Identification of external branch of superior laryngeal nerve during thyroid surgery: a prospective study

Abstract

<p class="abstract"><strong>Background:</strong> Identification of external branch of superior laryngeal nerve (EBSLN) according to Cernea et al classification and to describe a surgical technique of superior pole dissection to preserve EBSLN during thyroid surgeries.</p><p class="abstract"><strong>Methods:</strong> The study was done over 2 years period in a tertiary care hospital. 105 nerves were studied among the 90 patients who underwent thyroid surgeries. Avascular dissection over the JOLL’S triangle was carried out and identified EBSLN were classified according to Cernea et al classification. Individual ligation of superior pole vessels was carried out after identifying the nerve. Outcome was studied relating the identified nerve with sides of thyroidectomy performed, size of thyroid gland and nerves at risk according to Cernea et al classification. </p><p class="abstract"><strong>Results:</strong> Of the 105 nerves studied, in 81.90% of patients the nerve was identified. There were 34.88% of Type 1 nerves, 52.33% of Type 2A nerve and 12.79% of Type 2B nerves identified. Less number of nerves could be identified on the left side. Type 2B nerves were more common on left side inspite of less number of dissections carried out on left. Type 2 variation was more common in large goiters.</p><p><strong>Conclusions:</strong> Careful dissection should be done in superior pole in avascular cricothyroid space, with lateralization of superior pole and individual identification of superior pole vessels once the nerve is identified. Identification of the nerve is mandatory in all patients who undergo thyroid surgery for optimal functions of the larynx. These results showed a better identification of nerves by proper surgical techniques without use of any sophisticated equipments. </p>

A useful landmark to locate the external branch of the superior laryngeal nerve during thyroidectomy

“…Our study showed a high prevalence of Cernea type 2 nerves (91.9%) with 52.3% being type 2B nerves. Even counting the unidentified nerves as type 1 nerves, assuming they were not identified because of a high crossing, the prevalence of type 2 and type 2B nerves were 78.5% and 44.6% respectively, which is on the upper side of the range reported in the literature, where the rates of type 2 and type 2B nerves were 37-83% and 11-40.8% respectively (1,20,(29)(30)(31)(32)(33). A relatively high proportion of sizeable goiters in our series may account for this.…”

Anatomía Topográfica del Nervio Laríngeo Superior: Importancia Quirúrgica en las Tiroidectomías

“…No todos los centros asistenciales disponen del neuroestimulador para individualizar el nervio, de todos modos e independientemente de este detalle, el conocimiento de la anatomía topográfica del RLNLS es vital para su reconocimiento. El uso del neuroestimulador logra un mayor individualización del nervio y se nutre mejor del aporte brindado por la clasificación de Friedman (Aina & Hisham;Friedman et al;Kandil et al, 2015;Arun et al, 2016;Ekhar et al;Bruno;Gurleyik et al, 2019).…”

“…Sin embargo no merece tal atención el ramo lateral del nervio laríngeo superior (RLNLS), íntimamente relacionado al polo superior de la glándula tiroides y satélite de su pedículo vascular superior. Tal situación lleva a considerar al citado como "el ner-vio descuidado en la cirugía tiroidea" (Ekhar et al, 2018). El nervio laríngeo superior (NLS) se origina a nivel de la parte inferointerna del ganglio plexiforme del nervio vago, continúa un trayecto descendente dirigiéndose hacia la faringe dividiéndose en dos ramos, el ramo superior, el ramo interno (RINLS), que continúa a su nervio de origen siguiendo el asta mayor del hueso hiodes transcurriendo entre el músculo tirohioideo y la membrana tirohiodea, perforando esta última estructura, en compañía de los vasos laríngeos superiores, para terminar en el espesor de los repliegues 1 Profesor Adjunto de Anatomía descriptiva y Topográfica.…”

“…Algunos autores de centros muy especializados en cirugía tiroidea sugieren incluso, en base a esta relación, evitar el uso de electrocauterio en el manejo del polo superior de la glándula tiroides disminuir el riesgo de lesión nerviosa. El detalle técnico de buscar el nervio durate la cirugía en base a estas relaciones anatómicas los hace prescindir de utilizar de modo sitemático el neuroestimulador para tal efecto (Pagedar & Freeman, 2009;Ekhar et al).…”

A Focused Review on the Approach to the Recurrent Laryngeal Nerve & Identification during Thyroidectomy

“…Upper pole of thyroid gland and superior thyroid vessels forms the Lateral border. Superiorly, Attachment of the strap muscles, Medially is the Midline, The floor is formed by Cricothyroid muscle [38].…”