Endolymphatic Hydrops in the Setting of Vestibular Schwannoma: A Temporal Bone Study.

Hypothesis: Vestibular schwannoma (VS) may be associated with endolymphatic hydrops (EH). EH may account for symptomatology in a subset of patients with VS.

Background: Presenting symptoms of VS and EH overlap, and MRI evaluation of the membranous labyrinth in some patients with VS demonstrates EH. The aim of the current study is to evaluate whether EH is present in temporal bones of patients with VS.

Methods: The NIDCD and House Temporal Bone Laboratory at UCLA Eccles database was queried for the diagnosis of "acoustic neuroma." Exclusion criteria included concomitant ear disease and surgery. Temporal bones were analyzed for EH of the basal, middle, and apical turns and vestibule. Premortem audiometric and clinical data were gathered.

Results: Of 43 human temporal bones with VS, 6 met inclusion criteria. All temporal bones demonstrated VS that was undisturbed by surgery. Three of six demonstrated EH of at least one cochlear turn as well as vestibular hydrops. Three patients had severe to profound hearing loss. One patient carried a diagnosis of Menière's disease.

Conclusions: EH is demonstrated in the setting of VS in human temporal bones. EH may be one mechanism of hearing loss and dizziness in patients with VS.

Professional Practice Gap And Educational Need: The underlying mechanisms of symptoms of VS may be multifactorial. The association of EH in some patients with VS would modify our clinical approach to management.

Learning Objective: To discover if EH may be associated with VS.

Desired Result: To broaden understanding of pathophysiologic mechanisms in patients with VS.

Level Of Evidence: Level IVIRB Approved: UCLA IRB No. 10-001449.