Otologic Pearls
1990-2002

Jack M. Kartush, MD
Michigan Ear Institute

Introduction

What follows are a few hundred tips I have evolved over the years. I am grateful to many Fellows for helping collate these. Learn, internalize, and improve. Additions or revisions? Please advise.

[ General ] [ Tympanoplasty ] [ Cochlear Implants ]
[ KTP/YAG Laser ] [ Stapes ] [ T-Bone Cancer Staging ]
[ T-Bone Glomus Staging ] [ Posterior Fossa Approach ]
[ Translab Acoustic Neuroma ] [ Middle Fossa ]

General

Ear Prep:

• Check chart for side and allergies and write on board. Confirm with anesthesia if antibiotics and steroids were given preoperatively.
• Come early - be prepared: Read prior op-notes and audiograms
• Check for Scans - post on view box. Complete paperwork, Rx. Paperwork = 4 things to complete: (1) face sheet (2) put postop orders and scripts in chart (3) fill out procedures on yellow H + P form, (4) fill out post-op patient info sheet (5) Remember to increase number of ear drops and refills if patient has or will likely get a CWD procedure.
• Prepare microscope (balance, focus, laser, correct bend in arm, oculars @ -2)
• Look at board and confirm side again before marking prepping!
• Shave 2 fingerbreadths around ear, higher superiorly for revision cases
• Remove stray hairs with tape. Use Mastisol around ear
• Place steri-drapes, cut off extra length for anterior and inferior ones
• Inject post-auricularly. Remember to keep one finger on mastoid tip for orientation - do not inject local anesthetic near stylomastoid foramen, otherwise may get a post-op facial paralysis from local that may take hours to resolve!
• Tape head to headrest, not bed itself: 45 degrees away, chin down. Careful not to tape head too firmly - may get a pressure sore on scalp during longer cases.
• Prep with Betadine then blot dry - do not contaminate with towel edge
• Ensure that gel pad and foam are not touching skin, otherwise may get a pressure sore. Best to put a towel between head and any padding.
• For stapes and transcanal procedures, make sure that nurses are aware and have speculum holder in place.
• Stapes, transcanal and sac procedures tape head at shallow angle less than 45 degrees with chin down and shoulder retracted down.
• Note operative "Side" on marker-board (Consent, H&P, Film, Audio, "X" on ear)
• Note Allergies
• Balance microscope on all three axes
• Scrub set-up for patient prep (head and abdomen)
• Compression boots and foley
• Facial nerve monitor placed and tested
• Re-confirm side after patient rotation
• Laryngeal monitor tube taped in midline
• Slide bed top so head is as far as possible from table pedestal
• Complete face sheet, ck H&P, Rx's, Orders, Op Note, Admit note
• For skull base cases: Abx given, Ancef 1grm IV q8hrs, (Erythro), Gent 80mg IV Q12hrs X2, Anzimet 25mg, Decadron, Inform anesthesia to re-dose
• Betadine in EAC, Tape head appropriately
• No long acting paralytics

Mastoid Drilling Techniques:

• Long firm strokes for cortical bone. First stroke is continuous, beginning along temporal line, then curving down toward mastoid tip. Start with largest cutter: 6.5 mm cutting burr for chronic ears.
• Start posteriorly in front of sinodural angle
• Always orient drill parallel to important structures
• Always stroke opposite the spin direction of the burr
• Don't drill on cholesteatoma-it will spray squamous cells everywhere
• Be sure burr has completely stopped before removing it from the deeper field or your view!
• For pesky bleeding from bone, press bone wax into area with slowly turning diamond burr
• Control your burr! Minimize skipping. If drill jumps or skips: switch to diamond, widen the funnel (saucerize), change angle you're holding the drill, or use smaller cutter
• Know the drill speed at all times. 60K for lateral bone work. 20-40K for finer work. 5K to modify prostheses.

Laser:

• CO2 : 0.3-1 watt, 0.1 sec, 0.2 spot size for cutting, triple the spot size for coag
• KTP: 1.6W, 0.1 sec
• Stapes Surgitouch Scanner: turn on laser monitor. Press "last set-up". Set: 28 watts, .6 mm spot size. May need to adjust power or spot size based on case. Don't set up the Scanner until other work with the laser has been completed (severing tendon and lasering crus).
• Always suction away plume of hot smoke

Tympanoplasty

General Tips:

• Having nurse fold ear forward when placing sterile drape allows for more sticky draping posteriorly when you cut the opening, this assures a better water tight seal in front of your initial1/4 steridrapes (chronic ears only). For cases where you want to keep the ear canal covered with the sterile drape (i.e. TL acoustics) don't fold the ear forward.
• When harvesting temporalis fascia graft, irrigate with bacitracin prior to harvesting fascia. Ask nurse to dry fascia graft for 5 minutes under the heatlamp. Remove fat and muscle off of graft before drying.
• Place graft on mastoid cortex and spear it with Rosen needle, then advance it into location and release spear by pushing down on graft with sucker
• Flap protector can be fashioned from suture package foil when drilling a canalplasty; bend a right angle into it to help hold the flap away
• "J" cut into posterior temporalis muscle to allow better superior retraction for exposure
• Often consider doing a canalplasty for better visualization and in cases with a narrow bony canal. In doing so, minimize exposure of mastoid air cells.
• When removing retracted areas of TM, remove a portion of the normal drum around the retraction as well or it will reform
• Use local for hydro dissection when raising temporalis fascia graft
• Middle ear packed with Bacitracin gelfoam, outer ear packed with cortisporin soaked gelfoam and merocel pack (Schindler = small, Ambrus = large for meatoplasty)
• Thin Silastic to prevent scarring, thicker/layered silastic to create a middle ear space

Middle Ear Dissection Techniques:

• When stripping TM off of malleus, pull in an inferior direction (Rosen needle) to minimize mechanical trauma and avoid disruption of the MI joint, use a laser at the umbo
• Whirly bird is good for cleaning out the sinus tympani with an upward sweeping motion, stimulate to verify absence of dehiscent facial first
• For middle ear dissection with sticky tissue, apply slow but steady traction with an instrument and wait for the tissue to free itself (i.e. Off ossicles/stapes)
• Use laser to free anything off stapes to avoid mechanical trauma, all dissection in direction against pull of stapedial tendon
• For peeling cholest matrix off promontory, gently go back and forth with end of Rosen needle, laser any remnants left behind with a diffuse beam after verifying that you won't hit a dehiscent facial (use mirror to bank shot in sinus tymp)
• Keep Buckingham mirror on separate set as a special instrument so it doesn't get ruined with repeated autoclaving after every case
• Use small right angle hook to flip squamous epithelium out from under the malleus when it is wrapped around it
• Silastic in ME any time adhesions were present or mucosal surfaces are raw, bigger the better since it will make a capsule of mucosalized space that will be present upon removal at second look (if required)

OCR:

• Preserving tensor tendon keeps malleus from getting too floppy
• Drill Kartush prosthesis to size with a small diamond at half speed
• For PORP's, bevel your cut, keeping long side opposite the stapedial tendon
• Or for PORP's, cut a notch in both sides so that the prosthesis rides on the tendon and ant crus
• Drill away post canal wall if concerned that PORP will contact bone
• Kartush incus strut: when placing, put all force on pulling malleus laterally so as not to push medially on stapes
• Cut Kartush incus-stapes strut with sharp instrument ("toenail clipper")

Homografts:

• Anteriorly, windowshade the EAC skin laterally to keep the lateral blood supply to provide vascular supply when re-epithelializing the homograft
• Fashion a crescent of fascia to bridge the area of nude bone that is invariably present between the homograft and the replaced canal skin.
• Post op you want the person to switch to vinegar and water early rather than continued steroid/ antibiotic gtts

Meatoplasty:

Inject local first - meatoplasty tends to be bloodier than other procedures.

When you know you are going to do a meatoplasty, ask nurse for extra 3-0 undyed vicryl sutures, additional Cortisporin gelfoam and Ambrus ear pack.

• Use 15 blade and flip ear back and forth to watch cuts from both sides. Make cuts at both 12 and 6 o'clock. Retention sutures (through-and-through) with 2-0 vicryl. No exposed cartilage. No Bovie near cartilage(use bipolar)
• An absorbable stitch from the ant canal to the temporalis muscle superiorly will help suspend and keep open the meatus antero-superiorly. If needed cut away some of the overhanging temporalis muscle to allow the canal to be pulled more superiorly
• Watch placement of sutures - they will have a tendency to cause a cup ear deformity if not placed correctly.
• Clean cartilage with up and down scraping motion of 15 blade to see it well before cutting the crescent out of the concha. Have nurse hold ear forward with Senn rake.
• If tragus or soft tissue is hanging in the way, retract it with a temporary stitch
• Skin graft can be obtained from back of ear with 11 blade after injection with local as desired for cavity lining

Pack entire cavity with gelfom and COS, Ambrus Pack in Meatus

Vascular Strip/H-Flap:

• Injection is key, bevel toward bone, slow pressure, 3mm syringe gives more control over injection. Inject just lateral to bony-cartilaginous junction.
• If having trouble blanching, start more laterally and then advance needle after initial hydrodissection with a little local
• Flap length = 8 mm
• Once 72 blade is in position, don't remove it until the complete cut is made
• Sickle = #1, #64 beaver, 72 blade, Round knife/weapon, Rosen elevator, Black handled instrument (Richards 13-0045)
• Communicate high superior cuts with Belucci scissors, pulling flap ant/inf with suction
• Vascular strip can be modified to narrow between 1 and 4 o'clock at the TM allowing development of flaps superiorly and inferiorly along the annulus that can fold over the sides of the fascia graft for tympanoplasty
• Place Bacitracin on gelfoam immediately adjacent to TM graft, then go close behind the ear incision, when you return suck blood away down to the Bacitracin ointment
• As soon as the self retaining retractors are removed, have a Bovie and raytec in hand to obtain quick hemostasis to prevent blood from pooling on your EAC packing , obscuring your flap replacement yet to come
• Place at least one postauricular stitch to hold the ear in place before packing the vascular strip in place. This keeps you from avulsing its position when folding the ear over and sewing the postauricular incision, avoiding the postop complication of a stenotic web at that site. Stitch should ideally help hold vasc strip against bone as well.
• Evert vascular strip with right angle hook when replacing
• Keep pressure with gelfoam on vascular strip to prevent blood from clotting and thickening behind it (results in a stenotic canal)
• Bayonet scissors (curved and straight) are alternatives to Belucci scissors

Cochlear Implants

• Inverted "U" verses "C" shaped flap, don't come too far anterior at top of helix (area of potential necrosis). Design incision so that it is not over the BTE processor or implant.
• Thin skin flap only if thicker than 4mm to allow magnet to adhere
• Plan prosthesis just behind where pinna folds back, further back in kids or else you'll have excess electrode lead at final placement
• Keep the placement high (around where the sinodural angle is) to avoid lower emissary veins
• If the bone is too thin, make a bony island with the edges exposing dura to allow the implant to set in more easily
• When placing mounting holes, if the bone is too thin, expose dura and pass the suture just above the dura under the lip of bone
• Alternatively, lock prosthesis in with sutures from temporalis fascia/muscle to SCM
• In kids, the mastoid tip will grow, so keep the electrode from lodging down there or it may pull out
• When opening round window, don't be fooled by hypotympanic air cell. Make sure you visualize both the round window/basal turn and the hypotympanic air cell to be sure you position properly
• A notch can be made at the incus buttress to help secure the electrode lead
• Similarly, the whole recess can be opened and the lead can be slid medial to the ossicles.
• Once in place, patch the round window and middle ear with fascia/grunge
• If the facial nerve is exposed with drilling the facial recess, place fascia/grunge between it and electrode lead
• X ray should be taken from oblique angle aiming between eye and ear to best line up cochlea
• When closing skin on the "u" flap, suture behind the ear first, working from inferior to superior, being careful not to pick up the electrode lead with your stitches. Once that area is completely closed, then close the rest in a routine fashion
• 22 electrodes (17mm), 10 stiffening rings (for a total length of 24mm) for nucleus 22
• No Bovie once implant in, dictate that instruction card was completed and provided to family. Tell nurse to shut off monopolar cautery prior to opening cochlear implant on the field.
• For Contour, stylet is easily removed with medium right angle hook, while stabilizing electrode array with a claw.

KTP/YAG Laser

• Power 1.6 W
• 0.1 Sec
• High Aim
  
  
• 3 cords
• Eye, Scope, Pedal
• Calibrate

Stapes

Opening:

• Inject canal, then harvest posterior fascia before canal cuts. Get enough fascia if TM tears.
• Spec holder with adjust controls at right hand position, Spec itself with wide end oriented vertically
• Communicate sup and inf edges of H-flap to allow complete turning of flap (esp superiorly)
• Just before elevating annulus, place epi gelfoam for one minute to assure hemostasis
• Elevate annulus at the easiest spot where it can be visualized without a lip of overhanging bone
• When elevating annulus, scrape back and forth with Rosen to elevate. Once annulus is visualized, cut through the thin underlying mucosa to enter the ear. Sweep hook of Rosen superiorly to pull apart mucosa.
• Elevate annulus then place adrenalin gelfoam in middle ear before drilling to absorb bone dust
• Put Skeeter laterally initially so as not to startle the patient too much. Once tolerated, then move more medially. Do not expose chorda yet. Have nurse drip in saline as needed. Use largest cutter initially, then switch to diamond over the chorda to thin the bone. Avulse last segment over the chorda with small bone curette/hook
• Goal when removing posterior canal bone is to visualize post crus, tendon and pyramidal eminence if possible & inf aspect of facial nerve, without creating too much of a scutal defect that could allow a retraction pocket to develop post op

Middle Ear Work:

• Confirm malleus and incus mobility!
• Laser for hemostasis prior to cutting IS joint (KTP 1.6 watts, 0.1sec, CO2 1.0w). Don't cut tendon until IS joint is cut (reduce mechanical trauma). IS joint is cut with joint knife (joint is lower than you think)
• IS joint can be located by gentle traction on incus pulling laterally with the joint knife. This will show you the articulation
• Cut tendon and post crus with laser before downfracture (ant crus usually cannot be easily hit with laser)
• Laser post crus as close to footplate as possible before downfracturing so as not to obscure view of window for fenestration and prosthesis placement
• Open footplate with laser (0.3W, 0.1sec) making 0.6mm fenestra. Use 24 sucker to evac smoke for several seconds to allow cooling between laser hits
• Oval window rasp is 0.3 mm (McGee-Farrior/Storz)
• Use 4.25mm by 0.5mm McGee plat/stainless prosthesis (works 95% of time)
• Place gelfoam in sinus tympani before placing prosthesis, that way if it falls you don't have to go chasing or searching for it
• Assure position with strut guide, prosthesis should be locked in fenestra with gentle push
• If prosthesis moves over fenestra with push, use piston as your measuring device rather than a traditional measuring device to determine what you'll need. Traditional device is too difficult due to depth of field problems trying to visualize both ends
• Place and crimp, assure position and then place three pieces of fascia
• If crimper is inadequate due to a thin long process, use alligator turned backwards to crimp
• When replacing flap at end of procedure, suck the air out of the middle ear to hold the flap down and improve hearing
• Before instilling Bacitracin, hold the flap in position with the small suction laterally to prevent ointment from getting beneath flap
• If vein is used, place intima side out (vein, however, reduces ability to assure exact and proper placement)
• F/U 1 week, 5 weeks

T-Bone Cancer Staging

University of Pittsburgh
Squamous Cell Carcinoma

T1=Tumor limited the the EAC w/o boney erosion or soft tissue extension.

T2=Tumor with limited EAC erosion (not full thickness) or X-ray w/ limited (5mm) soft tissue extension.

T3=Full thickness EAC, w/ limited (5mm) soft tissue involvement, or involvement of ME/mastoid, or facial paralysis.

T4=Cochlea, Petrous apex, medial ME, Carotid, Jug, Dura, or (>5mm) soft-tissue invasion.

N Status
T1N1 = Stage 3
T2,3,4N1 = Stage 4

Mets = Stage 4

T-Bone Glomus Staging

Fisch

A- Middle Ear
B- Tymp-Mastoid, no infralab extent
C1- Destroy jug foramen/bulb, limited vertical carotid canal
C2- Infrlab extent, Vertical portion of carotid canal
C3- Infralab and Apical T-bone, Horizontal portion of carotid canal
D1- < 2cm intracranial extension, One stage procedure
D2- 7gt; 2cm intracranial extension, Two stage procedure
D3- Inoperable intracranial extent


Glasscock-Jackson

Tympanicum
I- Promontory
II- Middle Ear Space
III- Fill Mid Ear, Extend to Mastoid
IV- Through TM, EAC, Anterior ICA


Jugulare

I- Bulb, Mid Ear, Mastoid
II- Under IAC, May be intracranial
III- Petrous Apex, May be intracran
IV- Past Pet. Apex to Clivus or Infratemp Fossa, May be intracran

Glomus Tympanicum:

• Use laser coag for shrinking
• For hypotympanic lesions, an endaural approach can be used by following the chorda back toward facial (keep a rim of bone on the chorda to keep from injuring it), be sure to widen the posterior superior aspect of the canal to provide the angle to peer into the hypotympanum
• Use oxycel soaked in adrenalin to put more pressure on bleeding tumor.
• If too big a hypotympanic defect is made, reconstruct it with cartilage just as you would with an attic defect
• If the tumor is extending too far anteriorly, free tm off the malleus. Use a Rosen needle gently stroking the periosteum just below the short process and dissecting the tm off in a smooth back and forth motion along the manubrium (pull in direction of tensor tympani -toward umbo). As before, free off the umbo with the laser as a perf will often result due to the decussation of the fibers.

Glomus Jugulare:

• For jugulare tumors where the sigmoid will be extraluminally occluded, leave a lip of bone over the sigmoid midway in the mastoid to pack the oxycel under. Occlude the sigmoid at a level below the sup petrosal input to allow shunting of flow
• Mobilize facial with digastric attached and liberated from its groove
• Extended periosteal flap along with reflected SCM - consider temp-parietal fascia flap

Atresia:

• Leave a lip of bone over the TMJ if at all possible to prevent prolapse into the canal postop
• Use anterior approach: but make incision behind level of mastoid-elevate periosteun with flap/if you elevate a skin flap you might encounter FN as you dissect anteriorly.
• When freeing the ossicles, use a laser as possible to prevent vibrational trauma and delayed adhesions and scarring
• STSG sutured to meatus from behind as possible
• Place STSG on ossicles with fascia on either side of them, the ossicular blood supply can be used by the STSG as it takes, whereas fascia has none
• Prep thigh/buttock. Bump under hip
• Stimulate at high setting during initial incision. Nerve can be subQ!

Endolymphatic Sac Decompression:

• Place gelfoam in antrum as soon as it is open to prevent bone dust buildup in middle ear
• Pull decompressed dura posteriorly and endolymphatic duct will clarify its position where it is tethered
• Saucerization is important to be able to visualize down near the jugular bulb
• Place silastic over exposed sigmoid to prevent post op pulsatile tinnitus from the soft tissue collapsing on the sigmoid/dura and transmitting to the ear
• Sac is typically anteriorly displaced. Located inferior to Donaldson's line. Bone island over sigmoid.
• Do not over-expose attic. Identify the lateral canal, then proceed with the dissection. This prevents scarring to the middle ear space.

Posterior Fossa Approach

Soft tissue:

• Shave 5 fb behind, 3 fb above
• Incision should not extend too deep into neck
• Please confirm with Anesthesia: Mannitol, hyperventilation, decadron, Abx(ancef, gent) @ start
• Anzimet 15mg, Mannitol 25gms, hyperventilation PCO2 = 25, decadron 10mg, Abx @ start (ancef, gent 80mg)

Bone Work:

• For the bone window, need to get low along skull base, especially anteroinferiorly
• Foil protector can be fashioned to protect dura when drilling the anterior inferior corner to get closer to the skull base or enlarge exposure in any direction once bone plug has been removed
• Drill anterior limb of bone window to define sigmoid and transverse superiorly before making superior limb of the window.
• Expose, but stay behind sigmoid rather than right on top of it to make handling of emmisary vessels easier and to keep from lifting the bone plate directly off of the sigmoid and risking a tear.
• Wax any air cells of the mastoid and irrigate away bone dust before opening the dura

Opening Dura:

• When opening dura near sigmoid and transverse sinuses, remember these have a fusiform extension within the dura and your dural incision must be made sufficiently behind this area. Bone plate should stay 8 mm away from sigmoid and transverse sinus. to avoid getting into the sinus and to allow future sutures for dural reapproximation
• Open dura with microblade, initially just scratch it to mark your cuts
• When using a stitch to retract the sigmoid and dura anteriorly, place a small cottonoid on the brain just below where you want to put your stitch to help dissect the dura away and protect the brain. Drive stitch from inside out.
• Don't shrink the dura with the bipolar too much when getting hemostasis or you can't close it
• Important to avoid ligation of the sigmoid (especially right side) it is a different situation than the jugular vein ligation because the shunting between the superior, inferior and petrosal veins is lost when ligated above them, thus making it harder on the vein of Labbe.
• When opening dura, don't reflect the posterior flap back too much. There is no need to. The dura can serve as a protector for the brain as the retractor is placed
• After draining CSF from post. Fossa, cerebellum can be gently compressed by slowly placing a large piece of gelfoam into the CPA
• Protect cerebellum by place Bicol into CPA by folding it around the tip of the retractor, so that the anterior half can then be folded down further

IAC Drilling:

• Before drilling, place gelfoam on the sides of the 8th nerve complex to catch the bone dust and keep it out of the CSF
• Foil protector can sit on the 8th nerve complex and cerebellum to keep drill from injuring
• Cut window of periosteum and expose endolymphatic duct
• Closest structure will be the common crus superior/lateral

Surgical Tips:

• If doing a 5th nerve decompression, keep the fine arachnoid around the 7th and 8th nerve complex so as not to compromise the vascular supply to the cochlear nerve
• Cut the tentorial side of the nerve for vestibular nerve sections
• If bleeding along the cerebellum develops, apply pressure with a neuro patty with sucker and gently ease off while standing by with bipolar. Don't let the pooled blood obscure sensitive structures, irrigate and clean the operative bed while holding pressure on the bleeder before using bipolar if concern over structures exists
• Dissect tumor pulling away from brainstem so as not to avulse the nerve fibers from the cochlea
• Avoid over-use of bipolar
• Use the Apflebaum retractor early on in drilling to transition to brain retractor is easy later on
• Avoid drilling over a retractor under tension, it may spring up from its bone ledge and kick up the drill
• Bipolar set at 2-4
• Use Brackmann suction and Kartush Stimulating ring curette (high setting at first) then lower power as near nerve
• Cottonoids to protect lower cranial nerves
• If bradycardia = stop dissecting, release retractors. Robinol if mild, Atropine if severe

Closing Dura:

• When closing dura, if it is not water-tight, put temporalis muscle between the dural edges as a plug. Pass the stitch through the muscle plug. (4-0 Neurilon)
• Close dura, place fat, place bone plug, more fat, suture muscles making sling over fat

Translab Acoustic Neuroma

General Tips:

• Always be conscious of the patient's positioning, adjust the microscope rather than having patient at extreme angles to avoid pressure sores and peripheral neuropathies
• If using laryngeal monitoring for large tumors -> ET tube must be in midline (talk to anesthesia)
• Harvest fascia and "grunge" over mastoid - but preserve periosteum and temporalis to allow subsequent "fat hammock" to lock in fat during closure
• Tell anesthesia to begin hyperventilation and mannitol administration at about the same time as the bone work is begun

Labyrinthectomy:

• Initially, this part should be done with a diamond burr. Once you have achieved a level of comfort with the procedure, this can be done with a cutter
• Keep a cup of bone at tegmen and posterior fossa so that you are within a safe bowl of bone (Malcolm's cup)
• Keep a cup of bone on horizontal canal toward facial
• Open ampullated end of horizontal last
• Identify horizontal, then drill out posterior and find ampullated end to communicate with non-ampullated end of horizontal
• Then follow common crus around superior canal preserving ampullated end of sup canal
• Finally, open ampullated end of horizontal canal and vestibule
• Be careful not to undercut seven when working in vestibule and ampullated end of posterior
• At posterior ampullated end, don't be fooled by stapedius muscle fibers that may show up
• Overhanging dura may be shrunken down with brief bipolar parallel to dura.

Bone Work:

• Emissary vein can be controlled with bone wax followed by diamond burr pressure
• Keep temporalis muscle and partially reflected SCM for a large suture to hold in fat pack
• Be sure to completely decompress tegmen laterally to allow retraction of the dura superiorly for best exposure later in the case; however, leave thin shell of bone around labyrinth to protect it
• To decompress sigmoid, thin bone and advance a freer elevator to reflect away from bone, then drill off the bone just below the edge (make a cup just below the free edge) to avoid skipping into sigmoid
• Ok to bipolar and shrink sigmoid when decompressing, and make sure the sinodural angle is completely decompressed for best exposure and retraction
• Bipolar sinus under irrigation to keep it from burning
• Secure Apfelbaum retractor with rubberband and hemostat. Use 3/8" retractor blade. Keep retractor back a few millimeters from edge you're drilling (i.e. Porus) to allow better visualization, then just pull the dura back with the sucker to expose the lip of bone you're drilling on
• Be sure to smooth out all retrofacial and epitympanic air cells so that when the fat is placed at the end of the procedure, CSF will be less likely to leak around it
• Remove incus and malleus head and cut tensor tympani. Malleus head may have to be drilled away if nippers won't fit due to low lying tegmen or dehiscent facial nerve. If so, use a small diamond and press malleus away from facial to avoid injury (press head toward * goal is to visualize et orifice for future packing with grunge (mastoid periosteum)
• Don't remove incus until the lab is drilled out: keeps a safety buffer b/t drill and facial nerve in case of slip
• Do not confuse marrow of bone superior to IAC with the actual IAC when drilling it out
• Drill out IAC 270 degrees, especially inferiorly near porus before opening dura
• Meatal decompression, bill's bar is lateral and anterior to transverse crest, watch for yellow bone over facial as it turns up toward geniculate ganglion, there will be a little bleeding as you get close to the geniculate ganglion
• Use oxycel at areas where bone and tegmen/sigmoid/sup petrosal are bleeding, tucking the oxycel completely under the bone fragment so that it doesn't get caught in the drill bit later
• If the dura is too tense when drilling the IAC, make a small opening up high on the posterior fossa to decompress the CSF. Keeping it high allows you to continue drilling without getting irrigated bone dust or blood into the angle.
• If a hole in the dura is made and CSF decompresses, put some gelfoam into the hole to keep from getting bone dust in there
• Turn drill speed down when drilling near facial nerve at the meatus

CSF Leaks Intraop:

• Patch with temporalis muscle
• If too high a flow, suck out the CSF to lower the pressure and then patch
• Middle fossa will heal itself more easily than posterior fossa dura

Opening Dura:

• Flip the bony shell off IAC and open dura of IAC using stimulating right angle hook
• Before opening dura or dissecting around an area of tumor, place an adrenalin soaked gelfoam for vasoconstriction of the surrounding vessels
• When opening posterior fossa dura, put a gimmick in and cut with Belucci scissors over the top, always pulling outward to look for vessels (don't use the microscissors to open dura - retained bone chips will dull them)
• Open the IAC first and avulse the inf vestibular nerve peeling tumor back, then place gelfoam and start opening the dura in the angle
• Dura of the IAC inferiorly can be shrunken with the bipolar after safe mapping
• Be careful for traction potentials when opening the dura near the meatal foramen decompression
• When opening the dura of the post fossa, start a good centimeter below the sigmoid to avoid the fusiform edge of the sinus, cut down parallel to sup petrosal sinus
• If vessels are seen in the dura, bipolar them as you are pulling away from the facial nerve
• Open a triangle of dura for exposure at CPA, the triangle of tissue can be removed or just shrunken with the bipolar
• Place cottonoid on cerebellum and push with sucker, this will help open arachnoid to decompress CSF and will push vessels inferiorly away from the tumor and nerves
• Use Adrenalin-soaked Gelfoam for suspected arterial bleeders and thrombin-soaked Gelfoam for suspected venous bleeders.

Tumor dissection:

• Use Robinol before brainstem traction to prevent bradycardia
• When bipolaring tumor, pull it away from the facial prior to bipolaring and then cut with microscissors
• Meningioma will appear more red and granular than acoustics
• When working on tumor on the nerve, don't bipolar, instead use adrenalin and gelfoam
• Adrenalin (or thrombin) soaked gelfoam placed at tumor dissection planes will provide hemostasis and help dissect the tumor (push the gelfoam with the sucker to help dissect)
• Push the gelfoam into the dissection plane with a stimulating gimmick while retracting the tumor with the suction listening for traction potentials, if none are heard, this is a good way to dissect
• Use a small suction irrigator (#3) for your suction, this allows irrigation now and then to clear away blood and it allows a greater suction force to retract tumor while dissecting (requires one recognizes the potential for injury to the nerve vs. a Brackmann suction)
• Dissect tumor from both ends, alternating back and forth with adrenalin gelfoam placed while one end is not being dissected
• Start dissection with a stimulating hook and bluntly pull things apart, when they get sticky, switch to sharp dissection and bipolar (or adrenalin gelfoam if on nerve)
• Also can dissect with back side of the stimulating hook with gentle sweeps
• Use stimulating ring to separate brainstem and vessels/nerves from the tumor capsule in the CPA with gentle sweeping back and forth movements along the capsule
• When debulking a large tumor through an incised capsule, use gentle multiple sweeps with a stimulating ring curette and a 5 sucker, don't use a 5 sucker if you are near the nerve
• Keep cochlear nerve in place in IAC when dissecting tumor to lessen the traction on VII
• When bipolaring around the nerve, use very short bursts and keep suction in place to absorb convected heat (and smoke), irrigate frequently to cool the nerve thereby decreasing conducted heat injury
• Be very careful in the IAC between the cochlearvestibular nerve and facial, there is always a branch of AICA there!
• When in CPA, hold an instrument in front of suction tip to keep delicate tissues from being sucked in

Closing:

• When checking for bleeding, Trendelenberg with Valsalva and sucker to remove CSF, always have another instrument in your hand to place adjacent to the sucker while sucking CSF to avoid sucking on the facial nerve of vital structures (this also reduces CSF pressure when closing)
• To remove incus - Wedge hook between M-I joint and pull laterally
• Pack ET and ME with "grunge" = thick fibrous tissue / periosteum
• Temporarily place thrombin gelfoam in open CPA while packing grunge in middle ear. This protects the exposed facial while you pack and soaks up any blood dripping into the CPA from above. It also allows for a final check of hemostasis once removed before placing the fat.
• Place teardrop fat into CPA tucking it under dura with facial nerve monitor on and no Bovie activity. Push as much fat in as will advance easily without causing noise from the facial.
• Place fascia between teardrop fat and ME grunge to block off epitympanic and facial recess area, fold the fascia back on itself and put more grunge between it like a sandwich, then the fat can push the sandwich together
• Don't irrigate wound until after teardrop fat is placed to keep bone dust out of CPA (headache and sterile subarachnoiditis)
• Second larger fat graft is stitched in with horizontal mattress suture from SCM to temporalis (make a fat hammock), if too much fat to close, simply trim excess fat from bolstered graft

Middle Fossa

Soft Tissue:

• Think in terms of potential for use of temporal-parietal fascia flap
• Keep a rim of fascia on the temporalis muscle flap for strength when suturing it back in place
• Form a fan shaped flap of temporalis muscle rotated inferiorly (retract with dura hooks)
• Don't keep retractors too tight on temporalis muscle for fear of congesting the flap

Bone Work:

• Orient bone plate angled along axis of zygomatic arch and temporal line
• Remove bone plate with small cutter (long shank)
• Orient 2/3 anterior to EAC, 1/3 posterior to EAC
• Once window removed, lower inferior ledge to level of middle fossa floor. Use sucker or m.f. Retractor as protector to keep from skipping onto dura

Key Anatomy/Tips:

• Elevate dura from posterior to anterior (direction of GSPN) using a freer
• Petrosquamous suture is one cm deep and should not be confused with GSPN
• Lesser petrosal is ant and parallel to GSPN (not always seen)
• Oxycel for hemostasis at foramen spinosum and at post/inf corner
• GSPN is parallel to post petrous ridge, locate with stimulating instrument
• The ET/tensor tympani are parallel and lateral to the GSPN
• Posterior root of zygoma, malleus head and IAC are almost on a straight line
• To move and advance retractor, hold dura with sucker, then hold finger on advanced retractor blade, then tighten from behind
• Place the blade over the lip of the petrous ridge near the apex, directly in a line drawn even with the location of the EAC (or bisecting the angle formed by the GSPN and arcuate eminence)
• 10/5 rule locates the apex of the SSC based upon position of the anterior border of the Gen Gang
• Arcuate eminence is posterior to the SSC medially, varying by less than two to six mm
• SCC is perpendicular to petrous ridge
• The facial nerve, basal turn of cochlea and ampullated end of SSC are within a 4mm range
• The cochlea is medial to the GSPN and anteromedial to most of the labyrinthine segment
• For tumor cases, start drilling medially and define IAC, then move lateral
• Tumor dissection is always from medial to lateral along cochlear nerve
• Place temporalis in IAC after resection of acoustic (or temporal-parietal fascia flap)

When in doubt, ask!