Anatomy Pelvis Head Neck · Year 1 · from Anatomy Pelvis Head Neck
Case 1: Unilateral Recurrent Laryngeal Nerve Injury After Thyroid Surgery
Patient Demographics
- Age: 48 years old
- Sex: Female
- Occupation: Singer
Chief Complaint
Hoarse voice since thyroid surgery 2 weeks ago.
History of Present Illness
The patient underwent a total thyroidectomy for papillary thyroid carcinoma 2 weeks ago. She was told the surgery went well, but upon awakening she noticed her voice was weak and breathy. She is a professional soprano singer and is devastated that she cannot sing or project her voice. She also reports occasional coughing when drinking liquids. She denies any difficulty breathing or stridor.
Physical Examination
- Vitals: Within normal limits
- Neck: Well-healed surgical incision, no hematoma or swelling
- Voice: Breathy, weak, unable to raise pitch
- Flexible laryngoscopy: Left vocal fold immobile in the paramedian position; right vocal fold moves normally but cannot fully approximate the left; glottic gap present during phonation
Imaging Workup
- CT neck: Post-surgical changes; no evidence of hematoma or recurrent tumor
Diagnosis
Left recurrent laryngeal nerve injury (neuropraxia vs. transection) following thyroidectomy.
Anatomical Correlation
The recurrent laryngeal nerve (RLN) is vulnerable during thyroid surgery because of its intimate relationship with the inferior thyroid artery and the ligament of Berry, which attaches the thyroid to the cricoid cartilage. The nerve ascends in the tracheoesophageal groove and enters the larynx by passing deep to the inferior constrictor muscle. The left RLN is longer than the right because it loops under the aortic arch (versus the right subclavian artery), making it statistically more susceptible to injury. The RLN innervates all intrinsic laryngeal muscles except the cricothyroid (innervated by the external laryngeal nerve). Loss of RLN function causes paralysis of the posterior cricoarytenoid muscle (the only abductor of the vocal folds) and the lateral cricoarytenoid (primary adductor). In unilateral injury, the vocal fold assumes a paramedian position due to the unopposed action of the cricothyroid muscle, which is still functioning. The breathy voice results from air escape through the glottic gap, while aspiration occurs because the paralyzed fold cannot fully close during swallowing.
Treatment
- Voice rest and observation: Many neuropraxic injuries recover within 6-12 months
- Speech therapy: Compensation techniques while awaiting recovery
- Laryngeal electromyography: To assess nerve integrity and prognosis
- Medialization procedures: If no recovery by 12 months (injection laryngoplasty or thyroplasty)
- Swallowing evaluation: If aspiration symptoms persist