Abstract
Objectives: The aim of this study was to delineate the clinical and laboratory features suggestive of intralabyrinthine schwannoma (ILS).Methods: We compared the clinical features of 16 patients with ILS, who had been diagnosed at the Seoul National University Bundang Hospital from 2003 to 2018, with those of 18 patients with symptomatic unilateral intracanalicular schwannoma and randomly selected 20 patients with definite or probable unilateral Meniere's disease (MD).Results: Patients with ILS presented with either recurrent spontaneous dizziness/vertigo combined with auditory symptoms (n = 8), isolated auditory symptoms without dizziness/vertigo (n = 7), or recurrent spontaneous dizziness/vertigo without auditory symptoms (n = 1). Most patients reported no improvement (n = 11) or worsening (n = 1) of the symptoms despite medical treatments including intratympanic (n = 5) or intravenous steroids (n = 2). Conventional brain MRIs failed to detect ILS in about a half of the patients (7/16, 44%). However, ILS showed a filling defect on 3-dimensional (3D) heavily T2-weighted MRIs (n = 12), and nodular enhancement on 3D contrast-enhanced T1 (n = 15) or FLAIR MRIs (n = 13) targeted for the inner ear. Compared to MD or intracanalicular schwannoma, ILS showed mostly abnormal head-impulse tests (HITs, p = 0.001). In contrast, the incidence of canal paresis did not differ among the groups (p = 0.513).Conclusion: ILS may mimic MD by presenting recurrent dizziness/vertigo and auditory symptoms. ILS should be suspected in patients with recurrent audiovestibulopathy especially when (1) the duration of the dizziness is not typical for MD, (2) the patients do not respond to medical treatments, or (3) HITs are abnormal.
Highlights
Vestibular schwannoma is one of the common benign tumors that arise from the vestibulocochlear nerve
We retrospectively reviewed the medical records of 678 patients who had the diagnosis of vestibular schwannoma at Seoul National University Bundang Hospital from July 2003 to July 2018
We analyzed the findings of 18 patients with symptomatic unilateral intracanalicular schwannoma of which the length and diameter were
Summary
Vestibular schwannoma is one of the common benign tumors that arise from the vestibulocochlear nerve. It is termed intralabyrinthine schwannoma (ILS) when the tumor is originated from the Schwann cells surrounding the terminal branch of the vestibulocochlear nerve inside the membranous labyrinth [1, 2]. ILS was once found during labyrinthectomy in a patient with a preoperative diagnosis of intractable MD [5]. ILS may be an incidental finding at autopsy [5, 6]. Slow growth of ILS contributes to delayed diagnosis of the tumor [7]. Antemortem diagnosis of ILS remains challenging unless sought with a strong suspicion [4]
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