Periodic leg movements in spinal cord injury: evaluation of arousals and treatment effect

Abstract

Introduction Periodic Leg movements (PLM) have been previously reported in spinal cord injury (SCI), but never analyzed thoroughly. The objective of this study was to investigate the association between PLM and cortical and autonomic arousals in a patient with a complete SCI. Also the effect of a dopamine agonist was evaluated. Materials and methods Characterization of the SCI was done following the “International Standards for Neurological Classification of Spinal Cord Injury” and by performing a cervical MRI. Two separate baseline sleep recordings were performed with tibialis anterior EMG. A third similar recording was carried out under dopamine agonist medication. Results The SCI was found motor and sensory complete, indicating an injury of ASIA A severity. The MRI finding supported the clinical assessment of complete injury. PLM indexes were 148.2/h and 36.4/ h in the baseline sleep studies. Leg movements were disconnected from cortical arousals, as well as from respiratory or heart rate events. Heart rate events were associated with respiratory cortical arousals. All leg movements were abolished by pramipexole. Conclusion The presence of PLM in a patient with a complete cervical SCI indicates that they may appear without a generator of the movements in the brain. The disconnection of PLM from cortical, respiratory or cardiac events also supports a spinal pacemaker or peripheral trigger mechanism. Suppression of movements during the dopaminergic intervention suggests that the site of action of pramipexole in our patient is either in the spinal cord or periphery. Our observations add significant knowledge to the current models of the genesis for PLM and warrant studies in larger populations. Acknowledgements Professor Juha Ohman and Dr. Eerika Koskinen from Department of Neurosciences and Rehabilitation, University of Tampere, are acknowledged for their valuable contribution to the study.