## Vocal Cord Position in Unilateral Paralysis **Key Point:** The position of a paralyzed vocal cord depends on which laryngeal nerve is affected and the innervation pattern of the intrinsic laryngeal muscles. ### Recurrent Laryngeal Nerve (RLN) Paralysis When the RLN is damaged: - The vocal cord assumes a **paramedian (cadaverous) position** - This occurs because the RLN innervates ALL intrinsic laryngeal muscles EXCEPT the cricothyroid - With RLN paralysis, the vocal cord loses all abductor and adductor functions - The cord settles in a neutral, slightly abducted position due to passive tension and gravity - This is the most common cause of unilateral vocal cord paralysis ### Superior Laryngeal Nerve (SLN) Paralysis When the SLN is damaged: - The vocal cord assumes a **paramedian to lateral position** - The SLN innervates only the cricothyroid muscle (tensor of vocal cord) - Loss of cricothyroid function causes loss of pitch control and vocal cord tension - The cord position is less dramatically affected compared to RLN paralysis **High-Yield:** In clinical practice, RLN paralysis is far more common than SLN paralysis and causes the classic paramedian vocal cord position seen on laryngoscopy. **Clinical Pearl:** The paramedian position in RLN paralysis is clinically significant because it causes: - Breathy voice quality (incomplete glottic closure) - Weak cry in infants - Stridor only if bilateral ### Common Causes of RLN Paralysis | Cause | Mechanism | |-------|----------| | Thyroid surgery | Nerve injury during dissection | | Lung cancer | Tumor invasion at hilum | | Aortic aneurysm | Compression of nerve | | Cardiac surgery | Iatrogenic injury | | Idiopathic | Unknown (common) | [cite:Dhingra 8e Ch 12] 
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