The 3.5ms rule of stimulation latency in identification of non- recurrent laryngeal nerve (NRLN): Is it always true?

R. A. Raflis, N. A. Hakim, Rohaizak Muhammad, E. N. Aina

Research output: Contribution to journalArticle

Abstract

A non - recurrent laryngeal nerve (NRLN) has a shorter course to enter the larynx and theoretically will have a shorter latency period on electromyography (EMG). Previous report has shown that latency shorter than 3.5ms has a very high sensitivity and specificity for diagnosis of NRLN. We present two different types of NRLN with latency period longer than 3.5ms. Case 1: A 42 year old lady presented with a right thyroid nodule and scheduled for a right hemithyroidectomy. During dissection and stimulation of the right vagus (V1), the latency period was normal at 5.2ms. Further dissection at the inferior pole of the gland failed to identify the recurrent laryngeal nerve (R1). The dissection and mapping performed lateral to the gland identified a type 2B NRLN, entering at the posterior aspect of the larynx. Case 2: A 40 year old lady presented with a large nodular goiter and underwent total thyroidectomy. Left hemithyroidectomy was uneventful. During right hemithyroidectomy, stimulation of the right vagus (V1) nerve at the mid - cervical region was absent. The stimulation was extended superiorly on the vagus and there was a good amplitude with latency of 3.88ms, with suspicion of a right NRLN. Further meticulous dissection confirmed type 1 NRLN. Stimulation of the vagus nerve (V1) in the early stage of thyroidectomy is useful in helping to identify NRLN especially type 1, either by looking at the point of stimulation or latency period. Care still should be taken during the dissection as the sensitivity varies according to the different types of NRLN.

Original languageEnglish
Pages (from-to)228-229
Number of pages2
JournalSurgical Chronicles
Volume23
Issue number4
Publication statusPublished - 1 Jan 2018

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Recurrent Laryngeal Nerve
Dissection
Thyroidectomy
Larynx
Nijmegen Breakage Syndrome
Nodular Goiter
Vagus Nerve Stimulation
Thyroid Nodule
Vagus Nerve
Electromyography
Sensitivity and Specificity

Keywords

  • Non recurrent laryngeal nerve (NRLN), Intra-operative nerve monitoring (IONM)

ASJC Scopus subject areas

  • Surgery

Cite this

The 3.5ms rule of stimulation latency in identification of non- recurrent laryngeal nerve (NRLN) : Is it always true? / Raflis, R. A.; Hakim, N. A.; Muhammad, Rohaizak; Aina, E. N.

In: Surgical Chronicles, Vol. 23, No. 4, 01.01.2018, p. 228-229.

Research output: Contribution to journalArticle

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