Using focused ultrasound to treat dyskinetic cerebral palsy in young patients

Inclusion Criteria:

* The treating physician has chosen GPi-DBS or pallidotomy for the treatment of the secondary dystonia caused by cerebral palsy in this patient
* Patient and/or legal representative, if the patient is underaged or not capable to give consent himself, have chosen pallidotomy as treatment
* The consent to participate in the trial of the underaged patient, if he is capable to understand the study requirements, is required
* Age at enrolment 8-22 years
* Diagnosis of secondary dystonia due to cerebral palsy caused by perinatal hypoxic injury
* Anti-dystonic pharmacotherapy insufficient
* Stable anti-dystonic medication over the last 30 days
* Globus pallidus internus (pars posterior) and thalamus (motor part) intact on MRI (not older than 2 years - if possible)
* No fixed severe skeletal deformations with loss of function, which need immediate orthopaedic surgical intervention
* Sufficient compliance of the patient or the legal representative if the patient is underaged or not capable to give consent himself to take part in the study
* Informed consent to take part in the study from patient and/or legal representative if the patient is underaged or not capable to give consent himself
* Patient and/or legal representative if the patient is underaged or not capable to give consent himself, understands the study requirements and the treatment procedures and provides written informed consent before any study-specific tests or procedures are performed

Exclusion Criteria:

* Patients with known primary (e.g. DYT1) or idiopathic dystonia
* Severe axial hypotonia with total loss of head control (e.g. absence of control at "upper thoracic level" in the SATCo score) (medication effect excluded)
* Fixed hemi-dystonia
* Severe spasticity in knee- and elbow-flexors and -extensors (Modified Ashworth Scale \>3)
* Fixed severe skeletal contractions with loss of function which require immediate orthopaedic surgical intervention
* Patients with other severe concurrent neurological disease (e. g. brain tumor, neurodegenerative diseases, trauma etc.)
* Condition likely to require use of MRI in the future
* Any intracranial abnormality or medical condition that would contraindicate DBS surgery
* Any findings in neuropsychological screening assessments that would contraindicate DBS surgery
* Any current drug and / or alcohol abuse
* Any history of frequent grand-mal seizures without response to anticonvulsive treatment
* Any other active implanted device (e.g. Cochlear implant, pacemaker), whether turned on or off, would be allowed provided that they do not interfere with functioning of the device.
* The presence of DBS leads due the risks of these ferromagnetic devices in the MRI environment.
* A history of neurostimulation intolerance in any area of the body.
* Currently on any anticoagulant medications that cannot be discontinued during perioperative period.
* Any significant medical condition that is likely to interfere with study procedures or likely to confound evaluation of study endpoints, including any terminal illness with survival \<24 months.
* Participation in another drug, device, or biologics trial concurrently or within the preceding 30 days; any other trial participation should be approved by the Principal Investigator.
* A female that is breastfeeding or of childbearing potential with a positive urine pregnancy test or - if a person is sexually active - not using sufficient contraception with a Pearl Index of less than 1% including all forms of hormonal contraception ("antibaby-pill", hormonal plaster, NuvaRing®, Implanon®, hormonal depot injections, contraceptive coil), the tubal ligature (female sterilization). Alternatively, the female of child bearing potential is sexually abstinent.
* Subjects who have contraindications to anesthesia, in the judgment of the attending anesthesiologist
* Subjects who are unwilling or unable to undergo general anesthesia
* Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the subject or the quality of the data.
* Minimum head circumference \< 49cm
* Skull Density Ratio (SDR) \<0.40.