Should we routinely identify the superior laryngeal nerve in thyroid surgery

1
Should we routinely identify the superior
laryngeal nerve in thyroid surgery?

• Does identification aid in the functional
  preservation of the nerve?

2
Overview

• Background Anatomy
• EBSLN Classification System
• Mechanism of Injury
• Symptoms of injury
• Proposed mechanisms of Reducing injury
• Trial comparing 2 surgical techniques

3
Background

• SLN, branch lower end ganglion nodosum of vagus
  nerve
• divides into internal and external branches at
  level hyoid bone, in close proximity to STA
• Internal branch (sensory autonomic) supplies
  laryngeal mucosa superior to vocal folds -
  accompanies SLA to penetrate thyrohyoid membrane
• EBSLN (motor) descends behind larynx (superior
  thyroid vessels) on inferior constrictor before
  terminating in the cricothyroid muscle

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SLN (INTERNAL)
STA
Thyrohyoid membrane
SLA
EBSLN
ILA (ITA)
Cricothyroid muscle
ILN (RLN)
Cricothyroid muscle supplied by EBSLN tenses the
vocal folds thus increasing the pitch of the voice
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EBSLN Classification Systems
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Surgical Anatomy of EBSLN
EBSLN
STA
1 cm
Not identified
Type 1
Type 2a
Type 2b
Superior Pole of Thyroid
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Mechanism of Injury

• EBSLN may be stretched by retractor, or
  transected when these vessels are divided
• Incidence of EBSLN unknown
• 0-28

8
Symptoms of Injury

• Hoarseness (slight)
• Weakness
• Reduced range of pitch volume
• Voice Fatigue
• singers, professional speakers, lecturers/teachers

9
Proposed Methods of Reducing Nerve Injury

• Skeletization - individual ligation superior
  thyroid vessels adjacent capsule of gland
• Identification of nerve before ligation superior
  thyroid pole vessels
• Use of nerve stimulator or intraoperative nerve
  monitor

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Literature Search

• Medline 1966 - week4 March 2003, Premedline,
  CCTR, EmBase
• superior laryngeal nerve or laryngeal nerve or
  external branch of superior laryngeal nerve
• complication or injury or dysfunction or
  disability or impairement or iatrogenic
• thyroid surgery or thyroidectomy or
  hemithyroidectomy or lobectomy
• 1 and 3
• 2 and 4
• limit 6 to human
• 136 citations individually searched

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Is the identification of the external branch of
the superior laryngeal nerve mandatory in thyroid
operation? Results of a propsective randomised
study Bellantone et al.SURGERY
2001121055-1059
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Identification EBSLN in Thyroid Surgery.
Bellantone et al 2001

• 289 consecutive thyroidectomies underwent
  prospective phoniatric evaluation
• random allocation into 2 groups
• A137 (215) STA ligated after identificatio
  n EBSLN
• B152 (244) STA brs ligated separately
  on capsule of gland
• (NB no attempt to identify nerve was made)

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Exclusion Criteria

• Previous neck irradiation
• Previous laryngeal/thyroid surgery
• Any other anterior cervical operation

14
Methods

• 2 experienced endocrine surgeons
• Phoniatric Evaluation of both groups
• D -1
• D 2
• 1 month
• 6 months
• Videostrobolaryngoscopy spectrographic
  examination

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Surgical technique

• Low transverse collar incision
• Elevation of platysma flap
• Strap m. divided midline and elevated sharply off
  gland
• Early identification of RLN near inferior pole
• Visualisation Parathyroid glands

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Outcome Assessment

• 10 Outcome Measure
• Incidence EBSLN Injury using phoniatric
  evaluation
• 20 Outcome measures
• operative time
• duration of hospital stay
• incidence of complications
• intraoperative bleeding
• postoperative bleeding
• wound infection

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Group A (Cernea classification)
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Results (1)

• 7 patients dysphonic postoperatively
• 3 in group A, 4 in group B
• Phoniatric evaluation revealed unilateral RLN
  palsy in all cases
• VSL and spectrography at 6/12 demonstrated
  permanent RLN palsy 2 cases (one from each group)
• The other 5 cases were normal phoniatrically at
  6/12 demonstrating resolution of RLN paresis and
  thus no evidence of EBSLN injury

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Results (2)

• 3 patients (1 in group A, 2 in group B)
  complained of postoperative phonasthenia and
  decreased range of pitch volume but with normal
  phoniatric evaluation!
• Symptoms resolved spontaneously at 1, 2 and 2.5
  months respectively

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Results (3)

• Asymptomatic patients (both groups)
• Spectrography demonstrated absence of voice
  changes at D2, 1 month and 6 months
• Phoniatric assessment showed absence of
• assymetrical mucosal travelling wave
• inferior displacement of affected cord
• bowing of affected cord
• ipsilateral posterior glottic rotation

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20 Outcomes
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Reported EBSLN Identification and Injury Rates
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References

• Rocco Bellantone,MD, Mauro Boscherini,MD,
  Celestiano P. Lombardi,MD, Maurizio Bossola,MD,
  Francesco Rubino,MD, Carmela de Crea,MD,
  Pierfrancesco Alesina,MD, Emanuela Traini,MD,
  Tiziana Cozza,MD, and Lucia DAlatri,MD, Rome,
  Italy. Is the identification of the external
  branch of the superior laryngeal nerve mandatory
  in thyroid operation? Results of a prospective
  randomised study. SURGERY 2001 130(6)1055-1059
• Cernea CR, Nishio S, Hojaij FC. Identification of
  the EBSLN in large goitres. Am J Otol.
  199516307-311
• Alan P. B. Dackiw,MD, PhD, Lorne E. Ronstein,MD,
  and Orlo H. Clark,MD. Computer-assisted evoked
  electromyography for recurrent/external laryngeal
  nerve identification and parathyroid operation.
  SURGERY 2002 132(6)1100-1107
• E.N. AINA and A.N. Hisham. External Laryngeal
  Nerve in Thyroid Surgery Recognition and
  Surgical Implications. Aus.NZ J. Surg. 2001
  71212-214
• Peter F. crookes,MD,FACS, and James A. Recabaren,
  MD, FACS. Injury to the Superior Laryngeal Branch
  of the Vagus During Thyroidectomy Lesson or
  Myth? Annals of Surgery 2001 233(4)588-593
• Michael Friedman,MD Phillip LoSavio,BS Hani
  Ibrahim,MD. Superior Laryngeal Nerve
  Identification and Preservation in Thyroidectomy.
  Arch Otolaryngol Head Neck Surg. 2002
  128296-303
• Luis Mauricio Hurtado-Lopez,MD Felipe Rafael
  Zaldivar-Ramirez,MD. Risk of Injury to the
  External Branch of the Superior Laryngeal Nerve
  in Thyroidectomy. Laryngoscope 2002112626-629