Addressing research gaps on rapid palatal expansion effects on voice function in patients with cleft and extending the European Laryngological Society 2001 guideline

It may be surprising that even in recent years, the evaluation of voice function before and after treatment in patients with cleft palate has often been limited to the statistical analysis of formant frequencies, shimmer, and jitter. This reductionist approach fails to account for the complexity of voice function within an n-dimensional manifold. This review aims to address the methodology problems found in the literature and develop a comprehensive voice function assessment tool by extending the guideline of the European Laryngological Society for assessing the effect of rapid palatal expansion on voice function in patients with cleft. The scoping review was conducted according to the PRISMA guidelines, with the following research topic: ‘How is vocal function assessed before and after rapid maxillary expansion in patients with operated cleft lip and palate?’. Based on the final stage of the study selection process, only two studies were included in the review. The key differences between them involved age groups, expander types, the focus on nasalance, subjective ratings, and the presence of a well-structured classification based on hearing impairment. The basics of comprehensive voice function analysis before and after rapid palatal expansion in patients with cleft—especially when glottic-level issues are present—must start somewhere, and this is the first step: Everything is in everything.