- Email: [email protected]
Small fenestra stapedectomy with annular reconstruction
•
SMALL FENESTRA STAPEDECTOMY WITH -- ANNULAR RECONSTRUCTION MITCHELL K. SCHWABER, MD
This article presents the indications for and the technique of small fenestra stapedectomy with annular reconstruction. This technique emphasizes many of the skills used in chronic ear surgery, including incisions, flap elevation, bone exposure, creation of a fenestra, and sealing the oval window. The small fenestra stapedectomy with annular reconstruction is a procedure that can be readily incorporated into the practice of a general otolaryngologist and can be taught to the otolaryngology resident.
Recently, academic otolaryngologists have voiced concern regarding the instruction of residents in the technique of stapedectomy. Much of this concern is due to a declining number of otosclerosis cases and can best be summarized by the following questions: Should every resident be trained in stapedectomy, or only those specifically interested in otologic surgery? What is the minimum number of stapedectomy cases a practitioner must perform each year to maintain proficiency, and should other otologic surgery cases be taken into account? How should residents be trained to perform stapedectomy, ie, is there a stapedectomy technique that uses the same skills used in chronic ear surgery? The author's approach to this problem is to teach a stapedectomy technique that incorporates many of the same skills learned in chronic ear surgery. Specifically, this includes incisions, graft harvest, flap elevation, bony exposure, disarticulation of the incudostapedial joint, creation of a fenestra, sealing the oval window, and insertion of a prosthesis. The purpose of this article is to describe and illustrate a technique of stapedectomy that incorporates the skills of chronic ear surgery, the small fenestra stapedectomy with annular reconstruction. The indications and results of this technique are also reviewed.
INDICATIONS The patient with otosclerosis and a conductive hearing loss usually seeks medical attention because he or she desires treatment, ie, surgery or a hearing aid. The otosclerosis patient undergoes a complete history and neuro-otologic evaluation. The ear should be carefully examined for evidence of chronic otitis media, tympanosclerosis, and other pathology. The remainder of the neuro-otologic examination, including Hennebert's sign, examination for nystagmus, Romberg testing, gait evaluation, and dysmetria testing, should all be performed to
From the Department of Otolaryngology, Vanderbilt University Medical Center, Nashville, TN. Address reprint requests to Mitchell K. Schwaber, MD, Vanderbilt University Medical Center, Department of Otolaryngology, 5-2100 Medical Center North, Nashville, TN 37232-2559. Copyright © 1992 by w.e. Saunders Company 1043-1810/9210304·0014$05.00/0
220
rule out the possibility of vertigo and inner ear dysfunction. The remainder of the head and neck examination should also be performed, including examination of the nose, oropharynx, neck, and parotid gland. At the time of the initial visit, an audiogram should be obtained, even if the patient has had a previous audiogram. As part of the audiometric evaluation, both air and bone conduction with necessary masking should be performed. Also, speech discrimination tests, acoustic reflex testing, and tympanometry are helpful. In reviewing the audiogram with the patient, the author also performs tuning fork tests to confirm the conductive hearing loss. If the history, audiogram, and tuning fork tests are consistent with a conductive hearing loss due to otosclerosis, treatment is recommended. If the air-bone gap is 25 dB or greater, the patient is a candidate for either surgery or hearing aid placement. If the air-bone gap is less than 25 dB, the patient is followed up with yearly audiometric evaluations and examinations. If the patient has less than a 25-dB conductive component and still desires treatment, he or she is encouraged to wear a hearing aid until the stapes becomes completely "fixed."
SURGICAL TECHNIQUE The patient is brought to the operating room, and following the induction of general endotracheal anesthesia, the head is positioned in a three-fourth turned position, ie, the Juers position. The patient should be placed as close to the edge of the operating table as possible so that the surgeon does not have to extend the arms, which would cause fatigue during the case. After the induction of anesthesia and positioning of the patient, injections are made circum aurally using 1:100,000 epinephrine in 1% lidocaine. While the surgeon scrubs his or her hands, the nurse or resident cleans and prepares the ear using iodophor solution. The largest speculum possible is secured into the ear canal and is held in place using a speculum holder. A mixture of 1:100,000epinephrine and 1% lidocaine is then injected into the ear canal. The ear canal is then irrigated again with iodophor, followed by saline until no additional iodophor can be seen in the canal. After injecting the ear canal, an incision is made posterior to the dome of the tragus (Fig 1). The tragal carti-
OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY-HEAD AND·NECK SURGERY, VOL 3, NO 4 (DEC), 1992: PP 220·224
lage is identified, and the plane between the skin and the posterior tragal perichondrium is dissected using the curved dissecting scissors. The perichondrium and cartilage are incised so as to leave the dome of the tragus (Fig 2). This maneuver provides improved cosmesis for the donor site. In most cases, the anterior perichondrium is left in place, a maneuver that lessens the amount of blood loss. After removing the cartilage and perichondrial graft, the incision is reapproximated using interrupted 6-0 absorbable chromic suture. The perichondrium is elevated from the cartilage and set aside on the instrument table (Fig 3). A graft to cover the oval window is cut from the perichondrium, and it measures 5 mm by 5 mm. The incisions for a tympanomeatal flap are illustrated in Fig 4. The curved portion of the incision is made using an angled (no. 7200) Beaver blade (Rudolph Beaver,
Waltham, MA). The straight incision is made with either a sickle knife or with a hockey stick Beaver blade (no. 5900). Note the design of these incisions in Fig 4. A tympanomeatal flap is then elevated anteriorly to the level of the malleus handle. Care is taken to avoid injuring the chorda tympani nerve. After elevating the flap, the ossicular chain is carefully inspected and palpated to determine if fixation of the stapes is present. If tympanosclerosis or another pathology is identified, the appropriate procedure is performed. However, if otosclerosis is identified, the next step is to provide exposure of the . posterior quadrant. The bone of the posterior superior quadrant of the ear canal can be removed using either a stapes curette or the microdrill (Fig 5). By proceeding carefully, the chorda tympani nerve can be dissected and preserved. The scutal bone is removed until the pyrarni-
FIGURE 1. An incision is made on the posterior side of the tragus.
FIGURE 2. A cartilage graft is harvested leaving the dome of the tragal cartilage in place. MITCHELL K. SCHWABER
221
. . f or tyim panomeatal flap, FIGURE 4. InCIsIOns
222
. d ntu'the is FIGURE 5. Using the micro .scutal bone d the remove . d to expose the pyramidal eminence an facial nerve. SMALL FENESTRA STAPEDECTOMY
FIGURE 6. The crurotomy saw is used to cut the stapes crura near the base.
FIGURE 7. A O.B-mm diamond bur is used to create a fenestra in the center of the footplate.
FIGURE 8. (A) A sturdy right-angled pick is used to extract the posterior half of the footplate. (B) The completed fenestra.
FIGURE 9. (A) The fenestra is covered with a perichondrial graft and the area over the fenestra is dimpled using a blunt instrument. (B) The stem of the prosthesis is placed on the dimple and then attached to the incus. MITCHELL K. SCHWABER
223
dal eminence and the tympanic segment of the facial nerve can be clearly visualized. The incudostapedial joint is then disarticulated using a joint knife, and the stapes tendon is sectioned ~sing the Belluci scissors (Storz Instrument Co., St. LOUIS, MO). Using the crurotomy saw in the microdrill (XomedTreace, Jacksonville, FL), the crura are cut close to the stapes footplate (Fig 6). After removing the stapes superstructure, the pyramidal eminence can be drilled and removed in order to provide additional visualization of the stapes footplate. Using a 0.8-mm diamond bur, a fenestra is created in the center of the footplate (Fig 7). The diamond bur is first used to thin the bone until the endosteal membrane is identified. A small right-angled pick is then used to extract the posterior half of the footplate (Figs BA, B), creating a slightly larger fenestra. The perichondrial graft is then placed over the fenestra and positioned using the blunt House annulus dissector. The area of the graft that overlies the fenestra is dimpled using the blunt instrument (Fig 9A). In most cases, a 4.5-mm Moon-Lippy prosthesis is used. However, a 4-mm Robinson prosthesis with a narrow stem can also be used. The first maneuver is that the stem should be placed into the dimple that had been previously created (Fig 9B). In most cases, the prosthesis will remain in an upright position so that it can be readily placed underneath the incus. The bucket handle is rotated into its proper position to allow the prosthesis to be attached to the incus. Using a small right-angled pick to elevate the incus and a straight pick to slightly depress the stapes prosthesis, the cup or bucket of the prosthesis is placed under the lenticular process of the incus. The bucket handle is then rotated over the incus once this assembly is achieved. The light reflex can then be tested by first placing a small drop of saline in the round window niche and then observing the light reflex bending on palpation of the stapes prosthesis. The tympanomeatal flap is then returned to its normal position, and while carefully holding it in position, the incision line is covered with Gelfoam (Upjohn Co., Kalamazoo, MI). Additionally, the ear canal is filled with Bacitracin ointment, which serves both to prevent infection as well as to secure the placement of the flap. A cotton ball is then inserted into the ear canal.
224
RESULTS In a previous publication, 1 the author noted that the technique described here was satisfactory for cases in which the footplate was fractured. After further analysis of the postoperative results, it appears that patients with the oval window sealed with perichondrium and a MoonLippy prosthesis actually had better hearing, particularly in the low frequencies, as compared with the standard stapedectomy. In addition, once the oval window was covered by the perichondrial graft, the otolaryngology resident on the service could safely manipulate the prosthesis into position. As a consequence, this alternative procedure has now become the standard for resident teaching. In reviewing the results of the last 20 procedures performed using this technique, there has been closure of the air-bone gap to less than 10 dB in 18 cases and to less than 20 dB in all cases. There have been no cases of profound sensorineural hearing loss with this technique, and there have been no cases of perilymph fistula.
DISCUSSION The small fenestra stapedectomy with annular reconstruction is a procedure that allows the otologic surgeon to use technical skills which are also used during chronic ear surgery. This technique simplified the two critical portions of the procedure, ie, creation of the fenestra and placement of the prosthesis. As a result, with this technique, residents can be safely taught the principles and technique of stapedectomy.
ACKNOWLEDGMENT The author wishes to thank Lana Tackett for the illustrations and Patti M. Reilly for secretarial assistance.
REFERENCE 1. Schwaber MK: Small fenestra stapedectomy using a microdrill. Laryngoscope 99:768-770, 1989
SMALL FENESTRA STAPEDECTOMY
SMALL FENESTRA STAPEDECTOMY WITH -- ANNULAR RECONSTRUCTION MITCHELL K. SCHWABER, MD
This article presents the indications for and the technique of small fenestra stapedectomy with annular reconstruction. This technique emphasizes many of the skills used in chronic ear surgery, including incisions, flap elevation, bone exposure, creation of a fenestra, and sealing the oval window. The small fenestra stapedectomy with annular reconstruction is a procedure that can be readily incorporated into the practice of a general otolaryngologist and can be taught to the otolaryngology resident.
Recently, academic otolaryngologists have voiced concern regarding the instruction of residents in the technique of stapedectomy. Much of this concern is due to a declining number of otosclerosis cases and can best be summarized by the following questions: Should every resident be trained in stapedectomy, or only those specifically interested in otologic surgery? What is the minimum number of stapedectomy cases a practitioner must perform each year to maintain proficiency, and should other otologic surgery cases be taken into account? How should residents be trained to perform stapedectomy, ie, is there a stapedectomy technique that uses the same skills used in chronic ear surgery? The author's approach to this problem is to teach a stapedectomy technique that incorporates many of the same skills learned in chronic ear surgery. Specifically, this includes incisions, graft harvest, flap elevation, bony exposure, disarticulation of the incudostapedial joint, creation of a fenestra, sealing the oval window, and insertion of a prosthesis. The purpose of this article is to describe and illustrate a technique of stapedectomy that incorporates the skills of chronic ear surgery, the small fenestra stapedectomy with annular reconstruction. The indications and results of this technique are also reviewed.
INDICATIONS The patient with otosclerosis and a conductive hearing loss usually seeks medical attention because he or she desires treatment, ie, surgery or a hearing aid. The otosclerosis patient undergoes a complete history and neuro-otologic evaluation. The ear should be carefully examined for evidence of chronic otitis media, tympanosclerosis, and other pathology. The remainder of the neuro-otologic examination, including Hennebert's sign, examination for nystagmus, Romberg testing, gait evaluation, and dysmetria testing, should all be performed to
From the Department of Otolaryngology, Vanderbilt University Medical Center, Nashville, TN. Address reprint requests to Mitchell K. Schwaber, MD, Vanderbilt University Medical Center, Department of Otolaryngology, 5-2100 Medical Center North, Nashville, TN 37232-2559. Copyright © 1992 by w.e. Saunders Company 1043-1810/9210304·0014$05.00/0
220
rule out the possibility of vertigo and inner ear dysfunction. The remainder of the head and neck examination should also be performed, including examination of the nose, oropharynx, neck, and parotid gland. At the time of the initial visit, an audiogram should be obtained, even if the patient has had a previous audiogram. As part of the audiometric evaluation, both air and bone conduction with necessary masking should be performed. Also, speech discrimination tests, acoustic reflex testing, and tympanometry are helpful. In reviewing the audiogram with the patient, the author also performs tuning fork tests to confirm the conductive hearing loss. If the history, audiogram, and tuning fork tests are consistent with a conductive hearing loss due to otosclerosis, treatment is recommended. If the air-bone gap is 25 dB or greater, the patient is a candidate for either surgery or hearing aid placement. If the air-bone gap is less than 25 dB, the patient is followed up with yearly audiometric evaluations and examinations. If the patient has less than a 25-dB conductive component and still desires treatment, he or she is encouraged to wear a hearing aid until the stapes becomes completely "fixed."
SURGICAL TECHNIQUE The patient is brought to the operating room, and following the induction of general endotracheal anesthesia, the head is positioned in a three-fourth turned position, ie, the Juers position. The patient should be placed as close to the edge of the operating table as possible so that the surgeon does not have to extend the arms, which would cause fatigue during the case. After the induction of anesthesia and positioning of the patient, injections are made circum aurally using 1:100,000 epinephrine in 1% lidocaine. While the surgeon scrubs his or her hands, the nurse or resident cleans and prepares the ear using iodophor solution. The largest speculum possible is secured into the ear canal and is held in place using a speculum holder. A mixture of 1:100,000epinephrine and 1% lidocaine is then injected into the ear canal. The ear canal is then irrigated again with iodophor, followed by saline until no additional iodophor can be seen in the canal. After injecting the ear canal, an incision is made posterior to the dome of the tragus (Fig 1). The tragal carti-
OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY-HEAD AND·NECK SURGERY, VOL 3, NO 4 (DEC), 1992: PP 220·224
lage is identified, and the plane between the skin and the posterior tragal perichondrium is dissected using the curved dissecting scissors. The perichondrium and cartilage are incised so as to leave the dome of the tragus (Fig 2). This maneuver provides improved cosmesis for the donor site. In most cases, the anterior perichondrium is left in place, a maneuver that lessens the amount of blood loss. After removing the cartilage and perichondrial graft, the incision is reapproximated using interrupted 6-0 absorbable chromic suture. The perichondrium is elevated from the cartilage and set aside on the instrument table (Fig 3). A graft to cover the oval window is cut from the perichondrium, and it measures 5 mm by 5 mm. The incisions for a tympanomeatal flap are illustrated in Fig 4. The curved portion of the incision is made using an angled (no. 7200) Beaver blade (Rudolph Beaver,
Waltham, MA). The straight incision is made with either a sickle knife or with a hockey stick Beaver blade (no. 5900). Note the design of these incisions in Fig 4. A tympanomeatal flap is then elevated anteriorly to the level of the malleus handle. Care is taken to avoid injuring the chorda tympani nerve. After elevating the flap, the ossicular chain is carefully inspected and palpated to determine if fixation of the stapes is present. If tympanosclerosis or another pathology is identified, the appropriate procedure is performed. However, if otosclerosis is identified, the next step is to provide exposure of the . posterior quadrant. The bone of the posterior superior quadrant of the ear canal can be removed using either a stapes curette or the microdrill (Fig 5). By proceeding carefully, the chorda tympani nerve can be dissected and preserved. The scutal bone is removed until the pyrarni-
FIGURE 1. An incision is made on the posterior side of the tragus.
FIGURE 2. A cartilage graft is harvested leaving the dome of the tragal cartilage in place. MITCHELL K. SCHWABER
221
. . f or tyim panomeatal flap, FIGURE 4. InCIsIOns
222
. d ntu'the is FIGURE 5. Using the micro .scutal bone d the remove . d to expose the pyramidal eminence an facial nerve. SMALL FENESTRA STAPEDECTOMY
FIGURE 6. The crurotomy saw is used to cut the stapes crura near the base.
FIGURE 7. A O.B-mm diamond bur is used to create a fenestra in the center of the footplate.
FIGURE 8. (A) A sturdy right-angled pick is used to extract the posterior half of the footplate. (B) The completed fenestra.
FIGURE 9. (A) The fenestra is covered with a perichondrial graft and the area over the fenestra is dimpled using a blunt instrument. (B) The stem of the prosthesis is placed on the dimple and then attached to the incus. MITCHELL K. SCHWABER
223
dal eminence and the tympanic segment of the facial nerve can be clearly visualized. The incudostapedial joint is then disarticulated using a joint knife, and the stapes tendon is sectioned ~sing the Belluci scissors (Storz Instrument Co., St. LOUIS, MO). Using the crurotomy saw in the microdrill (XomedTreace, Jacksonville, FL), the crura are cut close to the stapes footplate (Fig 6). After removing the stapes superstructure, the pyramidal eminence can be drilled and removed in order to provide additional visualization of the stapes footplate. Using a 0.8-mm diamond bur, a fenestra is created in the center of the footplate (Fig 7). The diamond bur is first used to thin the bone until the endosteal membrane is identified. A small right-angled pick is then used to extract the posterior half of the footplate (Figs BA, B), creating a slightly larger fenestra. The perichondrial graft is then placed over the fenestra and positioned using the blunt House annulus dissector. The area of the graft that overlies the fenestra is dimpled using the blunt instrument (Fig 9A). In most cases, a 4.5-mm Moon-Lippy prosthesis is used. However, a 4-mm Robinson prosthesis with a narrow stem can also be used. The first maneuver is that the stem should be placed into the dimple that had been previously created (Fig 9B). In most cases, the prosthesis will remain in an upright position so that it can be readily placed underneath the incus. The bucket handle is rotated into its proper position to allow the prosthesis to be attached to the incus. Using a small right-angled pick to elevate the incus and a straight pick to slightly depress the stapes prosthesis, the cup or bucket of the prosthesis is placed under the lenticular process of the incus. The bucket handle is then rotated over the incus once this assembly is achieved. The light reflex can then be tested by first placing a small drop of saline in the round window niche and then observing the light reflex bending on palpation of the stapes prosthesis. The tympanomeatal flap is then returned to its normal position, and while carefully holding it in position, the incision line is covered with Gelfoam (Upjohn Co., Kalamazoo, MI). Additionally, the ear canal is filled with Bacitracin ointment, which serves both to prevent infection as well as to secure the placement of the flap. A cotton ball is then inserted into the ear canal.
224
RESULTS In a previous publication, 1 the author noted that the technique described here was satisfactory for cases in which the footplate was fractured. After further analysis of the postoperative results, it appears that patients with the oval window sealed with perichondrium and a MoonLippy prosthesis actually had better hearing, particularly in the low frequencies, as compared with the standard stapedectomy. In addition, once the oval window was covered by the perichondrial graft, the otolaryngology resident on the service could safely manipulate the prosthesis into position. As a consequence, this alternative procedure has now become the standard for resident teaching. In reviewing the results of the last 20 procedures performed using this technique, there has been closure of the air-bone gap to less than 10 dB in 18 cases and to less than 20 dB in all cases. There have been no cases of profound sensorineural hearing loss with this technique, and there have been no cases of perilymph fistula.
DISCUSSION The small fenestra stapedectomy with annular reconstruction is a procedure that allows the otologic surgeon to use technical skills which are also used during chronic ear surgery. This technique simplified the two critical portions of the procedure, ie, creation of the fenestra and placement of the prosthesis. As a result, with this technique, residents can be safely taught the principles and technique of stapedectomy.
ACKNOWLEDGMENT The author wishes to thank Lana Tackett for the illustrations and Patti M. Reilly for secretarial assistance.
REFERENCE 1. Schwaber MK: Small fenestra stapedectomy using a microdrill. Laryngoscope 99:768-770, 1989
SMALL FENESTRA STAPEDECTOMY