Ketamine to Treat Patients With Post-comatose Disorders of Consciousness

Study Overview
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Brief Summary
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The investigators will run a Randomized Clinical Trial with 30 patients with disorders of consciousness (DoC), with intravenous subanesthetic doses of ketamine. Patients will simultaneously undergo TMS-EEG. The piloting will be done on 3 patients, with EEG only.

Detailed Description
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The protocol will be organized in three phases: baseline, experimental, and follow-up. In the baseline, patients will receive a multimodal assessment [functional magnetic resonance imaging (fMRI), positron emission tomography (PET), electroencephalogram (EEG)]. The experimental phase is made of 2 sessions spaced 5 days apart: on day 1, patients will receive placebo (or ketamine), on day 5 patients will receive ketamine (or placebo). The order will be randomized and balanced. The investigators will use a targeted-controlled infusion (TCI) system to infuse a continuous subanesthetic dose of ketamine, which is known to have psychedelics effects, or a saline solution. The investigators will periodically assess for new signs of consciousness with the simplified evaluation of consciousness disorders (SECONDs) scale. The investigators will use transcranial magnetic stimulation coupled to EEG (TMS-EEG) to measure brain activity and calculate brain complexity. TMS-EEG will be performed from 20 minutes before the beginning of the infusion up to the max duration of the experiment (90 minutes). Another SECONDs will be performed on the following day of each session to control for carry-over effects. The primary outcomes are the emergence of new conscious behaviours and higher brain complexity following ketamine infusion. The secondary outcomes are baseline brain differences in neurophysiological and brain imaging measures between responders (new conscious behaviors or higher brain complexity) and non-responders (no new conscious behaviors or higher brain complexity). In the follow-up phase, patients' health will be evaluated at 1, 6, and 12 months.

Official Title
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Complexity-enhancing Drugs to Treat Disorders of Consciousness (DoC): a Ketamine Study

Conditions
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Disorder of Consciousness

Intervention / Treatment
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* Drug: Ketalar 50 MG/ML Injectable Solution
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Clinically stable Diagnosis of UWS or MCS based on repeated coma recovery scale-revised) (CRS-R) or SECONDs More than 28 days post-insult Informed consent from the legal representative of the patient Exclusion Criteria: Neurological medications other than anti-spasticity drugs in the last 2 weeks or 4 half-lives Previous neurological functional impairment other than related to their DoC A history of psychotic disorders Contraindication to MRI, EEG, PET or TMS Use of nitrates or other vasodilators, central nervous system acting agents such as barbiturates, morphine and related drugs. Use of drugs known to interact with ketamine (i.e., CYP3A4, diazepam, ...) Coronary insufficiency Other sympathomimetic drugs

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Double-blind, placebo-controlled, cross-over RCT
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Ketalar arm<br>Patients will receive ketamine (sold in the form of Ketalar) intravenously, up to 0.75 µg/ml concentration, for a maximum of 90' minutes. Ketalar concentration will be increased slowly in a step-wise manner unless new signs of consciousness are evident. | Drug: Ketalar 50 MG/ML Injectable Solution<br>* Intravenous solution (other info already provided)<br>* Other names: Ketamine;|
| Placebo Comparator: Placebo arm<br>Patients will receive placebo (saline solution) | Drug: Placebo<br>* Saline Solution<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| New conscious behaviours | New conscious behaviours (i.e., command following, visual pursuit) after the infusion of the ketamine as recorded via the simplified evaluation of consciousness disorders (SECONDs) behavioural scale, that are not seen before ketamine, during placebo infusion, or in baseline. The SECONDs has 8 items, with the most complex item linked to a higher conscious state. The score goes from 0 (coma) to 8 (emergent from the minimally conscious state). | Max 90 minutes from Ketamine Infusion | 
| Higher brain complexity | Higher brain complexity [perturbational complexity index (PCI) or Lempel-Ziv complexity (LZC)] during the infusion of ketamine. The investigators expect complexity to increase when new conscious behaviors are observed. If the patient does not show new signs of consciousness but has high complexity, the investigators expect to record memories of the experience in the follow-up phase. PCI and LZC values range from 0 (no complexity) to 1 (high complexity). The investigators expect complexity values to be proportional to the concentration of the drug. | Max 90 minutes from Ketamine Infusion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PET biomarker | Different baseline PET signal between responders (patients who show new signs of consciousness or higher brain complexity after the drug), and non-responders (who do not show new signs of consciousness or higher brain complexity). In particular, higher metabolism [measured by standardized uptake value (SUV)] in responders compared to non-responders. | From baseline | 
| MRI biomarker | Different baseline MRI between responders (patients who show new signs of consciousness or higher brain complexity after the drug), and non-responders (who do not show new signs of consciousness or higher brain complexity). In particular, higher resting-state BOLD activity in responders compared to non-responders and more preserved brain structures. | From baseline | 
| EEG power | Different baseline EEG signal between responders (patients who show new signs of consciousness or higher brain complexity after the drug), and non-responders (who do not show new signs of consciousness or higher brain complexity). In particular, higher alpha-band activity in responders compared to non-responders. | From baseline | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Psychedelics, Complexity, Ketamine, Clinical Diagnosis, Consciousness level