Nitrous oxide-induced myeloneuropathy in a Thai adolescent: a case report

Nitrous oxide, an inhalational anaesthetic, is popular with adolescents worldwide as an accessible recreational drug which induces a euphoric effect. However, chronic abuse leads to serious complications such as myeloneuropathy and bone marrow suppression by inactivation of vitamin B12. A 17-year-old girl presented with nitrous oxide-induced myeloneuropathy. She reported chronic nitrous oxide inhalation for 10 months and was admitted to the emergency department on account of repeated falls for 2 weeks. She also had ascending paraesthesia in both legs and urinary incontinence. Neurological examination demonstrated bilateral lower extremity weakness [motor power: proximal muscles 4/5, plantar flexion and extensor hallucis longus (EHL) 3/5], decreased sensation, proprioception and vibration of the lower extremities. Deep tendon reflexes were absent in the ankles and knees. Laboratory results demonstrated mild anaemia [Hb 11.2 g/dL (12.0-16.0), haematocrit 35.4% (36-50), MCV 89.4 fl (78-102)] with significant hypersegmented neutrophils in a peripheral blood smear. Serum vitamin B12 was 340 pg/mL (197-771), but serum homocysteine was increased at 65.8 µmol/L (5-15). A nerve conduction study was prolonged, and F-waves were absent from the bilateral perineal and tibial nerves, indicating diffuse demyelinating motor polyneuropathy. Magnetic resonance imaging of the whole spine demonstrated faint T2 hypersignal intensity and an inverted V-shape appearance at the posterior column of the upper thoracic cord (around T2-T6), a pathognomonic sign of vitamin B12 deficiency or subacute combined degeneration of the nitrous oxide-induced myeloneuropathy. A 7-day course of 1000 µg cyanocobalamin was given intramuscularly, followed by weekly doses for 4 weeks. Supplements of daily oral vitamin B1, B6 and B12 (65 µg vitamin B12) were administered, along with rehabilitation. At the 6-months outpatient follow-up, there were a few residual neurological abnormalities: weakness of the left EHL (grade 4/5) and an absent deep tendon reflex in the left ankle. This case emphasises the significant health consequences of chronic abuse of nitrous oxide, myeloneuropathy and megaloblastic anaemia, by inactivation of vitamin B12. The myelopathy is noticeably improved by cyanocobalamin.Abbreviations: EHL: extensor hallucis longus; MRI: magnetic resonance imaging; NCS: nerve conduction study.

The efficacy of infrared filter window film to prevent hyperthermia in neonatal hyperbilirubinemia with conventional phototherapy: a randomized control trial

BACKGROUND

Phototherapy is the first-line treatment of neonatal hyperbilirubinemia. Possible side effects caused by phototherapy include hyperthermia and dehydration. Currently, there are many types of infrared blocking film for potential use in reducing infrared radiation exposure and preventing hyperthermia. This study aims to evaluate the efficacy of infrared blocking film in preventing hyperthermia during the first 24 h of phototherapy.

METHODS

The randomized controlled trial study was carried out in 44 newborns with hyperbilirubinemia. Infrared filter film with 75% visible light transmission and 90% infrared rejection was used in the study. Body temperature was measured for the assessment of the efficacy of filter film from axillary and rectal routes.

RESULTS

There was a significantly lower incidence of hyperthermia from the axillary temperature in the group with infrared blocking film compared to the control group (p = 0.031). The axillary temperature between before and after initiation of phototherapy in filter film group was significantly better (p = 0.008). According to efficacy of treatment, the study demonstrated that infrared filter film did not interfere with the efficacy of phototherapy in reducing bilirubin level.

CONCLUSIONS

The infrared filter film was significantly more effective in preventing hyperthermia from phototherapy in the first 24 h without causing any significant difference in reduction of bilirubin level.

THAI CLINICAL TRIALS REGISTRY

TCTR20190619001.

Methotrexate induced pericarditis and pericardial effusion in psoriatic patient

We describe a 62-year-old woman with Psoriasis who presented as Methotrexate-induced pericarditis and pericardial effusion. Aspiration of the pericardium was required and the patient made a satisfactory recovery. At six-months follow-up, she remained well, psoriasis plaques was controlled by topical crude coal tar and topical corticosteroid. These complications are extremely rare, but have been described as isolated phenomena associated with methotrexate therapy.