Nitrous oxide abuse induced subacute combined degeneration despite patient initiated B12 supplementation

Temple, Courtney; Horowitz, B. Zane

doi:10.1080/15563650.2022.2046772

Cited by 20 publications

(21 citation statements)

References 11 publications

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“…Serum B12 levels were described in 21 case series 17–20,22–29,31,33–40 with 243 reported values; of which 111 were low, 126 were normal and six were high. Homocysteine, MMA, haemoglobin and MCV were described in 19, 18–20,22–29,31–35,37–39 five 24,26,34,35,37 and 12, 18,20,23–25,27,29,33,34,37–39 and 11 18,20,24,25,27,29,31,33,34,37,38 case series respectively. All 20 reported MMA results were elevated as were 187 of 208 reported homocysteine values.…”

Section: Resultsmentioning

confidence: 99%

“…Most case series reported neurological complaints with 23 studies reporting presentations of sensory change, weakness or autonomic dysfunction, [17][18][19][20][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] whereas seven described psychiatric symptoms. 18,21,23,27,30,31,33 Other conditions reported included hyperpigmentation, 22,25,39 pruritis 25 and haematological sequelae.…”

Section: Clinical Presentationmentioning

confidence: 99%

“…Serum B12 levels were described in 21 case series [17][18][19][20][22][23][24][25][26][27][28][29]31,[33][34][35][36][37][38][39][40] with 243 reported values; of which 111 were low, 126 were normal and six were high. Homocysteine, MMA, haemoglobin and MCV were described in 19, [18][19][20][22][23][24][25][26][27][28][29][31][32][33][34][35][37][38][39] five 24,26,34,35,37 and 12, 18,20,[23][24][25]27,…”

Section: Investigationsmentioning

confidence: 99%

“…MRI spine results were reported in 21 case series with dorsal column abnormalities demonstrated in 18 studies, [17][18][19][20][22][23][24][25]27,[29][30][31][32][33][34][37][38][39] lesions of unspecific location in one study 28 and two reported no cord lesion. 35,40 Cerebral white matter changes were identified in two case series.…”

Section: Investigationsmentioning

confidence: 99%

“…17,19,22,24,25,28,29,32,33,[35][36][37][38][39][40] Two reported progression in the setting of continued N 2 O use 27,35 and one no recovery. 39 Outcomes were not reported in eight studies 18,21,23,26,27,30,31,34 and four studies reported patients lost to follow up. 17,29,33,37 Within individual case reports, 36 subjects demonstrated a complete recovery, 40 only partially recovered, two did not recover and 12 were lost to follow up or had no outcome reported.…”

Section: Outcomementioning

confidence: 99%

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Review article: Clinical manifestations and outcomes of chronic nitrous oxide misuse: A systematic review

Marsden

Sharma

Rotella

2022

Emerg Medicine Australasia

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Recreational nitrous oxide (N2O) use is widespread, and complications associated with its use are increasingly common. We sought to identify risk factors, clinical features and outcomes in individuals presenting with effects of chronic N2O abuse to develop an approach to clinical assessment and management. A systemic literature review was completed with searches conducted across EMBASE, MEDLINE, PSYCINFO and Cochrane databases. Our search strategy identified 612 studies, 105 met inclusion criteria, and 10 were added via hand search. Subjects from 24 case series and 91 case reports were typically in their 20s, using over 100 bulbs daily for several months. Neurological presentations, including sensory change, gait disturbance or weakness, were characteristic. Serum Vitamin B12 was normal or raised in 133 out of 243 case series subjects and 37 out of 84 reports. Serum homocysteine and methylmalonic acid were usually raised. Macrocytosis and anaemia were not commonly seen. MRI findings were abnormal with dorsal column change where specified, typically involving the cervical spine. Nerve conduction studies mostly reported a sensorimotor polyneuropathy. B12 replacement was the treatment of choice and partial recovery was most reported. This review highlights the dose‐dependent nature of chronic N2O toxicity and recognises functional B12 deficiency as the cause. As B12 is often normal, homocysteine and methylmalonic acid are important biomarkers of disease. An approach to diagnosis is offered but requires validation in prospective studies. Research exploring B12 and methionine therapy is required to refine management.

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