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Gray's Minithyrotomy procedure
Dr. T. Balasubramanian M.S. D.L.O.
Introduction: Vocal cord mucosal lesions always heals with scar formation causing irrepairable damage to voice. If the scarring involves the vocal ligament then it becomes nearly impossible to treat this condition. To over come this problem Gray etal in 1999 introduced the "Gray's Minithyrotomy" procedure. In this procedure through a small external incision access to the vocal fold mucosa could be obtained without resorting to mucosal incision. Usually dissection is performed along the long axis of the vocal fold recreating the Reinke's space in the bargain.
Advantages of Gray's minithyrotomy:
1. This is a minimally invasive procedure
2. Since dissection is in the submucosal plane there is no scarring of vocal fold mucosa
3. Procedure is well tolerated by patients
4. Since the line of dissection is in an antero posterior direction Reinke space is recreated if already destroyed due to fibrosis
This surgery can be performed under local / topical anesthesia/GA. Intravenous supplimentation can be resorted to.
Skin and subcutaneous tissue over the prelaryngeal region is infiltrated with 1% xylocaine mixed with 1:100,000 adrenaline.
Topical anesthesia: 4% xylocaine is used topically to anesthetize the laryngeal mucosa and nasal mucosa. In rare instances superior laryngeal nerve block can be resorted to.
In cases where general anesthesia was preferred, the smallest possible endotracheal tube should be used to intubate the larynx to ensure endolaryngeal visibility.
Visualization of endolarynx: This is a very important step in the whole surgical procedure. A fibreoptic laryngoscope / Rigid suspension laryngoscope is used for this purpose. A camera is attached and the vocal cord is constantly monitored in the monitor during the whole procedure.
Patient is ideally placed in supine position with the neck slightly extended using a small shoulder roll. A horizontal incision of about 1 - 2 cms is made at the lower edge of thyroid cartilage. The incision is carried through the skin and subcutaneous tissue. Fat tissue for implantation can be harvested from this area itself. Amount of fat tobe harvested is about 1 - 2 cm3.
The infrahyoid muscles are separated in the midline exposing the larynx. The thyoid perichondrium is incised in the midline, and then horizontally about 1cm along the inferior borders of the side being treated. The perichondrium is elevated superolaterally as a triangular flap. Otologic drill using a 3mm - 4mm burr bit is used to perform thyrotomy. The long axis of the drill should be aligned obliquely with the cartilage, parallel to the axis of the vocal fold. The window should be created about 3-4 mm lateral to midline and 3-4 mm superior to the inferior edge of thyroid cartilage. Pressure is applied to the drill till the inner cartilagenous cortex yields. This is the time when endolaryrngeal visualization of larynx should ideally begin.
Otologic microinstruments are suited for dissection of tissue from here on. Utmost care should be taken to avoid perforation of vocal fold mucosa. Initially, a blunt 45 degree probe is introduced through the thyrotomy window. A properly positioned probe will be seen at the undersurface of vocal fold endolaryngeally.
In cases of bowing, atrophy of vocal folds blunt dissection in Reinke's space can be performed up to the level of vocal process. In cases of scarring / sulcus vocalis the scar must be dissected sharply. Once a pocket is created fat strips created out of harvested adipose tissue should be introduced into it. Amount of fat insertion should be monitored endolaryngeally. It is always better to over correct than under correct. It should be ensured that after correction the anterior edges of vocal folds nearly meet in midline. There should be adequate posterior glottic chink for airway. Dissection over the superior surface of vocal fold should be avoided. Dissection if any should be confined to the under surface of vocal fold. If vocal fold mucosa gets perforated while dissecting, it can be sealed with perichondrium. If the perforation is large still fat can be implanted, but the extrusion rate is pretty high in these cases.
The minithyrotomy site is closed using fibrin glue / bone wax. Wound is closed in layers.
Figure showing dissection being performed in the submucosal place under the vocal folds
Figure showing Reinke's space being created, and fat tissue being implanted
Figure showing the vocal fold position after successful implantation
1. Vocal cord palsy
2. Sulcus vocalis
3. Bowing of vocal folds
Fat implant serves dual purpose: It acts as a volume replacement, and it also acts as a barrier that prevents the elevated mucosa from scarring back down. It is also important for the pocket to be created over the medial surface of vocal folds and not over its superior surface. The inferomedial surface of the vocal fold is where the mucosal waves are generated during phonation. Fat augmentation of this surface helps in generation of good mucosal wave patterns.