Meningioma

CASE REPORTS

Introduction

A number of series have demonstrated Acoustic neuroma, followed by meningioma, to be the commonest cerebellopontine angle tumour pathologies. We report a very rare case of a patient in whom both pathologies co-existed at operation. Acoustic neuromata are benign tumours, usually arising from the sheath of the vestibular component of the VIIIth cranial nerve. They tend to outweigh meningiomas in the CPA by a ratio of at least 5: 1.

Case Report

A 70 year-old woman was admitted to hospital with a preoperative diagnosis of a left cerebello-pontine angle meningioma. She had an eight month history of unilateral high frequency hearing loss, mild disequilibrium and occasional vertiginous symptoms. There was no evidence of facial nerve dysfunction or Hitselberger's sign, trigeminal nerve involvement, or cerebellar symptoms or signs; her audiogram is shown in Figure 1a. Speech Discrimination was 91% in the right ear and 64% in the left ear. Pre-operative Gadolinium-enhanced MRI was interpreted as showing a 3cm left cerebello-pontine angle tumour with intracanalicular extension, consistent with a meningioma. It was noted that there was a discontinuity between the cerebello-pontine angle mass and its Internal Acoustic Meatus (IAM) extension, and an IAM mass further laterally; it was presumed that they were connected by a chord of cells, perhaps in an `en plaque' form. An elective retro-sigmoid craniotomy was performed. Two tumours were identified intra-operatively: a large 3cm posterior fossa mass displacing cranial nerves VIII, VII, and V was debulked and confirmed by frozen section to be meningioma; the extension of this meningioma was followed into the IAM, which was then opened, revealing a second lesion in the fundus of the IAM possessing the appearance of an acoustic neuroma. Frozen section showed this to be acoustic neuroma. The dura was closed, overlying fat fibrin-glued and bone replaced.

The patient was monitored in Neurosurgical High Dependency for the first 2 post-operative days and discharged on Day 6; the course was uneventful with no evidence of meningitis or CSF leak. At one month the patient had a grade 1 House-Brackman Facial nerve outcome and spared hearing (Figure 1b).

Discussion

To our knowledge, there is no report in the literature of such synchronous pathology as has occurred in this patient. Attempts have been made to distinguish acoustic neuromata from meningiomata in the CPA clinically, with varying degrees of success (Laird et al 1985). There is argument over radiographical discrimination of the two; some authors supporting the use of CT (Laird et al 1985), whilst others favour MRI (Worthington et al 1986, Lalwani et al 1993). The most frequently referred to features of meningioma of the CPA include a broad base, a dural "tail" and adjacent bony hyperostosis. For acoustic neuromas a globular shape and bony erosion of the IAM are characteristic. In hindsight, the patient reported here had an MRI that demonstrated a broad based 3cm mass with marked enhancent, and a separate intracanalicular lesion (Figures 2 and 3).

Controversy has existed as to whether meningiomata can exist primarily in the Internal Acoustic Canal and, whilst in our case the IAM contained dual pathology, there are reports in the literature of meningiomas arising in or extending into the canal (Zeitouni et al 1997, Buchsteiner et al 1997). This highlights the point that this patient's MRI may also have been misread as containing only meningioma, arising from the CPA with canal extension or vice versa. However the vast majority of T2 weighted images demonstrating intracanalicular tumour, will prove to be acoustic neuroma.

The underlying aetiology for this patient's dual pathology is unknown, although previous literature suggests the possibility of absent alleles on chromosome 22, as might occur in Neurofibromatosis (Fontaine et al 1991, Chio et al 1991). Both sporadic and NF-2 CPA meningiomata and acoustic neuromas are usually associated with such a chromosomal aberration.

References

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2. WORTHINGTON B.S., MAWHINNEY R.R., HOLLAND LM., et al. The relative contribution of magnetic resonance imaging to the assessment and differential diagnosis of cerebellopontine angle mass lesions. Acta Radiol Suppl 1986;369:170-2.

3. LALWANI A.K., JACKLER R.K. Preoperative differentiation between meningioma of the cerebellopontine angle and acoustic neuroma using MRI. Otolaryngol Head Neck Surg 1993; 109(1):88-95.

4. ZEITOUNI A.G., ZAGZAG D., COHEN N.L. Meningioma of the internal auditory canal. Ann Otol Rhinol Laryngol 1997;106(8):657-61.

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(acomm neuroma md ). Ann N Y Acad Sci 1991;615:33:43,

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STUART MACKAY, DAVID POHL, MICHAEL BESSER, CARSTEN PALME and GREG LVOFF

Royal Prince Alfred Hospital, Sydney, New South Wales

Stuart MacKay, B.SC (MED.) M.B.,B.S.(HONS)

ENT SRMO

Royal Price Alfred Hospital

Camperdown Sydney

David Pohl, M.B.B.S. FRACS

Consultant Otolaryngologist

Royal Prince Alfred Hospital

Michael Besser M.B.B.S. FRACS FRCSS FACS

Associate Professor Neurosurgeon

Royal Prince Alfred Hospital

Carsten Palme, M.B.B.S.

ENT Registrar

Royal Prince Alfred Hospital

Greg Lvoff, M.B.B.S., B.D.S., FRACDS

ENT Registrar

Royal Prince Alfred Hospital

Correspondence to:

Stuart MacKay

407/1 Poplar St

Surry Hills 2010

Ph: 02 9515 6111

Fax: 02 4226 4990

Email: sgmackay@hotmail.com

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