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Recurrent Laryngeal Nerve And Thyroid Surgery

Dr. MTD Lakshan MBBS(Col) MS(ORL-HNS) DOHNS(Eng)

FEB ORL-HNS FRCSEd ORL-HNS

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Outline

»  Surgical Anatomy –  Origin and function –  Relationship with ITA –  Suspensory Ligament

»  Anatomical variations –  Extra-laryngeal division –  Non-recurrent

»  Surgical considerations

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RLN

•  Motor : ALL intrinsic laryngeal musculature except cricothyroid

•  Sensory: Glottic larynx •  Arises from the vagus

–  Right : level of the subclavian artery –  Left : level of the aortic arch

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Surgical Anatomy •  Turn superior–medial to run toward the

tracheoesophagel (TE) groove •  Oesophageal and tracheal branches •  Close association with the trachea and esophagus •  Not necessarily in the true TE groove •  May run laterally in this visceral compartment R>L

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Inferior Thyroid Artery & RLN

•  Intimate relationship •  Nerves may pass

–  Superficial –  Deep –  Or between branches of the ITA

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Anatomical variations of the RLN and the ITA

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ITA and RLN

•  Variable branching pattern – nerve and artery •  Limits the ability to rely solely on the ITA

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Identifying RLN

above the thoracic inlet

•  Cricothyroid joint •  TE groove - posterior thyroid gland •  Suspensory ligament of the thyroid gland

(Berry’s Ligament)

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Berry’s Ligament

•  Pretracheal fascia condenses and attatches the thyroid to the upper two to three tracheal rings

•  Anchors the gland •  RLN often passes through

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Extralaryngeal division-RLN

•  35% to 80% of anatomic dissections •  Typically

–  anterior (motor division) –  posterior (sensory) –  but patterns with two to eight branches

described

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Anomalous or nonrecurrent nerve

•  0.3% to 0.8% •  Directly from the cervical portion of the vagus at

about the level of the larynx or thyroid gland •  Enters the larynx posterior to the cricothyroid

joint without looping low in the neck.

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Anomalous or non recurrent nerve

•  The vast majority → Right side –  in conjunction with an anomalous retro-

esophageal subclavian artery •  Rarely Left

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Surgical Considerations •  Hermann, in their review of 16,443 patients who

underwent thryroidectomy, showed that the incidence of temporary and permanent RLN paralysis was significantly reduced if the nerve was identified.

Hermann M, Alk G, Roka R, et al. Laryngeal

recurrent nerve injury in surgery for benign thyroid diseases: effect of nerve dissection and impact of individual surgeon in more than 27,000 nerves at risk. Ann Surg 2002;235:261–8.

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Surgical considerations Average permanent RLN injury rate

–  0.9% for localization only –  0.3% for partial dissection –  0.1% for complete dissection

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Factors that must be considered during dissecting

•  anatomic variations •  branching patterns •  scarring as a result of previous surgery •  radiation therapy •  underlying pathology •  extent and bulkiness of disease •  surgical experience •  mechanisms of injury.

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Mechanisms of injury-RLN

•  Stretch or traction, •  Compression or crush (eg, ligature

entrapment, hematoma formation •  Thermal •  Electrical •  Severing injuries (complete or incomplete

transection)

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RLN Injury

•  Paresis or a Temporary paralysis- 7.1% •  Permanent paralysis-3.6%

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Summary

»  Complicated course »  Relationship to ITA and Berry's

Ligament »  Anatomical variations »  Prevention of damage

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Any Questions?

»  Thank You!