Brain waves spectral analysis of human responses to odorous and non-odorous substances: a preliminary study.

OBJECTIVE: The aim of this study was to identify the potential electrophysiological biomarkers of human responses by comparing the electroencephalogram brain wave changes towards lavender versus normal saline in a healthy human population. METHOD: This study included a total of 44 participants without subjective olfactory disturbances. Lavender and normal saline were used as the olfactory stimulant and control. Electroencephalogram was recorded and power spectra were analysed by the spectral analysis for each alpha, beta, delta, theta and gamma bandwidth frequency upon exposure to lavender and normal saline independently. RESULTS: The oscillatory brain activities in response to the olfactory stimulant indicated that the lavender smell decreased the beta activity in the left frontal (F7 electrode) and central region (C3 electrode) with a reduction in the gamma activity in the right parietal region (P4 electrode) (p < 0.05). CONCLUSION: Olfactory stimulants result in changes of electrical brain activities in different brain regions, as evidenced by the topographical brain map and spectra analysis of each brain wave.

Early Transthyrohyoid Injection Laryngoplasty Under Local Anaesthesia in a Single Tertiary Center of Southeast Asia: Multidimensional Voice Outcomes.

Objective: To study the effectiveness of early percutaneous transthyrohyoid injection laryngoplasty under local anesthesia in improving voice quality in unilateral vocal fold paralysis (UVFP) patients. Methods: Longitudinal data of 29 UVFP patients who underwent injection laryngoplasty within six months from the onset of the symptoms were studied. The injectate (0.5-1 mL) was hyaluronic acid-based material (Juvéderm ULTRA XC; Allergan Industrie, France) that was delivered under local anesthesia with transthyrohyoid approach using a double-bend 21G needle. Multidimensional voice outcomes employing: 1) Malay-Voice-Handicap Index-10 (mVHI-10); 2) maximum phonation time (MPT); and 3) acoustic analysis [jitter%, shimmer% and noise-harmonic ratio (NHR)] were used to assess the treatment progress. The voice parameters were measured at baseline (2 weeks pre-injection), and at the first and third months post-injection. Results: The mean age of the 29 patients was 44.69 years, with a female-to-male ratio of 3.14:1. The voice outcomes measured at different time points were evaluated with repeated measures ANOVA. Significant improvement was observed from baseline to three months post injection laryngoplasty for mVHI-10, jitter, and NHR (p<0.001), shimmer (p=0.005) and MPT (p=0.018). Following the procedure, none of the patients developed any major complications. Conclusion: Office setting early transthyrohyoid injection laryngoplasty using a double-bend needle is a safe and effective procedure in patients with UVFP with evidence of significant improvement in voice and life quality.