The Pattern and Staging of Brain Atrophy in Spinocerebellar Ataxia Type 2 (SCA2): MRI Volumetrics from ENIGMA-Ataxia.

Objective: Spinocerebellar ataxia type 2 (SCA2) is a rare, inherited neurodegenerative disease characterised by progressive deterioration in both motor coordination and cognitive function. Atrophy of the cerebellum, brainstem, and spinal cord are core features of SCA2, however the evolution and pattern of whole-brain atrophy in SCA2 remain unclear. We undertook a multi-site, structural magnetic resonance imaging (MRI) study to comprehensively characterize the neurodegeneration profile of SCA2. Methods: Voxel-based morphometry analyses of 110 participants with SCA2 and 128 controls were undertaken to assess groupwise differences in whole-brain volume. Correlations with clinical severity and genotype, and cross-sectional profiling of atrophy patterns at different disease stages, were also performed. Results: Atrophy in SCA2 relative to controls was greatest (Cohen's d>2.5) in the cerebellar white matter (WM), middle cerebellar peduncle, pons, and corticospinal tract. Very large effects (d>1.5) were also evident in the superior cerebellar, inferior cerebellar, and cerebral peduncles. In cerebellar grey matter (GM), large effects (d>0.8) mapped to areas related to both motor coordination and cognitive tasks. Strong correlations (|r|>0.4) between volume and disease severity largely mirrored these groupwise outcomes. Stratification by disease severity showed a degeneration pattern beginning in cerebellar and pontine WM in pre-clinical subjects; spreading to the cerebellar GM and cerebro-cerebellar/corticospinal WM tracts; then finally involving the thalamus, striatum, and cortex in severe stages. Interpretation: The magnitude and pattern of brain atrophy evolves over the course of SCA2, with widespread, non-uniform involvement across the brainstem, cerebellar tracts, and cerebellar cortex; and late involvement of the cerebral cortex and striatum.

Charcot's Russian pupils.

The establishment of Russian neurology in the late 19th century was significantly shaped by the neurology department at La Salpêtrière Hospital under Professor Jean-Martin Charcot's leadership. A group of Russian neurologists, guided by Professor Kozhevnikov and featuring his disciples such as Korsakov, Minor, Darkshevich, and Bekhterev, had the privilege of being mentored by Professor Charcot. Subsequently, they played pivotal roles in founding various neurology services in Russia, greatly influenced by the teachings and insights they acquired under Charcot's tutelage.

A criação da neurologia russa no final do século XIX foi significativamente moldada pelo departamento de neurologia do Hospital La Salpêtrière, sob a direção do Professor Jean-Martin Charcot. Um grupo de neurologistas russos, orientado pelo Professor Kozhevnikov e com discípulos como Korsakov, Minor, Darkshevich e Bekhterev, teve o privilégio de ser orientado pelo Professor Charcot. Posteriormente, desempenharam papéis fundamentais na fundação de vários serviços de neurologia na Rússia, muito influenciados pelos ensinamentos e conhecimentos que adquiriram sob a tutela de Charcot.

Efficacy of subthalamic deep brain stimulation programming strategies for gait disorders in Parkinson's disease: a systematic review and meta-analysis.

Patients with advanced Parkinson's disease often suffer from severe gait and balance problems, impacting quality of live and persisting despite optimization of standard therapies. The aim of this review was to systematically review the efficacy of STN-DBS programming techniques in alleviating gait disturbances in patients with advanced PD. Searches were conducted in PubMed, Embase, and Lilacs databases, covering studies published until May 2024. The review identified 36 articles that explored five distinct STN-DBS techniques aimed at addressing gait and postural instability in Parkinson's patients: low-frequency stimulation, ventral STN stimulation for simultaneous substantia nigra activation, interleaving, asymmetric stimulation and a short pulse width study. Among these, 21 articles were included in the meta-analysis, which revealed significant heterogeneity among studies. Notably, low-frequency STN-DBS demonstrated positive outcomes in total UPDRS-III score and FOG-Q, especially when combined with dopaminergic therapy. The most favorable results were found for low-frequency STN stimulation. The descriptive analysis suggests that unconventional stimulation approaches may be viable for gait problems in patients who do not respond to standard therapies.

Global Presence and Penetrance of CSF1R-Related Disorder.

Objectives: To highlight the worldwide presence of CSF1R-related disorder (CSF1R-RD), discuss its penetrance, and provide the first haplotype analysis. Methods: Data on patients worldwide were collected, including demographics, genotype, family history, and clinical status. For haplotype analysis, polymorphisms of short tandem repeats in 3 distinct families with CSF1R p.Ile794Thr variant were examined. Results: Nineteen new patients were included, at a mean age of 38.7 years (ranging from 11 to 74 years), from 14 families from the Americas, Asia, Australia, and Europe, including the first from Mexico, North Macedonia, and Ukraine. Fifteen CSF1R variants were found, including 8 novel. Three patients were compound heterozygotes with disease onset at 1, 4, and 22 years. Patients with heterozygous CSF1R variants developed symptoms at a mean of 39.0 years (range 8-71 years). Four patients died at a mean of 3.3 years from onset (range 2-5 years). Negative family history was noted in 7 patients. In haplotype analysis, 2 families exhibited shared haplotype encompassing ∼6-Mb region downstream of the CSF1R while the third family displayed a different haplotype. Discussion: CSF1R-RD has a global prevalence. The reasons for negative family history include de novo variants (as shown by the haplotype analysis), mosaicism, and incomplete penetrance, which are possibly modulated by environmental and genetic factors.

Fulgence Raymond: from rural life and veterinary medicine to Charcot's successor at La Salpêtrière Hospital.

This paper provides a historical overview of Professor Fulgence Raymond, Charcot's eldest pupil, who was chosen as his successor. It explores Raymond's origins as a veterinary surgeon, his evolution as a neurologist under Charcot's mentorship, and his tenure as the professor's successor at the La Salpêtrière Hospital in Paris, France, from 1894 to 1910.

O presente artigo oferece um perfil histórico do professor Fulgence Raymond, que foi o pupilo mais velho do Professor Jean-Martin Charcot, é apresentado, destacando-se a origem de Raymond como cirurgião veterinário, sua carreira como médico neurologista sob supervisão de Charcot e, finalmente, a sua atuação como sucessor do professor , na cadeira de doenças do sistema nervoso do Hospital de La Salpêtrière, em Paris, França, entre os anos de 1894 e 1910.

An essay on the Charcot and Richer hysteria: from charcoal drawings to cell phones.

Hysteria, previously also known as the disease of the womb, has moved from being a woman's illness through the medieval times' stigma of demonic possession, to the modern concept of a functional neurological disorder. Interestingly to the present assay, Charcot (1825-1893) and Richer (1849-1933) described, in their 1887 work Les Démoniaques dans l'art, by means of iconography, semiological aspects of the so-called Grande Attaque Hystérique, which resembles features of psychogenic nonepileptic seizures emulating grand mal epileptic seizures. The aim of the present assay is to describe how those charcoal iconographic representations evolved through history and are nowadays portrayed in videos recorded at epilepsy monitoring units and patients' cell phones.

Histeria, previamente também conhecida como a doença do útero, passou de uma doença feminina, pelo estigma de possessão demoníaca ao longo dos tempos medievais, até o conceito moderno de um distúrbio neurológico funcional. Curiosamente para o presente ensaio, Charcot (1825­1893) e Richer (1849­1933) descreveram, em sua obra Les Démoniaques dans l'art, de 1887, por meio da iconografia, aspectos semiológicos do chamado Grande Attaque Hystérique, que se assemelha às características de crises não epilépticas psicogênicas que emulam crises epilépticas do tipo grande mal. O objetivo deste ensaio é descrever como essas representações iconográficas evoluíram ao longo da história e são retratadas nos dias de hoje em vídeos gravados em unidades de monitoramento de epilepsia e nos celulares de pacientes.

Polyneuropathy in Patients with Spinocerebellar Ataxias Types 2, 3, and 10: A Systematic Review.

Spinocerebellar ataxia (SCA) is an autosomal dominant hereditary disease with a low prevalence, for which more than 50 types have been described. This group of neurodegenerative diseases can present as different phenotypes with varying progression rates and clinical manifestations of different severities. Herein, we systematically reviewed existing medical literature to describe the main characteristics of polyneuropathy in patients with SCA types 2, 3, and 10. Using relevant keywords, 16,972 articles were identified from the databases. Of these, 5,329 duplicate studies were excluded before screening. Subsequently, 11,643 studies underwent title and abstract review, of which only 49 were selected for full-text review. Among these, 24 studies were included. The medical literature suggests peripheral neuropathy - probably in a polyneuropathy phenotype - in SCA types 2 and 3. It is not possible to determine whether there is peripheral neuropathy in patients with SCA type 10, as there is only one case series in Mexico that described peripheral neuropathy in this group. Further studies are required to investigate peripheral neuropathy in patients with SCA types 2, 3, and 10. The study and description of a possible statistical association between CAG repeats and SARA scale scores with the presence of peripheral neuropathy are important points requiring assessment in future research.

Evaluation of Quality of Life After Use the Virtual Reality in Patients with Neurodegenerative Disease.

Introduction Spinocerebellar ataxias (SCAs) are a heterogeneous group of neurodegenerative diseases. Objective To evaluate the living standard of patients with SCA, by applying the Vestibular Disorders Activities of Daily Living Scale (VADL) and Activitiesspecific Balance Confidence Scale (ABC) questionnaires. Methods An uncontrolled clinical trial study was conducted with 28 patients who underwent anamnesis, ENT evaluation, and vestibular assessment and the application of questionnaires VADL and ABC before and after rehabilitation with virtual reality. Results The vestibular exam was altered in 64.3% of the cases. The result between the correlation of the VADL and ABC questionnaires showed significant results in all cases (p < 0.005). The correlation between the ages and disease length with the VADL and ABC questionnaires was significant in the T3 assessment (p = 0.015). The correlation between the disease length and the VADL questionnaire was significant in all cases (p < 0.005). The comparison of the vestibular rehabilitation result (T1 to T2) showed a significant difference for all the applied games, except for the ski slalom. The comparison of the vestibular rehabilitation result (T1 to T3) showed significant difference for all the applied games (p < 0.005) (1st assessment before the start of rehabilitation designated T1, after 10 rehabilitation sessions, considered T2 and, at the end of 20 rehabilitation sessions, called T3). Conclusion We can point out a direct improvement in the living standard, reflected by the reduction of falls, better balance, and march, contributing to a higher self-confidence in patients in daily activities.

The prominent role of Charcot and the French neurological tradition in Latin America.

The establishment of neurology schools in Latin America during the late-nineteenth and early-twentieth centuries profoundly influenced the French neurology school. In the latter half of the nineteenth century, the neurology department at the Salpêtrière Hospital in Paris held a preeminent position as the global hub of neurology. Professor Jean-Martin Charcot, widely acclaimed as the father of modern neurology, was the most revered neurology professor of the nineteenth century. Many physicians from diverse countries across South America (notably Argentina, Uruguay, Peru, Brazil, and Colombia), the Caribbean (Cuba), and Mexico pursued specialized training in neurology under Charcot's tutelage, and even after his passing in 1893, they continued their training with his numerous disciples. As a result, nearly two centuries after the birth of Charcot, his enduring contributions to the field of neurology remain vibrantly influential, particularly in Latin America.

A hiatus in the rivalry between Pierre Marie and Jules Dejerine: a collaborative study on sensory disorders by Andre Pierre Marie and Gustave Roussy.

Personal and professional rivalries involving prominent neurologists mark the history of nineteenth-century French neurology. One of the great examples is the feud between Pierre Marie and Jules Dejerine. The dispute between the two, nevertheless, did not prevent Pierre Marie's son, André Marie, and Gustave Roussy - one of Dejerine's favorite pupils, from collaborating on significant research that led to the doctoral dissertation by Andre Marie regarding sensory disturbances associated with painful hemiagnosia found in thalamic lesions.

As rivalidades pessoais e profissionais entre neurologistas proeminentes marcaram a história da neurologia francesa do século XIX. Um dos grandes exemplos é a rivalidade entre Pierre Marie e Jules Dejerine. A disputa entre os dois, no entanto, não impediu que o filho de Pierre Marie, André Marie, e Gustave Roussy, um dos pupilos preferidos de Dejerine, colaborassem numa investigação significativa que resultou na tese de doutorado de André Marie sobre os distúrbios sensoriais associados à hemiagnosia dolorosa encontrada nas lesões talâmicas.

Spatiotemporal Gait Analysis of Patients with Spinocerebellar Ataxia Types 3 and 10 Using Inertial Measurement Units: A Comparative Study.

Given the high morbidity related to the progression of gait deficits in spinocerebellar ataxias (SCA), there is a growing interest in identifying biomarkers that can guide early diagnosis and rehabilitation. Spatiotemporal parameter (STP) gait analysis using inertial measurement units (IMUs) has been increasingly studied in this context. This study evaluated STP profiles in SCA types 3 and 10, compared them to controls, and correlated them with clinical scales. IMU portable sensors were used to measure STPs under four gait conditions: self-selected pace (SSP), fast pace (FP), fast pace checking-boxes (FPCB), and fast pace with serial seven subtractions (FPS7). Compared to healthy subjects, both SCA groups had higher values for step time, variability, and swing time, with lower values for gait speed, cadence, and step length. We also found a reduction in speed gain capacity in both SCA groups compared to controls and an increase in speed dual-task cost in the SCA10 group. However, there were no significant differences between the SCA groups. Swing time, mean speed, and step length were correlated with disease severity, risk of falling and functionality in both clinical groups. In the SCA3 group, fear of falling was correlated with cadence. In the SCA10 group, results of the Montreal cognitive assessment test were correlated with step time, mean speed, and step length. These results show that individuals with SCA3 and SCA10 present a highly variable, short-stepped, slow gait pattern compared to healthy subjects, and their gait quality worsened with a fast pace and dual-task involvement.

HLA dependency and possible clinical relevance of intrathecally synthesized anti-IgLON5 IgG4 in anti-IgLON5 disease.

Background: Anti-IgLON5 disease is a rare chronic autoimmune disorder characterized by IgLON5 autoantibodies predominantly of the IgG4 subclass. Distinct pathogenic effects were described for anti-IgLON5 IgG1 and IgG4, however, with uncertain clinical relevance. Methods: IgLON5-specific IgG1-4 levels were measured in 46 sera and 20 cerebrospinal fluid (CSF) samples from 13 HLA-subtyped anti-IgLON5 disease patients (six females, seven males) using flow cytometry. Intervals between two consecutive serum or CSF samplings (31 and 10 intervals, respectively) were categorized with regard to the immunomodulatory treatment active at the end of the interval, changes of anti-IgLON5 IgG1 and IgG4 levels, and disease severity. Intrathecal anti-IgLON5 IgG4 synthesis (IS) was assessed using a quantitative method. Results: The median age at onset was 66 years (range: 54-75), disease duration 10 years (range: 15-156 months), and follow-up 25 months (range: 0-83). IgLON5-specific IgG4 predominance was observed in 38 of 46 (83%) serum and 11 of 20 (55%) CSF samples. Anti-IgLON5 IgG4 levels prior clinical improvement in CSF but not serum were significantly lower than in those prior stable/progressive disease. Compared to IgLON5 IgG4 levels in serum, CSF levels in HLA-DRB1*10:01 carriers were significantly higher than in non-carriers. Indeed, IgLON5-specific IgG4 IS was demonstrated not only in four of five HLA-DRB1*10:01 carriers but also in one non-carrier. Immunotherapy was associated with decreased anti-IgGLON5 IgG serum levels. In CSF, lower anti-IgLON5 IgG was associated with immunosuppressive treatments used in combination, that is, corticosteroids and/or azathioprine plus intravenous immunoglobulins or rituximab. Conclusion: Our findings might indicate that CSF IgLON5-specific IgG4 is frequently produced intrathecally, especially in HLA-DRB1*10:01 carriers. Intrathecally produced IgG4 may be clinically relevant. While many immunotherapies reduce serum IgLON5 IgG levels, more intense immunotherapies induce clinical improvement and may be able to target intrathecally produced anti-IgLON5 IgG. Further studies need to confirm whether anti-IgLON5 IgG4 IS is a suitable prognostic and predictive biomarker in anti-IgLON5 disease.

François Rabelais and his dystonic giants.

Spasmodic torticollis was an early designation used for cervical dystonia. The origin of this name is attributed to French physician and writer François Rabelais in the mid-sixteenth century. This early description of torticollis in the book Pantagruel was an inspiration for the understanding of cervical dystonia. The art expressed in Rabelais' literature ‒ which was immortalized by the drawings of Gustave Doré ‒ influenced poetry, art, and photography, and led to the adoption of the term torticollis in the neurological sciences.

Uma designação inicial usada para distonia cervical era torcicolo espasmódico. A origem desse termo é atribuída ao médico e escritor francês François Rabelais em meados do século XVI. Essa descrição inicial do torcicolo no livro Pantagruel foi uma inspiração para a compreensão da distonia cervical. A arte exibida na literatura de Rabelais ‒ imortalizada pelos desenhos de Gustave Doré ‒ influenciou a poesia, a arte e a fotografia, e levou à adoção do termo torcicolo nas ciências neurológicas.

Sjögren: unique surname, two men, four syndromes and one disease.

Henrik and Torsten Sjögren (/'ʃoʊɡrən/ or SHOH-grən) were two Swedish physicians living in the same period, but completely unrelated, except for their notable contributions to Medicine. The first one described keratoconjunctivitis sicca, afterward called Sjögren's syndrome, and a fishing net aspect retinal pigmentation affecting visual acuity, nowadays known as Sjögren reticular dystrophy. The last one contributed to the understanding of Spielmeyer-Sjögren disease, Marinesco-Sjögren, and Sjögren-Larsson syndromes, all related to genetic disorders and neurological symptoms. In this paper, we aim to describe each disorder, in order to avoid any misunderstanding in diagnosis and for historical record.

Henrik e Torsten Sjögren (/ˈʃoʊɡrən/ ou SHOH-grən) foram dois médicos suecos que viveram na mesma época, mas não tinham nenhuma relação entre si, exceto por suas notáveis contribuições à medicina. O primeiro descreveu a ceratoconjuntivite sicca, posteriormente chamada de síndrome de Sjögren, e uma pigmentação da retina com aspecto de rede de pesca que afeta a acuidade visual, hoje conhecida como distrofia reticular de Sjögren. O último contribuiu para a compreensão da doença de Spielmeyer-Sjögren, das síndromes de Marinesco-Sjögren e Sjögren-Larsson, todas relacionadas a distúrbios genéticos e sintomas neurológicos. Neste artigo, pretendemos descrever cada desordem, a fim de evitar qualquer mal-entendido no diagnóstico e para registro histórico.

Effects of onabotulinum toxin type A injections in patients with Meige's syndrome.

BACKGROUND: Meige's syndrome is a type of facial dystonia characterized by the simultaneous occurrence of blepharospasm and oromandibular dystonia. Although botulinum toxin type A (OBTA) injections are the standard treatment, evidence of their effectiveness and safety in this scenario is still lacking. OBJECTIVE: Our research aimed to evaluate the improvement and occurrence of side effects following injections of onabotulinum toxin type A (OBTA) in patients with Meige's syndrome. METHODS: Patients with Meige's syndrome undergoing botulinum toxin injections were enrolled in this study. We assessed dystonia intensity before and 14 days after OBTA injection using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) to measure the response of symptoms in the eyes (blepharospasm) and mouth (oromandibular dystonia). Other variables, such as dosage, side effects, and demographic data, were also recorded. RESULTS: The study included 41 participants, with a mean age of 67.7 years and a female-to-male ratio of 3.5:1. The mean BFMDRS score before the injections was 8.89, and after 14 days, it was 2.88. The most reported side effect was ptosis, with a 7.3% incidence. OBTA significantly reduced dystonia severity (p < 0.0001). The clinical response for the blepharospasm component was superior to the oromandibular dystonia component. CONCLUSION: Our results support that OBTA seems to be an effective and safe therapeutic option for treating Meige's syndrome. The effect of OBTA was more pronounced in the treatment of blepharospasm than in oromandibular dystonia.

ANTECEDENTES: A síndrome de Meige (SM) é caracterizada pela ocorrência concomitante de blefarospasmo e distonia oromandibular. Embora a toxina onabotulínica do tipo A (TBA) seja o tratamento de escolha, há uma falta de evidências sobre sua eficácia e segurança nesse cenário. OBJETIVO: O objetivo do nosso estudo foi avaliar os efeitos obtidos com a aplicação de TBA em pacientes com SM. MéTODOS: Pacientes com SM que realizam aplicação de TBA foram convidados a participar desse estudo. Os participantes foram questionados sobre a intensidade da distonia antes e 14 dias após a injeção de TBA, utilizando a Escala de Distonia de Burke-Fahn-Marsden (EDBFM) para mensurar a resposta obtida em cada segmento. Outras variáveis, como dose, ocorrência de efeitos colaterais e dados demográficos, também foram registradas. RESULTADOS: O estudo contou com 41 participantes (idade média de 67,7; razão de 3,5 pacientes do sexo feminino para cada participante do sexo masculino). O escore médio na EDBFM antes das aplicações de TBA era 8,89, e, após 14 dias, 2,88. O efeito colateral mais reportado foi ptose (7.3%). A TBA foi capaz de reduzir a severidade da distonia (p < 0.0001), principalmente do blefarospasmo. CONCLUSãO: Nossos resultados corroboram que a TBA é uma terapêutica eficaz e segura no tratamento da SM. O efeito da TBA é superior no manejo do blefarospasmo em relação à distonia oromandibular.

Genotype-specific spinal cord damage in spinocerebellar ataxias: an ENIGMA-Ataxia study.

BACKGROUND: Spinal cord damage is a feature of many spinocerebellar ataxias (SCAs), but well-powered in vivo studies are lacking and links with disease severity and progression remain unclear. Here we characterise cervical spinal cord morphometric abnormalities in SCA1, SCA2, SCA3 and SCA6 using a large multisite MRI dataset. METHODS: Upper spinal cord (vertebrae C1-C4) cross-sectional area (CSA) and eccentricity (flattening) were assessed using MRI data from nine sites within the ENIGMA-Ataxia consortium, including 364 people with ataxic SCA, 56 individuals with preataxic SCA and 394 nonataxic controls. Correlations and subgroup analyses within the SCA cohorts were undertaken based on disease duration and ataxia severity. RESULTS: Individuals in the ataxic stage of SCA1, SCA2 and SCA3, relative to non-ataxic controls, had significantly reduced CSA and increased eccentricity at all examined levels. CSA showed large effect sizes (d>2.0) and correlated with ataxia severity (r<-0.43) and disease duration (r<-0.21). Eccentricity correlated only with ataxia severity in SCA2 (r=0.28). No significant spinal cord differences were evident in SCA6. In preataxic individuals, CSA was significantly reduced in SCA2 (d=1.6) and SCA3 (d=1.7), and the SCA2 group also showed increased eccentricity (d=1.1) relative to nonataxic controls. Subgroup analyses confirmed that CSA and eccentricity are abnormal in early disease stages in SCA1, SCA2 and SCA3. CSA declined with disease progression in all, whereas eccentricity progressed only in SCA2. CONCLUSIONS: Spinal cord abnormalities are an early and progressive feature of SCA1, SCA2 and SCA3, but not SCA6, which can be captured using quantitative MRI.

The Huntington's Disease Gene Discovery.

The gene for Huntington's disease (HD) was discovered in 1993, after an international collaborative initiative that led researchers to remote regions of South America. It was the most remarkable milestone, since George Huntington's initial description. Through the phenomenological discussions led by Jean-Martin Charcot and Willian Osler, and finally Americo Negrette's reports, which served as the inspiration for the Venezuela Project led by Nancy Wexler, the journey toward discovering the Huntington's disease (HD) gene was marked by substantial efforts. This monumental achievement involved the analysis of more than 18,000 blood samples and gathered dozens of researchers in an integrated effort, enabling the mapping of the gene on chromosome 4 in 1983 and leading, a decade later, to the precise localization and identification of the HTT gene. The discovery of the HD mutation represented a pivotal moment in the field of genetics and neurology, significantly enhancing our understanding of the disease and creating opportunities for future treatments. The progress made and the knowledge gained during this journey catalyzed the development of many innovative molecular techniques that have advanced research in other medical conditions. In this article, the authors celebrate three decades of this memorable event, revisiting the historical aspects, providing insights into the techniques developed, and delving into the paths that ultimately led to the discovery of the HD gene. © 2024 International Parkinson and Movement Disorder Society.

Imbalance and gait impairment in Parkinson's disease: discussing postural instability and ataxia.

Gait and balance difficulties pose significant clinical challenges in Parkinson's disease (PD). The impairment of physiological mechanisms responsible for maintaining natural orthostatism plays a central role in the pathophysiology of postural instability observed in PD. In addition to the well-known rigidity and abnormalities in muscles and joints, various brain regions involved in the regulation of posture, balance, and gait, such as the basal ganglia, cerebellum, and brainstem regions like the pontine peduncle nucleus, are affected in individuals with PD. The recognition of the cerebellum's role in PD has been increasingly acknowledged. Cortical areas and their connections are associated with freezing of gait, a type of frontal lobe ataxia commonly observed in PD. Furthermore, impairments in the peripheral nervous system, including those caused by levodopatherapy, can contribute to gait impairment and imbalance in PD patients. Consequently, individuals with PD may exhibit frontal ataxia, sensory ataxia, and even cerebellar ataxia as underlying causes of gait disturbances and imbalance, starting from the early stages of the disease. The complex interplay between dysfunctional brain regions, impaired cortical connections, and peripheral nervous system abnormalities contributes to the multifaceted nature of gait and balance difficulties in PD. Understanding the intricate mechanisms is crucial for the development of effective therapeutic approaches targeting these specific deficits in PD.