Meningiomas are mostly benign, slow-growing tumors of the CNS that originate from arachnoidal cap cells. While monosomy 22 is the most frequent genetic abnormality found in meningiomas, a multitude of other aberrant chromosomal alterations, signaling pathways, and growth factors have been implicated in its pathogenesis. Losses on 22q12.2, a region encoding the tumor suppressor gene merlin, represent the most common genetic alterations in early meningioma formation. Malignant meningioma progression, however, is associated with more complex karyotypes and greater genetic instability. Cytogenetic studies of atypical and anaplastic meningiomas revealed gains and losses on chromosomes 9, 10, 14, and 18, with amplifications on chromosome 17. However, the specific gene targets in a majority of these chromosomal abnormalities remain elusive. Studies have also implicated a myriad of aberrant signaling pathways involved with meningioma tumorigenesis, including those involved with proliferation, angiogenesis, and autocrine loops. Understanding these disrupted pathways will aid in deciphering the relationship between various genetic changes and their downstream effects on meningioma pathogenesis. Despite advancements in our understanding of meningioma pathogenesis, the conventional treatments, including surgery, radiotherapy, and stereotactic radiosurgery, have remained largely stagnant. Surgery and radiation therapy are curative in the majority of lesions, yet treatment remains challenging for meningiomas that are recurrent, aggressive, or refractory to conventional treatments. Future therapies will include combinations of targeted molecular agents as a result of continued progress in the understanding of genetic and biological changes associated with meningiomas.

OBJECTIVE:: To identify otologic and audiologic characteristics of superior (and posterior) semicircular canal dehiscence (SCD). STUDY DESIGN:: Retrospective case review. SETTING:: Tertiary referral center. PATIENTS:: Sixty-five adult patients were evaluated for SCD; 26 of 65 (35 ears) had dehiscence. INTERVENTION(S):: Otologic examination, high-resolution computerized tomography (CT), air and bone audiometry, tympanometry, acoustic reflex, and vestibular evoked myogenic potential (VEMP). MAIN OUTCOME MEASURE(S):: Imaging demonstrating canal dehiscence, preferentially including Poschel and Stenvers reconstructions. Audiologic findings of pseudoconductive loss, intact ipsilateral stapedial reflex, and abnormally low VEMP thresholds. RESULTS:: The most common presenting complaints were autophony of voice and a "blocked ear" (94%), mimicking patulous eustachian tube, including relief with Valsalva or supine position (50%), but without autophony of nasal breathing. Pseudoconductive loss was found in 86% of dehiscence ears, and 60% (21 of 35) of these ears had better than 0-dB-hearing-loss bone conduction thresholds at 250 and/or 500 Hz. Acoustic reflex was present in 89%. Assuming CT as the criterion standard, VEMP resulted in 91.4% sensitivity and 95.8% specificity. One false-positive CT, with abnormal VEMP, resulted in surgical explorations negative for superior SCD but positive for posterior SCD. CONCLUSION:: Semicircular canal dehiscence may present with various symptoms such as autophony, ear blockage, and dizziness/vertigo. A combination of high-resolution CT and audiologic testing is recommended for diagnosis. Low-frequency conductive loss with better than 0 dB hearing level (HL) bone conduction threshold and normal tympanometry, with intact acoustic reflexes, are audiologic signs of SCD. Vestibular evoked myogenic potential is highly sensitive and specific for SCD, possibly better than CT.

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The enlarged vestibular aqueduct remains a controversial entity with variable presentation, progression, and prognosis.