Diagnostics and therapy of sudden hearing loss

Abstract

This article reviews recent aspects of diagnostics, differential diagnostics, and evidence in systemic and local therapy of idiopathic sudden sensorineural hearing loss (ISSHL). Since a number of disorders can be accompanied by sudden hearing loss, a meaningful and targeted diagnostic strategy is of utmost importance. An important differential diagnosis of sudden hearing loss are intralabyrinthine schwannomas (ILS). The incidence of ILS is probably significantly underestimated. This may be due to the lack of awareness or lack of explicit search for an intralabyrinthine tumor on MRI or an inappropriate MRI technique for the evaluation of sudden hearing loss ("head MRI" instead of "temporal bone MRI" with too high slice thicknesses). Therefore, the request to the radiologist should specifically include the question for (or exclusion of) an ILS. With special MRI techniques, it is possibly today to visualize an endolymphatic hydrops. The evidence in the therapy of ISSHL is - with respect to the quality and not quantity of studies - unsatisfying. The value of systemically (low dose) or intratympanically applied corticosteroids in the primary treatment of ISSHL is still unclear. In order to investigate the efficacy and safety of high dose corticosteroids as primary therapy for ISSHL, a national, multicenter, three-armed, randomized, triple-blind controlled clinical trial is currently performed in Germany (http://hodokort-studie.hno.org/). After insufficient recovery of the threshold with systemic therapy of ISSHL, intratympanic corticosteroid therapy appears to be associated with a significantly higher chance of an improved hearing threshold than no therapy or placebo. Both, hearing gain and final hearing threshold, however, appear to be independent from the onset of secondary therapy. Based on currently available data from clinical studies, no recommendation can be made with respect to the type of corticosteroid and specifics of the intratympanic application protocol.

Keywords: differential diagnosis; intralabyrinthine schwannoma; intratympanic; sudden hearing loss.

Table 1. HINTS for diagnosing stroke in acute vestibular syndrome (adapted from Kattah et al. [10)]

Table 2. Percentages of pathological MRI findings in patients with sudden hearing loss (selected articles)

Table 3. Differential diagnostics of sudden hearing loss (modified according to [2], [6], [7], [29], [40])

Table 4. Vestibular schwannoma in studies on MRI diagnostics in the context of sudden hearing loss

Figure 1. Acute sensory hearing loss after minor trauma in a patient with large vestibular aqueduct syndrome (LVAS; syn.: large endolymphatic duct syndrome or large endolymphatic duct and sac (LEDS); arrows); a: pure tone audiometry (red: right side; blue: left side); b: computed tomography (native, axial); Department of Radiology, University Medicine Halle, courtesy of Prof. S. Kösling.

Figure 2. Hydropic ear disease, right-sided: a: The patient suffered from “recurrent sudden hearing losses” in the lower frequency range on the right side, which recovered during systemic high-dose prednisolone therapy (“fluctuating hearing loss”). Considering the imaging (b), the disease is classified as “primary hydropic ear disease of cochlear type” and when vertigo appears as “primary hydropic ear disease of the cochlea-vestibular type” or Menière’s disease [46]. b: MRI reveals an enlarged endolymphatic space in the cochlea (small arrow) and in particular in the vestibulum (large arrow) of the right side, indicating a moderate endolymphatic hydrops (3D IR sequence, 6 hours after intravenous application of contrast medium); CM: contrast agent; w: weighted. (b Department of Radiology, University Medicine Halle, courtesy of Prof. Dr. S. Kösling).

Figure 3. Intralabyrinthine schwannomas (a intracochlear; b intravestibular) with symptoms of sudden hearing loss: a, a’: Because of the symptoms of sudden hearing loss with mild to moderate medio-cochlear hearing loss, a MRI (axial, T1-w, contrast agent) had been performed in 2005. It showed a very small contrast enhancing mass in the right cochlea (arrow). In the course of 10 years, the tumor showed a progressive growth until it filled the whole cochlea. It was removed via subtotal cochleoectomy with partial reconstruction of the cochlea and insertion of a CI electrode dummy. The functions of the semicircular canals were preserved [53]. b, b’: Intravestibular schwannoma in the vestibule (arrow, T2-w, axial) with Menière’s disease like complaints and mild acute hearing loss in the lower frequency range. After increasing vertigo, the tumor was resected via labyrinthectomy and in the same session hearing rehabilitation was performed with cochlear implantation. CM: contrast medium; w: weighted. (b’: Department of Radiology, University Medicine Halle, courtesy of Prof. Dr. S. Kösling).

Figure 4. Spontaneous labyrinthine bleeding in the left inner ear. Acute left-sided deafness and vertigo of a patient after therapy for Non-Hodgkin-lymphoma of the central nervous system (Ann Arbor stage IV) 3 years before and drug-induced coagulopathy (anticoagulation medication) due to port thrombosis. In the area of the cochlear as well as the vestibular part of the inner ear, MRI revealed punctually clear signal decreases (arrows) in the T2-weighted (a) and a minor signal increase (arrows) in the native T1-weighted images (b). w: weighted. Department of Radiology, University Medicine Halle, courtesy of Prof. S. Kösling.

Figure 5. Comparison of the results of (randomized and non-randomized) trials on intratympanic, combined, and systemic primary and secondary therapy based on data from Liebau et al. [107], [111]. Left: Primary therapy of sudden hearing loss. Right: Secondary therapy (“salvage”, “rescue” therapy) after failed systemic therapy.

Figure 6. The finally achieved absolute hearing threshold seems to be independent from the onset of secondary therapy. This means that after 4–6 weeks after sudden hearing loss, intratympanic secondary therapy seems to lead to similar results compared to earlier (2–4 weeks) start of therapy.

Figure 7. Staged approach to therapy of idiopathic sudden sensorinerual hearing loss (modified according to Plontke (2013) [7]). *as currently applied in the Department of Otorhinolaryngology, University Medicine Halle. RWM: round window membrane.

Figure 8. Obstruction of the round window niche with a “false” round window membrane (left). Endoscopic view (middle) and condition after removal of the false membrane (right). P: promontory; ISJ: incudo-stapedial joint.

Figure 9. Tertiary therapy of sudden hearing loss with tympanoscopy and application of triamcinolone 10 mg/ml on Curaspon^® into the oval (c, d) and round window niche (a, b).

Figure 10. Bioabsorbable drug carrier (OZURDEX^® arrow) in the round window niche for continuous release of dexamethasone [117]. Endoscopic view into the right middle ear. ISJ: incudo-stapedial joint.

Figure 11. HODOKORT study (http://hodokort-studie.hno.org/) [86]: The triple-blind, three-armed study with parallel group design encompasses two different high-dose corticosteroid therapies (intravenous prednisolone or oral dexamethasone application in an equivalent dosage) as well as a control group (middle line) receiving the internationally recommended lower-dose standard therapy. German Study Center for Otolaryngology, Head & Neck Surgery (DSZ-HNO) of the German Society of Otolaryngology, Head & Neck Surgery and the German Association of Otolaryngologists; Principle investigator (PI): Stefan K Plontke (Halle/Saale); Study Coordination: Coordination Center for Clinical Trials of Halle, University Medicine Halle, Martin Luther University Halle-Wittenberg; sponsored by the Research Funding Program on “Clinical Studies with high Relevance for Patient Care” in the context of health research program of the Federal Ministry for Research and Development (BMBF), Germany. The figure is taken from the study protocol©, courtesy of Martin Luther University Halle-Wittenberg.