ENT - September 2020 - 530

530

Ear, Nose & Throat Journal 99(8)

Table 3. Audiologic Data and Plasma Prestin Levels in ISSHL Patients.
Treatment
Outcome
PTA Before
PTA After
Patient Number Treatment, dB Treatment, dB (Siegel Criteria)
1
2
3
4
5
6
7
8
9
10
11
12
13
14

77.5
77.5
83.75
80
63.75
66.25
97.5
116.25
87.5
36.25
42.5
68.75
105
80

21.25
50
51.25
35
28.75
72.5
88.75
117.5
60
20
41.25
50
83.75
27.5

Complete recovery
Slight improvement
Slight improvement
Partial recovery
Partial recovery
No recovery
No recovery
No recovery
Slight improvement
Complete recovery
No recovery
Slight improvement
Slight improvement
Partial recovery

Prestin Level
Sample Time
Prestin Level
Sample Time
After Onset, Before Treatment, After Onset, After Treatment,
pg/mL
Days
pg/mL
Days
5
3
7
5
6
3
4
2
5
4
4
4
6
5

347.70
2848.42
531.10
3831.05
9648.80
190.35
714.35
1471.85
426.35
1080.40
740.55
2408.35
295.25
2849.15

12
11
13
10
12
10
10
12
9
9
8
15
15
10

0.00
1862.55
6.65
7610.45
242.85
321.50
3108.00
2719.60
1289.25
1550.05
949.75
1769.60
400.10
1315.35

Abbreviations: ISSHL, idiopathic sudden sensorineural hearing loss; PTA, pure-tone average.

Results
Prestin was detected in the plasma samples of all patients.
Figure 1 shows the distribution of plasma prestin concentration
for the 2 groups. In control patients, prestin levels ranged from
85.4 to 1628.25 pg/mL, with an average of 840.24 + 496.22
(mean [SD]) pg/mL. Among patients with ISSHL, prestin levels
before treatment ranged from 295.25 to 9648.80 pg/mL, with an
average concentration of 1955.98 + 2501.48 (mean [SD]) pg/mL,
which is significantly higher than that of control patients
(Figure 2). Approximately half of patients with ISSHL had
levels above the average level of control patients.
Of the 14 patients with ISSHL, 10 patients were evaluated as
treatment responsive and 4 patients as treatment unresponsive
(Table 3). Correlation of initial plasma prestin level before
treatment with treatment outcome was calculated by Spearman
rank sum test. The result showed that plasma prestin levels
before treatment in patients with ISSHL did not correlate with
treatment outcomes according to the Siegel classification
(r ¼ À.327, P ¼ .254). Prestin levels after treatment ranged
from 0 to 7610.45 pg/mL, with an average concentration of
1653.26 + 1967.60 (mean [SD]) pg/mL. In the treatment
responsive group, the prestin levels of 6 patients decreased
after treatment compared to those of pretreatment, while the
prestin levels of all the 4 patients in treatment unresponsive
group increased in varying degrees.

Discussion
Lack of serum biomarkers has been an impediment to early
diagnosis and treatment of inner ear disorders. Recently, Parham et al demonstrated that otolin-1 may be able to act as a
serum biomarker for vestibular disease.6 Inspired by this finding, he suggested that prestin, the motor protein of cochlear
OHCs, may serve as a biomarker for OHC damage based on the

following reasons: First, prestin is exclusively expressed in the
lateral membrane of the OHCs. Second, after degeneration of
OHCs, prestin can be found in phagosomes in the supporting
cells which will end up in circulation. Third, prestin is 80 kDa
in size which is small enough to cross the blood-labyrinthine
barrier and enter circulation. Finally, because of extreme sensitivity of the ELISA, picogram quantities of prestin released
into circulation can be detected.2
Idiopathic sudden sensorineural hearing loss is a disease
with no known exact cause, generally defined as idiopathic and
thought to occur as a result of multifactorial causes. Although
the pathophysiology of ISSHL remains unknown, damage of
OHCs is thought to be one of the important events that lead to
ISSHL, especially in patients with high-frequency hearing
loss.7 The result of present study showed that prestin can be
detected and quantified using ELISA technique in plasma of
both patients with ISSHL and control patients without history
of hearing loss. Furthermore, the average concentration in
ISSHL is much higher than those of control patients. These
results can be explanatory. According to the theory of Parham,
serum prestin in control patients results in normal homeostatic
turnover in the membrane of healthy OHCs. Shortly after
OHCs damage, prestin concentration will rise and reach on a
peak on some day within 1 week.8 However, specificity is an
important criterion for an ideal biomarker. Although the average prestin concentration in the ISSHL group was higher than
that in the control group, the prestin concentrations in ISSHL
group significantly overlapped with those in normal control
group. Only half of the patients had higher concentration than
the average level of the control group. These results suggested
that OHCs damage happened only in part of patients with
ISSHL, and prestin may serve as a potential biomarker for
adjuvant diagnosis in these patients.
The result of Spearman rank sum test showed that there was
no correlation between the prestin values before treatment and

ENT - September 2020

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