SPECT findings on neuropsychiatric symptoms caused by nitrous oxide abuse

Abstract

ObjectiveThe aim of the study was to investigate the clinical, neuropsychological, and regional cerebral blood flow (rCBF) perfusion changes in patients with neuropsychiatric symptoms caused by nitrous oxide (N2O) abuse.MethodsA total of 16 patients with neuropsychiatric symptoms caused by nitrous oxide abuse were recruited for this study. The study was carried out in the withdrawal phase of N2O abuse. A 925–1110 MBq 99mTc-ECD was administered intravenously. SPECT/CT images were collected with a low-energy and high-resolution collimator. The region uptake statistics of different brain regions of interest between patients with N2O abuse and normal people of the databases for younger subjects from the Scenium DB Comparison software were calculated automatically.ResultsThe clinical manifestations of the 16 patients with neuropsychiatric symptoms were mood lability, anxiety, hallucination, delusion, agitation, confusion, and other psychiatric symptoms. In addition, 15 of the patients also complained of memory decline; 14 patients manifested numbness or paresthesia; 14 patients developed limb weakness, and their motor impairments were more severe in the lower limbs than in the upper limbs; and eight patients had urinary and defecation disturbances. In the neuropsychological examination, the BPRS score was 54.69 ± 11.48, the HAMD score was 30.00 ± 11.06, the HAMA score was 18.06 ± 5.77, the MMSE score was 28.06 ± 2.29, and the MoCA score was 25.06 ± 3.40. SPECT showed hypoperfusion in the frontal and temporal lobes, which is consistent with the clinical findings.ConclusionThis was the first study to demonstrate the obvious effect of N2O abuse on CBF in patients with neuropsychiatric symptoms. CBF perfusion imaging is helpful to detect the changes in the local brain functional activity in patients with N2O abuse.

Cerebral Infarction with Haemorrhagic Transformation and Cortical Laminar Necrosis Induced by Inhalation of Nitrous Oxide: A Case Report

“…Wang et al performed single-photon emission-CT/CT to assess cerebral perfusion in 16 patients who had abused N 2 O and found frontal lobe hypoperfusion in 56% (9/16) and temporal lobe hypoperfusion in 75% (12/16) of the patients. Frontal and temporal lobe hypoperfusion is consistent with the clinical manifestations of psychobehavioural abnormalities and cognitive decline caused by N 2 O abuse [21]. We hypothesised that our patient's longterm N 2 O abuse caused endothelial dysfunction and atherosclerotic changes in the vessels of the distal branches of the left middle cerebral artery and that vasospasm at the onset of the disease caused hypoperfusion of the deeply penetrating and cortical branches of the left middle cerebral artery.…”