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World J. Surg. 28, 755760, 2004DOI: 10.1007/s00268-004-7348-xWORLDJournal ofSURGERY 2004 by the Societe
Internationale de ChirurgieRecurrent Laryngeal Nerve Identification and Assessment during Thyroid
Surgery: Laryngeal PalpationGregory W. Randolph, M.D.,1 James B. Kobler, Ph.D.,2 Jamie Wilkins, M.Sc.31Department of Otology and Laryngology, Harvard Medical School, 243 Charles Street, Boston, Massachusetts 02114, USA2H.P. Mosher Laryngology Research Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts 02114, USA3Department of Audiology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, 02114 Boston, Massachusetts, USAPublished Online: August 3, 2004Abstract. Electrical identification and monitoring of the recurrent laryngeal nerve (RLN) has been proposed as an adjunct to standard visual identification of the nerve during thyroid and parathyroid surgery. This study
was undertaken to assess laryngeal palpation as an intraoperative technique for identifying and assessing the RLN during surgery and to investigate the relation between laryngeal palpation and associated laryngeal
electromyographic (EMG) activity. The postcricoid region of the larynx
during surgery was palpated through the posterior hypopharyngeal wall to
sense posterior cricoarytenoid muscle contraction in response to ipsilateral RLN stimulation (i.e., the laryngeal twitch response.) Laryngeal palpation was performed in a series of 449 consecutive thyroid and parathyroid surgeries with 586 RLNs at risk. All patients underwent preoperative
and postoperative laryngoscopy to assess vocal cord mobility. In a subset of
patients, laryngeal palpation and simultaneous laryngeal EMG recordings
were compared during intraoperative RLN stimulation. In this series,
there was no permanent RLN paralysis. There was one case of temporary
RLN paralysis secondary to neural stretch that resolved 6 weeks postoperatively (temporary paralysis rate: 0.2% of patients, 0.2% of nerves at
risk). Intraoperative laryngeal palpation of the laryngeal twitch response
reliably correlated with normal postoperative vocal cord function. Loss of
the laryngeal twitch response occurred in the single case of temporary paralysis in the setting of an anatomically intact nerve. Laryngeal palpation
correlated well with simultaneous laryngeal EMG activity. There were no
palpation-induced laryngeal injuries or laryngeal edema. There were also
no RLN injuries due to repetitive neural stimulation. Intraoperative laryngeal palpation during RLN stimulation is a safe, reliable method for neural
monitoring that can assist in RLN identification and assessment during
thyroid and parathyroid surgery. Most importantly, it provides important
prognostic information regarding ipsilateral vocal cord function at the
completion of the initial...