Vagal Nerve Stimulation to Treat Disorders of Consciousness

Condition(s) studied

Investigational drug(s) / intervention(s)

stimulated group: Participants will be randomly assigned to receive either taVNS applied to the tragus of the ear or a sham stimulation from the time of randomization for 90 days. Active simulations will be carried out daily using the Parasym device for 60 minutes twice daily during the acute phase (two sessions, one in the morning and one in the afternoon), and once daily (single session) during the rehabilitation phase. The stimulation waveform includes trains of pulses with widths of 200 µs and repetition rate of 20 Hz (Nurosym proprietary waveform); current delivery will be set at a predefined therapeutic level below 0.25 W/cm² (Watts per centimeter squared), that being the defined risk threshold for a thermal burn. The device adjusts stimulation intensity at 0.8 mA steps; the starting intensity will be set at 16 mA (level 20).

Sham (No Treatment): The sham stimulation involves placing the electrode on the same site without delivering any electrical current. The device will be applied to the tragus without electrical current delivered from the time of randomization for 90 days (i.e., the time of randomization coincides with the first stimulation session).

Study summary

This interventional study aims to assess the clinical efficacy of transcutaneous auricular vagal nerve stimulation (taVNS) against sham stimulation on the recovery of consciousness in patients with disorders of consciousness. The main question it aims to answer is: will taVNS improve patients' behavioral scores or will it produce an improvement in the diagnosed level of consciousness? Researchers will compare the results with non-stimulated unconscious patients to see if the re-gain of consciousness is faster in the treated group.

Participants will undergo taVNS stimulation using the Parasym device or sham stimulation will be applied from the time of enrolment.

Active stimulations will be carried out for 60 minutes twice daily during the acute phase and daily during the rehabilitation phase.

Eligibility

Primary outcome measure(s)

• Rate of response to stimulation — 90 days post-randomization
  A response is defined as an increase of at least 3 points in the Coma Recovery Scale-Revised (CRS-R), or a clinical change in the diagnosed level of consciousness: from coma to unresponsive wakefulness syndrome (UWS), from UWS to minimally conscious state (MCS), or emergence from MCS. Clinical markers for the diagnostic improvements are derived from the CRS-R scale: • The transition from coma to UWS will be defined as the appearance of eyes opening. • The MCS minus state will be defined by the appearance of visual pursuit, object localization, automatic motor responses, or object manipulation. • The MCS plus will be defined by the appearance of non-functional intentional communication, intelligible verbalization, object recognition, or movement to command. • Emergence from MCS will be defined by the appearance of functional accurate communication or functional object use.

Trial sites (11)

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