FUNCTIONAL MAGNETIC RESONANCE IMAGING OF BRAIN MOTOR AREAS IN HEREDITARY SPASTIC PARAPARESIS PATIENTS

Abstract

Background. Hereditary spastic paraparesis (HSP) is a heterogeneous group of disorders with corticospinal tract (CST) degeneration in which the main clinical feature is progressive bilateral lower limb spasticity. Functional imaging studies in patients with CST involvement have shown reorganization of motor cortex. Our study investigates functional adaptation of motor brain areas in HSP patients.Methods. Nine HSP patients and 10 healthy subjects were studied. Functional magnetic resonance imaging (fMRI) was used to measure activation of cortical motor areas and cerebellum during finger tapping. Image analysis was performed using general linear model and regions-of-interest (ROI) based approach. Laterality indexes (LI) were calculated for cortical and cerebellar ROIs.Results. Comparing patients and controls at the tapping rate of 1.8 Hz, there was higher fMRI activation in patients’ ipsilateral lateral sensorimotor (iLSM) area and contralateral cerebellum (cCRB) compared to controls, while controls showed higher activation in cLSM and iCRB. LI was significantly lower in patients’ LSM and CRB. Comparing patients and controls at 80% of their maximum tapping rates, the activation of cCRB was higher in patients, while cLSM and iCRB were higher in controls. LSM LI didn’t differ significantly between the HSP and control groups, but the cerebellar LI was significantly lower in patients.Conclusions. Our results suggest functional adaptation of the motor areas in HSP patients. The findings may reflect a combination of functional reorganization and compensatory brain activation at increased relative effort. Lower cLSM and iCRB activation in patients compared to controls might reflect the disorder of motor system in HSP.

Keywords

• fMRI
• voluntary movement
• hereditary spastic paraparesis
• motor cortex
• cerebellum