Prevalence of Internal Auditory Canal Diverticulum and Its Association with Hearing Loss and Otosclerosis

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Fig 1.
IAC diverticula on temporal bone CT. A, CT of the right temporal bone in a 41-year-old woman with vertigo. A CSF-density saccular outpouching of the anterior IAC medial to the cochlea is compatible with an IAC diverticulum (black arrow). B, CT of the left temporal bone in a 67-year-old woman undergoing evaluation of SNHL. A smaller diverticulum or notch is present along the anterior IAC in a location similar to that of the larger diverticula in A (black arrow).
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Fig 2.
IAC diverticulum with classic imaging findings of otosclerosis on temporal bone CT in a 34-year-old woman evaluated for mixed hearing loss. There is a small IAC diverticulum along the anterior IAC (black arrow) with focal lucency of the otic capsule adjacent to the anterior oval window near the fissula ante fenestram (white arrow).

Table 1:

Demographic characteristics for total study population

Characteristic	Total Population (n = 807)	IAC Diverticulum			Otosclerosis
Characteristic	Total Population (n = 807)	Present (n = 43)	Not Present (n = 764)	P Value	Present (n = 39)	Not Present (n = 768)	P Value
Median age (range) (yr)	52 (18–96)	61 (18–91)	52 (18–96)	<.01^{^a}	52 (22–85)	52 (18–96)	.69^{^a}
Sex (No.) (%)				.93^{^b}			.13^{^b}
Male	343 (42.5)	18 (41.9)	325 (42.5)		12 (30.8)	331 (43.1)
Female	464 (57.5)	25 (58.1)	439 (57.5)		27 (69.2)	437 (56.9)

Table 2:

Demographic characteristics by the presence of IAC or otosclerosis

Characteristic	IAC Diverticulum Only (n = 36)	Otosclerosis Only (n = 32)	IAC Diverticulum + Otosclerosis (n = 7)	None (n = 732)	P Value
Median age (range) (yr)	62 (18–91)	52 (18–91)	61 (30–70)	52 (18–96)	<.01^{^a}
Sex (No.) (%)					.47^{^b}
Male	15 (41.7)	9 (28.1)	3 (42.9)	316 (43.2)
Female	21 (58.3)	23 (71.9)	4 (57.1)	416 (56.8)
Temporal bone involvement (No.) (%)					.02^{^b}
Unilateral	9 (20.9)	15 (38.5)	5 (71.4)
Bilateral	34 (79.1)	24 (61.5)	2 (28.6)

Table 3:

Associations between IAC diverticulum or otosclerosis and hearing loss

Characteristic	IAC Diverticulum Only (n = 43)	Otosclerosis Only (n = 39)	IAC Diverticulum + Otosclerosis (n = 7)	P Value
Hearing loss (No.) (%)				<.01^{^a}
None	4 (9%)	7 (18%)	1 (14%)
SNHL	27 (63%)	10 (26%)	2 (29%)
PTA (average) (range) (dB)	53.5 (10.6–120)	55.3 (16.9–115)	97.5 (94.4–100.6)
CHL (No.) (%)	None	13 (33%)	1 (14%)
Mixed (No.) (%)	12 (28%)	9 (23%)	3 (43%)