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Thyroplasty is a phonosurgical technique designed to improve the voice by altering the thyroid cartilage of the larynx (the voice box), which houses the vocal cords in order to change the position or the length of the vocal cords.



There are four different types of thyroplasty procedures described by Isshiki:

Type 1 thyroplasty (medialization thyroplasty)

It is the most commonly used surgical procedure to correct unilateral vocal cord paralysis (a condition where the vocal cord of one side is paralysed).

The diagram (a), (b), (c) show different positions of vocal cords in different conditions. Unilateral Vocal Cord Paralysis.jpg
The diagram (a), (b), (c) show different positions of vocal cords in different conditions.


In this type of thyroplasty, a rectangular portion of the thyroid cartilage is mobilized and pushed towards the medial side using a piece of silastic block of proper shape under local anesthesia. [2]

Earlier, the piece of the thyroid cartilage was kept along with implant and the stitches were taken, but nowadays, the piece of the thyroid cartilage is cut and removed to avoid complications.

A piece of thyroid cartilage is cut and pushed towards the medial side by placing an implant. Medialization Thyroplasty.jpg
A piece of thyroid cartilage is cut and pushed towards the medial side by placing an implant.

Types of procedures

Currently, there are four types of implant procedures which are used to perform type 1 thyroplasty.

Montgomery Thyroplasty Implant system

This system was discovered after years of research and the main advantage of this implant system is that it eliminates the process of customizing the implant at the time of surgery. This system consists of different sizes and shapes of shims made of silastic. It has the most proven success rate and the duration of the procedure is slow in comparison to other implant system. The other advantage is that it does not require suturing. It has reduced incidence of trauma.

In this type of implant system, the thyroid cartilage is pushed towards the medial side using the silastic implant. Montgomery Thyroplasty Implant System.jpg
In this type of implant system, the thyroid cartilage is pushed towards the medial side using the silastic implant.
VoCoM system (vocal fold medialization)

This system consists of different sizes and shapes of implants made from hydroxyapatite (a naturally occurring mineral form of calcium apatite). It helps in achieving accurate vocal fold medialization. This procedure is technically reversible. But it should be used in candidates of permanent implantation due to its biocompatible clinical use lasting for nearly a decade.

TVFMI system

This system generally consists of two sizes of implants made out of pure titanium. It has a lot of advantages and the main one is that it reduces the operative time. Titanium is more safe than other implants. It has great biocompatibility. The implants are available in only two variants and they are designed in such a way that they ensure optimal fixation. The implant can be easily made as the titanium sheet is easy to shape. The technique is relatively simple and does not require expensive instruments.

Gore-Tex Implant system

In this type of implant system, the implant is made of homopolymer of polytetrafluoroethylene in form of minute beads arranged in a fine fiber mesh. It is malleable and can be inserted through a small window. [3]







Type 2 thyroplasty (lateralization thyroplasty)

It is a surgical procedure used in conditions like adductor spasmodic dysphonia (a condition in which there is distortion of the voice due to excessively tight closure of the glottis on phonation). Generally, lateralization thyroplasty is intended to prevent this tight closure of the glottis at the terminal stage of phonation by lateralizing the position of the vocal cord. This is a completely mechanical process.


An incision is made at midline of the thyroid cartilage. A silicon wedge is used to fix the incised thyroid cartilage in the newly abducted position.

Modified technique

A specially devised titanium bridge is used instead of silicon wedge. Nowadays, instead of one titanium bridge, two titanium bridges are used for permanent fixation of the thyroid cartilage.



Type 3 thyroplasty (relaxation thyroplasty)

This procedure is generally done to lower the vocal pitch by shortening the thyroid ala.


In this thyroplasty, the relaxation of the vocal cords is done by antero-posterior shortening of the thyroid ala.


Type 4 thyroplasty (stretching thyroplasty)


This procedure is done to elevate the vocal pitch. This procedure consists of lengthening of the thyroid cartilage. It includes cricothyroid approximation.



In some specific conditions, different types of thyroplasties are combined for the desired results.

Medialization thyroplasty with arytenoid adduction (rotation technique)


The main purpose of this combination is the medialization of the entire vocal cord (anterior and posterior).


  • Open posterior glottis.
  • In people with high vagal paralysis.
  • Recurrent laryngeal nerve paralysis with lateralized arytenoid.
  • Non-rotating aarytenoid.

Medialization thyroplasty with arytenoid adduction (fixation technique)


  • Medial vocal cord fixation.


  • Arytenoid fracture where there is anterior dislocation of the arytenoid cartilage.
  • In cricoarytenoid joint ankylosis where there is failed arytenoid adduction.

Medialization thyroplasty (type 1) with stretching thyroplasty (type 4)


  • The main purpose of this combination is stretching of the vocal cord with medialization of the affected side.


  • Unilateral superior laryngeal nerve weakness.

Medialization thyroplasty (type 1) with relaxation thyroplasty (type 3)


  • The main aim of this combination is relaxation and increased mass of one vocal cord.


  • In males with high-pitched, presbyphonic voice.

Bilateral medialization thyroplasty


  • Medialization of both the vocal cords.


  • Open anterior glottis.
  • In presbyphonia where there is bilateral vocal cord weakness.
  • When there is bilateral loss of muscle mass.
  • Tremor-induced abductor spasmodic dysphonia (AbSD).

Bilateral relaxation thyroplasty


  • Relaxation of both the vocal cords.


  • In males who have an overly high-pitched voice.
  • Stable abductor spasmodic dysphonia (AbSD) [9]

Related Research Articles

The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the definition used among those who study laryngeal anatomy and physiology and speech production in general. Phoneticians in other subfields, such as linguistic phonetics, call this process voicing, and use the term phonation to refer to any oscillatory state of any part of the larynx that modifies the airstream, of which voicing is just one example. Voiceless and supra-glottal phonations are included under this definition.

Larynx Voice box, an organ in the neck of amphibians, reptiles, and mammals

The larynx, commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The larynx houses the vocal folds, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The word larynx comes from a similar Ancient Greek word.

This is a glossary of medical terms related to communications disorders which are conditions that could have the potential to negatively impact the level at which an individual can hear, understand, and respond to others.

Laryngeal cancer

Laryngeal cancers are mostly squamous-cell carcinomas, reflecting their origin from the epithelium of the larynx.


Laryngitis is inflammation of the larynx. Symptoms often include a hoarse voice and may include fever, cough, pain in the front of the neck, and trouble swallowing. Typically, these last under two weeks.

Recurrent laryngeal nerve Nerve in the human body

The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerves, right and left. The right and left nerves are not symmetrical, with the left nerve looping under the aortic arch, and the right nerve looping under the right subclavian artery then traveling upwards. They both travel alongside of the trachea. Additionally, the nerves are one of few nerves that follow a recurrent course, moving in the opposite direction to the nerve they branch from, a fact from which they gain their name.

Rima glottidis Opening between the true vocal cords and the arytenoid cartilages of the larynx

The rima glottidis is the opening between the true vocal cords and the arytenoid cartilages of the larynx.

Posterior cricoarytenoid muscle

The posterior cricoarytenoid muscles are small, paired intrinsic muscles of the larynx that extend between cricoid cartilage to the arytenoid cartilages in the larynx.

Cricothyroid muscle

The cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation. It is innervated by the superior laryngeal nerve. Its action tilts the thyroid forward to help tense the vocal cords.

Bogart–Bacall syndrome

Bogart–Bacall syndrome (BBS) is a voice disorder that is caused by abuse or overuse of the vocal cords.

Hoarse voice Voice disorder

A hoarse voice, also known as dysphonia or hoarseness, is when the voice involuntarily sounds breathy, raspy, or strained, or is softer in volume or lower in pitch. A hoarse voice, can be associated with a feeling of unease or scratchiness in the throat. Hoarseness is often a symptom of problems in the vocal folds of the larynx. It may be caused by laryngitis, which in turn may be caused by an upper respiratory infection, a cold, or allergies. Cheering at sporting events, speaking loudly in noisy situations, talking for too long without resting one's voice, singing loudly, or speaking with a voice that's too high or too low can also cause temporary hoarseness. A number of other causes for losing one's voice exist, and treatment is generally by resting the voice and treating the underlying cause. If the cause is misuse or overuse of the voice, drinking plenty of water may alleviate the problems.

Laryngology is a branch of medicine that deals with disorders, diseases and injuries the larynx, colloquially known as the voice box. Laryngologists treat disorders of the larynx, including diseases that affects the voice, swallowing, or upper airway. Common conditions addressed by laryngologists include vocal fold nodules and cysts, laryngeal cancer, spasmodic dysphonia, laryngopharyngeal reflux, papillomas, and voice misuse/abuse/overuse syndromes. Dysphonia/hoarseness; laryngitis ; *Spasmodic dysphonia; dysphagia; Tracheostomy; Cancer of the larynx; and vocology are included in laryngology.

Vocal cord paresis, also known as recurrent laryngeal nerve paralysis or vocal fold paralysis, is an injury to one or both recurrent laryngeal nerves (RLNs), which control all muscles of the larynx except for the cricothyroid muscle. The RLN is important for speaking, breathing and swallowing.

Vestibular fold

The vestibular fold is one of two thick folds of mucous membrane, each enclosing a narrow band of fibrous tissue, the vestibular ligament, which is attached in front to the angle of the thyroid cartilage immediately below the attachment of the epiglottis, and behind to the antero-lateral surface of the arytenoid cartilage, a short distance above the vocal process.

Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand. The person's voice may also sound strained or they may be nearly unable to speak. Onset is often gradual and the condition is lifelong.

Puberphonia is a functional voice disorder that is characterized by the habitual use of a high-pitched voice after puberty, hence why many refer to the disorder as resulting in a ‘falsetto’ voice. The voice may also be heard as breathy, rough, and lacking in power. The onset of puberphonia usually occurs in adolescence, between the ages of 11 and 15 years, at the same time as changes related to puberty are occurring. This disorder usually occurs in the absence of other communication disorders.

Histology is the study of the minute structure, composition, and function of tissues. Mature human vocal cords are composed of layered structures which are quite different at the histological level.

Endoscopic laser cordectomy, also known as Kashima operation, is an endoscopic laser surgical procedure performed for treating the respiratory difficulty caused as a result of bilateral abductor vocal fold paralysis. Bilateral vocal fold paralysis is basically a result of abnormal nerve input to the laryngeal muscles, resulting in weak or total loss of movement of the laryngeal muscles. Most commonly associated nerve is the vagus nerve or in some cases its distal branch, the recurrent laryngeal nerve. Paralysis of the vocal fold may also result from mechanical breakdown of the cricoarytenoid joint. It was first described in by Kashima in 1989.

Arytenoid adduction is a surgical procedure used to treat vocal cord paralysis. A suture is used to emulate the action of the lateral cricoarytenoid muscle and position the paralyzed vocal cord closer to the midline. This allows the two vocal cords to meet and can improve speaking and swallowing ability for affected patients. Arytenoid adduction is often performed in conjunction with medialization thyroplasty.

Muscle tension dysphonia (MTD) was originally coined in 1983 by Morrison and describes a dysphonia caused by increased muscle tension of the muscles surrounding the voice box: the laryngeal and paralaryngeal muscles. MTD is a unifying diagnosis for a previously poorly categorized disease process. It allows for the diagnosis of dysphonia caused by many different etiologies and can be confirmed by history, physical exam, laryngoscopy and videostroboscopy, a technique that allows for the direct visualization of the larynx, vocal cords, and vocal cord motion.


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