Biological Diagnosis and Monitoring of Chronic Nitrous Oxide Abuse

Study Overview
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Brief Summary
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There is a toxicity linked to the chronic use of nitrous oxide, leading to neurological disorders such as combined sclerosis of the spinal cord. One thus frequently observes patients presenting disorders of walking or paresthesias, of more or less resolving evolution being able to go until the need for using a wheelchair and more recently cases of thrombosis were reported Serum or urine N2O assays are rarely performed routinely, because they do not allow to ensure a real exposure due to the very short half-life of this gas in the body. Thus, other biological monitoring markers are mentioned in the literature, such as vitamin B12 or homocysteine. Unfortunately, there are still no recommendations for biological monitoring of nitrous oxide consumption. Moreover, underlying mechanisms leading to clinical outcomes remains misunderstood.

Official Title
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Biological Alterations of Laughing Gas Outcomes in Neurology

Conditions
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Nitrous Oxide Abuse

Intervention / Treatment
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* Other: blood collection


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: A current or former recreational nitrous oxide user defined With associated clinical signs (group 1) Without associated clinical signs (group 2) With or without clinico-biological sequelae associated with use Consenting to the conduct of the study Socially insured Exclusion Criteria: Pregnant or breastfeeding women Never used nitrous oxide or stopped using it more than 6 months ago Lack of social security coverage Not willing to participate in the entire study

Ages Eligible for Study
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Minimum Age: 14 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Subjects consuming nitrous oxide with clinical outcomes<br>Subjects who consume nitrous oxide and who have been hospitalized in this context and who present clinical signs determined during a neurological evaluation according to the PND (Peripheral Neuropathy Disability) score or who have had a thrombotic accident related to the consumption of nitrous oxide. | Other: blood collection<br>* Biological analyses in the framework of care with conservation of blood samples<br>|
| Subjects consuming nitrous oxide without clinical outcomes<br>Subjects who consume nitrous oxide who do not present clinical signs related to this consumption and recruited during a routine medical consultation. | Other: blood collection<br>* Biological analyses in the framework of care with conservation of blood samples<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood markers related to nitrous oxide consumption | Biomarkers of cobalamin metabolism, methionine cycle and oxidative stress | through study completion an average of 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood markers related to nitrous oxide clinical outcomes. | Biomarkers of cobalamin metabolism, methionine cycle and oxidative stress and biological markers of neurological damage. | Baseline, at 4 weeks, at 3 months and at 6 months | 
| Estimated and self-reported nitrous oxide consumption |  | Baseline, at 4 weeks,and/or at 3 months and at 6 months | 
| The severity of the clinical signs related to nitrous oxide consumption. | The severity of the signs noted during the interrogation and consultation of the patients by filling out a pre-established form listing the neurological signs (gait disorders evaluated by the PND score, presence of paresthesia and associated clinical signs (thrombotic and psychiatric events) | Baseline, at 4 weeks,and/or at 3 months and at 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Nitrous Oxide, Neurology, Thrombosis, Biomarkers, Metabolis