Preserved Cochlear CISS Signal is a Predictor for Hearing Preservation in Patients Treated for Vestibular Schwannoma With Stereotactic Radiosurgery

Abstract

Decreased cochlear CISS signal may indicate a tumor's association with the cochlear neurovascular bundle, influencing endolymph protein concentration and creating an inability to preserve hearing. This important MRI characteristic can influence planning, counseling, and patient selection for vestibular schwannoma treatment.

Radiosurgery of vestibular schwannoma: prognostic factors for hearing outcome using 3D-constructive interference in steady state (3D-CISS)

“…They concluded that hearing loss in patients with reduced hearing preoperatively must be multifactorial and affected by other factors independent of 3D-CISS signal or labyrinthine protein concentration, such as neuronal or vascular compression or age-related hearing deterioration. In line with the results of Prabhu et al [15] we did not find any influence of the SRS on the signal intensities of the cochlea or utriculus/sacculus when we compared the intensities before and after therapy as well as the subjective and objective hearing K As explained in previous studies, the changes in the signal intensity in 3D-CISS can be considered a marker for changes of the inner ear protein content, which in turn represent a pathological alteration in patients with VS [11,28]. The absence of significant effects of the SRS on the signal intensities of cochlea and utriculus/sacculus in 3D-CISS support the low side-effect profile of SRS for the treatment of VS, independent of the cochlear dose when a prescribed dose of 12 Gy is administered.…”

“…Somers et al demonstrated a significant association between 3D-CISS in preoperative settings and hearing preservation after surgery [14]. This result was confirmed by Prabhu et al in their study on a larger patient cohort after radiosurgical treatment [15]. Additionally, Somers et al found a significant relationship between signal intensity in 3D-CISS and tumour involvement of the fundus of the internal auditory canal (IAC).…”

“…The 3D-FLAIR and 3D-CISS MRI sequences provide a visual representation of the inner ear in which the signal intensity is supposed to be an indicator of the endolymph's protein content [12,15]. It is suggested that protein interactions may have an impact on the preservation of posttreatment hearing outcome in VS patients treated with SRS.…”

“…Additional support for the labyrinthine protein disturbance theory comes from MRI signal abnormality. Protein sensitivity has recently been tested in 3D-CISS by Prabhu et al [15]; who demonstrated that cochlear signal before treatment was not associated with pretreatment hearing level. They concluded that hearing loss in patients with reduced hearing preoperatively must be multifactorial and affected by other factors independent of 3D-CISS signal or labyrinthine protein concentration, such as neuronal or vascular compression or age-related hearing deterioration.…”

“…According to Silverstein et al [11], the formation of these precipitates seems to be related to the increased protein content on the affected side. Based on the hypothesis of Bhadelia et al [12] and the results of further studies [13][14][15], evaluation of increased inner ear protein content in patients with VS can be carried out in vivo and noninvasively by means of dedicated magnetic resonance imaging (MRI) sequences-especially 3D fluid-attenuated inversion recov-ery (3D-FLAIR) and 3D-constructive interference in steady state (3D-CISS). Although both inner ear signal intensity (in 3D-FLAIR and 3D-CISS) and acidophilic-staining precipitates in histopathological studies are altered on the side affected by VS, the correlation between these findings and cochlear or vestibular symptoms is still weak.…”