Subcochlear approach for cholesterol granulomas of the inferior petrous apex BECHARA Y. GHORAYEB, MD. and ROBERT A. JAHRSDOERFER, MD, Houston, Texas
Cholesterol granulomas of the petrous apex are drained through two major extralabyrinthine routes: one, along the posterosuperlor chain of air cells, and two, along the anterolnferlor chain. Procedures that use the posterosuperlor chain approach the apex from the slnodural angle, the base of the zygomatlc arch, the attic, or through the arch of the superior semicircular canal. Operations that use the anterolnferlor chain reach the apex along the Internal carotid canal (Ramadler's operation) or by a pos terior Infralabyrlnthine approach between the descending facial nerve and jugular bulb. Inferior petrous apex cholesterol granulomas may be unreachable by any of these routes, and hence the subcochlear route is proposed as an alternative. The subcochlear approach starts in a triangle bounded superiorly by the cochlea, ante riorly by the Internal carotid canal and posteriorly by the deep iugular vein. This op eration requires lowering the Inferior bony canal wall to the level of the "crutch." It provides access to an Inferiorly situated cholesterol granuloma, yet preserves hearing. It allows enough room for the placement of a tube drain from the petrous apex to the mastoid. It Is particularly useful when a high jugular bulb precludes the use of the posterior Infralabyrlnthine route, (OTOLARYNGOL HEAD NECK SURG W0;103:60.)
The petrous apex is one of the most difficult areas to reach in the temporal bone. The multitude of surgical approaches only speaks for the absence of a single sat isfactory route. These routes can be divided into translabyrinthine and extralabyrinthine. The translabyrinthine approach obviously destroys the inner ear, whereas extralabyrinthine approaches are specifically designed to circumvent and spare inner ear structures. The extralabyrinthine routes are in turn divided into intrapetrosal and extrapetrosal. In addition to a mastoidectomy, extrapetrosal routes go through the middle fossa to gain access to the petrous apex, whereas in trapetrosal procedures stay within the confines of the temporal bone.1 In this article, we will briefly discuss the extra labyrinthine approaches. We will also present a sub-
From the Department of Otolaryngology-Head and Neck Surgery, The University of Texas Medical School—Houston. Presented at the Annual Meeting of the American Neurotology So ciety, San Francisco, Calif., March 31, 1989. Submitted for publication March 31, 1989; revision received Oct. 19, 1989; accepted Nov. 8, 1989. Reprint requests: Bechara Y. Ghorayeb, MD, Department of Otolaryngology-Head and Neck Surgery, University of Texas Medical School, 6431 Pannin Street, Suite 6.132, Houston, TX 77030. 23/1/18063
cochlear approach that we found useful in evacuating a cholesterol granuloma of the petrous apex when other routes were impractical. SUROICAL APPROACHES
The petrous apex refers to that portion of the petrous pyramid anteromedial to the bony labyrinth and carotid artery. Inferiorly, it rests on the jugular bulb and inferior petrosal sinus. Superiorly, it is bounded by the contents of the middle cranial fossa and, in particular, the gasserian ganglion. Posteriorly, it is in contact with the structures of the posterior cranial fossa. The apex of the pyramid is related to the foramen lacerum and the posterior clinoid process, to which it is attached with the petroclinoid ligament. Classically, there are two major extralabyrinthine routes to the apex: along the posterosuperior chain of air cells or along the anteroinferior chain. Procedures that use the posterosuperior chain approach the apex from the sinodural angle, the root of the zygomatic arch (Thornval's operation),2 the attic (Eagleton's opera tion),3 or through the arch of the superior semicircular canal (Frenckner's operation)4 (Fig. 1). Operations that use the anteroinferior chain of air cells reach the apex along the internal carotid canal (Ramadier's operation)5 or between the descending facial nerve and jugular bulb (posterior infralabyrinthine/sublabyrinthine approach).6,7 Also using this
60 Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
Volume 103 Number 1 July W o
Subcochlear approach for cholesterol granulomas
61
Fig. 1. Classical approaches to the petrous apex.
RIGHT EAR 250
500
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chain are the precochiear (Almour's operation)8 and the subcochlear approaches1' (Fig. 1). In the pre-antibiotic era, the major indications for these surgical procedures were petrous apicitis and Grade nigo's syndrome. With the advent of antibiotics, such fulminant infections of the petrous bone have become
anecdotal and surgery has found newer indications: ex tensive cholesteatomas, glomus tumors, and cysts of the temporal bone. Circumscribed lesions of the petrous apex do not require extensive dissection and may be approached by one specific route, depending on their location. The
Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
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OtolaryngologyHead and Neck Surgery
GHORAYEB and JAHRSDOERFER
Fig. 3. Cholesterol granuloma (open arrows] shows high-intenslly signal on magnetic resonance imaging.
Fig. 4. High-resolution computerized tomography shows erosion of petrous apex (between arrowheads).
Kopetzky-Almour approach is indicated when there is involvement of the superior portion of the petrous apex."' For inferior lesions, the attic and the anterosuperior chain of air cells need not be dissected. These inferior lesions may be reached via the sublabyrinthine route, without performing a radical mastoidectomy. Dissecting the infralabyrinthine air cells and following them anteriorly over the dome of the jugular bulb may be sufficient.7 When the jugular bulb is high, the inferior portion of the petrous apex is inaccessible by this route, and a more direct exposure becomes necessary. CASE REPORT
A 27-year-old woman had right-sided headaches, facial paresthesias, and loss of taste of 9 months duration. Physical
examination did not reveal any abnormalities and she had normal hearing by audiometry (Fig. 2). Magnetic resonance imaging showed a high signal intensity lesion (Fig. 3) and high-resolution computerized tomography of the temporal bones revealed a 2.5 x 3 cm defect in therightpetrous apex (Fig. 4), consistent with cholesterol granuloma. She under went a subcochlear approach to the petrous apex.
The Subcochlear Approach An intact canal wall mastoidectomy is performed and the vertical portion of the fallopian canal is clearly identified, down to the stylomastoid foramen. The sigmoid sinus and jugular bulb are skeletonized. When the dome of the jugular bulb is too high and the in fralabyrinthine tract too narrow to allow drilling medial
Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
Volume 103 Number 1
July w o
Subcochlear approach for cholesterol granulomas
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Fig. 5. Subcochlear triangle (arrow) between jugular bulb (JB) and internal carotid artery (C).
Fig. 6. Subcochlear approach. White arrow shows opening Into petrous apex between high jugular bulb and carotid canal.
to
the facial nerve, subcochlear dissection is then required. This approach uses the subcochlear triangle, w hich is bounded superiorly by the cochlea, anteriorly by the internal carotid canal, and posteriorly by the Jugular bulb (Fig. 5). Access to this triangle may be
restricted by a high posterior bony canal wall. This wall may be lowered, as in a radical mastoidectomy. Lowering of the inferior bony canal wall is required to uncover the subcochlear region. This is accomplished by elevating the inferior canal skin and drilling the
Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
64
OtolaryngologyHead and Neck Surgery
GHORAYEB and JAHRSDOERFER
Fig. 7. Six months postoperative magnetic resonance Imaging still shows a high signal Intensity on T1- and T2-weighted Images (open arrows).
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500
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Cholesterol granulomas of the petrous apex are drained through two major extralabyrinthine routes: one, along the posterosuperlor chain of air cells, and two, along the anterolnferlor chain. Procedures that use the posterosuperlor chain approach the apex from the slnodural angle, the base of the zygomatlc arch, the attic, or through the arch of the superior semicircular canal. Operations that use the anterolnferlor chain reach the apex along the Internal carotid canal (Ramadler's operation) or by a pos terior Infralabyrlnthine approach between the descending facial nerve and jugular bulb. Inferior petrous apex cholesterol granulomas may be unreachable by any of these routes, and hence the subcochlear route is proposed as an alternative. The subcochlear approach starts in a triangle bounded superiorly by the cochlea, ante riorly by the Internal carotid canal and posteriorly by the deep iugular vein. This op eration requires lowering the Inferior bony canal wall to the level of the "crutch." It provides access to an Inferiorly situated cholesterol granuloma, yet preserves hearing. It allows enough room for the placement of a tube drain from the petrous apex to the mastoid. It Is particularly useful when a high jugular bulb precludes the use of the posterior Infralabyrlnthine route, (OTOLARYNGOL HEAD NECK SURG W0;103:60.)
The petrous apex is one of the most difficult areas to reach in the temporal bone. The multitude of surgical approaches only speaks for the absence of a single sat isfactory route. These routes can be divided into translabyrinthine and extralabyrinthine. The translabyrinthine approach obviously destroys the inner ear, whereas extralabyrinthine approaches are specifically designed to circumvent and spare inner ear structures. The extralabyrinthine routes are in turn divided into intrapetrosal and extrapetrosal. In addition to a mastoidectomy, extrapetrosal routes go through the middle fossa to gain access to the petrous apex, whereas in trapetrosal procedures stay within the confines of the temporal bone.1 In this article, we will briefly discuss the extra labyrinthine approaches. We will also present a sub-
From the Department of Otolaryngology-Head and Neck Surgery, The University of Texas Medical School—Houston. Presented at the Annual Meeting of the American Neurotology So ciety, San Francisco, Calif., March 31, 1989. Submitted for publication March 31, 1989; revision received Oct. 19, 1989; accepted Nov. 8, 1989. Reprint requests: Bechara Y. Ghorayeb, MD, Department of Otolaryngology-Head and Neck Surgery, University of Texas Medical School, 6431 Pannin Street, Suite 6.132, Houston, TX 77030. 23/1/18063
cochlear approach that we found useful in evacuating a cholesterol granuloma of the petrous apex when other routes were impractical. SUROICAL APPROACHES
The petrous apex refers to that portion of the petrous pyramid anteromedial to the bony labyrinth and carotid artery. Inferiorly, it rests on the jugular bulb and inferior petrosal sinus. Superiorly, it is bounded by the contents of the middle cranial fossa and, in particular, the gasserian ganglion. Posteriorly, it is in contact with the structures of the posterior cranial fossa. The apex of the pyramid is related to the foramen lacerum and the posterior clinoid process, to which it is attached with the petroclinoid ligament. Classically, there are two major extralabyrinthine routes to the apex: along the posterosuperior chain of air cells or along the anteroinferior chain. Procedures that use the posterosuperior chain approach the apex from the sinodural angle, the root of the zygomatic arch (Thornval's operation),2 the attic (Eagleton's opera tion),3 or through the arch of the superior semicircular canal (Frenckner's operation)4 (Fig. 1). Operations that use the anteroinferior chain of air cells reach the apex along the internal carotid canal (Ramadier's operation)5 or between the descending facial nerve and jugular bulb (posterior infralabyrinthine/sublabyrinthine approach).6,7 Also using this
60 Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
Volume 103 Number 1 July W o
Subcochlear approach for cholesterol granulomas
61
Fig. 1. Classical approaches to the petrous apex.
RIGHT EAR 250
500
1K
-10 "
0
10 20
z «I
30 40 50 60 70 80 90
100 110
y :
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' ' ^Y ^ F~-* f
'
:
■
Summary
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2K 1
i ,;l.
*s, 2/ Si> ,:. ^ ^ 1 1 1 1 1 1 1 1 1
Right Ear 7
92 100
dB
Left Ear PTA
dB ST % „PBM.
dB
dB % %
Fig. 2. Preoperatlve audiogram.
chain are the precochiear (Almour's operation)8 and the subcochlear approaches1' (Fig. 1). In the pre-antibiotic era, the major indications for these surgical procedures were petrous apicitis and Grade nigo's syndrome. With the advent of antibiotics, such fulminant infections of the petrous bone have become
anecdotal and surgery has found newer indications: ex tensive cholesteatomas, glomus tumors, and cysts of the temporal bone. Circumscribed lesions of the petrous apex do not require extensive dissection and may be approached by one specific route, depending on their location. The
Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
62
OtolaryngologyHead and Neck Surgery
GHORAYEB and JAHRSDOERFER
Fig. 3. Cholesterol granuloma (open arrows] shows high-intenslly signal on magnetic resonance imaging.
Fig. 4. High-resolution computerized tomography shows erosion of petrous apex (between arrowheads).
Kopetzky-Almour approach is indicated when there is involvement of the superior portion of the petrous apex."' For inferior lesions, the attic and the anterosuperior chain of air cells need not be dissected. These inferior lesions may be reached via the sublabyrinthine route, without performing a radical mastoidectomy. Dissecting the infralabyrinthine air cells and following them anteriorly over the dome of the jugular bulb may be sufficient.7 When the jugular bulb is high, the inferior portion of the petrous apex is inaccessible by this route, and a more direct exposure becomes necessary. CASE REPORT
A 27-year-old woman had right-sided headaches, facial paresthesias, and loss of taste of 9 months duration. Physical
examination did not reveal any abnormalities and she had normal hearing by audiometry (Fig. 2). Magnetic resonance imaging showed a high signal intensity lesion (Fig. 3) and high-resolution computerized tomography of the temporal bones revealed a 2.5 x 3 cm defect in therightpetrous apex (Fig. 4), consistent with cholesterol granuloma. She under went a subcochlear approach to the petrous apex.
The Subcochlear Approach An intact canal wall mastoidectomy is performed and the vertical portion of the fallopian canal is clearly identified, down to the stylomastoid foramen. The sigmoid sinus and jugular bulb are skeletonized. When the dome of the jugular bulb is too high and the in fralabyrinthine tract too narrow to allow drilling medial
Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
Volume 103 Number 1
July w o
Subcochlear approach for cholesterol granulomas
63
Fig. 5. Subcochlear triangle (arrow) between jugular bulb (JB) and internal carotid artery (C).
Fig. 6. Subcochlear approach. White arrow shows opening Into petrous apex between high jugular bulb and carotid canal.
to
the facial nerve, subcochlear dissection is then required. This approach uses the subcochlear triangle, w hich is bounded superiorly by the cochlea, anteriorly by the internal carotid canal, and posteriorly by the Jugular bulb (Fig. 5). Access to this triangle may be
restricted by a high posterior bony canal wall. This wall may be lowered, as in a radical mastoidectomy. Lowering of the inferior bony canal wall is required to uncover the subcochlear region. This is accomplished by elevating the inferior canal skin and drilling the
Downloaded from oto.sagepub.com at The University of Iowa Libraries on June 5, 2016
64
OtolaryngologyHead and Neck Surgery
GHORAYEB and JAHRSDOERFER
Fig. 7. Six months postoperative magnetic resonance Imaging still shows a high signal Intensity on T1- and T2-weighted Images (open arrows).
RIGHT EAR 250
500
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2K
Summary
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:■-,: >:i':ï :::M, : :ï
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