Technetium-99m ethyl cysteinate dimer (ECD) cerebral accumulation and symptom and sign severity during hypothyroidism.

OBJECTIVE: The purpose of this study was to correlate hypothyroid-related symptomatology with regional cerebral blood flow (rCBF) during hypothyroidism.

MATERIALS AND METHODS: Nine thyroidectomized patients underwent neuropsychological testing and single photon emission computed tomography (SPECT) of their brains with technetium-99m (Tc-99m) ethyl cysteinate dimer (ECD), a lipophilic cerebral blood flow radiotracer, while hypothyroid, and again following thyroid hormone replacement. Neuropsychological test scores and TSH levels while hypothyroid were correlated with rCBF in hypothyroid-affected areas of the brain.

RESULTS: Correlations were found during hypothyroidism between the noted parameters and ECD radiotracer accumulation in the following respective regions, all of which demonstrated hypothyroid-related cerebral blood flow (CBF) aberrations: TSH and left middle occipital gyrus; psychomotor performance speed and left precentral gyrus; and depression and right middle frontal gyrus, left middle frontal gyrus, right insula, and left thalamus.

CONCLUSIONS: Severity of psychomotor impairment and depression, and TSH level during hypothyroidism appeared to correlate with CBF to brain regions associated with motor activity, mood and vision, respectively; and previously shown to manifest significantly altered rCBF during hypothyroidism.