Clin Exp Otorhinolaryngol.  2009 Sep;2(3):151-154.

Petrous Apex Cholesterol Granuloma Presenting as Endolymphatic Hydrops: A Case Report

• Kim HC
• An YS
• Ahn JH

Abstract

A petrous apex cholesterol granuloma (PACG) is the most common lesion of the petrous apex mass. Affected patients present with various symptoms such as hearing loss, vertigo, headache, tinnitus, facial spasms, and diplopia. We report the case of a 32-yr-old man with a PACG, who was first misdiagnosed with Meniere's disease. He was placed on a low-salt diet, and prescribed medication from another hospital, for several months, but the symptoms persisted and worsened. The patient presented to the emergency room complaining of left facial twitching and numbness. To rule out a central neurological lesion, temporal bone magnetic resonance imaging was carried out and a 2.5 cm mass with high signal intensity on T1- and T2-weighted imaging, without gadolinium enhancement, was found. Because of the hearing and facial problems, we drained cholesterol-bearing material via an infralabyrinthine approach using a computer aided image-guided surgical device, the BrainLAB(R). After the operation, the vertigo and hearing loss were no longer present. It is likely that the patent's Meniere's disease-like symptoms were due to the compression of the endolymphatic sac by a PACG.

Keyword

Cholesterol granuloma; Petrous apex; Endolymphatic hydrops

MeSH Terms

Cholesterol
Diet, Sodium-Restricted
Diplopia
Emergencies
Endolymphatic Hydrops
Endolymphatic Sac
Gadolinium
Granuloma
Headache
Hearing
Hearing Loss
Humans
Hypesthesia
Magnetic Resonance Imaging
Meniere Disease
Spasm
Temporal Bone
Tinnitus
Vertigo
Cholesterol
Gadolinium

Figure

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  Fig. 1 (A) This electrocochleogram showed that the patient's ratio of right cochlear summating potential to auditory nerve action potential ratio (SP/AP ratio) was 0.43-0.56. (B) Video caloric testing demonstrated a right unilateral weakness of 79%. (C) Vestibular evoked myogenic potential (VEMP) response was absent on the right side.

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  Fig. 2 Preoperative (A) T1-weighted, (B) T2-weighted, and (C) T1-weighted images with gadolinium-enhanced MRI scans showing a 2.5 cm-sized lobulating mass (arrow) at the right petrous apex.

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  Fig. 3 The computer-aided image-guided surgical device, BrainLAB®. Three infrared emitting fixed markers (red dots) and two pointers (green dots) are seen in the right upper area of the screen.

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  Fig. 4 Intraoperative findings. After a complete mastoidectomy, we drilled a 1 cm-diameter hole through the petrous apex. This enabled us to locate facial nerve anteriorly, the endolymphatic sac posteriorly, the posterior semicircular canal superiorly, and the jugular bulb inferiorly. The cholesterol granuloma sac was exposed and dark yellow color content was drained (arrow).FC: facial canal; JB: jugular bulb; PSCC: posterior semicircular canal.

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  Fig. 5 Pre- and post-operative pure tone audiometry (PTA). (A) Preoperative PTA showed decrease in the right hearing threshold at 0.25, 0.5, and 4 kHz. (B) Postoperative PTA showed improvement at both the lower and higher tone hearing thresholds.

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  Fig. 6 Histopathology of the petrous apex cholesterol granuloma. The cholesterol granuloma appeared as empty, irregularly shaped clefts, or as spaces surrounded by a foreign body giant cell reaction; fresh hemorrhage and hemosiderin pigment are apparent.

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