1

Introduction

Systemic malignant non-Hodgkin’s lymphoma (NHL) involves the nervous system rather uncommonly (5–10%) and usually tends to take the form of central nervous system (CNS) involvement with diffuse leptomeningeal or epidural infiltration . Additionally, internal auditory canal (IAC) is mainly invaded by vestibular schwannomas; neoplasms with different histology are rarely encountered . We report an extremely rare case of a lymphomatous infiltration (neurolymphomatosis) of IAC nerves bilaterally, in the setting of systemic NHL.

2

Case report

A 47-year-old male was referred to our department complaining of bilateral hearing loss associated with tinnitus, bilateral facial nerve palsy and disequilibrium.

Patient’s medical history revealed a Grade I, follicular center cell B-cell NHL diagnosed 7 years earlier, through a neck lymph node biopsy. History of psychosis, under treatment for the last 15 years, was also noted. Six months earlier, computed tomography scan (CT) performed, revealed multiple enlarged chest, abdominal and inguinal lymph nodes. On these grounds, the patient was scheduled for a 6-cycles chemotherapy course with R-COP (Rituximab, Cyclophosphamide, Vincristine, Prednisone). Nevertheless, due to a severe allergic reaction monoclonal antibody was discontinued after the first cycle. One day after completion of the sixth cycle, the patient experienced bilateral hearing loss and facial nerve palsy and was referred to our department.

On examination the patient was apyrexial and otoscopy was normal. Impedance audiometry was normal bilaterally (type-A tympanogram), while pure-tone audiometry confirmed severe bilateral sensorineural hearing loss. Otoacoustic emissions (OAEs) conducted via a standard ILO-292 system were bilaterally absent. Although, the patient did not self-report any typical symptoms of vertigo, he was reluctant to walk without help, complaining for disequilibrium and a vague sense of unsteadiness and oscillopsia. No spontaneous nystagmus was noted; Romberg, Unterberger and Weil-Babinski tests were inconclusive, whereas Dix-Hallpike test was negative and head impulse test was positive. Ultimately, caloric tests verified bilateral loss of vestibular function. Bilateral peripheral facial nerve palsy (House – Brackmann Grade III) was also revealed. The rest of the cranial nerves were clinically tested as grossly normal. Haematological findings showed only anaemia and high erythrocyte sedimentation rate (ESR = 37 mm). A tapering corticosteroids therapy was administered (8 mg iv dexamethazone, three times per day) and a CT and magnetic resonance imaging (MRI) scan were scheduled.

CT scan did not demonstrate any significant findings, whereas MRI modality although did not reveal any extra-axial lesions or masses, yet it identified increased signal intensity and thickening of IAC nerves bilaterally, particularly significant on the left side, consistent with malignant lymphomatous infiltration. Intravenous gadolinium produced enhancement along the nerves bilaterally ( Fig. 1 A ).

Axial MRI scans. T1-weighted images after intravenous gadolinium administration reveals enlargement and thickening of IAC nerves and enhancement along the nerves bilaterally (arrows), particularly on the left side (A). After treatment MRI scans reveal significant improvement of nerve infiltration (arrows) especially on the right side (B).

A lumbar puncture was preformed and cerebrospinal fluid (CSF) cytology revealed abundant large malignant cells with basophilic cytoplasm, oval nucleus and sole or multiple conspicuous nucleoli, typical of B cell NHL.

Treatment protocol applied, included eight cycles of intrathecal chemotherapy (Aracytin 25 mg, Methotrexate 15 mg, Solumedrol 40 mg) combined with whole brain irradiation (total dosage of 3600 cGy). No significant side effects were noted during treatment.

During treatment, patient’s hearing was closely monitored by pure-tone audiometry, while facial nerve palsy was regularly clinically examined; both displayed a gradually significant improvement. At the end of the treatment protocol, caloric testing verified that vestibular function was within normal. Multiple lumbar punctures were performed and no malignant cells were identified, already upon completion of the third chemotherapy cycle. Finally, a new MRI scan revealed significant bilateral improvement concerning IAC nerve infiltration ( Fig. 1 B).

The patient was referred to a specialized center, to be evaluated for a possible bone marrow transplant.