Table 2.

Summary of historical analyses of hearing loss vs. imaging characteristics in patients with vestibular schwannoma.

Reference	Size Technique	N	Imaging Sequence	Impaction	Tumor Characteristics	Outcome
						Significant	Not significant
Berrettini et al. (30)	MLD	42	MRI+ T1	IAC extent	Sporadic, unilateral Evaluation at initial presentation	–	No significant difference of HL between different sized tumors. No significant correlation of tumor origin and subjective HL.
Nadol et al. (31)	MLD IAC extent	75	MRI+ T1	IAC extent	Sporadic, unilateral Preoperative evaluation	Significant correlation between MLD and low-frequency SNHL severity.	No significant correlations between MLD and SNHL severity in high/mid-frequencies or SDSs, and lateral extent of the tumor within the IAC and SDSs.
Lalwani et al. (32)	Tumor volume Linear dimensions	40	MRI	–	NF2 Evaluation at initial presentation	PTA significantly worse in the “larger tumor” groups. Worsening SRT with larger tumor size (TV dimension, volume).	PTAs for individual frequencies were not correlated with tumor size.
Tanaka et al. (33)	MLD	34	MRI	–	Sporadic, unilateral Diagnostic intervention	–	No significant correlation between the detective threshold of compound action potential or cochlear microphonics (ECochG) and tumor size.
Massick et al. (34)	MLD Tumor volume	21	MRI+ T1	–	Sporadic, unilateral NF2 Sequential follow-up	Increasing TV correlates with HL (increased PTA, decreased WRS). Decline of initial auditory function class corresponds with an even quicker rate of audiometric decline with tumor growth.	–
Tschudi et al. (35)	MLD	74	MRI	–	Sporadic, unilateral Evaluation at initial presentation Sequential follow-up	–	Higher-frequency thresholds were more impacted than lower frequencies, but no significant correlation between tumor size and initial HL. No significant correlation between tumor growth and HL.
Wang et al. (36)	MLD	7	MRI	–	NF2 Diagnostic intervention	–	No significant relationship between tumor size and hearing level.
Caye-Thomasen et al. (15)	Tumor volume Localization	156	MRI- T2	IAC extent	Sporadic, unilateral Intracanalicular Evaluation at initial presentation Sequential follow-up	Significant correlation between absolute volumetric tumor growth rate and PTA deterioration rate.	HL diagnosis at time of presentation is irrespective of patient demographics, tumor sublocalization, and tumor-induced expansion of the IAC.
Day et al. (37)	MLD	44	MRI T1 MRI T2 MRI Proton density	IAC extent	Sporadic, unilateral Diagnostic intervention	Significant trend of correlation with tumor size and HL.	–
Fisher et al. (38)	MLD	52	MRI+ T1 MRI T2	–	NF2 Sequential follow-up	–	No significant association between VS size hearing for either side. No significant relation between change in tumor size and hearing deterioration.
Gerganov et al. (39)	MLD Tumor volume	99	MRI- T1 MRI- T2 MRI+ T1 MRI+ T2	IAC extent Tumor-fundus distance	Sporadic, unilateral Preoperative evaluation	Hearing ability correlated significantly with the tumor size, volume and coronal diameter, the degree of intrameatal tumor growth, and the distance between tumor end and fundus.	–
Sughrue et al. (40)	Localization	59	MRI	–	Sporadic, unilateral NF2, unilateral Evaluation at initial presentation Sequential follow-up	Hearing is lost at a quicker rate in faster-growing tumors than slow-growing tumors.	Initial tumor size at diagnosis did not significantly affect the time to serviceable HL.
Van de Langenberg et al. (12)	Tumor volume	63	MRI+ T1 MRI- T2	–	Sporadic Evaluation at initial presentation Sequential follow-up	Labyrinthine hypo-intensity (T2) and HL complaints at presentation predictive of faster hearing decline.	TV and change in TV does not correlate significantly with HL.
Asthagiri et al. (41)	Tumor volume	56	MRI- T1 MRI- FLAIR MRI+ T1 Co-registered T2-VISTA MRI+ delayed FLAIR	Cochlear aperture obstruction	NF2 Diagnostic intervention	–	Association between HL and tumor size (TV) is not strong enough. HL appears to possibly develop from cochlear aperture obstruction and intralabyrinthine protein accumulation.
Tutar et al. (42)	MLD (extrameatal)	76	MRI	–	Sporadic, unilateral Preoperative evaluation	–	No correlation found between tumor size and hearing levels at each frequency.
Holliday et al. (9)	Tumor volume	32	MRI+ T1 MRI- T2 TSE VISTA MRI- FLAIR	Cochlear aperture obstruction	NF2 Diagnostic intervention	Elevated intralabyrinthine protein correlated with larger tumors. Significant association between aperture obstruction and 4-tone PTA and ABR changes.	Tumor volume was not significantly correlated with 4-tone PTA.
Plotkin et al. (43)	Tumor volume	120	MRI+ T1	–	NF2 Sequential follow-up	Significant difference in time to hearing decline with medium/large tumors having a shorter median time to hearing decline compared with small tumors.	–
Van Linge et al. (44)	Tokyo consensus Localization	155	MRI+ T1 MRI- T2 FIESTA MRI- T2 CISS	–	Sporadic, unilateral Sequential follow-up	Tumor growth associated with faster AHDR for intracanalicular tumors.	PTA or SDS in the ipsilateral ear did not differ between classes of intensity of the cochlear fluid signal.
Kirchmann et al. (13)	MLD Localization	156	MRI	–	Sporadic, unilateral Sequential follow-up	Hearing is lost at a significantly faster rate in growing tumors.	Rate of SDS decrease is not significantly associated with tumor growth. No significant difference between HL progression in patients with intrameatal versus extrameatal tumors.
West et al. (45)	MLD (extrameatal)	124	MRI	–	Sporadic, unilateral Extrameatal Preoperative evaluation	–	Caloric tests and VEMPs are potential clinical factors for measuring tumor size, sensitive but remain unspecific. No correlation between increasing tumor size and HL and peripheral vestibular function.
Byun et al. (14)	MLD Localization	23	MRI+ T1 MRI- T2	–	Sporadic, unilateral Evaluation at initial presentation	Intracanalicular tumors associated with increased DRs than extracanalicular tumors.	No strong correlation between tumor size and WRS/PTA. No significant correlation with PTA and T2-weighted signal intensity.
Early et al. (16)	MLD	534	MRI	–	Sporadic, unilateral NF2 Evaluation at initial presentation Sequential follow-up	Patients with abnormal baseline hearing of the ipsilateral ear, demonstrated significantly higher likelihood of reaching moderate SNHL in the contralateral ear.	Patients with normal baseline hearing bilaterally demonstrated no significant difference in HL progression in VS-contralateral vs. control ears. Subgroup analysis by baseline tumor size did not show any specific trends for HL progression.
Selleck et al. (11)	MLD Cochlear FLAIR ratio	393	MRI- T2 FLAIR MRI- T2 CISS	Fundal cap size	Sporadic, unilateral Evaluation at initial presentation	An indirect, significant relationship exists between initial WRS and cochlear FLAIR ratio. Significant correlation was seen between decreasing WRSs and increasing fundal cap size.	No statistically significant correlation between initial PTA and cochlear FLAIR ratio. No statistically significant correlation between initial WRS and PTA, and fundal cap.