Médecine Nucléaire et Radiothérapie

99mTc HMPAO Cerebral Blood Flow Imaging Reveals Tourette’s Network when Compared to Healthy Controls

Abstract

Djekidel M, Leckman JF, Cohen BH and Bloch MH

Background: Published imaging abnormalities in Tourette’s syndrome (TS) patients are variable. The objective of this study was to measure changes in Cerebral Blood Flow (CBF) using SPECT HMPAO in adult patients with TS compared to Healthy Controls (HC). Based on prior volumetric MRI, nuclear medicine and post mortem studies our a priori hypothesis was that the CBF to the caudate nucleus would be reduced. Method: We measured CBF changes using 99mTc HMPAO SPECT in 10 adults with TS and 10 matched HC. Following injection of 30 mCi of 99mTc HMPAO, SPECT images were acquired. Statistical parametric mapping (SPM) analysis was performed using the Neuro-MIM software. Z scores were then generated for significant p values < 0.05. Results: TS subjects were 40 ± 13 years old with an average Yale Global Tic Severity Scale (YGTSS) of 28.4 ± 10.8. A significant decrease in CBF was noted in the caudate nucleus, putamen, the insula, the olfactory cortex and medial temporal lobe structures (amygdala, hippocampus and para-hippocampal gyrus) (Z scores: -2.01, -3.04, -1.89, -2.11, -2.66, -3.0, and -2.82, respectively). On the other hand, significant increases in CBF were noted in the occipital lobe and primary visual cortex regions (Z scores: +1.84, +1.82). Only borderline increases in the motor and somatosensory areas (Z scores: +1.2 and +1.47) were noted. Conclusion: Measurable changes in cerebral blood flow exist in the basal ganglia bilaterally as well as other brain regions in adult TS patients compared to HC. An abnormal blood flow network beyond the basal ganglia may exist and can be imaged in Tourette’s. This manifests as CBF decreases in the insula, caudate nucleus, olfactory cortex, and medial temporal lobe structures and increases in the occipital lobe. These findings need to be replicated in a larger cohort.