May 23, 2023
Vocal cord paralysis is a medical condition in which the ability to control the muscles that control the movement of vocal cords is lost. In vocal cord paralysis, there are two nerves; they are the superior laryngeal nerve and the recurrent laryngeal nerve.
Read this blog further to get a quick overview of this important topic for ENT and ace your NEET PG exam preparation.
Mandible, hyoid bone, clavicle, mediastinum, thyroid cartilage (midline of the neck), cricoid cartilage (continuous Inferior early as the trachea), cervical trachea (part of the trachea that lies in the neck), thoracic trachea.
Vagus nerve goes into the neck and cross near subclavian artery and then enter into the trachea and oesophageal groove. The right Vagus nerve gives off a branch recurrent laryngeal nerve at the level of the subclavian artery and winds around the subclavian artery. Superior laryngeal nerve supplies to above the larynx. The recurrent laryngeal nerve supplies below the larynx. Recurrent laryngeal nerve does not supply to the muscle of the pharynx. Superior laryngeal nerve is at the same position on both sides. The left vagus gives recurrent laryngeal nerve at the level of the arch of Iota. Recurrent laryngeal nerve supplies to the lower of the vocal cord and larynx except the cricothyroid. Left Recurrent laryngeal nerve goes into the mediastinum. Sensory Anastomosis is formed between the internal laryngeal nerve and the recurrent laryngeal nerve, which is Galen's anastomosis.
Sensory part of the superior laryngeal nerve is called the Internal laryngeal nerve, and the motor part is called the external laryngeal nerve. The sensory part innervates mucosa of the larynx, which is above vocal cords and the motor innervates cricothyroid muscle.
Recurrent laryngeal nerve supplies all laryngeal muscles except cricothyroid
|Recurrent laryngeal nerve||Superior laryngeal nerve|
|Sensory supply||Inferior part of larynx||Superior part of larynx|
|Motor supply||All muscles of larynx except cricothyroid||Cricothyroid|
|Paralysis||Impaired abduction mainly||Impaired tensor function|
During phonation vocal cords adduct and become tense. In paralysis of cricothyroid, vocal cords remain flaccid, sloopy and fail to adduct completely. So voice is affected in cricothyroid paralysis.
When the cricothyroid is paralysed, voice will be affected. During phonation, the vocal cord comes to the midline, and the cricothyroid is used. During respiration, the posterior cricothyroid help in abducting the vocal cords. If it is recurrent laryngeal nerve palsy, the posterior cricothyroid will be paralysed.
When breathing, the vocal cord goes away from the midline and is done by the posterior cricothyroid muscle. If there is recurrent laryngeal nerve palsy, respiration will also be affected. cricothyroid is pulling the vocal cord back to the midline, so if there is superior laryngeal nerve palsy, respiration will be affected too.
SLN pulls the vocal cord towards the midline. RLN pulls away from the midline. The vocal cord will be in an immediate position 3.5mm away from midline (cadaveric position). During breathing, tensors tense and pull the vocal cord away from the middle (7mm or 9mm distance). The air passes, but for respiration, the vocal cord comes back to midline.
|Position||Location of cord from midline||Situations in|
|Intermediate (cadaveric)||3.5 mm|
(This is neutral position of cricoarytenoid joint. Abduction takes place from this position.
|-||Combined paralysis (both RLN & SLN)|
|Gentle abduction||7 mm||Quiet respiration||Paralysis of adductors|
|Full abduction||9.5 mm||Deep inspiration||-|
If there is right recurrent laryngeal nerve palsy, only one side is paralyzed The right side recurrent laryngeal nerve palsy will lead to a sensory loss of the lower half of larynx and motor loss for all the muscles except cricothyroid. Position- the paralyzed cord will come in midline. As the right side post cricothyroid is paralysed which is abductor of vocal cords.Phonation will be slightly affected. Also, respiration is not be affected much because there is a space for air to pass through, but there will be dyspnoea during exertion.
In this the Position of the vocal cords is paralysed cord is in midline. The Phonation- slightly affected,Respiration- not affected much but dyspnoea can be seen during exertion.in this condition the Treatment is to wait and watch.
All muscles will be paralyzed on both sides except the cricothyroid. Phonation is not affected much since the vocal cord line is completely in the midline.Respiration is affected. It can cause palsy stridor.Palsy stridor is a high pitch squeaking or whistling sound. The treatment for this is tracheostomy followed by lateralization of the vocal cords.
Sensory loss - will be there on the upper half of larynx on the same side.
Motor loss - only cricothyroid is paralyzed. rest all muscles are functional.
Phonation : paralyzed cord will go into the abducted position as the cricothyroid is paralyzed. The vocal cords will be in an Askew position. So, pitch and tone will be affected. Respiration will not be affected but there is risk of aspiration.Treatment is medialisation of vocal cord is achieved with type 1 thyroplasty.
Sensory loss above half of the vocal cord will happen on both sides.Motor loss on paralyzed sides and only cricothyroid would be paralyzed on both sides , rest all muscles are functional.Position - The vocal becomes wavy loose, and lacks, and the vocal cords get pulled away from the midline completely. Phonation will be significantly affected. aphonia occurs. Respiration - The space will increase between the vocal cords and midline, so there is no phonation and a higher risk of aspiration (the action or process of drawing breath). The respiration will not be affected, but there is the risk of aspiration; Treatment is the medialization of vocal cords by thyroplasty, Epiglottopexy, tracheo esophageal diversion.
If both RLN and SLN are lost together, sensory loss will be there on the affected site,Phonation is affected but the patient can speak. Respiration will not be adversely affected but dyspnoea can occur during exertion.
Complete sensory loss of the entire larynx. All muscles will be paralysed.Both paralyzed cords are floppy and lie in an intermediate position. Aphonia occurs as cricothyroid muscle on both sides is paralyzed. Aphonia is seen in bilateral SLN palsy and bilateral combined palsy.Respiration not affected much. But the risk of moderate risk of aspiration as it is complete anesthesia of larynx. Cough reflux will be absent. Treatment includes Tracheostomy, Epiglottopexy, Vocal cord plication, Total laryngectomy.
|RLN- Unilateral palsy||RLN- Bilateral palsy||SLN-Unilateral palsy||SLN- Bilateral palsy||Combined- Unilateral palsy||Combined- Bilateral palsy|
|Sensory loss||Ipsilateral anesthesia of larynx below vocal cords.||Bilateral anesthesia of larynx below vocal cords||In SLN palsy, ipsilateral anesthesia above vocal cords.||In SLN palsy, bilateral anesthesia above vocal cords.||Complete ipsilateral anesthesia of larynx||Complete bilateral anesthesia of larynx|
|Motor loss||Ipsilateral paralysis of all intrinsic muscles except cricothyroid||Bilateral paralysis of all intrinsic muscles except cricothyroid||Ipsilateral paralysis of cricothyroid||Bilateral paralysis of cricothyroid||Ipsilateral paralysis of all intrinsic muscles except inter-arytenoid which receive bilateral innervation||All laryngeal muscles are paralyzed|
|Treatment||Nil||Lateralisation||Epiglottopexy and tracheostomy||Medialisation||1.Tracheostomy|
2.Vocal cord plication
|Normal||RLN- Unilateral palsy||RLN- Bilateral palsy||SLN-Unilateral palsy||SLN- Bilateral palsy||Combined- Unilateral palsy||Combined- Bilateral palsy|
|Vocal cord position during respiration||Normal position is gentle abduction as cricothyroideus are inactive||Median or paramedian||Median or paramedian||Both vocal cords are in gentle abduction but paralyzed cord is wavy and lax due to lack of tension||Both vocal cords are in gentle abduction and floppy||Cadaveric position and floppy||Cadaveric position and floppy|
|Phonation||Median||The Paralyzed cord is median. Normal cord becomes median. Voice is not much affected. Asymptomatic||Both cords are already in the median position. So voice is not affected||Paralyzed cord fails to adduct and becomes tense. So, voice is weak and voice cannot be raised||Both cords fail to adduct. So, voice is very weak||Paralyzed cord fails to adduct. So, voice is weak||Both cords fail to adduct. So aphonia|
|Deep inspiration||Full abduction||Paralyzed cord in median position but normal cord fully abducts. So sufficient airway and no stridor||Both cords fail to abduct and remain in median position--- insufficient airway-- stridor||Fully abduct– sufficient airway||Fully abduct– sufficient airway||Cadaveric position– sufficient airway||Cadaveric position- sufficient airway|
|Cough||Normal||normal||Ineffective as cords fail to meet||Ineffective as cords fail to meet||Ineffective as cords fail to meet||Ineffective as cords fail to meet|
|Aspiration||Nil as cords approximate||nil||Common as cords fail to meet and ineffective cough||Common as cords fail to meet and ineffective cough||Common as cords fail to meet and ineffective cough||Common as cords fail to meet and ineffective cough|
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Cricothyroid space of Reeves: This is supposed to be an avascular space between the upper pole of thyroid and the cricothyroid muscle. Dissection confined to this area helps the surgeon in avoiding injury to the surrounding important structures like the superior laryngeal nerve.
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