Auditory Brainstem Response in Patients with Tinnitus Associated with Vitamin B12 Deficiency

Abtract Objective: The auditory brainstem response (ABR) has been reported as normal in patients with vitamin B12 deficiency, but there have also been reported cases of interference in amplitude responses. However, studies investigating the effects of vitamin B12 on auditory response are limited in patients with tinnitus. The aim of this study was to investigate the ABR findings in patients with tinnitus together with vitamin B12 deficiency.

Twenty-eight patients with tinnitus-related vitamin B12 deficiency were included in the study. Their serum vitamin B12 levels were lower than 200 pg/ml. Patients were between 19 and 58 years with a mean age of 36.82 ± 11.19 (ratio: male/female, 6/22). ABR was performed in all patients. Latencies ( I, II, III, IV, V), interpeak latencies (I-III, III-V, I-V) and amplitudes were evaluated. Neurologic and ear physical examinations were evaluated and brain magnetic resonance imaging (MRI) was also performed in all patients.

Neurologic,ear-auditory physical examinations and brain MRI findings were normal in all patients. Wave latencies and interpeak latencies were normal in all patients. Six patients (21.42 %) had low amplitude in their ABR. In one of them, the left-sided response showed a mild amplitude decrease in all waves compared to the right-side. Bilateral mild low amplitude was observed in 4 (66.6 %) patients in ABR findings.

These results support that ABR findings can be influenced in vitamin B12 deficiency patients having tinnitus. More detailed studies are needed in tinnitus associated with vitamin B12 deficient patients. Key words: Auditory brainstem response, Tinnitus, Vitamin B12 deficiency, Neurophysiology, Low amplitude.