SPEECH-INDUCED CEREBRAL METABOLIC-ACTIVATION REFLECTS RECOVERY FROM APHASIA

Six stroke patients with clinically significant aphasia were studied 4 weeks and again 12-18 months after their first left hemispheric ictus . The regional cerebral metabolic rate of glucose (rCMR(glc)) was meas ured repeatedly by PET at rest and during word repetition, and severit y of speech impairment was assessed by a neuropsychologic test battery . The patterns of speech-associated activation of glucose metabolism w ere related to improvement in language performance as measured by the Token test. Three patients experienced significant recovery from aphas ia (Token test: 47 to 3, 45 to 12, and 37 to 5 points, respectively), whereas 3 patients had poor outcome (Token test: from 48 to 45, and fr om 47 to 39 and 24, respectively). Good recovery was related to activa tion of left hemispheric speech areas surrounding the infarct, especia lly left superior temporal gyrus. In contrast, the 3 patients with per sistent aphasia showed rCMR(glc) recruitment in right hemispheric regi ons and were unable to activate left hemispheric speech areas on follo w-up. These results indicate that favorable outcome is related to part ial sparing of speech areas of the dominant hemisphere that can be (re -) activated. Predominant recruitment of contralateral areas is not ef ficacious for a considerable recovery from aphasia, It rather indicate s unspecific involvement of widespread networks in the effort La perfo rm a complex task. (C) 1997 Elsevier Science B.V.