[The role of electromyography in cases of vocal cord paralysis]. / El papel de la electromiografía laríngea en la parálisis de cuerda vocal.

BACKGROUND: Several pathologies can involve muscles that control vocal folds. The abnormality can affect peripheral nerves or central nervous system centers. Clinically, muscle function can be assessed by observing the movement of structures themselves or by recording electrical activity of these muscles using (electromyography-EMG). Since EMG is an invasive technique, its use is not very widespread in the diagnosis and management of voice disorders, Laryngeal EMG can be helpful in those patients with voice problems of suspected neurological or neuromuscular etiology. OBJECTIVE: Assess the role of laryngeal EMG in the clinical evaluation of unilateral vocal cord immobility. METHODS: Twenty-five patients with unilateral vocal cord paralysis were studied. Twenty-five patients with unilateral arytenoid dislocation were studied as controls. The sensitivity and specificity of the EMG as a diagnostic marker for vocal fold paralysis were obtained. RESULTS: Laryngeal EMG showed a 100% sensitivity and 92% specificity. Only two patients displaying arytenoid dislocation displayed abnormal EMG recordings. CONCLUSIONS: EMG constitutes a safe and reliable tool to aid the evaluation of patients with vocal fold immobility. EMG recordings were helpful in differentiating vocal cord paralysis from arytenoid dislocation. Moreover, EMG can provide useful data regarding denervation and reinnervation of laryngeal muscles. Aside from its diagnostic usefulness, serial EMG can help to monitor recovery and establish a reliable prognosis. Hence, an adequate treatment plan can be determined.