Stapes surgery for otosclerosis

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Stapes surgery for otosclerosis:

Stapes surgery for otosclerosis Stapedectomy/stapedotomy

History:

History Shea in 1956 described the microsurgical technique of stapedectomy. In 1960’s Plester suggested technique of ‘partial stapedectomy’in which post.third of footplate was removed. Marquet and Shea in 1962 made a small opening in middle of footplate with fixation of prosthesis-STAPEDOTOMY

Definitions:

Definitions Stapedectomy — To remove complete fixed otosclerotic stapes and sealing of oval window with a graft along with placement of a prosthesis b/w incus and oval window. Stapedotomy - -TO ATRAUMATICALLY CREATE A FENESTRA IN FOOTPLATE AND REPLACE THE CRURAL ARCH WITH A PISTON PROSTHESIS OF APPROPRIATE SIZE AND LENGTH

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Normal stapes stapedotomy stapedectomy

Goal:

Goal Open the oval window for sound transmission Reconstruct sound conducting mechanism Avoid complications

Advantages of stapedotomy over stapedectomy:

Advantages of stapedotomy over stapedectomy Reduction of surgical inner ear trauma. Reduced risk of infection and perilymph fistula Reduced risk of lateral prosthesis displacement

Indications:

Indications Conductive deafness (due to fixation of stapes). Air bone gap of at least 30 dB. Presence of Carhart's notch in the audiogram of a patient with conductive deafness . Good cochlear reserve as assessed by the presence of good speech discrimination. Type As tympanogram with absent stapedial reflex

Contraindications :

Contraindications Poor general condition of the patient. Only hearing ear. Poor cochlear reserve as shown by poor speech discrimination scores Patient with tinnitus and vertigo Presence of active otosclerotic foci ( otospongiosis ) as evidenced by a positive flemmingo sign. Conductive deafness due to Ehlers- Danlos Syndrome (EDS) Pregnancy Active ear infection, poor eustachian tube function

Counselling of patients:

Counselling of patients Stapedectomy –is an elective procedure and not a vitally essential procedure. Should be carried in ear with less good hearing. Not to be carried in patients with one functional ear. Risk of post.op.deafness (incidence 1%) Risk of post. op.vertigo . Revision surgery may be needed. Temporary dysfunction of chorda tympani. Iatrogenic lesion of facial nerve.

Pre-operative preparation:

Pre-operative preparation Inspection of ear canal for evidence of external or middle ear infect. Hearing aids should be removed at least 2 wks before surgery. Pre anaesthetic check up. Well informed written consent

Investigations:

Investigations Routine blood investigations. Tunning fork tests. Pure tone audiometry . Tympanometry Speech discrimination test Acoustic reflex test High resolution CT scan.

Position:

Position Patient lies on his back and his head is turned away by surgeon and lowered slightly using the headpiece so that E A C assumes vertical position. The aural speculum is fixed to operating table with articulated metal holder that can be adjusted in all directions.

Anaesthesia:

Anaesthesia Can be performed under general anaesthesia or local anaesthesia Local anaesthesia – Advantages of performing this surgery under local anesthesia are: 1. Improvement in hearing can be ascertained on the table. 2. Bleeding is minimal under local anesthesia. One per cent lignocaine with adrenaline (1: 80,000 ) injected into ear canal at level of bony annulus by sliding the needle down inside of aural speculum, four to five injections made around the canal Caution take care that blisters are not formed in ear canal as they make tympanomeatal flap weak

List of instruments:

L ist of instruments Operating microscope-lens of working distance of 250mm is used with magnification of 6,10,16,25 and 40 or with continuous magnifications. Microdrill –with long burrs 0.5-1 mm dia. is used Ultralight skeeter microdrill considered best.No. of revolutions limited to 500hz to protect inner ear.

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Skeeter microdrill Picks of different sizes and microsuction device

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Straight and angled picks Cup forceps and alligator forcep

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Belluci microscissors Bone curette

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Mushroom pick Stapes needle suction #24 or #26 used McGee Crimper

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Measuring rod Tabb knife

PROSTHESIS :

PROSTHESIS PROSTHESIS A-adipose tissue prosthesis of schuknecht B –combine metal wire - teflon piston prosthesis of Guilford C –shea’s prosthesis made entirely of teflon D –Robinson’s prosthesis

PROSTHESIS:

PROSTHESIS A-HOUSE WIRE LOOP B-FISCH PROSTHESIS(0.4MM) C-RICHARD PLATINUM BAND-FLOUROPLASTIC PISTON PROSTHESIS(0.5MM) D-DE LA CRUZ PROSTHESIS WITH A SHORT FLOROPLASTIC PISTON(0.6MM) E-EXTRA LONG MALLEUS HANDLE-METAL WIRE PISTON PROSTHESIS F-SILICON DISC A B C D E F

SURGICAL PROCEDURE:

SURGICAL PROCEDURE

Approach:

Approach Endaural approach - IF CANAL IS SMALL OR IF OSTEOMATA IN EAR CANAL THIS APPROACH IS PREFERRED.

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Transcanal approach - WHEN SIZE 5 SPECULUM CAN BE EASILY INTRODUCED IN EAR CANAL THIS APPROACH IS ADEQUATE. Adv. Of transcanal approach- -no ext. skin incision. -elegant,quick,atraumatic. -minimal intraoperative bleeding with no scars.

ENDO MEATAL INCISION :

ENDO MEATAL INCISION Ideally the flap should hinge anteriorly on a line 2 millimetre anterior to incudostapedial joint Endomeatal incision-Starting from 6’o clock position a bone deep incision is given, creating a flap that is the largest in posteriosuperior segment and extending up to 12 o’clock position

Obtaining tissue graft:

Obtaining tissue graft Vein- from back of hand,with intima side up. Fat-from lobule of the ear. Temporalis fascia-from behind the ear. Perichondrium-from tragus. Other sealing material like GELFOAM,MEROGEL.

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STEP 1 Using circular knife elevate the flap till the tympanic annulus,by scraping along the bone.

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STEP 2 Gently elevate the tympanic annulus from the bony sulcus using sickle knife to enter in middle ear. Tympanic annulus is first elevated from posterior tympanic spine. If chorda is coming in way, preventing exposure of oval window,push the nerve anteriorly

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STEP 3 Scutum(postero-superior bony meatal wall)is curetted by using 2-0 sharp curette(like an ice cream scoop). Direction of curetting is from medial to lateral and outwards to prevent dislocation of incudo-malleolar joint .

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STEP 4 Bone is curetted untill the posterior crus,stapedial tendon,pyramidal process,facial canal and footplate is exposed.

Exposure of an oval window following removal of bone from the posterosuperior bony meatal rim.:

Exposure of an oval window following removal of bone from the posterosuperior bony meatal rim .

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STEP 5 Test for mobility of ossicles and its fixation. Malleus is moved from its undersurface using smooth curved pick. Incus mobility is confirmed by applying pressure on long process of incus. Stapes superstructure is directly palpated to confirm footplate fixation.

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STEP 6 Control fenestra is made in posterior third of footplate using 0.3 mm fisch perforator. In posterior third of footplate saccule and utricle lie more than 1mm below footplate.

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STEP 7 Fenestra is widened, first with 0.4mm and then with 0.6mm perforator.

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STEP 8 Distance b/w undersurface of footplate and lateral surface of incus is measured using footplate measuring tool. In majority, the distance is 4 to 4.5 mm

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STEP 9 Hold the piston using alligator forceps and place it b/w fenestra and incus. First place piston over fenestra and then align it, with incus.

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STEP 10 Piston is crimped using McGee crimper. Loose crimping-likely to get detached may induce necrosis. Tight crimping-avascular necrosis of long process of incus .

Crimping of loop over long process of incus:

Crimping of loop over long process of incus

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STEP 11 Cut the stapedial tendon using microscissors close to pyramid.

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STEP 12 Localize the joint space by applying pressure on the incus. Disarticulate the incudo-stapedial joint using tabb knife with movement from posterior to anterior.

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STEP 13 Cut the posterior crura using crurotomy scissors. After releasing posterior crura,anterior crus is fractured downwards away from facial nerve.(posterior crura is thick and short while anterior crura is thin and long)

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STEP 14 Remove superstructure of stapes by applying pressure at neck of stapes by rocking movement towards promontory using 90*angle pick.

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STEP 15 Confirm the correct length of piston being inserted by performing 2 tests. BEND test-After placing the piston,shaft of piston be moved back and forth.Observe whether the lower end of piston comes out of vestibule. LIFT test-After placing the piston, lift the incus from its undersurface using 90* pick.

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STEP 15 Seal the fenestra with the small pieces of graft tissue around the shaft of piston . Tympanomeatal flap is repositioned back.

Post operative care :

Post operative care Adequate analgesics given. Instructed to avoid straining or blowing of nose. To keep ear dry. Post operative audiometry-closure of air bone gap at frequencies -0.5,1,2 khz used for reporting results.

Post operative follow up :

Post operative follow up Patient seen in 2 to 4 weeks after operation. Best level of hearing recorded 3 months to 1 year post operatively. Flying is permitted 2wks. after surgery. A test applying tympanometric pressure of 400 mm H 2 O to ext. ear with recording of nystagmus can reveal whether flying /diving may be hazardous to patient post surgery.

Special Problems during surgery :

Special Problems during surgery A very tiny hole made with a diamond drill in the promontory edge of oval window and floating footplate should be lifted up with a 0.3mm hook. FLOATING FOOTPLATE

Obliterative otospongiosis :

Obliterative otospongiosis A DRILL OUT is required.With a diamond drill the bone in oval window is thinned out and then a opening made twice the width of 0.6mm piston.

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Dehiscent facial nerve Dehiscent facial nerve

Persistent stapedial artery:

Persistent stapedial artery

Perilymph gusher:

Perilymph gusher Perilymph filling the EAC after opening footplate. Due to wide communication b/w intracranial space and with vestibule along internal auditory canal Elevation of head end of table. Sealing of oval window by a tissue graft. Bed rest.

Complications :

Complications Facial palsy Chorda injury(30%,metallic taste,resolve in 3-4 mnths ) Vertigo (immediate post. Op.) Vomiting Perilymph fistula(tinnitus, vertigo,fluctuation in hearing) Perilymph gush Flotting footplate Tympanic membrane tear(1.9%) Labyrinthitis (serous–high freq.) Post stapedectomy granuloma ( reperative granuloma )

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1 . Avoid eardrum tears by elevation of the tympanic annulus. 2. Avoid incus dislocation by careful curettage of bony ear canal. 3. Avoid floating footplate when fracturing crural arch. 4. Precise measurement of footplate to incus distance to determine prosthesis length. 5. Seal large defects around piston with soft tissue to avoid perilymph fistula. 6. Prevent sensorineural hearing from granuloma by careful monitoring of hearing postoperatively. THINGS TO BE AVOIDED

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Lateral displacement of wire prosthesis Incus erosion due to lift of prosthesis by collapsed footplate Incus erosion due to tense and fibrosed vein graft Renewed forward growth of otosclerosis under vein graft Tilting of piston because footplate perforation too narrow Stapes revision surgery-causes