The incidence of superior laryngeal nerve (SLN) lesions and their consequences in terms of voice quality was studied in 20 patients undergoing thyroid surgery, performed by surgeons who were not specialists in endocrine surgery. The SLN function was examined by electromyography (EMG) of the cricothyroid muscles before and after surgery. Voice analysis was performed through the registration of the average pitch and range of the speaking voice and the upper pitch limit. The perceptual voice quality was judged by a panel of listeners. Voice problems were registered through a questionnaire. The larynx status was examined by indirect laryngoscopy before and after surgery. Three patients who had not previously been operated on in the neck had partial SLN lesions before surgery. According to the EMG, no SLN at risk developed a complete lesion, but 58% of the SLN's developed partial lesions which persisted 1 year after surgery in all but 1 of the examined patients. Seven of 10 patients with isolated SLN lesions had postoperative voice problems, which had disappeared after 1 year in 4 of them. Standard indirect laryngoscopy failed to diagnose an isolated partial SLN paresis. A significant correlation was found between SLN lesion and a reduction in the average pitch of the speaking voice (p < 0.05). Partial SLN lesions cannot be diagnosed exclusively on voice symptoms and standard indirect laryngoscopy. EMG registrations make a definite diagnosis possible. Measurements of the average pitch of the voice could be used as a noninvasive screening procedure.

To reduce the laryngeal obstruction in bilateral vocal cord paralysis, a new method of laterofixation was developed. The method is technically simple and less traumatic than previously published methods. No peroperative tracheostomy is needed. During surgery two needles are inserted through the thyroid cartilage. A nylon thread is passed through the needles and the needles are then withdrawn. The thread thus forms a permanent loop around the vocal cord. The effects of the laterofixation on breathing and on the voice are documented by assessment of upper airway resistance and by two listening panels respectively. Thirteen patients have been operated upon so far. In most cases the breathing was improved and the influence on the voice was moderate and adjustable. If needed the possibility to perform a more extensive surgical procedure still remains. We suggest our method of laterofixation to be the first treatment of choice in patients suffering from bilateral vocal cord paralysis.

Since 1979, we have treated patients suffering from bilateral vocal cord paralysis with laterofixation of one vocal cord, a simple and comparatively atraumatic method. To evaluate the long-term results of this method of laterofixation, 11 consecutive patients were examined at least 5 years postoperatively regarding breathing capacity, voice function, and swallowing ability. Breathing capacity was assessed by determination of orolaryngeal (upper) airway resistance and spirometry. Voice function was judged by two listening panels. Swallowing ability was studied by barium contrast radiography. Postoperative improvement of breathing capacity was, in most cases, found to be long lasting. Furthermore, there was no deterioration of voice function, nor were there aspiration problems during the postoperative follow-up period. We suggest this method of laterofixation as the treatment of choice in patients suffering from breathing difficulties due to bilateral vocal cord paralysis.

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