FUNCTIONAL RECOVERY OF VOICE FUNCTION IN PATIENTS WITH LARYNGEAL DYSFUNCTION: OBSERVATIONAL STUDY
Authors: Мratskova Galina , Petrov Damyan 
Published: December 2021

Introduction: Functional recovery of voice function in patients with laryngeal dysfunction is a slow and lengthy process that is associated with changes in social and economic living conditions. The serious functional damage can also lead to disorders in swallowing and respiratory function. It is believed that paresis passes into definitive if continues for more than 10-12 months due to irreversible changes in the tissues. According to literature data, spontaneous recovery in unilateral vocal cord paralysis is observed in 40% of cases. Low frequency currents with adjustable parameters are frequently used in the practice of electro diagnostics and electrical stimulation in damage of the neuromuscular system and in particular in laryngeal paresis and paralysis. In recent decades, an increase in the number of patients suffering from diseases associated with laryngeal dysfunction was noted by many authors. Interruption of nervous pulsation to laryngeal structures leads to sensory and motor disorders and development of subsequent paralysis of the muscles. Treatment depends on the cause, the severity of the symptoms and time of onset of the disease. It includes non-operative and operative treatment. Non-operative treatment is with good results and should precede surgery.
Purpose: The purpose of this study is to objectify the therapeutic options of neuromuscular elektro-phonatory stimulation /NMEPS/ in patients with laryngeal dysfunction.
Materials and methods: The study included 21 patients with unilateral dysfunction of n. laryngeus recurens after surgery of the thyroid gland. Patients with complete denervation were excluded from the study. Procedures are preceded by electro-diagnostic in direct laryngoscopy to establish the extent of damage of the nerve and to determin the coefficient of accommodation (ACC) and variable parameters for stimulus currents. Therapeutic session is implemented in two stages: (1) 'heating' with galvanic current, and (2) real NMEPS selective stimulation of the damaged muscle, leaving untreated antagonists or neighboring healthy muscles, accompanied by active and targeted implementation of Förster phonatoric exercises, coughing and breathing. Treatment is organized in courses for 10 days, 20 procedures per course.
Results: The results before and after completion of therapeutic course by assessing changes in the coefficient of accommodation(ACC), voice quality, degree of hoarseness, coughing efficiency, presence of dysphagia are reported.
After statistical processing of the obtained results a statistical dependence in relation to dysphonia before and after NMEPS therapy was established (p=0.0001), which is expressed in improvement of medium to mild dysphonia. In relation to dysphagia we found improvement from average-heavy to light form of dysphagia and absence of any symptoms of it after treatment, but there are patients with no change observed (44.4%) and statistical dependence (p=0.005) Patients with dysfunction regarding the effectiveness when coughing, before treatment they were: 16.7%, with severe dysfunction, 50.0% with moderate to severe and 33.3% with light. After NMEPS therapy improvement in the condition of patients with moderate-heavy to light form was observed. The non-parametric analysis proved statistical dependence (Z=3.58 ;p=0.0001). All patients were asked to assess the quality of their voice according to the Linkert five-point rating scale. In the beginning of the therapy 44.4% of the patients ranked their voice quality as poor, 50.0% as moderate and 5.6% as good. After treatment improvement in self-assessment of voice quality from moderate to very good and statistical dependence (p=0.0001) was observed.
Conclusion: The results of the observational study prove that NMEPS therapy is effective for functional recovery in complex treatment of laryngeal dysfunction. Because of the small number of patients included in the study for better objectifying of the effects of the neuro muscular elektro-phonatory stimulation, the studies should continue.