Background The younger generation in Korea easily exposed to nitrous oxide (N2O) under the name “Happy Balloon” may abuse it. N2O can irreversibly oxidize vitamin B12 and cause abnormal hematopoiesis or nervous system toxicity such as subacute combined degeneration (SCD). The objective of this study was to assist in early diagnosis of N2O-induced SCD of spinal cord by characterizing its clinical manifestations.
Methods Four patients with myelopathy after abusing N2O were enrolled. To characterize N2O-induced myelopathy, previously reported cases of N2O-induced SCD were searched through PubMed and KoreaMed. Collected cases and our four patients were analyzed.
Results A total of 30 patients with N2O-induced myelopathy (26 males and 4 females with mean age of 24 years) were analyzed. These patients took a median dose of 650 canisters for a median duration of 3.5 months. All patients presented sensory disturbances, which involved the lower extremities more frequently (100%) than the upper extremities (63.3%). Gait ataxia (76.7%), weakness in the upper (23.3%) and lower (36.7%) extremities, bladder symptoms (26.7%), Rhomberg sign (43.3%), and Lhermitte’s phenomenon (10.0%) were observed. Serum vitamin B12 levels were decreased in many (63.3%) patients and homocysteine levels were elevated in all. Of 20 patients who underwent magnetic resonance imaging (MRI) of the spine, 19 had abnormal findings. Three patients presented with contrast enhancement in lesions.
Conclusions We strongly recommend that history of N2O abuse should be asked for young patients with suspected myelopathy, especially those presenting with gait ataxia and sensory disturbances suggesting posterior column dysfunction and those presenting long-segment lesion involving the upper cervical cord on MRI.
Subacute combined degeneration (SCD) of the spinal cord, which is a result of vitamin B12 deficiency, may cause irreversible neurological deficits. The lesion in the spinal cord is typically localized to the posterior and lateral columns, as the name implies. In this paper, we report on two patients with SCD, whose lesions involved the bilateral anterior column as well as the posterior and lateral columns. This report illustrates the importance of awareness of clinical and radiologic variable characteristics of SCD.
Background Nitrous oxide (N2O) is used in surgery and dentistry for its anesthetic and analgesic effects. However, neurological and psychiatric manifestations of N2O abuse have been increasingly reported among Korean adults. The aim of this study was to demonstrate laboratory findings of N2O abuse in Korean patients.
Methods Patients diagnosed with N2O-induced neuropathy or myelopathy from August 2018 to December 2019 were enrolled. Their clinical presentations and laboratory and imaging findings were analyzed.
Results Sensory changes and limb weakness were present in nine of the enrolled patients. The laboratory findings revealed that seven patients had high homocysteine levels and five had high methylmalonic acid levels in their blood. Nerve conductions studies indicated that axonal neuropathy was present in four cases and longer F-wave and Hoffman’s-reflex latencies were present in two cases. Signal changes in cervical spine imaging occurred in five patients, while two had normal results.
Conclusions Chronic N2O abuse can cause neurological damage or psychiatric problems. Because N2O is illegal for recreational use in Korea, patients tend to hide their history of use. Even though the spinal imaging results were normal, clinicians should consider the possibility of N2O use, and further electrophysiological tests should be applied for precise evaluations.
Citations
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The prevalence, risks, and detection of driving under the influence of nitrous oxide Frederick R. J. Vinckenbosch, Dinesh Durán Jiménez, Hendrik Helmerhorst, Albert Dahan, Leon Aarts, Floris Bikker, Eef Theunissen, Johannes G. Ramaekers WIREs Forensic Science.2024;[Epub] CrossRef
Nitrous‐oxide‐induced polyneuropathy and subacute combined degeneration of the spine: clinical and diagnostic characteristics in 70 patients, with focus on electrodiagnostic studies L. T. Hassing, F. Y. Jiang, R. Zutt, S. Arends European Journal of Neurology.2024;[Epub] CrossRef
Severe Isolated Peripheral Polyneuropathy without Myelopathy after Nitrous Oxide Abuse: A Case Report Seung-Min Baek, Seungbok Lee, Yu-Mi Kim, Eun-Sil Kim Journal of Electrodiagnosis and Neuromuscular Dise.2022; 24(2): 50. CrossRef
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