The impact of headache disorders: a prospective analysis of headache referrals to outpatient and inpatient neurology and emergency services in an Irish University teaching hospital.

BACKGROUND: Headache represents a significant proportion of disability globally in general practice, neurology outpatient settings, and emergency departments. There is scant literature regarding the impact of headache on healthcare services in Ireland. AIMS: We aimed to investigate headache burden across the emergency department, inpatient stays, and neurology outpatient department referrals in an Irish University teaching hospital. METHODS: We prospectively collected data regarding emergency department presentations, inpatient neurology consultations, and neurology outpatient referrals for patients with headache between 13th January and 8th March 2020. Data were analyzed using descriptive statistics. RESULTS: There were 180 emergency department attendances, 50 inpatient consultations, and 76 outpatient referrals with headache. Neurological examinations were often incomplete; neuroimaging was commonly employed. Migraine was the most frequent headache diagnosis at discharge in the emergency department and among inpatients after neurology review. Diagnostic uncertainty was identified-33% of patients left the emergency department with no diagnosis, and "unknown/unspecified headache" was recorded on 49% of outpatient referrals and 30% of inpatient consult requests. Medication overuse headache coexisted with migraine in nine patients in the inpatient group. Prophylaxis had been trialed in 56% of patients with migraine referred to outpatients. CONCLUSIONS: Primary headache disorders have a large impact on hospital services. Diagnostic uncertainty is common; neuroimaging is relied upon. Appropriate care pathways, education, and resource allocation should be prioritized.

Frequency of inter-specialty consensus decisions and adherence to advice following discussion at a weekly neurovascular multidisciplinary meeting.

BACKGROUND/AIMS: Data are limited on the frequency of 'consensus decisions' between sub-specialists attending a neurovascular multidisciplinary meeting (MDM) regarding management of patients with extracranial carotid/vertebral stenoses and post-MDM 'adherence' to such advice. METHODS: This prospective audit/quality improvement project collated prospectively-recorded data from a weekly Neurovascular/Stroke Centre MDM documenting the proportion of extracranial carotid/vertebral stenosis patients in whom 'consensus management decisions' were reached by neurologists, vascular surgeons, stroke physicians-geriatricians and neuroradiologists. Adherence to MDM advice was analysed in asymptomatic carotid stenosis (ACS), symptomatic carotid stenosis (SCS), 'indeterminate symptomatic status stenosis' (ISS) and vertebral artery stenosis (VAS) patients, including intervals between index event to MDM + / - intervention. RESULTS: One hundred fifteen patients were discussed: 108 with carotid stenosis and 7 with VAS. Consensus regarding management was noted in 96.5% (111/115): 100% with ACS and VAS, 96.2% with SCS and 92.9% with ISS. Adherence to MDM management advice was 96.4% (107/111): 100% in ACS, ISS and VAS patients; 92% (46/50) in SCS patients. The median interval from index symptoms to revascularisation in 50-99% SCS patients was 12.5 days (IQR: 9-18.3 days; N = 26), with a median interval from MDM to revascularisation of 5.5 days (IQR: 1-7 days). Thirty patients underwent revascularisation. Two out of twenty-nine patients (6.9%) with either SCS or ISS had a peri-procedural ipsilateral ischaemic stroke, with no further strokes/deaths during 3-months follow-up. CONCLUSIONS: The high frequency of inter-specialty consensus regarding management and adherence to proposed treatment supports a collaborative/multidisciplinary model of care in patients with extracranial arterial stenoses. Service development should aim to shorten times between MDM discussion-intervention and optimise prevention of stroke/death.

PARKIN, PINK1, and DJ1 analysis in early-onset Parkinson's disease in Ireland.

BACKGROUND: Variants in PARKIN, PINK1, and DJ1 are associated with early-onset Parkinson' disease (EOPD, age-at-onset < 45). We previously reported a single PINK1 and a single DJ1 heterozygous variant carrier. PURPOSE: We aimed to expand upon our previous EOPD studies and investigate for any genotype-phenotype correlations in Irish PD. METHODS: Three hundred fourteen PD patients were recruited from Dublin Neurological Institute, Ireland. Genetic analysis was performed at the Mayo Clinic, Jacksonville, USA. We screened 81 patients with young-onset PD (age-at-onset < 50), of which 58 had EOPD. RESULTS: We identified 4 patients with homozygous/compound heterozygous variants and 3 heterozygote carriers (pathogenic PINK1/DJ1 variants were not found). Expansion of one of the pedigrees showed a novel variant in exon 9, in a symptomatic patient. We identified 6.89% PARKIN variant carriers associated with EOPD. CONCLUSION: These findings suggest that PINK1 and DJ1 are rarely associated with Irish YOPD, while PARKIN variant frequency is similar to that reported worldwide.

Pembrolizumab treatment of inflammatory progressive multifocal leukoencephalopathy: a report of two cases.

Progressive multifocal leukoencephalopathy (PML) is a rare but devastating neurological disease caused by reactivation of the JC virus in susceptible individuals. The illness has classically been associated with the human immunodeficiency virus (HIV) and multiple sclerosis (MS) patients who are treated with natalizumab. It is also associated with haematological malignancies, organ transplantation, autoimmune disease and immunodeficiency. Aside from natalizumab, a range of other immunomodulators including obinutuzumab and rituximab have been associated with PML. The nature of these associations is unclear due to the overall low incidence of PML associated with these drugs and the fact that most patients will have other confounding risk factors for developing the disease. There is no known effective treatment available for PML in the non-HIV, non-MS cohort. Recent case studies and series have proposed that pembrolizumab, an anti-PD-1 immune checkpoint inhibitor, may be a potentially efficacious option for these patients. We present two cases of non-HIV, non-MS patients with PML who were treated with pembrolizumab with little clinical benefit. The literature surrounding pembrolizumab use in PML is discussed, with a focus on potential indicators of successful outcomes for patients who receive this therapy.

Ondine's Curse in Frontotemporal Dementia with Parkinsonism Linked to Chromosome 17 Caused by MAPT Variants.

BACKGROUND: "Ondine's curse" or central hypoventilation, induces an apparently spontaneous failure of automatic respiratory drive, henceforth necessitating a conscious effort to breathe and sleep induced hypoventilation. It is typically seen in congenital central hypoventilation syndrome, but may be acquired. OBJECTIVES: To highlight Ondine's curse as part of frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) secondary to microtubule associated protein tau (MAPT) variants. METHODS: We describe the clinical and neuropathological findings in two patients with fatal Ondine's curse associated with FTDP-17 and secondary to MAPT variants (FTDP-17t). We discuss neuroanatomical correlates. We review two prior reports of central hypoventilation associated with MAPT variants suggesting that Ondine's curse occurs uncommonly in FTDP-17t. RESULTS: Despite variants affecting different regions of MAPT and a degree of heterogeneity in pathological findings, the patients reviewed all experienced central hypoventilation during their disease course. CONCLUSION: Tauopathy should be considered in patients with adult-onset Ondine's curse.

On the Emergence of Tremor in Prodromal Parkinson's Disease.

Clinical, neuropathological and neuroimaging research suggests that pathological changes in Parkinson's disease (PD) start many years before the emergence of motor signs. Since disease-modifying treatments are likely to be most effective when initiated early in the disease process, there has been significant interest in characterizing prodromal PD. Some people with PD describe autonomic symptoms at the time of diagnosis suggesting that autonomic dysfunction is a common feature of prodromal PD. Furthermore, subtle motor signs may be present and emerge prior to the time of diagnosis. We present a series of patients who, in the prodromal phase of PD, experienced the emergence of tremor initially only while yawning or straining at stool and discuss how early involvement of autonomic brainstem nuclei could lead to these previously unreported phenomena. The hypothalamic paraventricular nucleus (PVN) plays a central role in autonomic control including bowel/bladder function, cardiovascular homeostasis and yawning and innervates multiple brainstem nuclei involved in autonomic functions (including brainstem reticular formation, locus ceruleus, dorsal raphe nucleus and motor nucleus of the vagus). The PVN is affected in PD and evidence from related phenomena suggest that the PVN could increase tremor either by increasing downstream cholinergic activity on brainstem nuclei such as the reticular formation or by stimulating the locus ceruleus to activate the cerebellothalamocortical network via the ventrolateral nucleus of the thalamus. Aberrant cholinergic/noradrenergic transmission between these brainstem nuclei early in PD couldlead to tremor before the emergence of other parkinsonian signs, representing an early clinical clue to prodromal PD.

Association Between Glucocerebrosidase Mutations and Parkinson's Disease in Ireland.

Multiple studies implicate heterozygous GBA mutations as a major genetic risk factor for Parkinson's disease (PD); however, the frequency of mutations has never been examined in PD patients from the Irish population. We prospectively recruited 314 unrelated Irish PD patients (UK Brain Bank Criteria) and 96 Irish healthy controls (without any signs or family history of parkinsonism) attending. The Dublin Neurological Institute (DNI). Complete exon GBA Sanger sequencing analysis with flanking intronic regions was performed. The GBA carrier frequency was 8.3% in PD and 3.1% in controls. We identified a number of potentially pathogenic mutations including a p.G195E substitution and a p.G377C variant, previously described in a case study of Gaucher's disease in Ireland. On genotype-phenotype assessment hallucinations, dyskinesia, and dystonia were more prevalent in GBA-PD. The genetic etiology of PD in Ireland differs from the continental Europe as seen with the lower LRRK2 and higher than in most European countries GBA mutation frequency. Determining genetic risk factors in different ethnicities will be critical for future personalized therapeutic approach.

EBV driven natural killer cell disease of the central nervous system presenting as subacute cognitive decline.

Brain biopsy in patients presenting with subacute encephalopathyis never straightforward and only undertaken when a 'treatable condition' is a realistic possibility. This 63 year old right handed, immunocompetent Caucasian woman presented with an 8 month history of rapidly progressive right-sided hearing impairment, a 4 month history of intermittent headaches, tinnitus, 'dizziness', dysphagia, nausea and vomiting, with the subsequent evolution of progressive gait ataxia and a subacute global encephalopathy. The possibility of CJD was raised. Brain biopsy was carried out. Western blot for prion protein was negative. She died 9 days later and autopsy brain examination confirmed widespread subacute infarction due to an EBV positive atypical NK/T-cell infiltrate with positivity for CD3, CD56, granzyme B, perforin and EBER with absence of CD4, CD5 and CD8 expression. Molecular studies for T-cell clonality were attempted but failed due to insufficient DNA quality. Serology was consistent with past EBV infection (EBV VCA and EBNA IgG Positive). There was no evidence of disease outside the CNS. Primary central nervous system NK/T-cell lymphoma is extremely rare. The rare reported cases all present with a discrete intracranial mass, unlike the diffuse infiltrative pattern in this case. Whilst the diffuse interstitial pattern is reminiscent of chronic active EBV infection (CAEBV) seen in other organ systems such as the liver and bone marrow, the clinical presentation and epidemiologic profile are not typical for CAEBV.

A Wolf in Sheep's Clothing: An "Alien Leg" in Corticobasal Syndrome.

BACKGROUND: Alien limb phenomenon occurs in 50-60% of patients with corticobasal syndrome (CBS) and usually presents with an "alien hand" phenomenon. The "alien foot" presentation is rarer and may be misdiagnosed, as foot involvement can lead to erroneous localization of the clinical problem to the knee, hip, or back. Subsequently misdiagnoses such as myelopathy, radiculopathy, functional disorder, stiff leg syndrome, neuromyotonia, and painful leg moving toes syndrome may occur. CASE REPORT: We describe two patients with alien foot symptoms that resulted in multiple opinions from different specialists, multiple diagnostic and therapeutic procedures, and delayed diagnosis. Eventually a diagnosis of CBS was made in both. Alien foot symptoms may be more common than initially thought and can result in a delayed diagnosis of CBS. CONCLUSION: The inclusion of this clinical finding in recently proposed diagnostic criteria highlights the need for increased clinical awareness.

Mitochondrial targeting sequence variants of the CHCHD2 gene are a risk for Lewy body disorders.

OBJECTIVE: To assess the role of CHCHD2 variants in patients with Parkinson disease (PD) and Lewy body disease (LBD) in Caucasian populations. METHODS: All exons of the CHCHD2 gene were sequenced in a US Caucasian patient-control series (878 PD, 610 LBD, and 717 controls). Subsequently, exons 1 and 2 were sequenced in an Irish series (355 PD and 365 controls) and a Polish series (394 PD and 350 controls). Immunohistochemistry and immunofluorescence studies were performed on pathologic LBD cases with rare CHCHD2 variants. RESULTS: We identified 9 rare exonic variants of unknown significance. These variants were more frequent in the combined group of PD and LBD patients compared to controls (0.6% vs 0.1%, p = 0.013). In addition, the presence of any rare variant was more common in patients with LBD (2.5% vs 1.0%, p = 0.050) compared to controls. Eight of these 9 variants were located within the gene's mitochondrial targeting sequence. CONCLUSIONS: Although the role of variants of the CHCHD2 gene in PD and LBD remains to be further elucidated, the rare variants in the mitochondrial targeting sequence may be a risk factor for Lewy body disorders, which may link CHCHD2 to other genetic forms of parkinsonism with mitochondrial dysfunction.

Role for the microtubule-associated protein tau variant p.A152T in risk of α-synucleinopathies.

OBJECTIVE: To assess the importance of MAPT variant p.A152T in the risk of synucleinopathies. METHODS: In this case-control study, we screened a large global series of patients and controls, and assessed associations between p.A152T and disease risk. We included 3,229 patients with clinical Parkinson disease (PD), 442 with clinical dementia with Lewy bodies (DLB), 181 with multiple system atrophy (MSA), 832 with pathologically confirmed Lewy body disease (LBD), and 2,456 healthy controls. RESULTS: The minor allele frequencies (MAF) in clinical PD cases (0.28%) and in controls (0.2%) were not found to be significantly different (odds ratio [OR] 1.37, 95% confidence interval [CI] 0.63-2.98, p = 0.42). However, a significant association was observed with clinical DLB (MAF 0.68%, OR 5.76, 95% CI 1.62-20.51, p = 0.007) and LBD (MAF 0.42%, OR 3.55, 95% CI 1.04-12.17, p = 0.04). Additionally, p.A152T was more common in patients with MSA compared to controls (MAF 0.55%, OR 4.68, 95% CI 0.85-25.72, p = 0.08) but this was not statistically significant and therefore should be interpreted with caution. CONCLUSIONS: Overall, our findings suggest that MAPT p.A152T is a rare low penetrance variant likely associated with DLB that may be influenced by coexisting LBD and AD pathology. Given the rare nature of the variant, further studies with greater sample size are warranted and will help to fully explain the role of p.A152T in the pathogenesis of the synucleinopathies.

Closing the tau loop: the missing tau mutation.

Frontotemporal lobar degeneration comprises a group of disorders characterized by behavioural, executive, language impairment and sometimes features of parkinsonism and motor neuron disease. In 1994 we described an Irish-American family with frontotemporal dementia linked to chromosome 17 associated with extensive tau pathology. We named this disinhibition-dementia-parkinsonism-amyotrophy complex. We subsequently identified mutations in the MAPT gene. Eleven MAPT gene splice site stem loop mutations were identified over time except for 5' splice site of exon 10. We recently identified another Irish family with autosomal dominant early amnesia and behavioural change or parkinsonism associated with the 'missing' +15 mutation at the intronic boundary of exon 10. We performed a clinical, neuropsychological and neuroimaging study on the proband and four siblings, including two affected siblings. We sequenced MAPT and performed segregation analysis. We looked for a biological effect of the tau variant by performing real-time polymerase chain reaction analysis of RNA extracted from human embryonic kidney cells transfected with exon trapping constructs. We found a c.915+15A>C exon 10/intron 10 stem loop mutation in all affected subjects but not in the unaffected. The c.915+15A>C variant caused a shift in tau splicing pattern to a predominantly exon 10+ pattern presumably resulting in predominant 4 repeat tau and little 3 repeat tau. This strongly suggests that the c.915+15A>C variant is a mutation and that it causes frontotemporal dementia linked to chromosome 17 in this pedigree by shifting tau transcription and translation to +4 repeat tau. Tau (MAPT) screening should be considered in families where amnesia or atypical parkinsonism coexists with behavioural disturbance early in the disease process. We describe the final missing stem loop tau mutation predicted 15 years ago. Mutations have now been identified at all predicted sites within the 'stem' when the stem-loop model was first proposed and no mutations have been found within the 'loop' region as expected. Therefore we 'close the tau loop' having 'opened the loop' 21 years ago.

Exonic Re-Sequencing of the Chromosome 2q24.3 Parkinson's Disease Locus.

Genome-wide association studies (GWAS) in Parkinson's disease (PD) have identified over 20 genomic regions associated with disease risk. Many of these loci include several candidate genes making it difficult to pinpoint the causal gene. The locus on chromosome 2q24.3 encompasses three genes: B3GALT1, STK39, and CERS6. In order to identify if the causal variants are simple missense changes, we sequenced all 31 exons of these three genes in 187 patients with PD. We identified 13 exonic variants including four non-synonymous and three insertion/deletion variants (indels). These non-synonymous variants and rs2102808, the GWAS tag SNP, were genotyped in three independent series consisting of a total of 1976 patients and 1596 controls. Our results show that the seven identified 2q24.3 coding variants are not independently responsible for the GWAS association signal at the locus; however, there is a haplotype, which contains both rs2102808 and a STK39 exon 1 6bp indel variant, that is significantly associated with PD risk (Odds Ratio [OR] = 1.35, 95% CI: 1.11-1.64, P = 0.003). This haplotype is more associated than each of the two variants independently (OR = 1.23, P = 0.005 and 1.10, P = 0.10, respectively). Our findings suggest that the risk variant is likely located in a non-coding region. Additional sequencing of the locus including promoter and regulatory regions will be needed to pinpoint the association at this locus that leads to an increased risk to PD.

Mutations in the SPG7 gene cause chronic progressive external ophthalmoplegia through disordered mitochondrial DNA maintenance.

Despite being a canonical presenting feature of mitochondrial disease, the genetic basis of progressive external ophthalmoplegia remains unknown in a large proportion of patients. Here we show that mutations in SPG7 are a novel cause of progressive external ophthalmoplegia associated with multiple mitochondrial DNA deletions. After excluding known causes, whole exome sequencing, targeted Sanger sequencing and multiplex ligation-dependent probe amplification analysis were used to study 68 adult patients with progressive external ophthalmoplegia either with or without multiple mitochondrial DNA deletions in skeletal muscle. Nine patients (eight probands) were found to carry compound heterozygous SPG7 mutations, including three novel mutations: two missense mutations c.2221G>A; p.(Glu741Lys), c.2224G>A; p.(Asp742Asn), a truncating mutation c.861dupT; p.Asn288*, and seven previously reported mutations. We identified a further six patients with single heterozygous mutations in SPG7, including two further novel mutations: c.184-3C>T (predicted to remove a splice site before exon 2) and c.1067C>T; p.(Thr356Met). The clinical phenotype typically developed in mid-adult life with either progressive external ophthalmoplegia/ptosis and spastic ataxia, or a progressive ataxic disorder. Dysphagia and proximal myopathy were common, but urinary symptoms were rare, despite the spasticity. Functional studies included transcript analysis, proteomics, mitochondrial network analysis, single fibre mitochondrial DNA analysis and deep re-sequencing of mitochondrial DNA. SPG7 mutations caused increased mitochondrial biogenesis in patient muscle, and mitochondrial fusion in patient fibroblasts associated with the clonal expansion of mitochondrial DNA mutations. In conclusion, the SPG7 gene should be screened in patients in whom a disorder of mitochondrial DNA maintenance is suspected when spastic ataxia is prominent. The complex neurological phenotype is likely a result of the clonal expansion of secondary mitochondrial DNA mutations modulating the phenotype, driven by compensatory mitochondrial biogenesis.