Temporal lobe perfusion in the deaf: MR measurement with pulsed arterial spin labeling (FAIR)

Experimental studies in animals have shown that loss of a primary sensory modality early in life may result in substantial alterations in cortical organization. This study was performed to measure cerebral perfusion in auditory cortex in congenitally deaf adults using the FAIR (Flow-sensitive Alternating Inversion Recovery) magnetic resonance imaging technique. Our hypothesis was that there would be relatively intact perfusion in auditory cortex.

Twenty-six profoundly congenitally deaf subjects were compared with 15 control subjects. A FAIR perfusion slice was scanned through the superior temporal gyrus parallel to the Sylvian fissure while subjects were at rest. Perfusion maps were calculated and regions of interest were drawn over the superior temporal gyrus including auditory cortex and the medial occipital lobe.

The relative perfusion of the superior temporal gyrus (STG) was slightly less in the deaf (right STG = 0 .79 +/- 0.16, left = 0.93 +/- 0.29) compared with the hearing (right STG = 0.90 +/- 0.14, left = 0.98 +/- 0.31) when normalized to the occipital cortex, but the differences were not statistically significant. Both showed moderate left lateralization; however, only in the deaf did this reach statistical significance (P < .01).

In the resting state, the deaf demonstrate a relatively normal perfusion in the region of cortex usually associated with auditory function. Although the presumed underlying electrical activity may represent some degree of residual auditory function, it is likely that the normal level of perfusion reflects cortical reorganization and the early migration of nonauditory processing into this area.