# Biography of Muscle Tension Dysphonia: A Scoping Review
## 4 Discussion
### Diagnosis
Considering these more frequent profiles in MTD, it should be noted that, in some cases, increased rotation of the artytenoids may compress the VB and create the appearance of a vocal false folds phonation. Therefore, it is important to know how to interpret the role of this phenomenon in patients with dysphonia, including MTD, since there is not enough evidence to justify attributing any clinical value to this characteristic. While it is true that lateral compression (LC) can be present in MTD, according to work carried out by Stager and Behrman, this is not necessarily related to the degree, the seriousness, or the stage of dysphonia; as a clinical and diagnostic indicator, LC has less value than AP compression [80; 81]. As it has been found and reported previously, the best way to conduct the physical examination is with a transnasal fiberoptic laryngoscopy, because it is not possible to evaluate compression of the supraglottis well with a fixed lens. Stroboscopy is limited by the supraglottic compression, which can block the vision of the VC [82]. In patients with MTD, the higher the SgP value, the higher the degree of AP compression. AP1a: The anterior commissure is not visible during phonation; AP1b: Vocal processes are not visible during phonation due to the medial approximation of the artytenoids; AP2: only 2/3 of the vocal fold length is visible during phonation. As for acoustic analysis, although there are few studies that focus exclusively on this technique for the diagnosis of MTD, most of them include it. Although there is no characteristic pattern for this pathology, or a specific parameter with a characteristic alteration in patients with MTD, it is a technique that will always provide useful information on the phonatory function of a patient. A possible use of acoustic analysis in patients with MTD is to differentiate between MTD and spasmodic dysphonia (SD). Interruptions in an acoustic signal are highly suggestive of SD and can be a determining factor when differentiating between SD and MTD in severe cases [72; 83]. There is a parameter that began to be studied in 2010 by Stepp et al. [41], the RFF, from which it seems that biomechanical elements can be inferred. It is defined as the fundamental frequency of the cycles immediately preceding and following the production of a voiceless consonant, normalized by the \"steady-state\" fundamental frequencies of the voicing preceding and following the consonant (during a vowel-voiceless consonant-vowel (VCV) utterance). After several studies on this parameter, there is evidence that it may be an acoustic indicator of laryngeal tension. The studies that have compared the RFF of healthy subjects with that of patients with vocal hyperfunction have found significantly lower RFF values in the latter, although it is still not clear which values provide more  
Figure 2: Classification of Universidad de Navarra. information on laryngeal tension: those prior to the voiceless consonant or those after it. There is also evidence of its usefulness as a clinical follow-up tool to quantify progress before and after therapy [41; 84; 85]. However, its analysis has not yet been standardized in clinical voice evaluation, partly because it is currently very time-consuming to perform manually, and also because it requires lengthy training to properly identify the last cycles of a vocal transition [86]. More research is needed to prove its clinical utility and to better understand its underlying physiology, but it may be a very interesting parameter in the study of MTD. Aerodynamic analysis has proven to be a very useful tool in the evaluation of voice alterations. Among the parameters studied, SgP has the lowest variance in subjects without a voice alteration, and, in contrast to GF, SgP is not affected significantly by age or sex [39; 40]. In addition, as already mentioned, its relationship with the degree of anteroposterior compression has been demonstrated, so its study is of great value for the diagnosis of MTD. Espinoza et al.