Vocal cord paresis
Synonyms: Vocal cord paralysis, laryngeal nerve palsy, laryngeal paralysis, paralysis of the recurrent nerve.

# Overview
Vocal cord paresis (or paralysis) is weakness of one or both vocal folds that can greatly impact daily life, employment, job choice, social interactions and leisure time pursuits.  Symptoms of paresis include: hoarseness, vocal fatigue, mild to severe reduction in vocal volume, pain in the throat when speaking, shortness of breath, aspiration (food or liquids going down the trachea) with frequent resultant coughing, and in extreme cases may cause death.
Reduced vocal cord mobility may decrease the effectiveness of coughing, swallowing, or sneezing in removing mucosal wastes from the laryngeal area.  The resultant accumulations may allow for viral and bacterial colonization with an increased tendency for infections and throat discomfort.
Some causes of paresis include: viral infection, cancer or tumor compressing the recurrent laryngeal nerve, intramuscular tumor limiting vocal fold movement, trauma, compression of the vocal cord nerve from intubation, or laryngopharyngeal reflux.  Cardiac surgery represents a risk to normal voice function as the nerves serving the larynx are routed near the heart.  Damage to this nerve during open heart surgery is not uncommon.  Neurological diseases, such as Parkinson's can deteriorate vocal functions.  Paresis may occur from an unknown cause (idiopathic).
Vocal paresis is diagnosed by observing the lack of (or reduced) motion of one or both cords using a laryngoscope. EMG (electromyography) may be used to measure the strength of the neuromuscular signal from the brain to the muscles controlling the vocal folds.  This diagnosis can be made by a laryngologist or otolaryngologist with the assistance of a neurologist.  In situations involving inflammation, recovery of normal motion of the vocal cords may return spontaneously.

# Emotional and stress factors
The onset of vocal dysfunction may not display a clear physical or disease event.  Under such circumstances, additional attention can be directed toward matters of recent emotional concern to the person with voice weakness.

# Differential Diagnosis of Vocal Cord Paresis
In alphabetical order.  
- Alcohol
- Arsenic
- Bronchial carcinoma with mediastinal metastases
- Cardiac surgery
- Carotid endarterectomy
- Cerebrovascular accident
- Collagen Vascular Disease
- Complete vagal nerve paresis
- Diabetes Mellitus
- Esophageal Cancer
- Head trauma
- Heavy metals
- Herpes Simplex Viruses
- High forceps delivery causing damage to the recurrent laryngeal nerve
- Influenza
- Intubation and mechanical ventilation
- Larynx carcinoma
- Lead
- Lesion of the brain stem
- Lyme Disease
- Mediastinal tumor
- Mercury
- Mononeucleosis
- Neck dissection
- Neurosurgery
- Paralysis of the cranial nerve
- Phenytoin
- Polyarthritis of the arytenoid
- Sarcoidosis
- Tumors of the brain stem
- Tumors of the base of the skull
- Thyroid surgery
- Vagus neurinoma
- Vincristine

# Surgical intervention
In the event of significant voice weakness, surgery may be required to provide temporary or permanent medialization of the vocal cords.  These procedures will mechanically move the vocal cord and underlying muscular tissue toward midline (medialize) to allow a stronger "strike" against the opposite vocal cord, thus providing for a stronger and louder voice.   The injection of purified animal fat is a temporary means to accomplish medialization.  The surgical insertion of "buttons" of sculpted silicone or similar deformable plastic substances just inside the trachea wall will permanently medialize a vocal cord.  This procedure is done under local anesthetic, to allow the patient to phonate, thus allowing the surgeon to experiment with the best size and shape of the "button" for maximal remediation.  This procedure can be done unilaterally or bilaterally.  In all cases, after this surgery, the relaxed position of the vocal cords will allow the passage of less breath than before the medialization.  The airway is rendered smaller and this effect must be a significant consideration of the surgeon.