 Method: 20 PD patients will undergo thoracic spinal cord stimulation with high frequency in a prospective study for six months. Gait and freezing evaluation will consists in: timed up and go test, timed up and go test with dual task, 20 m walk test, 20 m walk test with obstacle, freezing of gait scale and falls scale. PDQ 39 and Schwab and England scales will be used to measure quality of life. Unified Parkinsons Disease Rating Scale for motor symptoms and general evaluation. All tests will be done before surgery, after one week, one, three, six months. All patients will be stimulated with the same parameters: High frequencies and 90 mcs pulse width and the sensory threshold will be measured. At the third month the parameters of SCS will be changed and comparative tested for low frequency in a double blind trail. 