Regional brain blood flow in congenital dysphasia: studies with technetium-99m HM-PAO SPECT

Congenital dysphasia is a developmental speech disorder not explained by deafness, phonation disorder, mental retardation, neurologic lesion, or psychiatric disease. The existence of brain lesions has often been postulated but conventional investigations fail to demonstrate any cerebral abnormality. By means of [99mTc]hexamethyl-propyleneamine oxime (HM-PAO) brain single photon emission computed tomography (SPECT) we have studied 14 children suffering from congenital dysphasia. The brain computed tomographic scan was normal in all cases. In two patients with expression impairment the SPECT study demonstrated a hypoperfusion in the inferior frontal convolution of the left hemisphere, involving the Broca's area. In nine of 12 patients with global dysphasia (deficits in both comprehension and expression), SPECT study showed two hypoperfused areas: an abnormality in the left temporoparietal region and a hypoactivity in the upper and middle areas of the right frontal lobe. These results suggest that congenital dysphasia could be due, like acquired aphasia, to specific impairment of the language cerebral areas and that brain SPECT studies with [99mTc]HM-PAO could be useful for a better comprehension of the physiopathology of these disorders.