Objective: To identify CMD patients’ selection criteria predictive of a good response to CEN by retrospective analysis of a treated cohort.

Background: Continuous Electrical Neuromodulation (CEN) of the Globus Pallidus Internus (GPi) has been shown to be effective in cervical dystonia and reported improvement on the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) (≥55%). Results are more heterogeneous when Cervical Movement Disorder (CMD) is isolated, whatever may be the presentation: abnormal head position due to dystonic contraction and/or dyskinetic movements (regular or not). In this population, a functional (psychogenic) participation is often questioned susceptible to limit CEN efficacy but difficult to assess.

Methods: Thirty-two patients, followed-up for idiopathic CMD in our center (January 2000 to January 2015), were included in this retrospective study. Eighteen patients were operated for GPi-CEN according to our center clinical guidelines. Among the fourteen not operated patients, one is anticipated for surgery, six refused GPi-CEN, two others had good response to toxin or a mild intensity of the symptomatology and the last two ones, presenting with a family history of CMD, are still under screening. Only three patients presented with a strong evidence of psychogenic disorder. Data were retrospectively collected using a standardized spreadsheet compiling familial and demographic data, clinical history, precipitating events, psychogenic features, secondary gain, response to pharmacological treatment/botulinum toxin injections, anatomic and/or functional imaging abnormalities. Clinical assessment and standardized videotape recordings was performed pre- and post-operatively using the TWSTRS.

Results: At one year evaluation, 5/18 operated patients failed to improve. These patients didn’t initially present with any contraindication criteria for CEN. Neither clinical nor radiological data allowed us to distinguish them from other patients.

Conclusions: In the population of non-responder patients, we suspected a functional over-expression of symptoms although we failed to diagnose it on the basis of current evaluation protocol. A more detailed analysis of clinical, psychological and radiological patterns should be needed for a more accurate definition of criteria for selection.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/do-predictors-of-good-response-to-deep-brain-stimulation-in-primary-cervical-movement-disorders-exist/