Mario Sanna, M.D.,* Carlo Zini, M.D.,t Roberto Gamoletti, M.D.,* Niccolo Frau, M.D.,* Abdel Kader Taibah, M.D.,* Alessandra Russo, M.D.,* and Enrico Pasanisi, M.D.t Petrous Bone Cholesteatoma Improvements in skull base surgery and recent ad- may be involved. Posteriorly, the cholesteatoma may vances in radiologic imaging have changed attitudes in spread toward the posterior aspect of the bony labyrinth management of petrous bone cholesteatoma. In particular and the retrolabyrinthine mastoid cells. high resolution computed tomography (CT) and magnetic An infralabyrinthine cholesteatoma (Fig. 2A, B) resonance imaging (MRI) allow the exact pathologic defi- arises in the hypotympanic and infralabyrinthine regions nition preoperatively and an accurate follow-up of any and extends anteriorly toward the internal carotid artery possible recurrence after surgery. This advance has made and posteriorly toward the posterior cranial fossa. it possible to switch from open techniques to more oblit- A massive labyrinthine cholesteatoma (Fig. 3A, B) is erative techniques that avoid exposure of the carotid ar- a diffuse type and involves the entire posterior and anterior tery, dura, and the internal auditory canal to the exterior labyrinth. The site of origin within the petrous bone is not environment. certain, but it may result from an extension of supra- labyrinthine or infralabyrinthine cholesteatoma. It often develops from a primary acquired cholesteatoma. It is DEFINITION AND CLASSIFICATION usually asymptomatic, but slight unsteadiness, facial palsy, and partial or total sensorineural hearing loss may We have used the term "petrous bone cholestea- occur. toma" to define an epidermoid cyst of the petrous portion An infralabyrinthine-apical cholesteatoma (Fig. 4A, of the temporal bone. We have divided petrous bone B) may arise in the infralabyrinthine or the apical com- cholesteatomas into five types: supralabyrinthine, infra- partments. The first extends anteriorly into the petrous labyrinthine, massive labyrinthine, infralabyrinthine- apex and may involve the sphenoid sinus and the horizon- apical, and apical. A supralabyrinthine cholesteatoma tal portion ofthe internal carotid artery. The latter arises in (Fig. IA, B) is characteristically congenital or may result the apical compartment and then extends superiorly to the from deep ingrowth of an acquired epitympanic choles- sphenoid sinus and inferoposteriorly to the infralabyrin- teatoma. It involves the anterior epitympanum and extends thine compartment. These are generally congenital in medially toward the internal auditory canal and anteriorly origin. toward the carotid artery. The basal turn of the cochlea An apical cholesteatoma (Fig. 5A, B) is an uncom- Skull Base Surgery, Volume 3, Number 4, October 1993 *Gruppo Otologico, Piacenza, Italy, andt.N.T. Department, University of Parma, Parma, Italy Reprint requests: Dr. Sanna, Gruppo Otologico, Via Emmanueli 42, 29100 Piacenza, Italy Copyright ©) 1993 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved. 201 SKULL BASE SURGERYNOLUME 3, NUMBER 4 OCTOBER 1993 Sph.S . s.P.S. B Figure 1. A, B: The supralabyrinthine type of choles- teatoma. I.C.A.: internal carotid artery; I.P.S.: inferior pe- trosal sinus; Sph.S: sphenoid sinus; S.P.S.: superior pe- A Acf trosal sinus; S.S.: sigmoid sinus; V n.c.: trigeminal nerve. Sph. S. s.P.S. B A Figure 2. A, B: The infralabyrinthine type of choles- 202 AcI teatoma. See Figure 1 for abbreviations. PETROUS BONE CHOLESTEATOMA-SANNA ET AL. B Figure 3. A, B: Massive labyrinthine cholesteatoma. A Acft See Figure 1 for abbreviations. Sph. S. S.P.S. B Figure 4. A, B: The infralabyrinthine-apical type of A Ac.tv cholesteatoma. See Figure 1 for abbreviations. 203 SKULL BASE SURGERYNOLUME 3, NUMBER 4 OCTOBER 1993 Sph. S . K B Figure 5. A, B: The apical type of cholesteatoma. A See Figure 1 for abbreviations. mon congenital lesion. It may involve only the apical when hearing of the affected ear is normal. The modified compartment ofthe temporal bone. It can cause erosion of transcochlear approach is performed for massive labyrin- the internal auditory canal. It may extend toward the thine, infralabyrinthine-apical, and apical cholesteatomas posterior cranial fossa or anteriorly to the trigeminal extending to the clivus, and in all cases of internal auditory nerve. canal involvement and cerebrospinal fluid (CSF) leak. The modified transcochlear approach is based on a wide petrosectomy with exposure and rerouting of the SURGICAL MANAGEMENT facial nerve exposure of the middle and posterior cranial fossa dura, sigmoid sinus and jugular bulb, and petrous The ideal treatment for petrous bone cholesteatomas carotid artery. The external and middle ear are removed is radical surgical removal, although destruction of the with blind sac closure of the external ear canal, the eu- labyrinth and rerouting of the facial nerve may be re- stachian tube is closed, and the cavity is obliterated with quired. This approach may have to be modified, depend- abdominal fat. The infratemporal approach type B is used ing on the status of the contralateral ear. The choice of the when petrous bone cholesteatoma involves the horizontal actual surgical approach is based on the location and portion of the internal carotid artery or the sphenoid sinus. extent of the lesion, but it must provide adequate and safe This approach can be extended to the neck (type A) when exposure of the middle and posterior fossa dura, carotid the sigmoid sinus and jugular bulb are involved by choles- artery, lateral sinus and jugular bulb, and facial nerve. teatoma and are to be removed with ligature of the jugular Our attitude in the management of petrous bone vein in the neck. cholesteatoma has evolved from 1984 and the present guidelines can be summarized as follows. Radical petro- mastoid exenteration with marsupialization ofthe cavity is PROBLEMS IN SURGERY done only in cases ofinfralabyrinthine cholesteatoma with limited extension. Radical petromastoid exenteration with Surgical Removal Versus Inner closure of the eustachian tube, obliteration of the cavity Ear Function Preservation with abdominal fat, and blind sac closure of the external ear canal, is done in those large and deep cavities resulting At the beginning of our surgical experience, we at- from infralabyrinthine cholesteatomas. We use the middle tempted to preserve inner ear function despite laby- cranial fossa approach only for small supralabyrinthine rinthine involvement by petrous bone cholesteatoma. Our 204 cholesteatomas without posterior or anterior extensions results, however, showed that we were rarely able to pre- PETROUS BONE CHOLESTEATOMA-SANNA ET AL. serve hearing. Therefore now we do not hesitate to remove unable to distinguish between them. In this case the sur- the otic capsule when it is required. Of course, the status geon has three options: (1) if the cavity is not infected, the of the contralateral ear determines our therapeutic ap- involved dura can be removed and the defect is closed with proach in fact; an only hearing ear with petrous bone fascia; (2) use 90% ethyl alcohol, as proposed by Fisch; cholesteatoma is managed with regular radiologic follow- and (3) bipolar coagulation of all the suspected portions of up and watchful waiting. dura mater to destroy all the possible remnants of choles- teatoma matrix (this is our method of choice). This method can be used in all instances without exceptions. Facial Nerve Involvement Involvement of the facial nerve poses particular Cerebrospinal Fluid Leaks problems. In some instances the cholesteatoma can be easily dissected and simple decompression is the treat- CSF leaks may result from dural tears occurring ment ofchoice. When preoperative facial palsy is present, during matrix removal. Leaks are stopped by inserting a the involved segment may be compressed but anatomi- free muscular flap into the subarachnoid space through the cally intact, interrupted, or replaced by fibrous degenera- dural opening. Large dural tears are repaired with muscle tion. In the first instance the nerve may be freed and plugs and suturing of the dural margins over the muscle. decompressed. When the nerve is interrupted, continuity is reestablished by rerouting and direct anastomosis or with a cable graft. In the third instance the degenerated PATIENTS AND METHODS portion is removed and continuity is reestablished with the methods already mentioned. If facial nerve palsy dates Fifty-four cases of petrous bone cholesteatomas have back more than 2 years, a hypoglossal-facial anastomosis been treated at the E.N.T. Department of the University of is done. Parma, Italy, and at The Gruppo Otologico, Piacenza, Italy, from January 1978 to January 1990 (24 supra- labyrinthine, 12 infralabyrinthine, 13 massive labyrin- Carotid Artery Involvement thine, and five infralabyrinthine-apical cholesteatomas). A draining ear was the most frequent complaint (39 cases), The surgeon should plan an approach that allows the followed by vertigo (25 cases), facial nerve function dis- complete control of the artery. When the horizontal por- turbances (23 cases), otalgia (11 cases), tinnitus (four tion is involved, only the infratemporal fossa approach cases), and headache (two cases). Symptoms were present type B with downward dislocation of the mandible gives for more than 1 year in 76% of the patients. direct control of the vessel. The dissection of the matrix Otoscopy showed an epitympanic perforation in 28 from the artery poses no particular problems but requires cases, a subtotal perforation in 11 cases, a radical cavity in extreme caution and skill. nine cases, a closed tympanoplasty in four cases, and a normal eardrum in two cases. A mixed hearing loss was present in 56% ofcases, a conductive hearing loss in 33%, Sigmoid Sinus and Jugular Bulb total deafness in 9%, and normal hearing in 2%. Involvement The surgical approach has evolved from open tech- niques adopted in the majority of cases from 1978 to 1985 Complete removal of pathologic tissue from the sig- to closed techniques adopted in over 70% of cases in the moid sinus is difficult and problems increase when the last 4 years.