NeuropathyN2ONCT05469321
Neurological Impairment in a Young Population Exposed to Recreational Nitrous Oxide
An observational study of Neuropathy, run by Centre Hospitalier Universitaire de Nīmes at 1 site in France.
Trial summary
Nitrous oxide (N2O) is a colorless, flammable, analgesic gas used in surgery and dentistry. The consumption of N2O has increased among young French people aiming to relax because of its short-lived neuropsychological effect (euphoria, depersonalization, analgesia) and its wide availability on the market. Read more about this study
- Who is it for?
- Ages 15 years and older
- Conditions the study is for
- Neuropathy
- What is being tested?
- None, pure observationnal study
- How many people
- 20 participants
- Where
- 1 siteFrance
- Study dates
- 22 Aug 2022to 3 May 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 15 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: patients presenting to the CHU of Nîmes with an acute or sub-acute neurological picture after having consumed N2O
patients presenting to the CHU of Nîmes with an acute or sub-acute neurological picture after having consumed N2O
-
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Retrospective Study of Neurological Impairment in a Young Population Exposed to Recreational Nitrous Oxide
Nitrous oxide (N2O) is a colorless, flammable, analgesic gas used in surgery and dentistry. The consumption of N2O has increased among young French people aiming to relax because of its short-lived neuropsychological effect (euphoria, depersonalization, analgesia) and its wide availability on the market.
It can be responsible in case of prolonged use and overdose of a vitamin B12 deficiency with possible neuropsychiatric complications: sensitivomotor neuropathy, myelopathy, behavioral and cognitive disorders of acute or sub-acute installation.
Read more
N2O inhibits the activitý of methionine synthase, decreases the activitý of methylmalonyl-CoA mutase leading to vitamin B12 deficiency but in addition to the interference with vitamin B12 metabolism there seems to be a direct toxicity of N20.
Myelin alteration was the typical electromyography finding but new axonal profiles were also described. Since myelopathy affects both the posterior and lateral cords, combined spinal cord sclerosis is the most common location of injury associated with N2O intoxication.
- Conditions
- Neuropathy
- Being tested
- None, pure observationnal study
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
None, pure observationnal studyOther
None, pure observational study following the usual management of the patients
| Study group | Role | What they receive |
|---|---|---|
| Patients | patients presenting to the CHU of Nîmes for an acute or subacute neurological picture after having consumed N2O. Receives: Other: None, pure observationnal study |
What is being measured
The primary outcome is the main question the study is designed to answer.
MRC score
MRCss - Medical Research Council sum score : This score assigns a rating to each muscle group: "0" = absence of visible contraction visible contractions, " 1 " = visible contractions without movement of limbs, " 2 " = insufficient 2" = insufficient movements to overcome weightlessness, "3" = movements to overcome weightlessness, "4" = movements against weightlessness and resistance, "5" = normal muscle strength.
Measured: baseline
Romberg score
A positive Romberg test means the presence of sensory ataxia
Measured: Baseline
INCAT Sensory Sum score (ISS)
grades from 0 (no involvement) to 20 (severe involvement)
Measured: Baseline
ONLS - Overall Neuropathy Limitations Scale
Overall Neuropathy Limitation Scale = arm scale (range 0 to 5) + leg scale (range 0 to 7); (range: 0 (no disability) to 12 (maximum disability)
Measured: Baseline
Rankin score
disability measurement score from 0 (none) to 6 (death)
Measured: Baseline
vitamin B12 level
vitamin B12 level in µmom/L
Measured: baseline
methyl malonic acid level
methyl-malonic acid level
Measured: baseline
electroneuromyogram
Normal Yes/No
Measured: baseline
Cerebral MRI
lesions yes/No
Measured: baseline
Pan-medullary MRI
lesions yes/No
Measured: baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Jul 2022
- Study start22 Aug 2022
- Primary completion3 May 2025
- Study completion3 May 2025
Why it stopped: Start of the PI
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for NeuropathyStudies of the same condition, open and under way.
- More trials run by Centre Hospitalier Universitaire de NīmesThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Retrospective
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Centre Hospitalier Universitaire de Nīmes
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Anissa MEGZARI, Study director, Centre Hospitalier Universitaire de Nīmes
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05469321
- Sponsor's protocol ID
- Local/2022/II-03
- Acronym
- N2O
- Status last verified
- May 2026
- First submitted
- 19 Jul 2022
- Last updated
- 17 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 17 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Retrospective Study of Neurological Impairment in a Young Population Exposed to Recreational Nitrous Oxide
- ClinicalTrials.gov ID
- NCT05469321
- Acronym / sponsor ID
- N2O / Local/2022/II-03
- Conditions
- Neuropathy
- Study type
- Observational
- Recruitment status
- TerminatedReason stopped: Start of the PI
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Centre Hospitalier Universitaire de NīmesUniversity, hospital or other
- Study start
- 22 Aug 2022 (actual)
- Primary completion
- 3 May 2025 (actual)
- Study completion
- 3 May 2025 (actual)
- First posted
- 21 Jul 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Nitrous oxide (N2O) is a colorless, flammable, analgesic gas used in surgery and dentistry. The consumption of N2O has increased among young French people aiming to relax because of its short-lived neuropsychological effect (euphoria, depersonalization, analgesia) and its wide availability on the market.
It can be responsible in case of prolonged use and overdose of a vitamin B12 deficiency with possible neuropsychiatric complications: sensitivomotor neuropathy, myelopathy, behavioral and cognitive disorders of acute or sub-acute installation.
N2O inhibits the activitý of methionine synthase, decreases the activitý of methylmalonyl-CoA mutase leading to vitamin B12 deficiency but in addition to the interference with vitamin B12 metabolism there seems to be a direct toxicity of N20.
Myelin alteration was the typical electromyography finding but new axonal profiles were also described. Since myelopathy affects both the posterior and lateral cords, combined spinal cord sclerosis is the most common location of injury associated with N2O intoxication.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Patients | – | Other: None, pure observationnal studypatients presenting to the CHU of Nîmes for an acute or subacute neurological picture after having consumed N2O. |
Who may qualify
- Ages
- 15 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- patients presenting to the CHU of Nîmes with an acute or sub-acute neurological picture after having consumed N2O
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| None, pure observationnal studyNone, pure observational study following the usual management of the patients | Other | Patients |
Primary outcome
MRC score
Time frame: baseline
MRCss - Medical Research Council sum score : This score assigns a rating to each muscle group: "0" = absence of visible contraction visible contractions, " 1 " = visible contractions without movement of limbs, " 2 " = insufficient 2" = insufficient movements to overcome weightlessness, "3" = movements to overcome weightlessness, "4" = movements against weightlessness and resistance, "5" = normal muscle strength.
Romberg score
Time frame: Baseline
A positive Romberg test means the presence of sensory ataxia
INCAT Sensory Sum score (ISS)
Time frame: Baseline
grades from 0 (no involvement) to 20 (severe involvement)
ONLS - Overall Neuropathy Limitations Scale
Time frame: Baseline
Overall Neuropathy Limitation Scale = arm scale (range 0 to 5) + leg scale (range 0 to 7); (range: 0 (no disability) to 12 (maximum disability)
Rankin score
Time frame: Baseline
disability measurement score from 0 (none) to 6 (death)
vitamin B12 level
Time frame: baseline
vitamin B12 level in µmom/L
methyl malonic acid level
Time frame: baseline
methyl-malonic acid level
electroneuromyogram
Time frame: baseline
Normal Yes/No
Cerebral MRI
Time frame: baseline
lesions yes/No
Pan-medullary MRI
Time frame: baseline
lesions yes/No
Results and safety
The study was stopped early (reason given: Start of the PI). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Anissa MEGZARI study director
Centre Hospitalier Universitaire de Nīmes
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Neuropathy, run by Centre Hospitalier Universitaire de Nīmes at 1 site in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 17 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study was stopped early (reason given: Start of the PI). Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
MRC score (time frame: baseline). The study lists 10 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Jun 2026.