The neurophysiologic mu rhythm reflect the sensorimotor cortex activity. Cerebral palsy (CP) is a sensorimotor network defect. As an easily accessible biomarker of its cortical part, mu rhythm could help to better understand cerebral palsy physiopathology and neural basis of rehabilitation. We aimed to characterised mu rhythm in CP through a systematic review and an experimental study.

All English-written original articles in Pubmed and Medline studying neurophysiology of the sensorimotor cortex in children with CP and published between 1980 and 2016 were reviewed. A systematic analysis was proceed because meta-analysis was not possible. A pediatric exploratory study of mu rhythm in unilateral CP was performed. Mu rhythm at rest and during motor-execution and action-observation was recorded and compared between the lesed-hemisphere and the healthy-one.

Ten articles were included. In all of them, mu rhythm was found in both the lesed and the healthy hemisphere. At rest, mu rhythm amplitude was sometimes lower in the lesed-one. Mu rhythm reactivity was regularly altered in the lesed-hemisphere, compared with the healthy-one or with control. Alterations were found on type and amplitude of the mu rhythm reactivity. Four children with unilateral CP were included in the exploratory study with similar results. No shared pattern of reactivity during action-observation could be determined.

Mu rhythm was found in both the lesed- and the healthy-hemisphere, but altered in the lesed-one, in children with CP. Theses results could be support by different characteristics of the CP sensorimotor network: a weaker electrical generator; altered interactions between the sensory and the motor cortices; a primary sensory impairment and a motor planning impairment. A better quantification of mu rhythm, especially during action-observation, could rise to a better comprehension of the CP physiopathology and on an innovant, custom-made neuro-rehabilitation.