Case reportLipoma of the cerebellopontine angle
Introduction
Intracranial lipomas are extremely unusual lesions, with an incidence of 0.08% in autopsy series [1]. Only 0.1% of tumors in the cerebellopontine angle (CPA) or internal auditory canal (IAC) are lipomas [2], [3], [4], [5], [6], [7], [8], [9], [10], a region in which 75% to 90% of tumors are vestibular schwannomas (acoustic neuromas) [3], [5], [6], [10]. Unlike other benign lesions of the skull base, CPA/IAC lipomas often splay and engulf cranial nerve (CN) fibers as opposed to simply compressing these structures, complicating attempts at surgical resection [1], [3]. Because CPA lipomas are slow-growing tumors with infiltrative growth characteristics, surgery is only indicated in cases of intractable symptoms to minimize iatrogenic cranial neuropathies [3], [5], [6], [7], [11].
Section snippets
Case report
A 42-year-old otherwise healthy woman presented with a 1-year history of progressive left-sided hearing loss. She also reported worsening left-sided hemifacial spasm. Her physical examination was unremarkable except for synkinesis of the left facial nerve. Audiometric evaluation demonstrated a downsloping sensorineural hearing loss in the left ear with a speech reception threshold of 25 dB and word discrimination score of 84%. The right ear was normal.
Magnetic resonance imaging (MRI) revealed a
Discussion
Lipomas of the CPA/IAC are rare lesions that resemble more common benign neoplasms of the skull base both clinically and radiographically. Unlike vestibular schwannomas, complete surgical resection of CPA/IAC lipomas is difficult to achieve and is rarely indicated, and therefore an accurate radiologic diagnosis is crucial. These tumors are indolent but infiltrate along CNs, making complete removal difficult and increasing the risk for postoperative cranial neuropathies. Subtotal resection of
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2020, World NeurosurgeryCitation Excerpt :Similar to other benign tumors of the cerebellopontine angle (CPA), IAC lipomas present with symptoms of sensorineural hearing loss (75%), tinnitus (25%), and vertigo (62.5%).7,8 In addition, other cranial neuropathies associated with cranial nerves V, VII, IX, X, and XI have been reported.9 In contrast with schwannomas, these benign lesions tend to surround, rather than compress, neurovascular structures, making complete lesion removal challenging.
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