Introdução: Electromyography (EMG) is a technique developed and used in neurology for diagnosis and prognostic definition of neuromuscular diseases. Study design: Clinical prospective. Material and method: Thirty (30) patients with vocal fold immobility have been grouped according to the diagnostic hypothesis clinically established. Results: LEMG diagnosed periphery neuropathic injury, central neuropathic injury or fixation of cricoarytenoid cartilage in all patients who presented vocal fold immobility with no defined cause. In those patients with vocal fold immobility on account of clinically defined mechanical traumatic cause, LEMG confirmed peripheral neuropathic damage in 70% of the cases and for the remaining 30% of the cases, it determined other causes such as peripheral neuropathy by compression, myopathy and fixation of cricoarytenoid cartilage. Conclusion: LEMG confirmed chronic neuropathic damage in those patients with vocal fold immobility by virtue of compression caused by a possible clinically defined tumor.683369375Desmedt, J.E., Borenstein, S., Collateral innervation of muscle fibers by motor axons of dystrophic motor units (1973) Nature, (246), pp. 500-501Dumitru, D., (1995) Electrodiagnostic medicine. 1 ed., pp. 229-234. , Hanley-Belfus IncFaaborg-Andersen, K., Electromyographic investigation of intrinsic laryngeal muscle in humans (1957) Acta Physiol Scand (suppl), 41 (SUPPL.), p. 140Gorio, A., Carmignoto, G., Finesso, M., Polato, P., Nunzi, M.G., Muscle reinnervation II. Sprouting, synapse formation and repression (1983) Neuroscience, (8), pp. 403-416Gorio, A., Marini, P., Zanoni, R., Muscle reinnervation III. Motoneuron sprouting capacity, enhancement by exogenous gangliosides (1983) Neuroscience, (8), pp. 417-429Gupta, S.R., Bastian, R.W., Use of laryngeal electromyography in prediction of recovery after vocal cord paralysis (1993) Muscle & Nerve, pp. 977-978. , SetHirano, M., Nozoe, I., Shin, T., Maeyama, T., Electromyographic findings in recurrent laryngeal nerve paralysis. A study of 130 cases (1974) Practice Otologia Kyoto, (67), pp. 231-242Kimaid, P.A.T., Resende, L.A.L., Quagliato, E.M.A.B., Viana, M.A., Crespo, N.A., Wolf, A., Eletromiografia Laríngea: Estudo normativo do potencial de unidade motora dos músculos tireoaritenoideus e cricotiroideus (2001) Arq Neuropsiquiatr, 59 (3 B), pp. 58-59Kimura, J., (1989) Electrodiagnosis in Diseases of Nerve and Muscle. 2ed., pp. 249-274. , Philadelphia: F.A. Davis CompanyKotby, M.N., Fadly, E., Madkour, O., Barakah, A., Khidr, A., Allousb, T., Saleh, M., Electromyograpby in neurolaryngology (1992) Journal of Voice, (2), pp. 159-187Koufman, J.A., Walker, F.O., Johardji, G.M., The cricothyroid muscle does not influence vocal fold position in laryngeal paralysis (1995) Laryngoscope, (105), pp. 368-372Lovelace, R.E., Blitzer, A., Ludlow, C.L., Clinical laryngeal electromyography (1992) Neurologic Disorders of the Larynx, pp. 66-81. , Blitzer A, Sasaki CT, Fahn S, Brin A, Harris KS. New York: Thieme PublishersMu, L., Yang, S., Electromyographic study on end-to-end anastomosis of the recurrent laryngeal nerve in dogs (1990) Laryngoscope, 100, pp. 1009-1017Mu, L., Yang, S., An experimental study on the laryngeal electromyography and visual observations in varying types of surgical injuries to the unilateral recurrent laryngeal nerve in the neck (1991) Laryngoscope, 101, pp. 699-708Munin, M.C., Murry, T., Rosen, C.A., Laryngeal electromyography. Diagnosis and prognostic applications (2000) Otolaryngologic Clinics of North America, 4, pp. 759-771Rontal, E., Rontal, M., Silverman, B., Kileny, P.R., The clinical differentiation between vocal cord paralysis and vocal cord fixation using electromyography (1993) Laryngoscope, 103, pp. 133-137Schaefer, S.D., Laryngeal electromyography (1991) Otolaryngologic Clinics of North America, 5, pp. 1053-1057Schweizer, V., Woodson, G.E., Bertorini, T.E., Single-fiber electromyography of the laryngeal muscle (1999) Muscle & Nerve, 22, pp. 111-114Shindo, M.L., Herzon, G.D., Hanson, D.G., Cain, D.J., Sahgal, V., Effects of d dennervation on Laryngeal muscle: A Canine Model (1992) Laryngoscope, 102, pp. 663-669Simpson, D.M., Sternman, D., Graves-Wrigth, J., Sanders, I., Vocal Cord paralysis: Clinical and electrophysiologic features (1993) Muscle & Nerve, 16, pp. 952-957Traissac, L., Gioux, M., Rovira, H.P., Henry, C., Bertrand, B., L'Electromyographie (EMG) du larynx dans le diagnostic des immobilités larynges spontanées ou post-thyroïdectomie (1991) Revue de Laryngologie, 112 (3), pp. 205-207Tucker, H.M., Vocal cord paralisis-1979: Etiology and management (1980) Laryngoscope, 89, pp. 504-507Verhulst, J., Gioux, M., Castro, E., Quintero, R., Traissac, L., Intérêt et role de l'electromyographie dans l'evaluation d'um trouble de la mobilité laryngée et son pronostic (1995) Vet Laryngol Otol Rhinol, 116 (4), pp. 289-292Wolf, A.E., Crespo, A.N., Qualiato, E., Kimaid, P.A., Viana, M., Eletromiografia Laríngea: Aspectos Técnicos (2000) 35 a Congresso Brasileiro De Otorrinolaringologia, p. 95. , Rio Grande do Norte. Temas Livres, Rio Grande do Norte, Sociedade Brasileira de Otorrinolaringologia, 2000. (Resumo, TL-L-12)Woodson, G.F., Clinical value of laryngeal EMG is dependent on experience of the clinician (1998) Arch Otolaryngol Head Neck Surg, 124 (4), p. 476Weddel, G.B., Feinstein, B., The electrical activity of the voluntary muscles in man under normal and pathological conditions (1944) Brain, 67, pp. 178-242Yin, S.S., Qiu, W.W., Stucker, F.J., Value of electromyography in differential diagnosis of laryngeal joint injuries after intubation (1996) Ann Otol Rhinol Laryngol, 105, pp. 446-451Yin, S.S., Qiu, W.W., Stucker, F.J., Major patterns of laryngeal electromyography and their clinical application (1997) Laryngoscope, 107, pp. 126-136Yin, S., Stucker, F., Qiu, W.W., Batchelor, B.M., Clinical evaluation of neurolaryngological disorders (2000) Ann Otol Rhinol Laryngol, 109, pp. 832-838