PHONOSURGERY - PURPOSE & PROCEDURE
The term Phonosurgery denotes restoration of Voice by using various surgical techniques. The melody of human voice depends on the vocal ligament an elastic structure of the vocal folds, which is not present in any other species. So there is no experimental model for human voice.
Human voice acts as a primary instrument to project our personalities in the society. Voice problems may arise from laryngeal or systemic disease or trauma or misuse. The result of voice dysfunction is sometimes dewasting, endanger the life of professional voice users like singers, actors, politicians, educators etc.
Many people, suffering from voice disorders live desperately in society with the opinion that no proper treatment is available for their problems. In fact invention of phonosurgical techniques has created a ray of hope for such victims of voice disorders.
Voice problems may be of congenital, traumatic, inflammatory, neoplastic, neurological or functional origin. The diagnosis of voice disorders starts with detailed history from the patient and indirect laryngoscopic examination by the otolaryngologist. For a long time perceptual voice analysis (by hearing the patients voice and judging its quality) has been a basic tool in deciding the prognosis of the patients. Recently computerised objective voice analysis methods like voice spectrograms electroglottography, phonotograms etc are gaining importance in judging the prognosis and also for documentation. The invention of video laryngoscopy, and videolaryngostroboscopy techniques have made diagnosis more precise in the voice care.
The management of voice disorders is a team work consisting of otolaryngologist, speech pathologist, Voice coach, psychiatrist, and sometimes plastic surgeons and pediatricians etc.
The voice disorders may be of functional or organic (eg.vocal nodules) orgin, and it is sometimes difficult to demarkate between these two as one may predispose the other. Voice therapy plays a greater role in the correction of most of the functional voice disorders which form 80% of voice problems. It also acts as an important adjuvant treatment modality before and after voice surgery or phonosurgery.
PHONO SURGERY - HISTORICAL ASPECTS
Hippocrates described the importance of lungs, trachea, lips and tongue in phonation in the early 5th century B.C. Claudius Galen who was the founder of laryngology and voice science first recognised the importance of brain in controlling phonation and distinguished between speech and voice. In 1805 Manuel Garcia, famous opera singer invented indirect laryngoscopy by using a dental mirror is still a basic tool for visualising vocal folds by otolaryngologists.
The term phonomicrosurgery was first introduced by Von Laden in 1962. The term phomomicrosurgery was introduced in 1994. Use of surgical microscope for endolaryngeal microsurgery was introduced by Kleinsasser in 1960. Hirano's description of structured layer of vocal fold in early 20th Century has formed the basis for Phonomicrosurgical techniques.
The techniques of laryngoplastic phonosurgery were first introduced by Payr in 1915, but the real concept was created by Isshiki in 1975. Isshiki, a japanese surgeon has the credit for the concept of modern laryngeal framework surgery in the management of voice disorders. It was popularised by Koufman and Zeitels in United States since 1986. It has been practised in India since 1996 and gaining a lot of popularity as a subspeciality of otolaryngology.
The phonosurgical techniques broadly consists of
I.Phonosurgery over the Vocal folds for voice generation
A. Phonomicrosurgery of mass lesions like nodules, cysts, deficits of vocal folds etc.
B. Laryngoplastic Phonosurgery (Thyroplasty) for correcting position of vocal fold as in vocal cord paralysis and also for correcting the tension of the vocal fold.
C. Nerve muscle innervation techniques.
D. Vocal Fold Injection Techniques.
II.Phonosurgery for voice resonance.
The includes correction of cleft paltate, cleftlip, orthodontic surgery pharyngoplasty and endoscopic sinonasal surgeries.
Phonomicrosurgical techiques have revolutionised the management of benign vocal fold lesions like vocal cysts, nodules, polyps without damaging the voice. For centuries the benign vocal fold lesions like cysts were managed by direct excision of the mass or cyst over the vocal fold by stripping of the vocal fold either by naked eye direct laryngoscopy or by microlaryngeal surgery. In the recent times this technique is abandoned as it was found to produce scarring of the vocal folds resulting in poor voice. The modern concept of phonomicrosurgery is based on Hirano's principle of structured layer of the vocal folds. In this technique the vibratory epithelium is protected during excision of the mass for preserving the voice.
This surgery is done under endotracheal general anesthesia using an operating microscope. The basic procedure consists of injection of vocal fold with normal saline and microflap dissection for removing the mass over the vocal folds by preserving the vibratory epithelium. This technique is also applied for augmentation of vocal folds with fat or fascia for correction of voice for vocal cord atrophy with bowing of vocal folds which may be either congenital or developmental. This surgery has come into practice in India very recently, This has become a ray of hope for correction of voice disorders in professional voice users like singers, politicians, educators etc.
Most of the phonomicrosurgery techniques are done with cold, steel instruments reserving the laser for more vascular lesions, as the laser produces heat and scarring of the vocal fold.
This is otherwise known as thyroplasty, or laryngeal frame work surgery. This is of 4 types.
1. Thyroplasty type I :
This is also known as medialisation laryngoplasty (M.L)
I N D I C A T I O N S :
A). Unilateral vocal cord paralysis, paralytic dysphonia : Thyroplasty type I has largely replaced the teflon injection technique, which was practised for several years in the management of paralytic dysphonia. In this technique, under local anaesthesia a window is cut in the thyroid lamina in the neck on the paralysed side and the piece of thyroid cartilage is depressed inwards towards the midline until the normal cord touches the paralysed cord, thus closing the glottic gap resulting in normal voice. The thyroid cartilage in the window is held in place with a silastic block. As this surgery is done under local anaesthesia patients voice can be monitored on the operating table itself. This technique is sometimes supplemented by another technique called arytenoid rotation to close large posterior glottic gaps in vocal cord paralysis. This is the commonest type of thyroplasty in practice. The success rate is of about 80%.
B). Other indications M.L. are vocal cord atrophy, bowing of the vocal cord etc.
2. Thyroplasty type II :
In this technique the vocal folds are displaced laterally away from the midline under local anaesthesia. This technique is presently applied in the management of spastic dysphonia.
3. Thyroplasty type III :
In this technique the vocal cords are pushed back posteriorly thus shortening the vocal folds resulting in lowering of the pitch. This technique is commonly applied in the management of puberity Dysphonia a developmental disorder of larynx in males, refractory to voice therapy. By applying this technique the high pitched voice or feminine voice in males can be converted into low pitched or normal voice.
4. Thyroplasty type IV :
Thyroplasty Type-IV of Isshiki also described as Cricothyroid Approximation. It is indicated for raising of pitch in females who have male voice (Androphonia)
Nerve muscle innervation techniques :
Nerve muscle pedicle surgery involves implanting a portion of sternohyoid muscle with its intact motor branch from ansa hypoglossi into a paralysed posterior cricoarytenoid muscle. This is indicated in the management of bilateral vocal cord paralysis of varied aetiology. The operation has not been universally satisfactory because of its varried success rate.
Laryngeal injection techniques :
For several years injection of Teflon into the vocal folds has been practised for correction of paralytic dysphonia. Eventhough it has been largely replaced by techniques of thyroplasty and arytenoid rotation it is still indicated for preventing aspiration in children with vocal fold paralysis. Injection of fat and collagen are widely practised for correction of paralytic dysphonia as temporaty methods before proceeding to thyroplasty techniques.
C O N C L U S I O N : Introduction of phonomicrosurgery and laryngoplasitc phonosurgery techniques has revolutionised the management of voice disorders. It has created a ray of hope for victims of voice problems thus forming a new subspeciality in the field of Otolaryngology.