Introduction: Radiation injury resulting in sudden, late onset sensorineural hearing loss is a recognised complication in patients who have received head and neck irradiation. We describe the magnetic resonance imaging (MRI) of the internal acoustic canal (IAC) of 3 such patients and postulate a cause for these findings. Clinical Picture: A total of 63 patients were referred for MRI IAC for sudden-onset sensorineural hearing loss. Of these patients, only 5 patients had abnormal MRI finding in the affected ear and the remaining patients had normal studies. Two patients had acoustic neuromas. Three patients demonstrated high T1-weighted signal in the labyrinths of the affected ears and had past histories of head and neck irradiation. The MRI findings and medical records of these 3 patients were reviewed and described in this case series. Outcome: High labyrinthine signal on unenhanced T1-weighted images in the symptomatic ear of these patients was observed, suggesting the possibility of haemorrhage. In the patient who had a history of brain tumour, susceptibility artifacts were also seen in the right hemipons on the gradient-echo images, indicating the presence of paramagnetic substances from previous therapy. Conclusion: We postulate that labyrinthine haemorrhage is a rare, late complication of head and neck irradiation, resulting in sudden sensorineural hearing loss
The auditory apparatus and vestibular part of the inner ear are often included in the radiation field treatment of patients with head and neck tumours.1-5 Radiation injury resulting in late-onset sensorineural hearing loss is a recognised complication, but the underlying pathological processes are poorly understood.4 Magnetic resonance imaging (MRI) of the brain and internal acoustic canal (IAC) has become an important modality in the diagnosis of various diseases that may be responsible for sudden deafness. In this case series, we report the finding of labyrinthine high signal on unenhanced T1-weighted MRI of the IAC in patients who presented with sudden onset sensorineural hearing loss 5 to 20 years following head and neck irradiation. We postulate that these findings are due to labyrinthine haemorrhage as a rare, delayed complication of head and neck irradiation.
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