The purpose of this study is to evaluate a surgical technique for the preservation of the function of the external branch of the superior laryngeal nerve (EBSLN) during total thyroid lobectomy and total thyroidectomy. Permanent injury to this nerve can be a disaster, especially in singers and professional speakers who depend on control of pitch, and a clear and forceful voice. Voice changes may be either obvious or subtle. For better voice analysis, a detailed questionnaire is necessary. Thus, the evaluation in this study is based on laryngoscopy of 934 nerves in 675 patients and detailed subjective voice evaluation of 66 patients during the last 2 years of the study. There are 2 surgical principles. First, the EBSLN is not routinely exposed; the distal 1.5 to 2.0 cm (critical area) of the superior thyroid vessels are carefully dissected, exposed, and ligated, preferably independently. Careful observation ensures that the EBSLN is not included in the ligature. Second, the ultimate evaluation of the surgical technique is the effect of voice changes on the patient's lifestyle. Laryngoscopy of 934 nerves found bowing, temporary in 4 patients and permanent in 1 patient (limited follow-up). Of the 66 patients with voice evaluations, 14 had changes: 9 had temporary changes, while 5 had permanent changes. In these 14 patients, voice changes had no effect on lifestyle in 13, and the effects were indeterminate in 1 (unavailable for follow-up). The estimated deleterious effect of voice changes on lifestyle is no greater than 1.5% of the 66 patient responders.

A technique of exposure and preservation of the recurrent laryngeal nerve at the very onset of thyroidectomy and preservation of the external branch of the superior laryngeal nerve at the close of the procedure is described, which is believed to afford maximum protection to these nerves during total thyroid lobectomy and isthmusectomy as well as total thyroidectomy. At the same time, preservation of the parathyroid glands is achieved. In 120 exposures and preservations of the recurrent laryngeal nerve there have been no instances of a single permanent paralysis of this nerve. In 111 total thyroid lobectomies in which the external branch of the superior laryngeal nerve was placed in jeopardy, only one patient had a slight bowing of the vocal cord with excellent voice function during a limited follow-up period.

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The nature of the RCTs is that they are difficult to use to evaluate surgical techniques. Some options are available to minimize these difficulties. Designing and conducting RCTs to evaluate surgical interventions require careful planning and some compromises. Unless the previously mentioned criteria are applied, the validity of the RCT can be considered no greater than that of other trials.

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