Lactate is produced from anaerobic glycolysis, which occurs in most tissues in the human body. Blood lactate is tested in most physiologically unwell patients in the Emergency Department and helps to guide treatment and prognosis. Cerebrospinal fluid (CSF) lactate, however, is not often measured. Various central nervous system (CNS) conditions lead to a rise in CSF lactate, including acute neurological infection, stroke, seizures and mitochondrial pathologies. This article discusses the utility and limitations of CSF lactate, highlighting specific clinical situations where it can help in the diagnosis of CNS infections and unexplained encephalopathy.

Amyotrophic lateral sclerosis (ALS) is an invariably fatal adult-onset neurodegenerative disorder; 10% of ALS is autosomal dominant but even sporadic ALS exhibits significant heritability. Dysfunctional voltage- gated sodium channels (NaVs) have been implicated in both sporadic and familial forms of the disease, but it is unclear whether these are an upstream cause or a downstream consequence. Rare missense mutations in the SCN4A gene, encoding NaV1.4, disrupt membrane excitability and cause autosomal dominant muscle channelopathies such as myotonia and hypo/hyperkalaemic periodic paralysis. We report two patients with congenital SCN4A channelopathy due to p.S1159P and p.R672H mutations who developed ALS in later life. Based on our finding we hypothesised that ALS may be linked to genetic mutations in other voltage gated ion channels. Rare-variant burden testing using whole genome sequenc- ing data from 4,495 ALS patients and 1,925 controls within the superfamily of voltage-gated ion channels (Accession: ssf81324) identified one gene, SCN7A, which passed multiple testing correction (p=0.0002, Firth logistic regression) consistent with an enrichment of ALS-associated mutations. We propose that genetic mutations within NaVs leading to neuromuscular excitotoxicity are an upstream cause of ALS. Early identification of ALS patients carrying NaV mutations might lead to personalised therapy with a sodium channel-blocking agent such as riluzole.j.franklin@doctors.org.uk

IntroductionThe differential diagnosis of patients presenting with cavernous sinus (CSS) or orbital apex syndromes (OAS) are broad and can be challenging with regards to both diagnosis and treatment.MethodsWe performed a retrospective cohort study of such presentations at our institution from 2015–2021, collecting demographics, investigations and their yield, final diagnosis and management & outcomes.Results30 patientsMean age 50 ± 18.3 yearsProminent pain in 87%Raised ESR in 27% which subsequently normalisedIgG4 subsets raised in 7%Matched oligoclonal bands and raised CSF protein were the commonest CSF anomaliesAll had cross-sectional imaging2 patients with an initially normal MRI had a repeat diagnostic MRI within 2 weeks30% of patients had either lymph node or retro-orbital tissue biopsy76% had idiopathic retro-orbital inflammation, 7% neurosarcoidosis and 7% IgG4 disease10% had a neoplastic processGood recovery seen for idiopathic retro-orbital inflammation treated with IVMP and steroid taperConclusionA high number of patients in our cohort with CSS/OAS have a presumed inflammatory aetiology but with excellent clinical outcome. When clinical suspicion remains high, patients should have interval MR imaging. Bloods & lumbar puncture generally demonstrate non-specific abnormalities and a tissue diagnosis should be obtained if possible for diagnostic security.aravindhan.baheerathan1@nhs.net

A 33 year old male with no significant past medical history presented to the emergency department with an acute onset 4 day history of an odd sensation over his tongue and slurring of his speech. He had noted that his tongue deviated to the left when he stuck it out. There was no headache and no taste disturbance.Clinical examination revealed a left sided hypoglossal nerve palsy. Sensation of the tongue to pin-prick and taste was normal. There was no Horner’s syndrome.CT Angiogram of aortic arch and carotid vasculature demonstrated marked irregular calibre and increase in wall thickness of the left internal carotid artery (ICA), just adjacent to the external aperture of the hypoglossal canal, in keeping with a localised left ICA dissection. There was no clinical or radiological evidence of infarction. He was treated with high-dose anti-thrombotic treatment.An acute isolated hypoglossal nerve palsy as a sequelae of a high ICA dissection is a rare but well docu- mented clinical presentation. The hypoglossal nerve is vulnerable to compression as it passes between the internal jugular vein and internal carotid artery at the skull base. It is crucial that neurologists and stroke physicians swiftly recognise this clinico-radiological syndrome to facilitate prompt, appropriate investigation and commencement of appropriate treatment.aravindhan.baheerathan1@nhs.net

IntroductionGlobal efforts in vaccine development against SARS-CoV-2 saw the Pfizer-BioNTech vaccine approved for use in the United Kingdom (UK) on 2nd December 2020. There have long been discussions around vaccination in patients with multiple sclerosis (pwMS). We conducted a patient survey as part of the UK MS Register (UKMSR), to understand pwMS views on COVID vaccination.MethodPwMS were invited by email to complete a COVID-19 vaccine online questionnaire as part of the UKMSR on 7th December 2020.ResultsA total of 3092 pwMS completed the survey by 7th January 2021. 69.1% of patients indicated they are definitely going to get a COVID-19 vaccine, 16.1% probably, 9.1% possibly, 3.4% probably not and 2.3% definitely not. Factors examined includes gender, age, highest educational attainment and type of MS. Additionally, we explored whether previous experiences of vaccinations affected attitudes towards COVID vaccination. The top reasons for not taking a COVID vaccine included safety concerns and insufficient information.ConclusionThis UKMSR patient survey showed 85.2% of pwMS intend to get vaccinated against SARS- CoV-2, which is higher than the UK general public of 67% (1). More information on vaccine safety in pwMS would be helpful in making informed decisions.ReferencesYouGov Research: How many Britons are willing to take a coronavirus vaccine? 11–12 November 2020yun.huang@nhs.net