An important element of research on ISSHL is to identify prognostic factors for this disease. Many studies have described predictive indicators to identify patients with a good prognosis needing no or minimal treatment. Some of these studies have concluded that the earlier the patient receives treatment, the better the outcome
The most widely accepted treatment options for ISSNHL are systemic steroid therapy and ITS injection. Nonetheless, it is important treatment be started immediately, because time is limited and treatment initiated after 30 days is unhelpful because damage at this time is permanent. Systemic steroids are the major agents used due to their potent anti-inflammatory effects
Based on this study, it was found that only 12 (30%) patients were improved while 28 (70%) patients did not improve. This low frequency of recovery could be explained by majority (65%) of patients came with late onset that exceeded 2 weeks. The majority of studies on adult ISSNHL patients have concluded presentation at > 10 days after hearing loss results in poor outcomes [8,9,10,11].
Another explanation for this point in the current is that severity of hearing loss ranged between severe to total hearing loss in majority of patients (23 patients; 57.5%). It is known that patients with a down-sloping hearing pattern or profound hearing loss showed a tendency toward poor hearing recovery .
In comparison between patients who achieved improved hearing loss and those did not achieve improvement, we found that both groups had insignificant difference as regards age and comorbidities but majority (58.3%) of improved patients was females while majority (75%) of not-improved group was males. Also, frequency of vertigo was significantly higher among patients without improvement (17 (60.7%) vs. 3 (25%); p = 0.03).
This was in line with Uhm et al. (2021) who found that both recovery and non-recovery groups had insignificant difference as regards age and comorbidities among studied patients. They also, reported that recovery rate was higher among females’ patients in comparison to males’ patients but with no significant effect in regression analysis (72.6% vs. 63.3%) .
Shimanuki et al. (2021) although they found that sex had no statistical effect on the recovery of ISSNHL but they noticed that patients who did not achieve improvement had significant higher mean age (62 vs 56 years; p < 0.001). Also, they agreed with our results and found higher frequency of vertigo among patients without improvement (33.6% vs. 11.9%; p < 0.001) .
In another study, baseline characteristics included age, sex, comorbidities, and frequency of vertigo had no significant differences between improved and not-improved patients . These differences in the reported studies as regards effect of patients’ characteristics’ on outcome of ISSNHL may be attributed to different sample size, selection criteria, and duration and type of therapy
We found that tinnitus was frequently found in all patients either recovery or non-recovery group. In some previous reports, tinnitus was found to be a positive prognostic factor and dizziness to be a negative prognostic factor of adult ISSNHL outcome. Ha et al. (2019) found that 33.3% of their patient cohort had accompanying dizziness and 78.6% had tinnitus. They found significant positive relation between tinnitus recovery but no relation between dizziness and recovery .
In the current study, regarding onset of symptoms, it was found that majority (58.3%) of improved patients had onset was less than 2 weeks while majority (75%) of not-improved group had onset more than 2 weeks with significant difference between both groups (p = 0.04). this was consistent with many previous studies that concluded treatment should be started immediately, because time is limited and treatment initiated after 30 days is unhelpful [12, 13, 15, 16].
Considering the treatment prognoses of 494 patients with ISSHL, Kang et al. (2017) identified age, histories of diabetes and dyslipidemia, co-presentation of dizziness, duration between symptom onset and treatment, initial PTA results, speech discrimination score, treatment methods, and duration between symptom onset and ITSI administration as prognostic factors .
In the current study, we found that improved patients had higher frequency of low LMR (41.7% vs. 10.7%; p = 0.03) in comparison to those failed to recover. There are several measures of inflammatory status have been proved to be significantly associated with ISSHL in clinical practice, including white blood cell count, interleukin 6 (IL-6), C-reactive protein, tumor necrosis factor-α, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) .
Recently, Gupta et al. (2021) showed no significant difference seen in the group with and without improvement concerning gender, duration, and other laboratory investigations and NLR and LMR ratio .
Ha et al. (2019) observed NLR and PLR values were significantly higher in the ISSNHL group than in normal controls. Also, we found that NLR and PLR values increased as the hearing recovery was poor in ISSNHL patients. But, in comparisons of each group of ISSNHL patients and control group, it was difficult to conclude that PLR value has any statistically significant meaning .
The main limitations of the current study included: (1) relatively small sample size, (2) short-term follow-up of those patients and (3) the study performed in only one center. We plan to increase the number of cases and examine the prognostic predictors according to the severity of hearing loss in future studies with multiple centers studies.
In conclusion, poor initial hearing level, presence of vertigo, and late onset of presentation were identified as poor predictors of hearing recovery after ISSHL. In patients with these pre-treatment factors, hearing recovery is unlikely and early additional treatment may be considered. Also, it is recommended to perform such studies with increase the number of cases and examine the prognostic predictors according to the severity of hearing loss in future studies with multiple centers studies.