Abnormal Enhancement in the Region of the Vestibular Aqueduct on Magnetic Resonance Imaging in a Cerebellopontine Angle Meningioma

Abstract

The vestibular aqueduct and the endolymphatic duct and sac have been described by high-resolution computed tomography (CT) and high-resolution three-dimensional magnetic resonance imaging (MRI).l,2 We describe what we believe to be abnormal enhancement of the endolymphatic duct and sac with surrounding cerebellopontine angle (CPA) meningioma. To our knowledge, abnormal enhancement of these structures has never been described in cases of meningioma. CASE REPORTA 40-year-old woman was evaluated for a4-month history of occasional ringing in her right ear and an intermittent, strange sense ofmotion when she was at rest. She denied vertigo, hearing loss, headache, nausea, vomiting, diplopia, weakness, or sensory loss. Her physical examination yielded normal findings, and she was neurologically intact. The results of her laboratory studies were unremarkable.An MRI examination performed on a 1.5-T (GE, Milwaukee, Wis) superconductive scanner, using a slice thickness of 4 rom, showed a mass in the right CPA and internal auditory canal (lAC). This mass was isointense on precontrast Tl-weighted images (Fig lA) and showed intense enhancement with a Fig 1. AxialTl-weighted magnetic resonance images. A) Precontrast (TRITE 400112).showing cerebellopontine angle mass (asterisk) with involvement ofright internal auditory canal (lAC). Mass was relatively isointense to brain parenchyma on both Tl-and TI-weighted (not shown) images. Note hypointense comma-shaped structure (arrow) posterior to right lAC. anatomically corresponding to vestibular aqueduct. B) Postcontrast (400112), corresponding to A, showing marked enhancement of mass, lAC. and comma-shaped structure. (Gadoliniumdiethylenetriamine pentaaeetic acid. dose 0.1 mmollkg as recommended by manufacturer.)