Alternating and Direct Current Stimulation for Neuropathic Eye Pain

Not Applicable

Recruiting

• Conditions: Eye Pain; Neuropathy, Optic; Cerebral Injury
• Interventions: Device: DC-Stimulator Plus (NeuroConn GmbH, Germany); Device: Sooma direct current stimulator (Sooma, Finland)

• Registration Number: NCT05931250
• Lead Sponsor: Neil Lagali

Brief Summary

The goal of this clinical intervention is to test if two forms of transcranial current stimulation, transcranial direct current stimulation (tDCS) or transcranial alternating current stimulation (tACS) can alleviate neuropathic eye pain in a sample of 20 patients.

The main aims are:

* Test if tDCS/tACS can alleviate neuropathic eye pain and/or other cerebral symptoms: brain fatigue, migraine, light sensitivity, etc.

* Test if one stimulation method is superior to the other Patients will be treated for a total of fifteen 30-minute stimulation sessions, three times a day over a five-day period, each stimulation separated by approximately 4 hours, with either active tACS or tDCS over the scalp corresponding to primary sensory and motor areas.

The patients will have questionnaires to monitor subjective experiences and pupillometry before and after treatment to monitor experimental outcomes.

Detailed Description

Brief Summary sufficient

Study Timeline

• Study Start: 2023-06-16
• Study First Submitted: 2023-06-16
• Study First Submitted QC: 2023-06-26
• Status Verified: 2023-07
• Last Update Submitted: 2023-07-04
• Study First Posted: 2023-07-05
• Last Update Posted: 2023-07-06
• Primary Completion: 2024-12-31
• Study Completion: 2025-12-31

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 20

Inclusion Criteria

• persistent eye pain for at least 6 months
• average eye pain intensity of 4 or more on a 0-10 numerical rating scale
• naive to transcranial stimulation
• eye pain having neuropathic-like characteristics

Exclusion Criteria

• contraindication to transcranial stimulation (i.e., pacemaker, cardioverter defibrillator, neuro-stimulation (brain or spinal cord), bone growth stimulations, indwelling blood pressure monitors, epilepsy, pregnancy)
• presence of ocular diseases that are the likely cause of pain (i.e., corneal and conjunctival scarring, corneal edema, uveitis, iris transillumination defects, etc.)
• current participation in another study with an investigational drug or device within one month prior to screening

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Transcranial alternating current stimulation	DC-Stimulator Plus (NeuroConn GmbH, Germany)	Transcranial alternating current stimulation (tACS) device using 50x70 mm electrodes that are placed bilaterally between EEG coordinates C3/C5 for left hemisphere and C4/C6 for right hemisphere (corresponding to S1 and M1 of the eye). The alternating current electrodes are in-phase and have the same peak to peak stimulation 3mA, for 30 minutes duration at 10Hz. An impedance value under 15 ohms is required at all times to ensure patient comfort and safety.
Transcranial direct current stimulation	Sooma direct current stimulator (Sooma, Finland)	Transcranial direct current stimulation (tDCS) device using 50x70 mm electrodes that has the anodal electrode placed contralateral to most prominent ocular pain or, in the case of bilateral pain symptoms, contralateral to the dominant hand between EEG coordinates C3/C5 for left hemisphere and C4/C6 for right hemisphere (corresponding to S1 and M1 of the eye), and the cathode placed on the patient's upper arm. A current peaking at 3mA will ramp up for 20 secs and be delivered for a total of 20 minutes, thereafter, ramping down for 20s. An impedance value under 15 ohms is required at all times to ensure patient comfort and safety.

Primary Outcome Measures

Name	Time	Method
Change from baseline subjective pain via neuropathic pain symptom inventory for the eye (NPSI-eye) at 1 month	through treatment completion, 1 month	Assesses pain related symptoms on a scale from 0 indicating no pain (better outcome) to10 indicating worst pain imaginable (worse outcome)
Change from baseline subjective mental symptoms via Mental Fatigue Scale (MFS) at 1 month	through treatment completion, 1 month	Assesses mental symptoms on a scale from 0 indicating no effect (better outcome) to 3 indicating extreme effect (worse outcome)
Change from baseline pupil diameter in millimeters at 1 week	through treament completion, 1 week	Minimum and maximum pupil diameter in millimeters
Change from baseline pupil latency in milliseconds at 1 week	through treament completion, 1 week	Pupil latency latency in milliseconds
Change from baseline subjective pain via neuropathic pain symptom inventory for the eye (NPSI-eye) at 1 week	through treatment completion, 1 week	Assesses pain related symptoms on a scale from 0 indicating no pain (better outcome) to10 indicating worst pain imaginable (worse outcome)
Change from baseline subjective pain effect experiences via Defense and Veteran Pain Rating Scale (DVPRS) at 2 weeks	through treatment completion, 2 weeks	Assesses pain related symptoms effecting sleep, stress, disposition, life quality, on a scale from 0 indicating no effect (better outcome) to10 indicating maximum effect (worse outcome)
Change from baseline subjective mental symptoms via Mental Fatigue Scale (MFS) at 2 weeks	through treatment completion, 2 weeks	Assesses mental symptoms on a scale from 0 indicating no effect (better outcome) to 3 indicating extreme effect (worse outcome)
Change from baseline subjective ocular symptoms and symptom frequency via custom ocular pain questionnaire at 1 week	through treatment completion, 1 week	Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)
Change from baseline subjective ocular symptoms and symptom frequency via custom ocular pain questionnaire at 1 month	through treatment completion, 1 month	Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)
Change from baseline pupil velocity in millimeters per second at 1 week	through treament completion, 1 week	Pupil change velocity in millimeters per second
Change from baseline subjective pain effect experiences via Defense and Veteran Pain Rating Scale (DVPRS) at 1 week	through treatment completion, 1 week	Assesses pain related symptoms effecting sleep, stress, disposition, life quality, on a scale from 0 indicating no effect (better outcome) to10 indicating maximum effect (worse outcome)
Change from baseline subjective pain effect experiences via Defense and Veteran Pain Rating Scale (DVPRS) at 1 month	through treatment completion, 1 month	Assesses pain related symptoms effecting sleep, stress, disposition, life quality, on a scale from 0 indicating no effect (better outcome) to10 indicating maximum effect (worse outcome)
Change from baseline subjective pain via neuropathic pain symptom inventory for the eye (NPSI-eye) at 2 weeks	through treatment completion, 2 weeks	Assesses pain related symptoms on a scale from 0 indicating no pain (better outcome) to10 indicating worst pain imaginable (worse outcome)
Change from baseline subjective mental symptoms via Mental Fatigue Scale (MFS) at 1 week	through treatment completion, 1 week	Assesses mental symptoms on a scale from 0 indicating no effect (better outcome) to 3 indicating extreme effect (worse outcome)
Change from baseline subjective ocular symptoms and symptom frequency via custom ocular pain questionnaire at 2 weeks	through treatment completion, 1 month	Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)
Number of patients with treatment-related adverse events as assessed by ocular pain questionnaire	through treatment completion, 1 month	Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)

Secondary Outcome Measures

Name	Time	Method
Treatment compliance rate	through study completion, 1 year	Evaluation of completed treatment from a total of 15

Trial Locations

Locations (1)

Eye Clinic, University Hospital in Linköping; 🇸🇪 Linköping, Other / Non-US, Sweden