Efficacy of Dorso-lateral Prefrontal Cortex Stimulation by tDCS in Motor Conversion Disorder Patients

Condition(s) studied

Investigational drug(s) / intervention(s)

Neurostimulation with non-implanted electrodes: Neurostimulation with non-implanted electrodes

Study summary

Conversion disorder refers to impaired voluntary motor or sensory functions that are not compatible with a well-known neurological condition. This disorder affects up to 30% of hospitalized patients in neurology departments and symptoms persist in 35% of patients after 12 years of evolution. Despite a poor prognosis, no treatments have been validated to date.

The development of non-invasive brain stimulation techniques has allowed the creation of treatments focused on dysfunctional brain regions associated with motor conversion disorder. Hypoactivation of prefrontal dorso-lateral cortex underlies the course of functional motor symptoms. Results of the HYCORE study conducted at Nîmes University Hospital (including 20 patients, clinicaltrial.gov NCT02329626) confirmed these results and related hypoactivation of PFDLC to persistent motor disability at 3 months and 6 months follow-up. Activation of the PFDLC could restore executive control and thus promote the recovery of motor symptoms.

However, in most repeated Transcranial Magnetic Stimulation (rTMS) the primary motor areas were targeted and the clinical improvement was related to self-suggestion induced by the motor response produced.

Among the different techniques, transcranial Direct Current Stimulation (tDCS) is a medical neuromodulation device that delivers a direct, low-intensity electric current to cortical areas, facilitating neuronal activity. Recently, PFDLC stimulation via tDCS has been used to treat several neuropsychiatric disorders and shown to be effective in depression. In addition, this technique has several advantages compared to rTMS: its use is simpler and costs 5 to 8 times less, the device is portable and there is no titration procedure. The tolerance of the tDCS is also better with no risk of epileptic seizure, neuronal depolarization being absent.

Eligibility

Primary outcome measure(s)

• Evaluation of the efficacy of tDCS stimulation of the left PFDLC to treat motor disability in patients with conversion disorder 3 months after the intervention. — 3 months after the intervention
  Evaluation of the efficacy of tDCS stimulation of the left PFDLC to treat motor disability in patients with conversion disorder at 3 months after the stimulation procedure with the EDSS (Expanded Disability Status Scale). The Expanded Disability Status Scale is a rating scale of disability divided into eight systems or functional parameters, four major: pyramidal function, cerebellar function, sensory function and brainstem function; four minor: sphincters,vision, mind and others. An encrypted score of increasing severities (0 to 6 or 7) is given to each functional parameter. The overall score of the scale is measured on a scale of 20 levels (0 to 10 per half-point). Up to level 3.5, the score obtained in each functional parameter and the number of affected functional parameters automaticaly determines the EDSS score. From 4 to 7, the definition of each level is also given by the inability to walk (ability to walk without stopping - need for assistance).

Trial sites (8)

More Centre Hospitalier Universitaire de Nīmes trials in France