Tardive dyskinesia in Asia- current clinical practice and the role of neurologists in the care pathway.

Tardive dyskinesia (TD) is a movement disorder that can arise as a side effect of treatment with dopamine receptor-blocking agents (DRBAs), including antipsychotic drugs (APDs) used to manage psychotic illnesses. Second-generation APDs (SGAs) are often preferred to first-generation drugs due to their lower propensity to cause TD, however many SGAs-treated patients still develop the condition. Although TD is a global health concern, evidence regarding the occurrence of TD and how it is managed in Asian countries is currently limited. This article reports the results of a systematic review of the published literature on TD focusing on its prevalence, types of patients, knowledge of the condition, causative factors, and usual treatment pathways in clinical practice in Asian countries. Epidemiological data suggest that the prevalence of TD is increasing globally due to an overall rise in APD use, contributing factors being polypharmacy with multiple APDs, the use of higher than necessary doses, and off-label use for non-psychotic indications. Although exact prevalence figures for TD in Asian countries are difficult to define, there is a similar pattern of rising APD use which will result in increasing numbers of TD patients in this region. These issues need to be addressed and strategies developed to minimize TD risk and manage this disabling condition which impacts patients' quality of life and daily functioning. To date, both research into TD has been predominantly psychiatry focused and the perspectives from neurologists regarding the clinical management of this challenging condition are scarce. However, neurologists have an essential role in managing the movement disorders manifestations that characterize TD. Optimum management of TD, therefore, should ideally involve collaboration between psychiatrists and neurologists in joint care pathways, wherever practical. Collaborative pathways are proposed in this article, and the challenges that will need to be addressed in Asian countries to improve the care of people with TD are highlighted, with a focus on the neurologist's viewpoint and the implications for the management of TD globally.

Movement disorders in Indochina: Resource challenges and future solutions.

Movement disorders are a major cause of disability worldwide and their increasing prevalence predicts a substantial future burden of care. Impactful patient care requires availability of, and accessibility to, effective medications, knowledge, and disease awareness among both medical professionals and patients, driven by skilled personnel to harness and manage resources. The highest burden of movement disorders is in low-to-middle income countries where resources are often limited and infrastructure is insufficient to meet growing demands. This article focuses on the specific challenges faced in the management and delivery of care for movement disorders in Indochina, the mainland region of Southeast Asia comprising the neighboring countries of Cambodia, Laos, Malaysia, Myanmar, Thailand, and Vietnam. The first Indochina Movement Disorders Conference was held in August 2022 in Ho Chi Minh City, Vietnam, to provide a platform to better understand the situation in the region. Future management of movement disorders in Indochina will require progressive adaptation of existing practices to reflect modern approaches to care delivery. Digital technologies offer an opportunity to strengthen these processes and address the challenges identified in the region. Ultimately, a long-term collaborative approach by regional healthcare providers is key.

Genetic study of early-onset Parkinson's disease in the Malaysian population.

BACKGROUND: About 5-10% of Parkinson's disease (PD) cases are early onset (EOPD), with several genes implicated, including GBA1, PRKN, PINK1, and SNCA. The spectrum and frequency of mutations vary across populations and globally diverse studies are crucial to comprehensively understand the genetic architecture of PD. The ancestral diversity of Southeast Asians offers opportunities to uncover a rich PD genetics landscape, and identify common regional mutations and new pathogenic variants. OBJECTIVES: This study aimed to investigate the genetic architecture of EOPD in a multi-ethnic Malaysian cohort. METHODS: 161 index patients with PD onset ≤50 years were recruited from multiple centers across Malaysia. A two-step approach to genetic testing was used, combining a next-generation sequencing-based PD gene panel and multiplex ligation-dependent probe amplification (MLPA). RESULTS: Thirty-five patients (21.7%) carried pathogenic or likely pathogenic variants involving (in decreasing order of frequency): GBA1, PRKN, PINK1, DJ-1, LRRK2, and ATP13A2. Pathogenic/likely pathogenic variants in GBA1 were identified in thirteen patients (8.1%), and were also commonly found in PRKN and PINK1 (11/161 = 6.8% and 6/161 = 3.7%, respectively). The overall detection rate was even higher in those with familial history (48.5%) or age of diagnosis ≤40 years (34.8%). PRKN exon 7 deletion and the PINK1 p.Leu347Pro variant appear to be common among Malay patients. Many novel variants were found across the PD-related genes. CONCLUSIONS: This study provides novel insights into the genetic architecture of EOPD in Southeast Asians, expands the genetic spectrum in PD-related genes, and highlights the importance of diversifying PD genetic research to include under-represented populations.

From parasomnia to agrypnia excitata - An illustrative case on diagnostic approach.

The diagnostic approach to sleep-related movements disorders is seldom discussed. We report a case of fatal familial insomnia who initially presented with persistent limb movements in sleep, which later progressed to a state of agrypnia excitata. Here, the evaluation of abnormal movements in sleep is discussed using a step-by-step diagnostic approach. Although no cure is available for fatal familial insomnia, prompt recognition of this condition is important to facilitate proper management, including the involvement of interdisciplinary neuropalliative care.

A South East Asian perspective of neuropsychiatric startle syndromes of latah.

Latah is a culture-specific syndrome characterized by exaggerated startle response, echolalia, palilalia, echopraxia, coprolalia, forced obedience and involuntary vocalization in response to startle. Latah is stimulus-induced and is associated with behavior and psychiatric features. The aim of this review is to provide a comprehensive description on latah from a regional perspective based on previous literature and clinical experiences and highlight the clinical characteristics of latah from a movement disorders perspective. The pathophysiology of latah is complex and poorly understood although psychological stressors have been implicated. In view of the distressing psychosocial impact of latah, this neuropsychiatric startle syndrome warrants further studies to understand the pathophysiology and identify the appropriate treatments.

Glucocerebrosidase (GBA) gene variants in a multi-ethnic Asian cohort with Parkinson's disease: mutational spectrum and clinical features.

GBA variants are associated with increased risk and earlier onset of Parkinson's disease (PD), and more rapid disease progression especially with "severe" variants typified by p.L483P. GBA mutation screening studies from South-East Asia, with > 650 million inhabitants of diverse ancestries, are very limited. We investigated the spectrum of GBA variants, and associated clinico-demographic features, in a multi-ethnic PD cohort in Malaysia. Patients (n = 496) were recruited from seven centres, primarily of Chinese (45%), Malay (37%), and Indian (13%) ethnicities. All GBA coding exons were screened using a next-generation sequencing-based PD gene panel and verified with Sanger sequencing. We identified 14 heterozygous GBA alleles consisting of altogether 17 missense variants (8 classified as pathogenic or likely pathogenic for PD) in 25 (5.0%) patients, with a substantially higher yield among early (< 50 years) vs. late-onset patients across all three ethnicities (9.1-13.2% vs. 1.0-3.2%). The most common variant was p.L483P (including RecNciI, n = 11, 2.2%), detected in all three ethnicities. Three novel variants/recombinant alleles of uncertain significance were found; p.P71L, p.L411P, and p.L15S(;)S16G(;)I20V. The common European risk variants, p.E365K, p.T408M, and p.N409S, were not detected. A severe disease course was noted in the majority of GBA-variant carriers, across a range of detected variants. We report a potentially novel observation of spine posture abnormalities in GBA-variant carriers. This represents the largest study on GBA variation from South-East Asia, and highlights that these populations, especially those with EOPD, would be relevant for studies including clinical trials targeting GBA pathways.

Association study of MCCC1/LAMP3 and DGKQ variants with Parkinson's disease in patients of Malay ancestry.

BACKGROUND: Genome-wide association studies (GWAS) have shown that variants in the 3-methylcrotonyl-CoA carboxylase (MCCC1)/lysosome-associated membrane protein 3 (LAMP3) loci (rs10513789, rs12637471, rs12493050) reduce the risk of Parkinson's disease (PD) in Caucasians, Chinese and Ashkenazi-Jews while the rs11248060 variant in the diacylglycerol kinase theta (DGKQ) gene increases the risk of PD in Caucasian and Han Chinese cohorts. However, their roles in Malays are unknown. Therefore, this study aims to investigate the association of these variants with the risk of PD in individuals of Malay ancestry. METHODS: A total of 1114 subjects comprising of 536 PD patients and 578 healthy controls of Malay ancestry were recruited and genotyped using Taqman® allelic discrimination assays. RESULTS: The G allele of rs10513789 (OR = 0.83, p = 0.001) and A allele of rs12637471 (OR = 0.79, p = 0.007) in the MCCC1/LAMP3 locus were associated with a protective effect against developing PD in the Malay population. A recessive model of penetrance showed a protective effect of the GG genotype for rs10513789 and the AA genotype for rs12637471. No association with PD was found with the other MCCC1/LAMP3 rs12493050 variant or with the DGKQ (rs11248060) variant. No significant associations were found between the four variants with the age at PD diagnosis. CONCLUSION: MCCC1/LAMP3 variants rs10513789 and rs12637471 protect against PD in the Malay population.

Delivering patient-centered care in Parkinson's disease: Challenges and consensus from an international panel.

An international panel of movement disorders specialists explored the views and perceptions of people with Parkinson's disease (PD) about their condition and its treatment, including the potential mismatch between the clinician's view of the patient's condition and their own view of what aspects of the disease most affect their daily lives. The initiative was focused on Asian countries, so participants comprised experts in the management of PD from key centers in Asia, with additional insight provided by European and the North American movement disorders experts. Analysis of peer-reviewed publications on patient perceptions of PD and the factors that they consider important to their wellbeing identified several contributing factors to the mismatch of views, including gaps in knowledge of PD and its treatment, an understanding of the clinical heterogeneity of PD, and the importance of a multidisciplinary approach to patient care. The faculty proposed options to bridge these gaps to ensure that PD patients receive the personalized treatment they need to achieve the best possible outcomes. It was considered essential to improve patient knowledge about PD and its treatment, as well as increasing the awareness of clinicians of PD heterogeneity in presentation and treatment response. A multidisciplinary and shared-care approach to PD was needed alongside the use of patient-centered outcome measures in clinical trials and clinical practice to better capture the patient experience and improve the delivery of individualized therapy.

LRRK2 N551K and R1398H variants are protective in Malays and Chinese in Malaysia: A case-control association study for Parkinson's disease.

BACKGROUND: The LRRK2 gene is associated with Parkinson's disease (PD) as a number of mutations within the gene have been shown to be susceptibility factors. Studies on various global populations have determined that mutations such as G2019S, G2385R, and R1628P in LRRK2 increase the risk of developing PD while the N551K-R1398H haplotype is associated with conferring protection against developing PD. Here we report a study looking at the N551K and R1398H variants for the first time in the Malaysian population. METHODS: Cases (523) which conformed to the United Kingdom PD Brain Bank Criteria for PD were recruited through trained neurologists and age- and ethnically matched controls (491) were individuals free of any neurological disorder. The N551K and R1398H mutations were genotyped using the Taqman SNP genotyping assay. RESULTS: A significant protective association for N551K was found in those of Malay ancestry, with a protective trend seen for R1398H. A meta-analysis of Chinese individuals in this cohort with other published cohorts of Chinese ancestry indicated a significant protective role for N551K and R1398H. CONCLUSION: This study reports that the N551K-R1398H haplotype is also relevant to the Malaysian population, with a significant protective effect found in those of Malay and Chinese ancestries.

Exploring bedside clinical features of parkinsonism: A focus on differential diagnosis.

The proper diagnosis of parkinsonian disorders usually involves three steps: identifying core features of parkinsonism; excluding other causes; and collating supportive evidence based on clinical signs or investigations. While the recognition of cardinal parkinsonian features is usually straightforward, the appreciation of clinical features suggestive of specific parkinsonian disorders can be challenging, and often requires greater experience and skills. In this review, we outline the clinical features that are relevant to the differential diagnosis of common neurodegenerative parkinsonian disorders, including Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration. We aim to make this process relatable to clinicians-in-practice, therefore, have categorised the list of clinical features into groups according to the typical sequence on how clinicians would elicit them during the examination, starting with observation of facial expression and clinical signs of the face, spotting eye movement abnormalities, examination of tremors and jerky limb movements, and finally, examination of posture and gait dysfunction. This review is not intended to be comprehensive. Rather, we have focused on the most common clinical signs that are potentially key to making the correct diagnosis and those that do not require special skills or training for interpretation. Evidence is also provided, where available, such as diagnostic criteria, consensus statements, clinicopathological studies or large multi-centre registries. Pitfalls are also discussed when relevant to the diagnosis. While no clinical signs are pathognomonic for certain parkinsonian disorders, certain clinical clues may assist in narrowing a differential diagnosis and tailoring focused investigations for the individual patient.

Thymoma-associated myasthenia gravis and LGI1-encephalitis, with nephrotic syndrome post-thymectomy.

Thymoma is associated with a wide spectrum of autoimmune paraneoplastic syndromes, though it is uncommon for multiple paraneoplastic syndromes to be present in a single individual. We report a rare case of an elderly gentleman who was found to have thymoma-associated myasthenia gravis and LGI1-encephalitis with myokymia, who presented with nephrotic syndrome (minimal change glomerulopathy) after thymectomy. The latter two paraneoplastic syndromes had manifested when prednisolone was tapered down to low dose. This case serves to remind neurologists that apart from paraneoplastic neurological manifestations, thymoma may also be associated with renal disease. Nephropathy in myasthenia patients with thymoma should be properly evaluated, as it is treatable with immunotherapy, and it may even occur post-thymectomy.

Prevalence of neuromyelitis optica spectrum disorder in the multi-ethnic Penang Island, Malaysia, and a review of worldwide prevalence.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) occurs worldwide in all ethnicities. Recently, population-based studies have shown that NMOSD is more common among non-White populations. There is scarce data about NMOSD prevalence in South East Asian populations. METHODS: (1) A population-based study was undertaken to estimate NMOSD prevalence in the multi-ethnic Penang Island, Malaysia, comprising Chinese, Malays, and Indians. Medical records of NMOSD patients followed up at the Penang General Hospital (the neurology referral centre in Penang Island) were reviewed. The 2015 diagnostic criteria of the International Panel for NMO Diagnosis were used for case ascertainment. (2) A review of population-based prevalence studies of NMOSD worldwide was carried out. PubMed and conference proceedings were searched for such studies. RESULTS: Of the 28 NMOSD patients, 14 were residents of Penang Island on prevalence day [13 (93%) Chinese and one (7%) Malay]. All 14 patients were females and aquaporin 4 seropositive. The prevalence of NMOSD in Penang Island was 1.99/100,000 population; according to ethnicities, the prevalence in Chinese was significantly higher than in Malays (3.31/100,000 vs 0.43/100,000, respectively, p = 0.0195). CONCLUSION: Based on our and other population-based studies, among Asians, East Asian origin populations (Chinese and Japanese) appear to have higher NMOSD prevalence than other Asian ethnic groups. Worldwide, Blacks seem to have the highest NMOSD prevalence. More studies in different geographical regions and ethnic groups will be useful to further inform about potential factors in NMOSD pathogenesis.

Paraneoplastic autoimmune movement disorders.

PURPOSE OF REVIEW: To provide an overview of paraneoplastic autoimmune disorders presenting with various movement disorders. RECENT FINDINGS: The spectrum of paraneoplastic autoimmune disorders has been expanding with the discovery of new antibodies against cell surface and intracellular antigens. Many of these paraneoplastic autoimmune disorders manifest as a form of movement disorder. With the discovery of new neuronal antibodies, an increasing number of idiopathic or neurodegenerative movement disorders are now being reclassified as immune-mediated movement disorders. These include anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis which may present with orolingual facial dyskinesia and stereotyped movements, CRMP-5 IgG presenting with chorea, anti-Yo paraneoplastic cerebellar degeneration presenting with ataxia, anti-VGKC complex (Caspr2 antibodies) neuromyotonia, opsoclonus-myoclonus-ataxia syndrome, and muscle rigidity and episodic spasms (amphiphysin, glutamic acid decarboxylase, glycine receptor, GABA(A)-receptor associated protein antibodies) in stiff-person syndrome. SUMMARY: Movement disorders may be a presentation for paraneoplastic autoimmune disorders. Recognition of these disorders and their common phenomenology is important because it may lead to the discovery of an occult malignancy.

Eleven episodes of recurrent optic neuritis of the same eye for 22 years eventually diagnosed as neuromyelitis optica spectrum disorder.

It is difficult to predict whether a particular attack of neuromyelitis optica spectrum disorder (NMOSD) will affect the optic nerve [optic neuritis (ON): unilateral or bilateral], spinal cord (myelitis), brain or brainstem, or a combination of the above. We report an interesting case of recurrent ON of the same eye for a total of 11 episodes in a Chinese woman. Over a period of 22 years, the attacks only involved the left eye, and never the right eye and also no myelitis. For a prolonged duration, she was diagnosed as recurrent idiopathic ON. Only until she was tested positive for aquaporin 4 antibody that her diagnosis was revised to NMOSD. Optical coherence tomography revealed thinning of the retinal nerve fibre layer (RNFL) for the affected left eye, while the RNFL thickness was within normal range for the unaffected right eye. The disability accrual in NMOSD is generally considered to be attack-related - without a clinical attack of ON, there shall be no visual impairment, and no significant subclinical thinning of RNFL. Our case is in agreement with this notion. This is in contrast to multiple sclerosis where subclinical RNFL thinning does occur. This case highlights the importance of revisiting and questioning a diagnosis of recurrent idiopathic ON particularly when new diagnostic tools are available.