Subtotal petrosectomy - Vula - University of Cape Town

327Lic. Silvina Alejandra AlzugarayÍndiceTitulo……………………………………………. Pág. 3Resumen………………………………………… Pág.3Palabras clave…………………………………... Pág.3Introducción……………………………………. Pág. 4 a 10.Desarrollo………………………………………. Pág. 10 a 19.Conclusiones…………………………………… Pág. 19 a 21.Bibliografía……………………………………… Pág. 21 a 22.2

transect the anterior canal safely bycutting onto the curved clamp. Thisavoids injury to the facial nerve(Figure 10)Figure 11: Elevating skin of externalcanalFigure 10: Safely transecting anteriorwall of ear canalEversion of auditory canal skinOcular magnifying loupes are usefulfor this stepThe skin of the cartilaginous canal iselevated for 1cm from the cut marginwith tympanoplasty scissors tofacilitate eversion of the canal (Figure11)It is important that the skin of theexternal canal is not breached. Toavoid this, direct the curve of thetympanoplasty scissors towards thecartilageIt may be difficult to find the correctplane, especially if a previous openmastoidectomy with a widemeatoplasty was performedTwo 2-0 vicryl stay sutures are placedat 6 and 12 0’clock. These are placedas 2 purse string sutures with the freeends on the inside of the canal (Figures12, 13)Figure 12: Placing stay suturesFigure 13: Stay suturesA curved artery clamp is passedthrough the canal from externally andapplied to each of the free ends of thetwo stay sutures. Tension is applied tothe stay sutures to evert the canal skin(Figure 14)4

Chorda tympani is divided with a largeBellucci scissorsThe incudo-stapedial joint is separatedwith a 45° 1,5mm hookThe malleus is cut at its neck with amalleus nipperTensor tympani tendon is cut with alarge Bellucci scissorsThe tympanic membrane (with handleof malleus attached) is now beremoved along with the incus and headof malleusMastoidectomyIt is important that all mastoid cells areexenterated and no mucosa is leftbehind as this can potentially formmucocoelesStructures like dura, sigmoid sinus andfacial nerve have to be skeletonised,not exposedUsing a mastoid raspatory elevate thesoft tissues off the mastoidThe sternocleidomastoid muscle isfreed from its insertion into the mastoidtipPlace a 2-0 silk stay suture from theedge of temporalis muscle to its fasciato expose the area above the temporallineNext proceed as for open mastoidoepitympanectomy(see chapter onmastoidectomy)After performing an open mastoidoepitympanectomythe additional cells areremoved to complete the subtotalpetrosectomy:The stapes superstructure is removedby using crurotomy scissors to cut theanterior and posterior crusThe inferior surface of the external earcanal cam be lowered to the level ofthe hypotympanumBefore skeletonising the jugular bulb, itis important to review the CT scan toconfirm once again that the jugularbulb is not high-ridingThe pericarotid cells are exenterated byfirst approaching the anterocarotidcells. The carotid is recognised by itswhitish colour beneath bone. Thecarotid is not infrequently dehiscent atits bend medial to Eustachian tubeThe mastoid tip may be left in place,but is drilled down to the level of thedigastric ridgeRetrofacial, retrosigmoid, retrolabyrinthine,supralabyrinthine, infralabyrinthine,and supratubal cells are allexenterated. Figure 19 shows themastoid cavity once all the cell trackshave been exenteratedFigure 19: Mastoid cavity with all celltracks have been exenteratedTechnical pointsWhen drilling in the supralabyrinthinesegment a diamond drill is used inreverse when operating on the right earto avoid injuring the facial nerveThe mucosa of the middle ear can beremoved by using the microraspatoryand scraping the mucosa with a smallcotton ball, taking care not to subluxthe stapes superstructure if left intactObliteration of Eustachian tubeThe internal carotid artery is followedsuperiorly to the medial wall of theeustachian tube (watch out for adehiscent carotid at this point!)6

The mucosa of the bony eustachiantube is removed as far as the isthmuswith a 2mm/3mm diamond burrAt this point the remaining mucosa iscoagulated with bipolar forceps and theeustachian tube is obliterated with bonewax (Figure 20)Technical pointsThe tensor tympani muscle can bedissected out of its semicanal bydrilling its lateral surface and reflectingit anteriorly with a microraspatory intothe protympanum and the eustachiantube orificeBone wax is then placed over this sothat the muscle lies sandwichedbetween two layers of bone wax, thusobliterating the eustachian tubeObliteration of Operative CavityFigure 20: Eustachian tube obliteratedwith bone waxUsing a cottonoid, the bone wax maybe pushed into the orifice of theeustachian tube with a suction tip. Thetip of the microraspatory is directedaway from the carotid (Figure 21)The middle ear cleft is obliterated withabdominal fat harvested from the lowerquadrant of the abdomen (Figure 22)It is important to achieve meticuloushaemostasis as the most commoncomplication of subtotal petrosectomyis a haematoma of the abdominalwoundA suction drain is placed in theabdominal woundThe abdominal wound closed in layersusing 3-0 vicryl subcutaneously andmonocryl 3-0 or nylon 3-0 to skinWith osteoradionecrosis of thetemporal or chronic infection it isadvisable not to use abdominal fat toobliterate the cavity. Rather use onlytemporalis muscleFigure 21: Microraspatory directedaway from carotidA temporalis muscle musculofascialgraft is used as an additional seal oforifice by placing it lateral to the bonewaxFigure 22: Abdominal fat7

Transposition of temporalis muscleThe skin incision is extendedsuperiorly above the temporal line toexpose the temporalis muscleRemaining in a plane above thetemporalis fascia, the skin and softtissue edges are underminedUsing two skin rakes, the assistantretracts the skin edges for adequateexposureThe posterior 2/3 of the temporalismuscle is mobilized by creating a flapusing a diathermy knifeTo facilitate mobilisation andtransposition of the temporalis flapover the mastoid cavity, a smallinverted v-shaped incision is made atthe base of the temporalis muscleThe muscle flap is rotated inferiorlyover the cavity and sutured to thesternocleidomastoid muscle and softtissues of the occiput with 2-0 vicrylsuture (Figure 23)Figure 23: Temporalis flap andabdominal fat in petrosectomy defectInevitably the fat used to obliterate thecavity will atrophy, therefore more fatis placed in the cavity once thetemporalis muscle has been sutured tothe soft tissues via the superior pocketcreated by the transposed temporalisflap (Figure 24)Figure 24: Additional fat placed indefectWound ClosureA 3mm suction drain is placed underthe scalp over the squamous part of thetemporal bone and not over the mastoidcavityThe wound is closed in layers with 2-0vicryl sutures subcutaneously and skinclipsA compression bandage is appliedPostoperative careAntibiotics (amoxicillin with clavulanicacid) are continued for one weekpostoperativelyThe drain is left in place until thedrainage is less than 10mls/24hrs.If the surgery was done for CSF leak,then the drain is removed on the firstpostoperative dayThe abdominal drain is removed whenthe drainage is less than 10mls/24hrsClips/sutures are removed after 10 daysThe resorbable vicryl sutures withinthe external ear canal are removed at 4weeksLong-term follow-upImagingWhere subtotal petrosectomy isperformed for chronic otitis media, CT8

scans are routinely performed after oneyear and then again at 3 yearsIn cases of previous cholesteatoma, adiffusion weighted non-EPI MRIwould detect recurrent diseaseAuditory rehabilitationThis depends on the status of hearing ofopposite ear, the degree and type ofhearing loss and cochlear function. Theoptions are: bone anchored hearing aid(BAHA), if the inner ear function has beenpreserved of the ipsilateral or contralateralear; active middle ear implant (e.g. Vibrantsoundbridge) where there is good cochlearreserve; or cochlear implant (bilateraldeafness)References1. Fisch U, Mattox D, eds. Microsurgeryof the Skull Base. Stuttgart,Germany:Georg Thieme Verlag, 1988.2. Linder T, Schlegel C, DeMin N, vander Westhuizen S.Active Middle EarImplants in Patients UndergoingSubtotal Petrosectomy: NewApplication for the VibrantSoundbridge Device and ItsImplication for Lateral Cranium BaseSurgery. Otol Neurotol. 2008;30:41-7AcknowledgementsThis guide is based on the text byProfessor Fisch (Microsurgery of the SkullBase) and personal experience of ProfessorLinder, as well as course materials for thelateral skull base course conductedannually by Professors Fisch and Linder atthe Department of Anatomy, University ofZurich, Switzerland.AuthorTashneem Harris MBChB, FCORL,MMed (Otol), Fisch InstrumentMicrosurgical FellowENT SpecialistDivision of OtolaryngologyUniversity of Cape TownCape Town, South Africaharristasneem@yahoo.comSenior AuthorThomas Linder, M.D.Professor, Chairman and Head ofDepartment of Otorhinolaryngology,Head, Neck and Facial Plastic SurgeryLucerne Canton Hospital, Switzerlandthomas.linder@ksl.chEditorJohan Fagan MBChB, FCORL, MMedProfessor and ChairmanDivision of OtolaryngologyUniversity of Cape TownCape TownSouth Africajohannes.fagan@uct.ac.zaTHE OPEN ACCESS ATLAS OFOTOLARYNGOLOGY, HEAD &NECK OPERATIVE SURGERYwww.entdev.uct.ac.zaThe Open Access Atlas of Otolaryngology, Head &Neck Operative Surgery by Johan Fagan (Editor)johannes.fagan@uct.ac.za is licensed under a CreativeCommons Attribution - Non-Commercial 3.0 UnportedLicense9