Spasticity is usually a useful substitute for deficiency of motor strength. However not infrequently, it may become harmful leading to an aggravation of motor disability. When excessive spasticity is not sufficiently controlled by physical therapy and pharmacological treatment, patients can have recourse to neurosurgery: neurostimulation, intrathecal baclofen or selective ablative procedures. Because excessive hypertonia has to be reduced without suppression of the useful muscular tone or impairment in the residual motor and sensory functions, neuroablative procedures must be as selective as possible. These selective lesions can be performed at the level of peripheral nerves, spinal roots, spinal cord, or the dorsal root entry zone (DREZ lesions).