Objective: Improving the diagnostic capability by discriminating the psychogenic part of the disorder using a dedicated “home-made” questionnaire completed with the Minnesota Multiphasic Personality Inventory (MMPI).

Background: Abnormal head posture can be induced by dystonia and/or dyskinesia but psychogenic participation origin is often questioned susceptible to limit the efficacy of Continuous Electrical Neuromodulation (CEN) of Globus Pallidus Internus (GPI). This neurosurgical procedure is effective for patients with generalized dystonia-dyskinesia syndrome. It appeared that results are more difficult to predict in the situation of isolated abnormal head posture. In this particular situation, psychogenic participation can be difficult to identify.

Method: We elaborated a 2-part study : 1/ a retrospective one including 21 patients treated by GPI-CEN (11/2000 – 08/2016) presenting with “cervical dystonia”. Six patients did not respond to neuromodulation (3 patients were explanted) and were considered as “dysfunctional patients”, retrospectively. One criterion was given by the specifically dedicated questionnaire. Among the other responder patients, as a guide, 5 of them accepted to fill-in the personality assessment using the MMPI (12/2015-12/2017). 2/ a prospective evaluation of 21 out clinic patients for preoperative evaluation. According to our center clinical guidelines, we apply in the same time the questionnaire and the personality evaluation (12/2015-12/2017) to these patients.

Results: According to the questionnaire answer, among the 21 out-clinic patients, 12 showed psychogenic clues and 9 were preselected for GPI-CEN. Among these 9 patients, one is still under evaluation, one is lost for survey, one refused the operation and one have a behavior disorder. For the 5 last patients, the complementary examination of the personality enabled to retain only one patient for surgery.

Conclusion: The need of quantitative criteria for evaluating the risk of psychogenic participation to a movement disorder is obvious in daily practice. Our data show that most patients (26 patients in 42) initially diagnosed with a “cervical dystonia” have a functional participation or origin. It can be factitious, malingering, conversive. The diagnosis remains challenging given the close interface that exists between behavioral and neurological disorders. The neurophysiological understanding of frontier syndromes needs to be clarified.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/preoperative-quantitative-evaluation-of-psychological-determinants-in-abnormal-head-postures/