Transcranial direct current stimulation (tDCS) is one of the latest post-stroke dysphagia treatment modalities, and the effect of tDCS is known to be affected by various factors including genetic polymorphisms. However, the role of catechol-O-methyltransferase (COMT) polymorphisms on tDCS in swallowing is unclear. In this prospective pilot study, we aim to explore the effect of tDCS on the swallowing cortex and subsequent swallowing motor function according to COMT polymorphism. Twenty-four healthy participants received either anodal tDCS or sham mode tDCS on the mylohyoid motor cortex at random order, after inhibitory repetitive transcranial magnetic stimulation (rTMS) for preconditioning. The primary outcome was the changes of mylohyoid-motor-evoked potentials (MH-MEP) amplitude in each COMT polymorphism group, from the post-inhibitory rTMS baseline state to immediate, 30, and 60 min after tDCS. The secondary outcomes were the changes in swallowing function. The results showed that COMT Val/Val polymorphism showed improvement across time in the MH-MEP amplitudes and triggering time of swallowing after tDCS, whereas COMT Met carrier group did not show significant changes of MH-MEP or swallowing function across time. This therapeutic response variability of tDCS in the mylohyoid motor system according to COMT polymorphism support the importance of genetic analysis in individualized dysphagia treatment.

This study aimed to evaluate whether genetic polymorphism is associated with an increased risk of infection, specifically post-stroke aspiration pneumonia. Blood samples were obtained from a total of 206 post-stroke participants (males, n = 136; mean age, 63.8 years). Genotyping was performed for catechol-O-methyltransferase (rs4680, rs165599), dopamine receptors (DRD1; rs4532, DRD2; rs1800497, DRD3; rs6280), brain-derived neurotrophic factor (rs6265), apolipoprotein E (rs429358, rs7412), and the interleukin-1 receptor antagonist gene (rs4251961). The subjects were stratified into two groups, aged < 65 (young) and ≥ 65 (elderly). Functional parameters and swallowing outcomes were measured at enrollment and at 3 months post-onset. The primary outcome was the incidence of aspiration pneumonia. Analysis of the association between genetic polymorphisms and aspiration pneumonia history showed that a minor C rs429358 allele was associated with the occurrence of aspiration pneumonia in the young group, both in the additive and the dominant models (odds ratio: 4.53; 95% CI: 1.60–12.84, p = 0.004). In the multivariable analysis, the minor C rs429358 allele increased the risk of post-stroke aspiration pneumonia in young stroke patients by 5.35 (95% CI: 1.64–20.88). In contrast, no such association was observed in the elderly group. Apolipoprotein E polymorphism may affect the risk of post-stroke aspiration pneumonia.

Anti-Hu antibodies usually present in small cell lung cancer are associated with encephalomyelitis, encephalitis, cerebellitis, and neuropathies. However, to our knowledge, non-small-cell lung cancer (NSCLC) related anti-Hu syndrome presenting acute exacerbation of dysphagia has not been reported. Herein, we report a rare case of atypical dysphagia in an anti-Hu positive NSCLC patient resulting in a fatal outcome. A 73-year-old Korean male went through surgical interventions for recurrent tongue cancer and NSCLC. After the surgery, he resumed full oral feeding with a regular diet. However, four weeks later, he developed a sudden difficulty in swallowing. Neck computed tomography angiography, brain magnetic resonance imaging, brain positron emission tomography, computed tomography and electromyography all showed nonspecific findings. A paraneoplastic antibody test was positive for anti-Hu antibodies. His dysphagia worsened and eventually, he expired due to malignant pleural effusion. Our case shows that anti-Hu antibodies can be expressed in NSCLC and when associated with dysphagia, the outcome can be fatal.