Optimization of VIM Targeting in Essential Tremor Surgery
Condition: Essential Tremor
MeSH terms: Tremor; Essential Tremor
Study type: Interventional

Summary: 
      Deep brain stimulation (DBS) for essential tremor is based on the intermedius ventralis
      nucleus of the thalamus (VIM) stimulation. This structure is however very difficult to
      target, as it remains invisible on imaging. The current procedure based on awake surgery with
      clinical and electrophysiological testings has several limitations that lead us to develop a
      probabilistic model to locate precisely the target. This study aims to show that asleep DBS
      surgery based on this new targeting method leads to at least the same clinical results than
      the classical procedure.
    

Detailed description: 
      The intermedius ventralis nucleus of the thalamus (VIM), which represents the target for deep
      brain stimulation (DBS) in essential tremor, still remains invisible on 1,5 tesla MRI (the
      only magnetic field available for stereotactic surgery). The target coordinates currently
      used are based on stereotactic atlases or mean coordinates from retrospective series. They
      are so imprecise that intra-operative clinical testing and micro-electrode recordings are
      mandatory to locate the exact position of the VIM. This procedure is long lasting, requires
      that the patient is awake, and increases the risk of intracerebral haemorrhage and nosocomial
      infections. Furthermore, some patients are not improved despite a DBS lead implanted in the
      electrophysiologically and clinically defined target. To overcome these limitations,
      investigators developed a probabilistic model based on data extracted from imaging of
      patients with particularly good outcomes after DBS surgery. This machine-learning model
      allows calculating to coordinates of the VIM according to the position of radio-anatomical
      landmarks with a mean precision of 1,65mm.

      The aim of this study is to validate this new targeting method on a prospective cohort of
      patients. DBS surgery will be performed under general anaesthesia, without intra-operative
      clinical and electrophysiological testing, with a surgical robot and under CT-scan guidance
      (O-Arm ©).

      Neurostimulation device programming will be performed as usual. Patients' tremor and quality
      of life will be evaluated pre and post-operatively at 3 months, according to the
      Fahn-Tolosa-Marin (FTM) scale and with an accelerometry recording (for tremor) and with the
      mPDQ-39 scale for quality of life. Surgical complications and side effects related to
      neurostimulation will be gathered all along the follow-up.
    

Intervention name(s): Opti-VIM targeting in DBS surgery
Intervention type(s): Procedure
Intervention description(s): DBS surgery will be performed under general anaesthesia, without intra-operative clinical and electrophysiological testing, with a surgical robot and under CT-scan guidance (O-Arm ©). The VIM coordinates will be calculated with the probabilistic model that have been developed.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Essential Tremor; Deep brain stimulation; Ventro-intermediate nucleus of the thalamus; Targeting; Asleep surgery