Background Neurological presentations resulting from nitrous oxide (N2O) abuse are increasing in Australia and worldwide. Despite known neuropsychiatric sequelae, N2O canisters remain readily available and its use unregulated. Aims To examine the demographics, clinical and electrophysiological findings of patients presenting with neurological complications of N2O abuse, and thus inform clinicians and public health decision‐makers of the significant public health concerns of this increasing practice. Methods Consecutive patients presenting to a tertiary referral metropolitan hospital were included in this series. Patients were identified by a search of discharge summaries of patients admitted with acute or subacute neuropathy or myelopathy and a history of N2O abuse, and from the electrophysiology database. Results Thirteen patients were identified, most presenting with subacute paraesthesia, sensory ataxia and lower limb weakness. Eleven had low serum vitamin B12. Spinal magnetic resonance imaging was consistent with subacute combined degeneration in eight. Nerve conduction studies revealed a motor or sensorimotor axonal neuropathy (three with motor predominance). There was a bimodal demographic distribution consisting of socially isolated, international university students and local residents with a history of mental illness and polydrug abuse. Conclusions Recreational N2O use is an emerging health problem in Australia. International university students and patients with pre‐existing mental illness or polydrug use appear to be at increased risk. A severe motor neuropathy may emerge following vitamin B12 replacement. Public health measures are required to limit the availability of N2O and to educate adolescents and young adults about the potential for significant harm.

The widespread use of highly active antiretroviral therapy (HAART) in HIV-infected individuals mostly in developed countries has dramatically improved their prognosis. In such advantaged regions of the world, therefore, many patients are now transitioning from middle into older age, with altered patterns of disease. While previously a rare complication of HIV infection, cerebrovascular disease (particularly that associated with atherosclerosis) is becoming relatively more important in this treated group of individuals. This review summarises the evidence regarding the shifting epidemiology of cerebrovascular diseases affecting HIV-infected individuals. While outlining the association between HIV infection and AIDS and cerebrovascular disease, as well as opportunistic diseases and HIV-associated vasculopathies, the current evidence supporting an increase in atherosclerotic disease in treated HIV-infected individuals is emphasised and a management approach to ischaemic stroke in HIV-infected individuals is presented. Evidence supporting the important role of HAART and HIV infection itself in the pathogenesis of atherosclerotic disease is discussed, together with preventative approaches to this increasingly important disease process as the population ages. Finally, a discussion regarding the significant association between cerebrovascular disease and HIV-associated neurocognitive disorder is presented, together with possible mechanisms behind this relationship.

Levodopa-carbidopa intestinal gel (LCIG) is effective for the control of motor fluctuations in Parkinson’s disease (PD). The objective of this study is to report the reduction of dyskinesias after transitioning from 16 to 24-h/day LCIG infusion. From a cohort of 74 PD patients treated with LCIG for motor fluctuations, we identified 12 patients that were treated with 24-h per day infusion with the aim to control troublesome daytime dyskinesia. Clinical, demographic, dyskinesia rating scales were evaluated. Daytime dyskinesia was reduced in 75% (9/12) patients following treatment with 24-h therapy, including 7 who were compared with 16-h therapy and 2 that were transitioned from oral dopaminergic therapy to 24-h LCIG. Combining the data from all 12 subjects, troublesome dyskinesias were reduced during 24-h LCIG; UPDRS 4.1 (time spent with dyskinesias) mean change was −1.5 ± 0.75, p = 0.010 (Wilcoxon signed-rank test) and UPDRS 4.2 (functional impact of dyskinesias) mean change was −1.7 ± 0.90, p = 0.016, without changing their UPDRS part 3 “ON” scores (p = 0.138) or H&Y (p = 0.157). In 5 patients, improvement in dyskinesia occurred despite an overall increase in the total daily levodopa dose. None of the patients had worsening of dyskinesia after a median follow-up of 28 months. 24-h per day infusion of LCIG may be a useful strategy in the management of troublesome dyskinesias in PD patients with disabling dyskinesias resistant to attempts to optimise 16-hours per day therapy. We postulate that this may be due to a pharmacodynamic as opposed to pharmacokinetic mechanism.

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BackgroundIntramuscular injections of botulinum toxin A (BTX-A) have been used in the treatment of sleep bruxism (SB) however controlled trials are limited and the optimal injection strategy and dose is not known.MethodsThis double-blind, randomised, placebo-controlled, cross-over study evaluated the efficacy and safety of BTX-A in participants with SB. Average bruxism events per hour of sleep (Bruxism Index, BI) was calculated using surface electromyography. Participants with BI >5 were included and randomised by order of injection (active or placebo with the opposite 20 weeks later) and into one of three differing treatment groups: bilateral masseter (60 units(U)), bilateral masseter and temporalis (90U) and bilateral masseter, temporalis and medial pterygoid muscles (120U). Change in BI and subjective measures of headache, pain, and bruxism at 4 and 12 weeks was calculated following intervention, and differences between treatment groups analysed.Results41 participants were recruited, 35 randomised and data from 22 participants (14 female) were analysed. BI was significantly lower at 4 weeks after active treatment when compared with placebo (mean=−1.66, p=0.003), not sustained at 12 weeks. The difference was greater with higher doses injected and among those with greater baseline BI. There was no difference in subjective measures at any time point. Five participants injected had mild, transient side effects.DiscussionTargeted BTX-A injection is a safe and effective treatment for SB. A greater benefit may be achieved by administering BTX-A into more muscles and at higher total doses and among those with higher baseline BI.Trial registration numberACTRN12618001430224.

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Chronic graft‐versus‐host disease (cGVHD) complicating allogeneic haemopoietic stem cell transplantation rarely involves the nervous system; oromandibular parafunction has not been previously reported. We describe five patients with cGVHD, presenting with bruxism, limitation of mouth opening, jaw locking, pain and masseter hypertrophy. Pathophysiological mechanisms are discussed. Targeted botulinum toxin injections were an effective treatment with minimal side‐effects.