approaches, we revisited the relationship between increased rates of meiotic recombination and genome imprinting. We constructed metric linkage disequilibrium (LD) maps for all human chromosomal regions known to contain one or more imprinted genes. We show that imprinted regions contain significantly more LD units (LDU) and have significantly more haplotype blocks of smaller sizes than flanking nonimprinted regions. There is also an excess of hot-spots of recombination at imprinted regions, and this is likely to do with the presence of imprinted genes, per se. These findings indicate that imprinted chromosomal regions are historical "hot-spots" of recombination. We also demonstrate, by direct segregation analysis at the 11p15.5 imprinted region, that there is remarkable agreement between sites of meiotic recombination and steps in LD maps. Although the increase in LDU/Megabase at imprinted regions is not associated with any significant enrichment for any particular sequence class, major sequence determinants of recombination rates seem to differ between imprinted and control regions. Interestingly, fine-mapping of recombination events within the most male meiosis-specific recombination hot-spot of Chromosome 11p15.5 indicates that many events may occur within or directly adjacent to regions that are differentially methylated in somatic cells. Taken together, these findings support the involvement of a combination of specific DNA sequences and epigenetic factors as major determinants of hot-spots of recombination at imprinted chromosomal regions.

Interindividual variability and parent of origin DNA methylation differences at specific human Alu elements.

We investigated the CpG methylation of 19 specific members of Alu sub-families in human DNA isolated from whole blood, using an assay based on methylation-sensitive restriction endonuclease digestion of genomic DNA and 'hot-stop' polymerase chain reaction. We found significant interindividual variability in the level of methylation for specific Alu elements among the members of 48 three-generation families. Surprisingly, some of the elements also displayed quantitative parent of origin methylation differences; i.e. the mean level of methylation differed significantly when the insertions were transmitted through paternal versus maternal meiosis. Bisulfite sequence analysis of individual elements at such loci suggests, further, that maternal and paternal elements differ in the propensity of particular CpG sites to become unmethylated. Some individuals who exhibited high levels of methylation at specific Alu elements came from families in which more than one member also exhibited abnormal patterns of methylation at the differentially methylated regions of the IGF2/H19 or IGF2R loci, suggesting that there may be heritable differences between individuals in the fidelity with which allelic DNA methylation differences are established or maintained. Quantitative parental origin differences in methylation were identified only for Alu elements that lie in sub-telomeric or sub-centromeric bands of human chromosomes, whereas those assayed at intermediate positions did not exhibit any significant differences. The centromere/telomere restricted location of the methylation differences and the fact that none of these differences occur in regions of chromosomes known to contain transcriptionally imprinted genes suggest that maternal/paternal epigenetic modifications may play additional roles in processes other than transcriptional control.