Treatment algorithm for idiopathic sudden sensorineural hearing loss based on epidemiologic surveys of a large Japanese cohort

Figures & data

Table 1. Summary of the nationwide epidemiological surveys on SSNHL in Japan before 2014.

	Investigation period	Subjects	Number of hospitals which responded	Reported number of patients	Average age of patients	Estimated annual number of patients per 100,000
First survey	From July 1, 1971 to June 30, 1973	University hospitals, other hospitals	228	2723	39.1	3.9
Scond survey	From January 1, to December 31, 1987	University hospitals, hospitals with 200 beds or more	417	7775	45.4	14.2
Third survey	From January 1, to December 31, 1993	University hospitals, other hospitals	388	8149	49.3	19.4
Fourth survey	From January 1, to December 31, 2001	University hospitals, other hospitals	419	12,468	51.3	27.5
Fifth survey	From April 1, 2012 to March 31, 2013	University hospitals, other hospitals, and private clinics in only three prefectures in Japan	381	4753	54.2	60.9

Table 2. Summary of the epidemiological survey in 2017.

Subjects
Number of patients	3419
Sex
Male	51.8% (1771)
Female	48.2% (1614)
Affected ear
Right	46% (1549)
Light	53% (1761)
Bilateral	1% (31)
Age (average: 54.2 years)
≦15	2.6%
16–64	66%
≧65	31.4%
Time from the onset to the start of treatment (average 6.0 days)
≦ 7 days	81.7%
8–14 days	12.3%
≧ 15 days	6.0%
Treatment
Systemic corticosteroid without IT	69%
Systemic corticosteroid with IT (initial)	1%
Systemic corticosteroid with IT (salvage)	13%
IT corticosteroid without systemic	9%
No corticosteroids	8%
Concomitant drugs
Corticosteroid with PGs	29.9%

Table 3. Criteria for the diagnosis of idiopathic SSHNL.

Main symptoms

Suddden onset

Sensorineural hearing loss, usually severe

Unknown etiology

For reference

Hearing loss (i.e. hearing loss of 30dB or more over three consecutive  frequencies)

Sudden onset of hearing loss, but may progressively deteriorate   over 72 h

No history of recurrent episodes

Unilateral hearing loss, but may be bilateral at the onset

May be accompanied by tinnitus

May be accompanied by vertigo, nausea, and/or vomiting, without recurrent episodes

No cranial nerve symptoms other than from cranial nerve VIII

Definite diagnosis; all of the above main symptoms are present

Table 4. Criteria for grading hearing loss in SSNHL.

Grade	Criteria
1	PTA <40 dB
2	40 dB ≦PTA <60 dB
3	60 dB ≦PTA <90 dB
4	90dB ≦ PTA

This grading system was established by the Research Committee of the Ministry of Health and Welfare in Japan in 1988. PTA, arithmetic mean of the five frequencies; 250, 500, 1000, 2000, and 4000 Hz.

Table 5. Hearing improvement criteria for SSHNL as defined by the Ministry of Health and Welfare in Japan.

Hearing improvement status	Criteria
Complete recovery	All five frequencies of final audiograms are 20 dB or less, or improvement to the same degree of hearing in the unaffected side
Marked improvement	PTA improvement ≧ 30 dB
Slight improvement	10dB ≦ PTA improvement <30 dB
No change	PTA improvement <10 dB

PTA, arithmetic mean of the five frequencies; 250, 500, 1000, 2000, and 4000 Hz.

Figure 1. Treatment algorithm for idiopathic sudden sensorineural hearing loss based on an epidemiologic survey of a large Japanese cohort.

Figure 2. Relationship between the duration from onset of idiopathic SSNHL and hearing recovery (criteria shown in Table 3). The rate of a good improvement (complete recovery or marked improvement) gradually decreased with the increase in the duration from onset. In the 29 days or more group, the criteria of “no change” reached over 75%.

Figure 3. Result of IT steroid therapy as salvage therapy for each grade of hearing loss. The average percent hearing improvement was calculated using following equation: percent hearing improvement = (HLpre-salvage – HLfinal)/(HLpre-treatment – HLcontra). The IT steroid injection was more effective in patients with severe hearing loss (Grade3/4).

Figure 4. Relationship between the duration from onset of idiopathic SSNHL and IT steroid therapy as salvage therapy. Recovery means a PTA improvement of 10 dB or more from the start of salvage therapy, and no recovery means a PTA improvement of under 10 dB. The treatment effect of IT corticosteroids as a salvage therapy was limited in the patients treated over 21 days from the onset of SSNHL.

Figure 5. Comparison between outpatient care and hospitalization for SSNHL patients. (A) The difference in the selection of outpatient care or hospitalization between grade1/2 and grade3/4 patients with SSNHL. (B) Results of treatment in patients with SSNHL. The upper row of the graph shows the results for patients treated by outpatient care, and the lower row shows the results for patients treated in hospital.