Pre-operative evaluations for DBS in dystonia

Background: The preoperative evaluation in dystonia aims at characterizing the severity and topography of motor symptoms in patients, who have previously been selected for deep brain stimulation (DBS). Methods: The literature search was performed using PubMed, CINAHL, and the Cochrane Collaborative databases. Results: Commonly used scales for clinical assessment are the Burke-Fahn-Marsden dystonia rating scale for generalized dystonia and the Toronto Western Spasmodic Torticollis Scale for cervical dystonia. Motor assessment is completed by quality of life and functional scales, such as the Short-Form Health Survey (SF-36) or the Parkinson's Disease Questionnaire 39. Validated rating scales for cranial or upper limb dystonia are lacking. Discussion: In common clinical practice, these outcome measures can be administered in an open-label fashion because double blind assessment is only required for ascertaining new treatment indications or research purposes. The same measures are to be used postoperatively to revaluate outcome after DBS. Brain MRI is required to confirm diagnosis and assess structural abnormalities. Other imaging techniques, particularly functional imaging, are used for research purposes.