Changing faces of mitochondrial disease: autosomal recessive POLG disease mimicking myasthenia gravis and progressive supranuclear palsy.

Background: Mitochondrial disorders are known to cause diverse neurological phenotypes which cause a diagnostic challenge to most neurologists. Pathogenic polymerase gamma (POLG) variants have been described as a cause of chronic progressive external ophthalmoplegia, which manifests with ptosis, horizontal and vertical eye movement restriction and myopathy. Autosomal dominant progressive external ophthalmoplegia is rarely associated with Parkinsonism responsive to levodopa. Methods: We report a case of a 58-year-old man who presented with an eye movement disorder then Parkinsonism who made his way through the myasthenia then the movement disorder clinic. Results: A diagnostic right tibialis anterior biopsy revealed classical hallmarks of mitochondrial disease, and genetic testing identified compound heterozygous pathogenic gene variants in the POLG gene. The patient was diagnosed with autosomal recessive POLG disease. Conclusions: It is important to maintain a high index of suspicion of pathogenic POLG variants in patients presenting with atypical Parkinsonism and ophthalmoplegia. Patients with POLG-related disease will usually have ptosis, and downgaze is typically preserved until late in the disease. Accurate diagnosis is essential for appropriate prognosis and genetic counselling.

Delivering an advice and guidance service in neurology.

It is increasingly common for secondary care to provide advice to primary care without an outpatient appointment. Even before the increased telemedicine during COVID-19, many hospital services gave advice alone for some referrals, yet there are few published data about patient outcomes. Does advice and guidance alter outpatient numbers or simply mean that patients are seen later? Which neurological conditions can we manage at a distance? Do complaints increase from either primary care or patients? Do clinics become more complex and time consuming? Our department has developed an advice and guidance service embedded within the English electronic referral system since 2017, allowing detailed analysis of the outcome of 6500 patients over 2.5 years. We suggest ways to set up and run a neurology advice and guidance service, looking at the potential benefits and the barriers.

Behavioral and brain mechanisms mediating conditioned flight behavior in rats.

Environmental contexts can inform animals of potential threats, though it is currently unknown how context biases the selection of defensive behavior. Here we investigated context-dependent flight responses with a Pavlovian serial-compound stimulus (SCS) paradigm that evokes freeze-to-flight transitions. Similar to previous work in mice, we show that male and female rats display context-dependent flight-like behavior in the SCS paradigm. Flight behavior was dependent on contextual fear insofar as it was only evoked in a shock-associated context and was reduced in the conditioning context after context extinction. Flight behavior was only expressed to white noise regardless of temporal order within the compound. Nonetheless, rats that received unpaired SCS trials did not show flight-like behavior to the SCS, indicating it is associative. Finally, we show that pharmacological inactivation of two brain regions critical to the expression of contextual fear, the central nucleus of the amygdala (CeA) and bed nucleus of the stria terminalis (BNST), attenuates both contextual fear and flight responses. All of these effects were similar in male and female rats. This work demonstrates that contextual fear can summate with cued and innate fear to drive a high fear state and transition from post-encounter to circa-strike defensive modes.

Unusual cause of treatable Parkinsonism.

A 78-year-old woman presented with features of bilateral, asymmetric Parkinsonism for 1 year, with prominent difficulties with continence, swallowing and apathy. Brain imaging showed evidence of chronic venous sinus thrombosis with dilated serpiginous vessels over the brain surface in keeping with a dural arteriovenous fistula, together with high T2 signal on MRI in the basal ganglia. Having responded only modestly to levodopa, she received 6 months of anticoagulation followed by embolisation of the dural arteriovenous fistula, with good response. Cerebral dural arteriovenous fistula is a rare, structural cause of atypical Parkinsonism.

Early Onset Parkinson's Disease in a family of Moroccan origin caused by a p.A217D mutation in PINK1: a case report.

BACKGROUND: Bi-allelic mutations in the genes Parkin (PARK2), PINK1 (PARK6) and DJ-1 (PARK7) are established causes of autosomal recessive early-onset Parkinson's Disease (EOPD). PINK1 mutations are the second commonest cause of EOPD. Specific mutations may be relatively common in certain populations because of a founder effect. Homozygous p.A217D PINK1 mutations were previously shown to cause EOPD in a large Sudanese kindred. CASE PRESENTATION: Here we report the segregation of homozygous PINK1 p.A217D mutations in a family originating in Morocco with a history of parental consanguinity. From the clinical information available for the index case, the phenotype of mild, slowly-progressive Parkinsonism is consistent with previous reports of p.A217D disease and of PINK1 disease phenotype more generally. The reported features of early prominent lower-limb symptoms and gait disturbance with asymmetrical onset are more frequent among PINK1 disease cases. CONCLUSIONS: Together, reports of p.A217D in families of Moroccan and Sudanese origin suggest that p.A217D is a North African mutation due to a founder effect. Wider genetic analyses of EOPD in North Africa would be useful to estimate the prevalence of Parkinsonism caused by PINK1 p.A217D. In the absence of bi-allelic Parkin mutations, PINK1 mutations should be considered in cases with evidence of autosomal recessive inheritance of EOPD and presentation of atypical features such as early lower-limb symptoms and gait disturbance with asymmetrical onset, which appear to be common in Mendelian EOPD.

Neurological disorder screening in the elderly in low-income countries.

There are few data on neurological disorder prevalence from developing countries, particularly in the elderly in sub-Saharan Africa (SSA). This is in part due to the lack of a feasible and valid screening instrument. We aimed to develop (and pilot) a brief screening instrument for neurological disorders in an elderly population in SSA. Our study population of 2,232 was selected at random from the entire 70 years and over population of a demographic surveillance site in rural Tanzania. One village, with a population of 277, was randomly selected as a pilot site prior to screening the rest of the study population. We designed a screening questionnaire based on the neurological section of the WHO International Statistical Classification of Diseases and Related Health Problems 10th Revision for use by non-medical interviewers (NMI). Of the 277 participants aged 70 years and over in the pilot village, 82 had neurological disorders, with a further 267 identified as having neurological disorders during the study extension to the remaining study population of 1955. The questionnaire was practical, acceptable to recipients, and easily performed by an NMI. The sensitivity and specificity of the questionnaire were 87.8 and 94.9 %, respectively, in the pilot and 97.0 and 90.4 %, respectively, in the extension. This is the first published screening instrument for measuring the prevalence of neurological disorders in a developing country, which is dedicated to the elderly population. It is feasible to use and has high sensitivity and specificity.

Intergroup dialogue courses on sexual orientation: lesbian, gay and bisexual student experiences and outcomes.

Intergroup dialogue is a method of social justice education. Most intergroup dialogue research explores race and gender identities. Sexual orientation dialogues are uncommon and not yet examined empirically. This qualitative study explores sexual orientation dialogue courses from the perspective of lesbian, gay, and bisexual (LGB) student participants. Understanding target, or marginalized, group perspective of planned intergroup experiences is important given concerns raised in the literature. We document student motivations for participating in dialogues, core outcomes, and main challenges that arose in dialogue. Core outcomes include learning about and accepting one's sexual identity and empowerment. Challenges include those stemming from invisibility of sexual orientation identity. Recommendations are made for intergroup dialogue practice and research.

NMDA receptor encephalitis--expanding the clinical spectrum.

A young woman presented with memory problems of subacute onset. Imaging was normal. She was admitted with severe complex partial status epilepticus requiring intensive care support and ventilation. Fits proved difficult to control requiring high dose anticonvulsants. She developed a profound amnesic syndrome. A clinical diagnosis of autoimmune encephalitis was considered and she was treated with intravenous steroids with an excellent cognitive outcome. She continues to have occasional seizures.

Intact coupling of M1 receptors and preserved M2 and M4 receptors in the cortex in progressive supranuclear palsy: contrast with other dementias.

Progressive supranuclear palsy (PSP) is a neurodegenerative disease characterised clinically by motor and cognitive symptoms. Cholinergic dysfunction is thought to be responsible for much of the cognitive symptomatology. To date, however, cholinergic replacement therapies have been ineffective. We used receptor specific radioligand autoradiography to measure M1, M2, and M4 receptor density, and the functional status of the principal cortical subtype, M1, in the frontal cortex in post-mortem brain tissue of PSP patients (n=14). Results were compared to normal controls (n=17) and patients with dementia with Lewy bodies (DLB, n=12) and Alzheimer's disease (AD, n=15). In PSP there were no changes in M1, M2, or M4 muscarinic receptor densities or M1 coupling. DLB cases showed a non-significant increase in M1 receptors. In AD there was a reduction in M1 receptors and coupling in most frontal cortical areas which reached significance, compared to DLB, for M1 receptors in the cingulate (p<0.05). We conclude from this first systematic study of cortical muscarinic receptors in PSP that functioning cortical muscarinic receptors are preserved. A further, larger trial of cholinergic therapy, such as an M1 agonist, may be warranted.

Muscarinic receptors in the thalamus in progressive supranuclear palsy and other neurodegenerative disorders.

Progressive supranuclear palsy (PSP) is a neurodegenerative disease with motor, cognitive, and behavioral symptomatology. Cholinergic dysfunction is thought to underpin several key symptoms. There is known pathologic involvement of the corticobasal ganglia-thalamocortical loops in PSP, but little attention has been focused on potential thalamic dysfunction. Using autoradiography, we measured muscarinic M2 and M4 receptors in specific thalamic nuclei involved in the limbic and motor loops in patients with PSP (n = 11) and compared results from brain tissue of subjects with Lewy body dementias (including dementia with Lewy bodies and Parkinson disease with dementia, n = 31), Alzheimer disease (n = 22) and normal elderly control subjects (n = 27). In the thalamus M2 receptors were more abundant than M4 receptors and were most densely concentrated in the anteroprincipal (AP) and mediodorsal (MD) nuclei, which connect to limbic cortices. M2 receptor binding was reduced in the AP nucleus in PSP compared with control subjects and those with Lewy body dementias. M4 receptors were markedly reduced in the MD nucleus in those with PSP compared with control subjects. M4 receptors were also reduced in the subthalamic nucleus in patients with PSP. M4 receptor binding was reduced in the MD nucleus in the Lewy body dementia and Alzheimer disease groups compared with control subjects. There were no significant changes in the ventrolateral nucleus (motor). Cholinergic dysfunction within the AP and MD nuclei of the thalamus may contribute to behavioral and cognitive disturbances associated with PSP.

Basal ganglia cholinergic and dopaminergic function in progressive supranuclear palsy.

Progressive Supranuclear Palsy (PSP) is a progressive neurodegenerative disorder. In contrast to Parkinson's disease (PD) and dementia with Lewy bodies (DLB), replacement therapy with dopaminergic and cholinergic agents in PSP has been disappointing. The neurochemical basis for this is unclear. Our objective was to measure dopaminergic and cholinergic receptors in the basal ganglia of PSP and control brains. We measured, autoradiographically, dopaminergic (dopamine transporter, 125I PE2I and dopamine D2 receptors, 125I epidepride) and cholinergic (nicotinic alpha4beta2 receptors, 125I 5IA85380 and muscarinic M1 receptors, 3H pirenzepine) parameters in the striatum and pallidum of pathologically confirmed PSP cases (n=15) and controls (n=32). In PSP, there was a marked loss of dopamine transporter and nicotinic alpha4beta2 binding in the striatum and pallidum, consistent with loss of nigrostriatal neurones. Striatal D2 receptors were increased in the caudate and muscarinic M1 receptors were unchanged compared with controls. These results do not account for the poor response to dopaminergic and cholinergic replacement therapies in PSP, and suggest relative preservation of postsynaptic striatal projection neurones bearing D2/M1 receptors.

Toward future therapies in progressive supranuclear palsy.

There is a stern therapeutic challenge for progressive supranuclear palsy (PSP) that has not yet been met. The lack of randomized, controlled trials and negative outcomes from the vast majority of studies make it impossible to set therapeutic standards, or to give clear recommendations. We review progress to date in this area and briefly consider future potential therapeutic strategies.