"Mystic" transient recurrent nerve palsy after thyroid surgery

Clinical observation of end-to-end neuroanastomosis in the treatment of complete injury of the unilateral recurrent laryngeal nerve

Background

Complete injury of the recurrent laryngeal nerve (RLN) is a serious complication of thyroid surgery. Increasingly researches focus on the voice recovery of patients with RLN injury. This paper studied the effect of immediate end-to-end neuroanastomosis after complete injury of the unilateral RLN during thyroid surgery on postoperative vocal function.

Methods

Thirteen patients who underwent end-to-end neuroanastomosis for the treatment of complete injury of the unilateral RLN caused by thyroid surgery in Hunan Provincial People's Hospital between October 2009 and January 2020 were selected. The basic information, cause of RLN injury, postoperative voice recovery, recovery time, and subjective assessment of voice by auditory perception results (Grade, Roughness, Breathiness, Asthenia, and Strain, the GRBAS score) of the patients were recorded.

Results

Among the 13 cases with RLN injury, the cause of RLN injury in 10 cases was transection by sharp instruments, and the voice was recovered one day after the operation. The cause of RLN injury in one case was suture of the RLN branch, and the voice was recovered one day after the operation. The cause of RLN injury in two cases was thermal injury, and the times for voice recovery after end-to-end neuroanastomosis were 3 and 4 months. The patients with a GRBAS score of 0 or 1 recovered their voice one day after the operation. The GRBAS score reached 1 in the two thermal injury cases, with voice recovery at 3 and 4 months after surgery. By 6 months, the voice recovery rate of the patients was 100%.

Conclusions

After complete injury of the unilateral RLN, immediate end-to-end anastomosis of the RLN can maximally preserve the postoperative vocal function of patients.

Guidelines for radiographic imaging of cranial neuropathies

Disruption of the complex pathways of the 12 cranial nerves can occur at any site along their course, and many, varied pathologic processes may initially manifest as dysfunction and neuropathy. Radiographic imaging (computed topography or magnetic resonance imaging) is frequently used to evaluate cranial neuropathies; however, indications for imaging and imaging method of choice vary considerably between the cranial nerves. The purpose of this review is to provide an analysis of the diagnostic yield and the most clinically appropriate means to evaluate cranial neuropathies using radiographic imaging. Using the PubMed MEDLINE NCBI database, a total of 49,079 articles' results were retrieved on September 20, 2014. Scholarly articles that discuss the etiology, incidence, and use of imaging in the context of evaluation and diagnostic yield of the 12 cranial nerves were evaluated for the purposes of this review. We combined primary research, guidelines, and best practice recommendations to create a practical framework for the radiographic evaluation of cranial neuropathies.

Neurological complications in thyroid surgery: a surgical point of view on laryngeal nerves

THE CERVICAL BRANCHES OF THE VAGUS NERVE THAT ARE PERTINENT TO ENDOCRINE SURGERY ARE THE SUPERIOR AND THE INFERIOR LARYNGEAL NERVES: their anatomical course in the neck places them at risk during thyroid surgery. The external branch of the superior laryngeal nerve (EB) is at risk during thyroid surgery because of its close anatomical relationship with the superior thyroid vessels and the superior thyroid pole region. The rate of EB injury (which leads to the paralysis of the cricothyroid muscle) varies from 0 to 58%. The identification of the EB during surgery helps avoiding both an accidental transection and an excessive stretching. When the nerve is not identified, the ligation of superior thyroid artery branches close to the thyroid gland is suggested, as well as the abstention from an indiscriminate use of energy-based devices that might damage it. The inferior laryngeal nerve (RLN) runs in the tracheoesophageal groove toward the larynx, close to the posterior aspect of the thyroid. It is the main motor nerve of the intrinsic laryngeal muscles, and also provides sensory innervation to the larynx. Its injury finally causes the paralysis of the omolateral vocal cord and various sensory alterations: the symptoms range from mild to severe hoarseness, to acute airway obstruction, and swallowing impairment. Permanent lesions of the RNL occur from 0.3 to 7% of cases, according to different factors. The surgeon must be aware of the possible anatomical variations of the nerve, which should be actively searched for and identified. Visual control and gentle dissection of RLN are imperative. The use of intraoperative nerve monitoring has been safely applied but, at the moment, its impact in the incidence of RLN injuries has not been clarified. In conclusion, despite a thorough surgical technique and the use of intraoperative neuromonitoring, the incidence of neurological complications after thyroid surgery cannot be suppressed, but should be maintained in a low range.