Unusual Bilateral Lesions of the Internal Auditory Canals

Abstract

A 61-year-old man had sudden deafness of the right ear that was treated with steroids without any improvement. The patient was referred 2 months later to our department because of left progressive sensorineural hearing loss (SNHL), tinnitus, and vertigo. His medical history included heavy smoking and popliteal vein thrombosis. On admission, the physical and neurologic findings were normal. Pure tone audiometry revealed profound SNHL on the right side with a speech reception threshold of 100 dB and no speech discrimination. On the left side, pure tone audiometry showed moderate SNHL with a speech reception threshold of 45 dB and speech discrimination of 96%. Recording of auditory brain stem evoked responses revealed normal responses on the left side and an absence of all of the waves on the right side. Electronystagmographic examination revealed directional-changing positional nystagmus without significant spontaneous nystagmus. The results of oculometric tests were normal. A bithermal caloric test showed right canal paresis.A magnetic resonance imaging (MRI) scan performed with the 3-dimensional fast spin-echo technique showed a bright cerebrospinal fluid signal with filling defects in both internal auditory canals (lACs; Fig I).Blood tests for electrolytes, ammonium, liver and kidney functions, antinuclear antibody and complement, the Venereal Disease Research Laboratory test, serology for Epstein-Barr virus and cytomegalovirus, levels of vitamin B12 and folic acid, and a complete blood count were all normal. However, the level of anticardiolipin IgM antibodies was high. A lumbar puncture revealed a normal cell count without pathological cells; the glucose, protein, and lactate contents were normal, and no oligoclonal bands were found. A radiograph of the chest appeared normal. A full ophthalmologic examination yielded normal results.Although the patient was treated with steroids, carbon dioxide inhalation, and subcutaneous injections of enoxaparin, a progressive deterioration in his hearing level became evident. Repeated MRI with gadolinium showed enhancement of the lAC and of the inner ear structures bilaterally (Fig 2).At this point the possibility of autoimmune disease was raised, and the steroid treatment was changed to azathioprine; the patient was later treated with plasmapheresis without improvement. Further evaluations, including a total-body positron emission tomographic scan and bone marrow biopsy, yielded normal findings.One month later, because of persistent severe left tinnitus that did not respond to medication and profound bilateral SNHL, and after a promontory test was performed on the left ear with a positive result, the patient underwent left cochlear implantation without any response. Two weeks later, the patient developed right complete peripheral facial nerve paralysis, an ataxic gait, and a tendency to fall to the left side. The patient was admitted to the neurologic department for evaluation.The differential diagnosis at this point, in which the patient presented with multiple cranial ner...