# Vocal Fold Paralysis: Evaluation and Treatment

## Overview
Vocal fold paralysis (VFP) results from disruption of the vagus nerve or its branches (recurrent and superior laryngeal nerves). It may be unilateral or bilateral, with drastically different presentations and management. Unilateral VFP causes breathy, weak voice and potential aspiration, while bilateral VFP causes airway obstruction with a relatively preserved voice. Treatment ranges from observation and injection laryngoplasty to framework surgery and reinnervation procedures.

## Etiology

### Unilateral Vocal Fold Paralysis
**Iatrogenic/surgical** (most common, 30-40%): thyroid surgery, anterior cervical spine surgery, carotid endarterectomy, cardiac/thoracic surgery (left RLN at risk from aortic arch procedures). **Malignancy** (20-30%): lung (left RLN), thyroid, esophageal, skull base tumors, cervical metastases. **Idiopathic** (15-25%): presumed viral neuritis; diagnosis of exclusion. **Neurologic**: stroke, Arnold-Chiari malformation, multiple sclerosis, Parkinsonism. **Trauma**: neck/chest trauma, intubation injury. **Inflammatory**: sarcoidosis, Lyme disease. Left side more commonly affected than right (longer nerve course).

### Bilateral Vocal Fold Paralysis
Thyroid surgery (most common iatrogenic cause). Neurologic: brainstem lesion, Arnold-Chiari malformation. Skull base surgery or tumor, Idiopathic, Bilateral may result from sequential unilateral injuries.

## Evaluation

### History
Voice quality: breathy, weak, diplophonia, effortful phonation. Dysphagia and aspiration: coughing with liquids, recurrent pneumonia. Dyspnea, stridor (bilateral VFP). Timeline: acute (surgical) vs. insidious (malignancy, neurologic). Previous surgery (thyroid, cervical spine, cardiothoracic). Associated symptoms: weight loss, hemoptysis, neurologic deficits.

### Physical Examination
Flexible nasopharyngolaryngoscopy: vocal fold position (paramedian, lateral, cadaveric), mobility, arytenoid movement. Assess supraglottic compensation (false fold phonation, anteroposterior squeeze). Videostroboscopy: mucosal wave present (rules out fixation), glottic closure pattern, vibratory asymmetry. Complete head and neck examination including cranial nerves.

### Differentiating Paralysis from Fixation
**Paralysis**: impaired neural input; passive arytenoid mobility preserved; mucosal wave present. **Cricoarytenoid joint fixation**: mechanical restriction; passive mobility absent; arytenoid may appear anteriorly displaced. Causes of fixation: prolonged intubation, rheumatoid arthritis, posterior glottic stenosis, radiation fibrosis. EMG and palpation under anesthesia help differentiate.

### Imaging
CT from skull base to aortic arch (left) or subclavian artery (right): evaluates the entire course of the vagus and RLN. MRI brain/skull base: if high vagal lesion suspected or cranial neuropathies present. Chest CT: lung apex mass, aortopulmonary window lymphadenopathy.

### Laryngeal Electromyography (LEMG)
Needle EMG of the thyroarytenoid and cricothyroid muscles. Performed 4-6 weeks after onset (allows Wallerian degeneration). Findings: **Fibrillation potentials and positive sharp waves**: active denervation. **Polyphasic motor unit potentials**: reinnervation (favorable prognosis). **Absent motor unit recruitment**: complete denervation (poor prognosis for spontaneous recovery). **Synkinesis**: aberrant reinnervation; motor units present but discoordinated. Prognostic value: presence of motor unit recruitment on volitional tasks predicts recovery; absence predicts permanent paralysis. LEMG can distinguish RLN from SLN lesion (CT vs. TA muscle).

## Management of Unilateral Vocal Fold Paralysis

### Observation
Appropriate for first 6-12 months in idiopathic or post-surgical cases. Spontaneous recovery occurs in ~60% of idiopathic cases within 12 months. Speech therapy: compensatory strategies, vocal hygiene.

### Injection Laryngoplasty

| Material | Duration | Category |
|----------|----------|----------|
| Hyaluronic acid (Restylane) | 3-6 months | Temporary |
| Carboxymethylcellulose (Radiesse Voice Gel) | 2-3 months | Temporary |
| Micronized Alloderm | 2-4 months | Temporary |
| Calcium hydroxyapatite (Radiesse Voice) | 12-18 months | Longer-lasting |
| Autologous fat | Variable (years with 30-50% resorption) | Longer-lasting |

**Temporary materials** (for early medialization or therapeutic trial): Hyaluronic acid (Restylane): lasts 3-6 months. Carboxymethylcellulose (Radiesse Voice Gel): lasts 2-3 months. Micronized Alloderm: lasts 2-4 months. **Longer-lasting materials** (once permanence is desired): Calcium hydroxyapatite (Radiesse Voice): lasts 12-18 months. Autologous fat: variable resorption (30-50%); may last years. Technique: transcervical (via thyrohyoid membrane, cricothyroid membrane, or through thyroid cartilage) or transoral (peroral with flexible laryngoscope or rigid). Office-based injection under local anesthesia is increasingly preferred. Injected lateral to the vocal fold to medialize it.

### Medialization Laryngoplasty (Thyroplasty Type I)
Framework surgery through a window in the thyroid cartilage. Implant (Silastic, Gore-Tex, Montgomery) placed lateral to the inner perichondrium to medialize the vocal fold. Performed under local anesthesia with sedation: allows real-time voice optimization. Indications: permanent unilateral VFP, inadequate response to injection, large glottic gap. Can be combined with arytenoid adduction for large posterior gap.

### Arytenoid Adduction
Simulates the action of the lateral cricoarytenoid muscle. Suture placed through the muscular process of the arytenoid and pulled anteriorly. Indicated for large posterior glottic gaps, vocal process height mismatch, or arytenoid prolapse. Often combined with medialization thyroplasty. More technically demanding; risk of hematoma, airway compromise.

### Laryngeal Reinnervation
**RLN-ansa cervicalis anastomosis**: ansa cervicalis nerve anastomosed to the distal RLN. Provides tone and bulk to the thyroarytenoid muscle without restoring motion. Prevents denervation atrophy. Best results when performed early (within 6 months of onset). Increasingly used as primary treatment in select patients, Friedman procedure, Crumley procedure.

## Management of Bilateral Vocal Fold Paralysis

### Airway Management
Bilateral VFP presents with stridor and dyspnea; voice may be near-normal. Tracheotomy may be required for acute airway compromise. Goal: adequate airway without tracheotomy while preserving voice.

### Surgical Options
**Posterior cordotomy**: laser division of the posterior vocal fold at the vocal process level; widens the posterior glottis. **Arytenoidectomy**: partial or total removal of one arytenoid; endoscopic laser or open approach. **Suture lateralization**: lateralization of the vocal fold with sutures. **All procedures trade voice quality for airway**: wider airway = breathier voice. Bilateral RLN-ansa cervicalis reinnervation: restores tone and may improve airway without sacrificing voice; results take 4-6 months.

### Decannulation
After surgical enlargement of the airway, decannulation trial. Serial downsizing of tracheotomy tube, then capping trials. Monitor with polysomnography or sleep endoscopy in select cases.

<image>Laryngoscopic images of vocal fold paralysis. Panel A: Left unilateral vocal fold paralysis in paramedian position during phonation showing incomplete glottic closure with a large posterior gap. Panel B: Same patient during quiet respiration showing immobile left vocal fold. Panel C: Bilateral vocal fold paralysis with both folds in paramedian position showing a narrow glottic airway during inspiration. Panel D: After left injection laryngoplasty showing improved glottic closure with the medialized left vocal fold. Labels indicate the paralyzed fold position, glottic gap, and arytenoid status in each panel.</image>

<image>Medialization laryngoplasty (thyroplasty type I) surgical technique. Step-by-step illustration showing: (1) horizontal skin incision over the thyroid cartilage at the level of the vocal fold, (2) cartilage window marked and cut at the appropriate position (determined by vocal fold level), (3) inner perichondrium elevated, (4) Silastic implant carved and inserted through the window to medialize the vocal fold, (5) final position with the implant secured. An inset shows the cross-sectional view of the larynx demonstrating the implant position lateral to the inner perichondrium and medial to the outer thyroid cartilage, pushing the vocal fold toward the midline. The vocal fold level relative to the thyroid cartilage landmarks (midpoint between notch and inferior border) is indicated.</image>

<image>Laryngeal EMG interpretation guide. Four panels showing EMG tracings with corresponding clinical significance. Panel A: Normal motor unit recruitment during phonation. Panel B: Fibrillation potentials and positive sharp waves indicating active denervation. Panel C: Polyphasic motor unit potentials indicating reinnervation with favorable prognosis. Panel D: Absent recruitment with electrical silence during volitional tasks indicating complete denervation with poor prognosis. Each panel includes a schematic of the needle position in the thyroarytenoid muscle via cricothyroid membrane approach.</image>

## Clinical Pearls
All patients with vocal fold immobility of unknown cause require imaging from the skull base to the aortic arch to rule out malignancy along the vagus/RLN course. Laryngeal EMG performed at 4-6 weeks provides the most useful prognostic information; the presence of motor unit recruitment predicts favorable recovery. Early injection laryngoplasty with a temporary filler (within weeks of onset) significantly improves quality of life without precluding observation for spontaneous recovery. Office-based injection laryngoplasty is the fastest-growing procedural trend in laryngology; it avoids general anesthesia and allows immediate voice feedback. In bilateral VFP, all surgical procedures to improve the airway compromise voice quality; the patient must understand this tradeoff before proceeding. Laryngeal reinnervation (RLN-ansa cervicalis anastomosis) is an underutilized option that restores vocal fold tone and bulk without restoring motion; best outcomes occur when performed within 6 months of onset.

## References
- Sulica L. "The natural history of idiopathic unilateral vocal fold paralysis: evidence and problems." *Laryngoscope*. 2008;118(7):1303-1307.
- Rosen CA, Gartner-Schmidt J, Hathaway B, et al. "A nomenclature paradigm for benign midmembranous vocal fold lesions." *Otolaryngol Head Neck Surg*. 2012;147(5):813-826.
- Paniello RC, Edgar JD, Kallogjeri D, Piccirillo JF. "Medialization versus reinnervation for unilateral vocal fold paralysis: a multicenter randomized clinical trial." *Laryngoscope*. 2011;121(10):2172-2179.
- Woodson GE. "Spontaneous laryngeal reinnervation after recurrent laryngeal or vagus nerve injury." *Ann Otol Rhinol Laryngol*. 2007;116(1):57-65.