ABSTRACT
<p><b>BACKGROUND</b>Bilateral sudden sensorineural hearing loss (BSSHL) is rare and assumed to be a different clinical entity compared to unilateral SSHL (USSHL). This study examined the differences between the idiopathic BSSHL and USSHL.</p><p><b>METHODS</b>Forty-six sequential BSSHL patients (Se-BSSHL) and 68 simultaneous BSSHL (Si-BSSHL) were consecutively admitted between June 2008 and December 2015. Two sets of patients served as control groups: (1) USSHL patients with healthy contralateral ear and (2) USSHL patients with contralateral preexisting hearing loss (USSHLwCHL). We retrospectively analyzed differences among four cohorts using analysis of variance, Kruskal-Wallis test, Welch's t-test, and Chi-square test as appropriate before and after propensity score matching (PSM) based on age, gender, and body mass index (BMI).</p><p><b>RESULTS</b>The prevalence of idiopathic BSSHL was 8.6% (114/1329) among the total SSHL patients. In the total cohort, USSHL patients tended to be younger, female, and tended to have lower BMI, renal parameters, and total cholesterol in addition to higher high-density lipoprotein compared to the other three groups. Most routine blood indicators, some coagulation markers, and immunoglobulin M (H = 13.4, P = 0.004) were significantly different among the study groups. After PSM, the major significant differences were found in audiometric characteristics. Si-BSSHL and Se-BSSHL patients demonstrated similar hearing thresholds as USSHL but were significantly better than the USSHLwCHL patients across most frequencies before and after treatment (H = 30.0, P < 0.001 for initial hearing and H = 12.0, P = 0.007 for final hearing). Moreover, the BSSHL patients showed different hearing loss distribution patterns (more descending type, χ2 = 33.8, P = 0.001) with less hearing gain (H = 17.5, P < 0.001) compared to the USSHL patients.</p><p><b>CONCLUSIONS</b>Idiopathic BSSHL is a relatively rare subtype of SSHL with a higher rate of descending audiogram type and inferior hearing outcome rather than being classified as a completely different disease entity compared to USSHL.</p>
ABSTRACT
<p><b>BACKGROUND</b>The prevalence of sudden sensorineural hearing loss in children (CSSNHL) is consistently increasing. However, the pathology and prognosis of CSSNHL are still poorly understood. This retrospective study evaluated clinical characteristics and possible associated factors of CSSNHL.</p><p><b>METHODS</b>One hundred and thirty-six CSSNHL patients treated in Department of Otolaryngology-Head and Neck Surgery and Institute of Otolaryngology at Chinese PLA General Hospital between July 2008 and August 2015 were included in this study. These patients were analyzed for clinical characteristics, audiological characteristics, laboratory examinations, and prognostic factors.</p><p><b>RESULTS</b>Among the 136 patients (151 ears), 121 patients (121 ears, 80.1%) were diagnosed with unilaterally CSSNHL, and 15 patients (30 ears, 19.9%) with bilateral CSSNHL. The complete recovery rate of CSSNHL was 9.3%, and the overall recovery rate was 37.7%. We found that initial degree of hearing loss, onset of treatment, tinnitus, the ascending type audiogram, gender, side of hearing loss, the recorded auditory brainstem response (ABR), and distortion product otoacoustic emissions (DPOAEs) had prognostic significance. Age, ear fullness, and vertigo had no significant correlation with recovery. Furthermore, the relevant blood tests showed 30.8% of the children had abnormal white blood cell (WBC) counts, 22.1% had elevated homocysteine levels, 65.8% had high alkaline phosphatase (ALP), 33.8% had high IgE antibody levels, and 86.1% had positive cytomegalovirus (CMV) IgG antibodies.</p><p><b>CONCLUSIONS</b>CSSNHL commonly occurs unilaterally and results in severe hearing loss. Initial severe hearing loss and bilateral hearing loss are negative prognostic factors for hearing recovery, while positive prognostic factors include tinnitus, gender, the ascending type audiogram, early treatment, identifiable ABR waves, and DPOAEs. Age, vertigo, and ear fullness are not correlated with the recovery. Some serologic indicators, including the level of WBC, platelet, homocysteine, ALP, positive CMV IgG antibody, fibrinogen, and some immunologic indicators, are closely related to CSSNHL.</p>