# Clinical Cases: Larynx and Trachea ## 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 1. **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 1. **Voice rest and observation:** Many neuropraxic injuries recover within 6-12 months 2. **Speech therapy:** Compensation techniques while awaiting recovery 3. **Laryngeal electromyography:** To assess nerve integrity and prognosis 4. **Medialization procedures:** If no recovery by 12 months (injection laryngoplasty or thyroplasty) 5. **Swallowing evaluation:** If aspiration symptoms persist --- ## Case 2: Bilateral Vocal Fold Paralysis with Airway Compromise ### Patient Demographics - **Age:** 62 years old - **Sex:** Male - **Occupation:** Retired engineer ### Chief Complaint Progressive shortness of breath and noisy breathing since neck surgery. ### History of Present Illness The patient underwent a completion thyroidectomy for recurrent thyroid cancer 3 days ago. He notes that his voice is remarkably normal but has developed progressive inspiratory stridor and shortness of breath, especially with exertion. He denies dysphagia or aspiration. His breathing difficulty has worsened despite nebulizer treatments. He becomes dyspneic with minimal activity and has noticed that his breathing sounds "squeaky" or "whistling." ### Physical Examination - **Vitals:** HR 98 bpm, BP 148/92 mmHg, RR 26, SpO2 91% on room air, improving to 94% on 4L nasal cannula - **General:** Anxious, using accessory muscles of respiration - **Neck:** Well-healed incisions from current and prior surgeries - **Respiratory:** Biphasic stridor (both inspiratory and expiratory), no wheezing - **Voice:** Surprisingly normal in quality, though weak - **Flexible laryngoscopy:** Both vocal folds immobile in the paramedian position; narrow glottic aperture; no mucosal lesion ### Diagnosis **Bilateral recurrent laryngeal nerve palsy** with critical airway narrowing. ### Anatomical Correlation Bilateral RLN injury is a surgical emergency because both vocal folds are paralyzed in the paramedian position, leaving only a narrow glottic aperture for breathing. The voice may be paradoxically preserved because the vocal folds can still come together, but the airway is critically compromised because neither fold can abduct. The posterior cricoarytenoid muscles, which abduct the vocal folds during inspiration, are both paralyzed. This is in contrast to unilateral injury, where the contralateral functioning fold can approximate the paralyzed fold for phonation but leaves a sufficient airway. The cricoid cartilage is the only complete cartilaginous ring in the airway, forming the narrowest fixed point of the adult airway at the level of C6. In bilateral vocal fold paralysis, the rima glottidis becomes the critically narrowed segment. Stridor is biphasic because both inspiration and expiration are obstructed by the immobile folds. ### Treatment 1. **Emergent airway management:** Intubation (may be difficult due to narrowed glottis) or surgical airway 2. **Tracheostomy:** Required in most cases of bilateral vocal fold paralysis 3. **Long-term airway options:** - Posterior cordotomy (laser incision of one vocal fold) - Arytenoidectomy (removal of one arytenoid cartilage) - Both procedures sacrifice voice quality for improved airway 4. **Future reinnervation procedures:** Experimental approaches to restore abduction --- ## Case 3: Emergency Cricothyrotomy for Complete Upper Airway Obstruction ### Patient Demographics - **Age:** 45 years old - **Sex:** Male - **Occupation:** Chef ### Chief Complaint Sudden onset of severe throat swelling and inability to breathe. ### History of Present Illness The patient has a known history of angiotensin-converting enzyme (ACE) inhibitor use for hypertension. He was eating dinner at a restaurant when he suddenly developed progressive swelling of his tongue and lips. Despite administration of epinephrine and diphenhydramine by paramedics, his airway obstruction worsened. He became unable to speak and developed stridor, then complete airway obstruction. Multiple attempts at endotracheal intubation were unsuccessful due to massive tongue and pharyngeal edema. ### Physical Examination - **Vitals (pre-arrest):** HR 140 bpm, BP undetectable, RR agonal, SpO2 undetectable - **General:** Unresponsive, cyanotic, massive facial and oral edema - **Airway:** Complete obstruction, bag-mask ventilation ineffective - **Neck:** Landmarks identifiable; thyroid cartilage and cricoid cartilage palpable ### Procedure Given failed intubation and inability to ventilate, emergency surgical cricothyrotomy was performed. The cricothyroid membrane was identified between the thyroid cartilage superiorly and the cricoid cartilage inferiorly. A horizontal stab incision was made through the membrane, the scalpel handle was used to dilate the opening, and a 6.0 cuffed tracheostomy tube was inserted. Immediate return of ventilation was achieved with SpO2 rising to 96%. ### Clinical Image ![Cricothyrotomy Anatomy](case_01_image.jpg) *Anatomical illustration demonstrating the location of the cricothyroid membrane between the thyroid and cricoid cartilages, the site for emergency surgical airway access.* **Image Source:** Wikimedia Commons - Larynx anatomy, Creative Commons Attribution-Share Alike 3.0 ### Diagnosis **ACE inhibitor-induced angioedema** with complete upper airway obstruction requiring emergency surgical airway. ### Anatomical Correlation The cricothyroid membrane is the preferred site for emergency surgical airway access because it is superficial, avascular, and provides direct access to the airway. It lies between the inferior border of the thyroid cartilage and the superior border of the cricoid cartilage, measuring approximately 9 mm in height and 30 mm in width. The membrane is covered only by skin, subcutaneous tissue, and the investing layer of deep cervical fascia. The superior and inferior cricothyroid arteries (branches of the superior thyroid artery) anastomose across the upper portion of the membrane, so the incision is made in the lower third of the membrane to minimize bleeding. The cricothyroid membrane is located at the level of C5-C6. Landmarks are identified by palpating the laryngeal prominence (Adam's apple), sliding inferiorly over the thyroid cartilage to the gap above the cricoid cartilage. This procedure is preferred over tracheostomy in emergencies because it is faster and more superficial, though tracheostomy is preferred for long-term airway management. ### Treatment 1. **Emergency cricothyrotomy:** Immediate airway access 2. **Convert to formal tracheostomy:** Once stabilized, typically within 72 hours 3. **ICU monitoring:** Continued airway management and edema resolution 4. **Medication management:** Discontinue ACE inhibitor permanently; substitute alternative antihypertensive 5. **Allergy documentation:** Ensure ACE inhibitor allergy prominently documented