Case report

A 63-year-old woman with a 10-year history of Sweet's disease, associated with myelodysplasia, visual disturbance, mild parkinsonian symptoms and skin ulcerations, was referred for investigation of sudden, rapid, bilateral hearing loss. The patient's diagnosis of Sweet's disease had initially been confirmed by a skin biopsy; prednisone (10 mg daily) had been commenced and continued long term for disease control. Bilateral SNHL had first been noted seven years prior, during a particularly severe exacerbation of Sweet's disease. Over the subsequent three years, serial pure tone audiograms indicated progressive, symmetrical, bilateral SNHL affecting the higher frequencies. A hearing aid had been fitted for the right ear, followed by the left, but their effectiveness had declined over time.

Over the few months prior to the current presentation, the patient reported the rapid onset of sudden, profound hearing loss, with no accompanying tinnitus or vertigo.

The patient appeared cushingoid and profoundly deafened, but clinical examination was otherwise unremarkable.

Pure tone audiography demonstrated near-symmetrical, severe to profound SNHL bilaterally, with no recordable speech perception (Figure 1). Lip-reading was compromised by poor vision. Anti-nuclear antibody testing was positive, with a homogeneous, speckled pattern and a titre of 160; however, the rest of the autoimmune screen was unremarkable, as was blood biochemistry and inflammatory marker analysis. Assay for heat shock protein 70 was negative. A magnetic resonance imaging scan of the brain, performed two years previously, was within normal limits.

Fig. 1 Pure tone audiogram recorded prior to cochlear implantation, showing severe to profound, sensorineural hearing loss (SNHL) for the left ear, and for the right ear a profound SNHL in the low frequencies, sloping up to a severe SNHL in the high frequencies.

The patient's hearing loss was suspected to be due to an autoimmune aetiology in the context of Sweet's disease. Three doses of 500 mg pulsed intravenous methylprednisolone were administered, and the patient's subjective hearing improved remarkably; she was able to use the telephone within 24 hours. Unfortunately, her hearing loss again deteriorated to profound levels over the next two to three weeks, despite ongoing immunosuppression with oral prednisone (50 mg daily), mycophenolate (250 mg twice daily) and a course of intratympanic dexamethasone injections to the right ear. Cyclosporin was trialled but was ceased due to side effects. The dose of mycophenolate was increased to 500 mg twice daily, but this was ceased after three months when the patient's hearing did not improve. Low dose prednisone (8 mg daily) was continued for control of Sweet's disease. A repeated analysis of inflammatory markers was within normal limits.

As she had no residual hearing despite hearing amplification, the patient was thoroughly assessed for cochlear implant candidacy. No measurable response was obtained in either ear on electrocochleography. Tympanometry was normal, and stapedial reflexes were absent bilaterally. No consistent responses were obtained upon promontory stimulation. Brainstem evoked response audiometry demonstrated normal auditory nerve and brainstem conduction. Pre-operative computed tomography imaging of the petrous temporal bones was unremarkable.

The patient underwent cochlear implantation of the right ear, using a Nucleus CI-24RE(ST) implant (Cochlear Ltd, Lane Cove, NSW, Australia), 12 months after initial presentation. Post-operative recovery was uncomplicated.

When the patient's device was switched on, three weeks post-operatively, her speech discrimination scores were greatly increased. At three months post-operatively, her speech perception with the cochlear implant (auditory mode only), as assessed by the City University of New York sentence test (an open-set speech perception test, delivered via pre-recorded compact disc in quiet (65 dB SPL) and in noise (+10 signal to noise ratio)), was 99 per cent correct in quiet conditions and 41 per cent correct in noisy conditions. The aided average for the right ear across four frequencies (0.5, 1, 2 and 4 kHz) was 23.75 dB. The patient conversed well with others and could use the telephone via her cochlear implant. She reported considerable improvements to her overall quality of life.

At the time of writing, the patient was awaiting cochlear implantation of her left ear.

The precise association between Sweet's disease and progressive, bilateral SNHL has not been clearly elucidated, due to the rare occurrence of such cases. An immune process targeting the inner ear has been suspected, given the immunological aetiology of Sweet's disease. The rapid, fluctuating and relentless nature of the SNHL observed in our patient mirrored the clinical picture of other reported immune-mediated inner ear diseases. In such cases, thorough investigation and timely initiation of first-line corticosteroid therapy is warranted, given the potential to preserve residual inner ear function and reverse hearing loss. In cases unresponsive to immunotherapy, auditory rehabilitation with hearing aids and cochlear implants should be considered. Highly successful outcomes of cochlear implantation have been demonstrated in adults post-lingually deafened by immune-mediated SNHL. Such success may be due to: the relatively short duration of profound deafness; the pathological site of deafness being limited to the organ of Corti; preservation of the spiral ganglion cell population, auditory nerves and higher pathways; and retained memories of sounds.Reference Summerfield and Marshall⁸ A theoretical risk of post-operative infection and wound dehiscence associated with a considerable history of immune-suppression has been reported; however, such complications were not evident in our patient.