The larynx is a "box" where the sound is produced and emitted. It is made up of muscles and cartilage and surrounded by various organs such as the thyroid, esophagus, vessels and nerves.
Voice production is a complex phenomenon involving multiple anatomical, physiological, and physical factors that together lead to the transformation of vocal chordal vibration into sound.
The "motor" that leads to the vibration of the vocal chords and the production of the voice and depends on the conversion of the aerodynamic energy, generated by the breathing, into acoustic energy. The sound produced by the vibration of the vocal cords is then modified and filtered by the organs that are in the mouth and pharynx, that is, it depends on the anatomy of each of us.
Recurrent laryngeal nerves are responsible for providing the vocal chords with the mobility necessary for the emission of sound. They are located behind the thyroid and run its posterior face until they enter the larynx to innervate the vocal cords that are inside. This intima relationship of the nerves with the thyroid gland implies the careful and delicate detachment of the entire course during the surgery, in order to allow the removal of the thyroid safely.
Observation of laryngeal function and careful recording of it is mandatory prior to neck surgery. Generally, the multidisciplinary team that studies and treats thyroid and parathyroid diseases, includes an experienced Otorhinolaryngologist.
It is quite frequent that in the preoperative observation are diagnosed changes in laryngeal function that the patient was unaware of because there are compensatory mechanisms of the voice that allow to hide these lesions. For this reason and because of the possibility of pre-existing diseases of the vocal cords and larynx, this is an important screening query.
During the surgical procedure, which may be more or less complex, the nerve is manipulated and this manipulation may result in a change in the nerve impulse transmission capacity and decrease the mobility of the respective vocal cord.
Dysphonia, commonly called hoarseness, is wrongly considered the most feared consequence of thyroid surgery, since postoperative voice changes are usually transient and occur rarely in patients operated by experienced surgeons.
The change in voice projection with decreased volume (unable to scream) and the impossibility of making high-pitched sounds are present in all patients undergoing neck surgeries, essentially impacting those who use the voice professionally. This is a transient situation, but it should be clarified and accompanied by the surgeon. Sometimes, the patient may need to be reobserved by the Otorhinolaryngologist, preferably by the same, in order to compare the current data with the previously collected data, clarify the patient and guide their follow-up.
In the absence of severe nerve damage, recovery of vocal cord mobility is usually complete, and recovery may vary in length depending on the ability of each organism.
In some cases, the presence of paresis can be recorded, less mobility of the vocal cord, which usually has complete recovery. In more complex surgeries with greater trauma of the recurrent laryngeal nerves, paralysis of the vocal cord can occur, in these cases the vocal cord has no mobility. Fortunately, the compensation of the voice for the increased mobility of the other vocal chord is often observed.
The preoperative speech therapy allows to improve voice quality for those who use it professionally and also for those who present, before surgery, functional changes of the larynx.
Speech therapy should be continued after surgery in the above cases and in those with functional abnormalities again.
An article by the doctor Maria Olímpia Cid, specialist in General Surgery at Hospital Infante Santo CUF.