Amygdalohippocampal involvement in tinnitus and auditory memory.
CONCLUSIONS
The preliminary results suggest that in chronic unilateral tinnitus the contralateral amygdalohippocampal complex does seem to be involved in tinnitus perception of pure tones.


OBJECTIVE
Functional neuroimaging studies have revealed that the hippocampus and amygdala are involved in tinnitus perception. The amygdala and hippocampus are supplied by the anterior choroidal artery. Selective amobarbital injections in the anterior choroidal artery result in a non-functional amygdalohippocampal area for 10 min. The aim of this study was to assess the influence of this procedure on tinnitus perception.


METHODS
Amobarbital (80 mg in total) was injected selectively in two sessions in the left and right anterior choroidal artery in six male patients with tinnitus: four with unilateral tinnitus, two with bilateral tinnitus. Of the patients with unilateral tinnitus, three had right-sided tinnitus and one had left-sided tinnitus. The average age was 57.3 years (range 43-69). Average tinnitus duration was 5.3 years (range 1-10). The differences in visual analogue scale (VAS) scores before and after the amytal tests were analysed.


RESULTS
Amytal injection ipsilateral to the side where the tinnitus was perceived resulted in a maximum of 30% tinnitus suppression, whereas amytal injection contralateral to the tinnitus side yielded a 60-70% tinnitus suppression in three patients with unilateral chronic tinnitus (>4 years). Only pure tone tinnitus was suppressed, white noise was not. Two patients with bilateral tinnitus had no suppression, irrespective of the tinnitus type. A third patient without clinical tinnitus suppression had tinnitus of more recent origin (1.5 years).
De Ridder
Dirk
D
Department of Neurosurgey, University Hospital Antwerp, Belgium. dirk.de.ridder@neurosurgery.be
Fransen
Hendrik
H
Francois
Olivier
O
Sunaert
Stefan
S
Kovacs
Silvia
S
Van De Heyning
Paul
P
D000328:Adult; D000368:Aged; D000654:Amobarbital / Q000008:administration & dosage; D000679:Amygdala / Q000098:blood supply / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001307:Auditory Perception / Q000502:physiology*; D002533:Cerebral Angiography; D002536:Cerebral Arteries; D002560:Cerebrovascular Circulation; D005260:Female; D018757:GABA Modulators / Q000008:administration & dosage; D006624:Hippocampus / Q000098:blood supply / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007269:Injections, Intra-Arterial; D008144:Loudness Perception / Q000502:physiology; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000453:epidemiology*; D008875:Middle Aged; D010468:Perceptual Disorders / Q000453:epidemiology*; D010898:Pitch Perception / Q000502:physiology; D012720:Severity of Illness Index; D014012:Tinnitus / Q000453:epidemiology* / Q000503:physiopathology*
D018757:GABA Modulators; D000654:Amobarbital