CHPT 126 Cranial-Base Surgery

1. CHPT 126Cranial-Base Surgery • See quiz handout

2. CHPT 127Surgical Techniques to Enhance Prosthetic Rehabilitation

3. Mastoid Surgery Quinton Gopen, M.D. UCLA Medical Center April 25th, 2012

4. Mastoidectomy • Canal Wall Up • Facial Recess approach • Atticotomy • Canal Wall Down

5. Canal Wall Up • Skin incision • Fascia harvest • Periosteal incision • Bone removal • Sequential landmarks • Identify • Tegmen • Mastoid antrum • Lateral semicircular canal • Optional • Incus • Facial Nerve • Sigmoid sinus

14. Facial Recess • Perform a canal wall up mastoidectomy • Thin the posterior canal wall Boundaries: • Superior: incus or incus buttress • Posterior: facial nerve • Anterior: bony ear canal, chordae tympani • Inferior: bifrication of facial nerve and chordae tympani

15. Facial Recess

17. Atticotomy • Only indicated for disease limited to the attic and middle ear space • Do not use for posterior extension into the mastoid/antrum!

20. Canal Wall Down

21. Canal Wall Down • Keys: • Take canal wall down to level of facial nerve • (avoid high facial ridge) • Wide meatoplasty • For postoperative mastoid bowl cleaning and aeration • Line mastoid cavity • Split thickness skin graft or fascia • Avoids excessive granulation tissue and drainage • Saucerize and remove air cells thoroughly • No rough edges – smooth cavity • Remove mastoid tip • Helps to avoid difficult to reach inferior extent of cavity

22. Labyrinthine Fistula

23. Controversies • CWU vs CWD • Mandatory CWD • Unreconstructable EAC defect • Labyrinthine fistula • Poor health • Poor compliance • 2nd look procedure • Recividism or recurrence • Middle ear endoscopy • Mastoid Oblitteration • Pediatrics vs. Adult

24. Controversies • Pediatric Cholesteatoma more aggressive than adult? • DeCorso 2006 Review of 60 children versus 308 adults with acquired cholesteatomas • All underwent CWD T/M • Found higher incidence of incus and malleus erosions, more advanced stage, and higher incidence of recurrence • Generally accepted that more extensive disease in children compared to adults and that residual and recurrent disease found at higher rates

25. Board Review

26. Board Review • Where is the most likely area a fistula will form when cholesteatoma is present? • Choices: • Cochlea • Posterior SSC • Lateral SSC • Superior SSC

27. Board Review • A surgeon performing a cholesteatoma excision via a canal wall up mastoidectomy calls you. The surgeon states that the cholesteatoma was not difficult to remove and that a facial nerve monitor was in use and did not demonstrate any aberrant responses. The child awoke with facial weakness per his report. He states that the eye closure is good but there is no lip movement upon maximal effort. He calls you for your management?

28. Board Review • Lesion within petrous apex that is hyperintense on T1 and T2 MRI sequences that does not enhance with gadolinium? • Choices: • Normal bone marrow • Cholesteatoma • Cholesterol granuloma • Glomus tumor • Acoustic neuroma

29. Board Review • Lesion within petrous apex that is hypointense on T1, hyperintense on T2 and does not enhance with gadolinium • Choices: • Normal bone marrow • Cholesteatoma • Cholesterol granuloma • Glomus tumor • Acoustic neuroma

30. Board Review • While in surgery, the surgeon notes that the cog has been eroded by cholesteatoma. What is the most likely other structure to be affected? • Choices • lateral semicircular canal • vertical facial nerve segment • tympanic facial nerve segment • intracannalicular facial nerve segment • Jugular bulb

31. Cog and Supratubal RecessAJNR 18: 1109-1114 1997

32. Board Review • What is a boundary of the sinus tympani? • Choices: • chorda tympani • cochleariform process • pyramidal eminence • tensor tympani • tympanic membrane

33. Board Review Discussion: The sinus tympani is a depression along the posteromedial wall of the middle ear cavity. It lies between the bony labyrinth medially and the pyramidal eminence and facial nerve laterally - can be seen on the following histologic section answer: pyramidal eminence

34. Board Review • Patient has a tympanic retraction pocket extending into the sinus tympani. The retraction pocket is inadvertently transected during middle ear exploration. The tympanic membrane defect was repaired with a graft. Which postoperative complication is he at greatest risk for? • Choices: • cholesteatoma of the mesotympanum medial to the incus • cholesteatoma of the epitympanum lateral to the incus • tympanic membrane perforation • damage to the lateral semicircular canal • perilymphatic fistula at the oval window

35. Board Review Discussion: The patient is at risk for cholesteatoma given the retained pocket left in the sinus tympani. Since the sinus tympani is NOT in the epitympanum but rather lives in the mesotympanum as a depression along the medial wall along with the round window niche (inferior) and the oval window niche (superior) I would expect the cholesteatoma to be in the mesotympanum medial to the incus answer: cholesteatoma of the mesotympanum medial to the incus Anatomy of the Temporal Bone With Surgical Implications (Gulya/Schuknecht)

36. Board Review • Difficult removal of cholesteatoma but surgeon thinks nerve was not injured. Postoperatively patient has complete facial nerve paralysis persisting for one week. On POD #7 stimulation of facial nerve on that side results in brisk movement of face. How to manage this patient? • Choices: • middle ear exploration with facial nerve decompression • Observation • MRI scan • Middle fossa approach with facial nerve decompression • Transmastoid approach with facial nerve decompression

37. Board Review Discussion: Within the first 3 days after onset of complete paralysis, the results of NET, MST, and ENoG yield little useful information as Wallerian degeneration distal to the stimulation area has not yet occurred and the results always indicate incomplete degeneration. Because of this limitation, the prognosis cannot be established until the sixth or seventh day after paralysis by NET, MST, or ENoG. In this case we are 7 days out, the nerve still stimulates implying that it is intact - so I would argue that we leave it alone! • answer: observation only