TINNITUS AND ENTHORINAL CORTEX IN PATIENTS WITH OCCUPATIONAL EXPOSURE TO SOLVENTS, METALS AND NOISE: ASPECT NEUROIMAGING STUDY. We describe the clinical case of a 56-year-old painter who was exposed for 30 years to low levels of noise (79-81,6 dB Lepd), solvents (urinary levels of hippuric acid found to be between 1.5 and 2 mg/100 ml) and metals (high serum levels of Al and Mn). He suffered from seemingly noise-induced hearing loss that was apparently incompatible with the low noise exposure and also had a tinnitus that he could modulate by opening and closing his mouth. We conducted a series of audiological studies which comprised pure tone audiometry, vocal audiometry, impedenzometric exam, otoacoustic emissions and acufenometry. We also analysed the cerebral blood flow by single photon emission tomography (SPECT) with [99m-tecnetium] hexamethyl propyleneamineoxime ([99mTc]HMPAO). The extreme peculiarity of the case derives from the presence of tinnitus which is modifiable by oro-facial movements (OFM). We found that the tinnitus was associated with a basal condition hypo-perfusion of the entorhinal cortex and limbic areas demonstrated by SPECT study. When the patient opens his mouth there is a reduction of the haematic hypo-perfusion associated with a subjective reduction of the tinnitus. We think that, in this case, the direct effects of the occupational noxae (solvents and/or metals) on the encephalic structures, documented by the SPECT study, may derive from direct adsorption of these substances through the olfactory pathway.
Tinnitus and enthorinal cortex in patients with occupational exposure to solvents, metals and noise: a SPECT neuroimaging study
PIRA, Enrico;
2004-01-01
Abstract
TINNITUS AND ENTHORINAL CORTEX IN PATIENTS WITH OCCUPATIONAL EXPOSURE TO SOLVENTS, METALS AND NOISE: ASPECT NEUROIMAGING STUDY. We describe the clinical case of a 56-year-old painter who was exposed for 30 years to low levels of noise (79-81,6 dB Lepd), solvents (urinary levels of hippuric acid found to be between 1.5 and 2 mg/100 ml) and metals (high serum levels of Al and Mn). He suffered from seemingly noise-induced hearing loss that was apparently incompatible with the low noise exposure and also had a tinnitus that he could modulate by opening and closing his mouth. We conducted a series of audiological studies which comprised pure tone audiometry, vocal audiometry, impedenzometric exam, otoacoustic emissions and acufenometry. We also analysed the cerebral blood flow by single photon emission tomography (SPECT) with [99m-tecnetium] hexamethyl propyleneamineoxime ([99mTc]HMPAO). The extreme peculiarity of the case derives from the presence of tinnitus which is modifiable by oro-facial movements (OFM). We found that the tinnitus was associated with a basal condition hypo-perfusion of the entorhinal cortex and limbic areas demonstrated by SPECT study. When the patient opens his mouth there is a reduction of the haematic hypo-perfusion associated with a subjective reduction of the tinnitus. We think that, in this case, the direct effects of the occupational noxae (solvents and/or metals) on the encephalic structures, documented by the SPECT study, may derive from direct adsorption of these substances through the olfactory pathway.
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