Evidence and practices of the use of next generation sequencing in patients with undiagnosed autosomal dominant cerebellar ataxias: a review / Evidências e práticas do uso do sequenciamento de nova geração em pacientes com ataxias cerebelares autossômicas dominantes não diagnosticadas: uma revisão

ABSTRACT Autosomal dominant cerebellar ataxias (ADCA) are heterogeneous diseases with a highly variable phenotype and genotype. They can be divided into episodic ataxia and spinocerebellar ataxia (SCA); the latter is considered the prototype of the ADCA. Most of the ADCA are caused by polyglutamine expansions, mainly SCA 1, 2, 3, 6, 7, 17 and Dentatorubral-pallidoluysian atrophy (DRPLA). However, 30% of patients remain undiagnosed after testing for these most common SCA. Recently, several studies have demonstrated that the new generation of sequencing methods are useful for the diagnose of these patients. This review focus on searching evidence on the literature, its usefulness in clinical practice and future perspectives.

RESUMO As ataxias cerebelares autossômicas dominantes (ACAD) são doenças heterogêneas com fenótipo e genótipo altamente variáveis. Podem ser divididas em ataxia episódica e ataxia espinocerebelar (SCA), sendo este último considerado o protótipo do ACAD. A maior parte das ACAD são causadas por expansões de poliglutaminas, principalmente SCA 1, 2, 3, 6, 7, 17 e atrofia dentatorubro-palidoluisiana (DRPLA). No entanto, 30% dos pacientes permanecem sem diagnóstico após o teste para essas SCA mais comuns. Recentemente, vários estudos têm demonstrado que a nova geração de métodos de sequenciamento são ferramentas úteis para o diagnóstico desses pacientes. Esta é uma revisão sistemática da literatura, com foco em sua utilidade na prática clínica e em perspectivas futuras.

Ataxias cerebelosas e infecciones virales: caracterización clínica y mecanismos neuropatogénicos / Cerebellar ataxias and viral infections: clinical characterization and neuropathogenic mechanisms

Introducción: La ataxia constituye una alteración en la coordinación de los movimientos, resultado de una disfunción del cerebelo, sus conexiones, así como alteraciones en la médula espinal, nervios periféricos o una combinación de estas condiciones. Las ataxias se clasifican en hereditarias, esporádicas y en adquiridas o secundarias, en las cuales los virus neurotrópicos constituyen los principales causantes. Objetivo: Actualizar los conocimientos relacionados con las ataxias causadas por virus neurotrópicos y los mecanismos neurodegenerativos que pudieran tener relación con la ataxia. Métodos: Se realizó una revisión bibliográfica incluyendo artículos publicados en las principales bases de datos bibliográficas (Web of Sciences, Scopus, SciELO). Se utilizaron las palabras claves: ataxia, virus neurotrópicos, ataxias cerebelosas, ataxias infecciosas, en inglés y español. Análisis e integración de la información: Los virus más conocidos que provocan ataxias infecciosas son el virus de inmunodeficiencia humana, virus del herpes simple, virus del herpes humano tipo 6, virus de la varicela zoster, virus Epstein-Barr, virus del Nilo Occidental, y enterovirus 71, aunque existen otros virus que causan esta afectación. Los mecanismos neuropatogénicos sugeridos son la invasión directa del virus y procesos inmunopatogénicos desencadenados por la infección. Estos virus pueden causar ataxia cerebelosa aguda, ataxia aguda posinfecciosa, síndrome opsoclono-mioclono-atáxico y ataxia por encefalomielitis aguda diseminada. Aunque la mayoría de los reportes de casos informan la evolución satisfactoria de los pacientes, algunos refieren complicaciones neurológicas e incluso la muerte. Conclusiones: Actualmente existe la necesidad de profundizar en el estudio de este tipo de ataxia para favorecer su diagnóstico y tratamiento(AU)

Introduction: Ataxia is an alteration in the coordination of movements caused by a dysfunction of the cerebellum and its connections, as well as alterations in the spinal cord, the peripheral nerves, or a combination of these factors. Ataxias are classified into hereditary, sporadic and acquired or secondary, in which neurotropic viruses are the main causative agents. Objective: Update knowledge about ataxias caused by neurotropic viruses and the neurodegenerative mechanisms which could bear a relationship to ataxia. Methods: A review was conducted of papers published in the main bibliographic databases (Web of Sciences, Scopus, SciELO), using the search terms ataxia, neurotropic virus, cerebellar ataxias, infectious ataxias, in English and in Spanish. Discussion: The best known viruses causing infectious ataxias are the human immunodeficiency virus, herpes simplex virus, human herpesvirus 6, varicella zoster virus, Epstein-Barr virus, Western Nile virus and enterovirus 71, though other viruses may also cause this condition. The neuropathogenic mechanisms suggested are direct invasion of the virus and immunopathogenic processes triggered by the infection. These viruses may cause acute cerebellar ataxia, acute postinfectious ataxia, opsoclonus-myoclonus-ataxia syndrome and ataxia due to acute encephalomyelitis disseminata. Though most case reports describe a satisfactory evolution of patients, some refer to neurological complications and even death. Conclusions: There is a current need to carry out further research about this type of ataxia to improve its diagnosis and treatment(AU)

Acute cerebellar ataxia: differential diagnosis and clinical approach / Ataxia cerebelar aguda: diagnóstico diferencial e abordagem clínica

ABSTRACT Cerebellar ataxia is a common finding in neurological practice and has a wide variety of causes, ranging from the chronic and slowly-progressive cerebellar degenerations to the acute cerebellar lesions due to infarction, edema and hemorrhage, configuring a true neurological emergency. Acute cerebellar ataxia is a syndrome that occurs in less than 72 hours, in previously healthy subjects. Acute ataxia usually results in hospitalization and extensive laboratory investigation. Clinicians are often faced with decisions on the extent and timing of the initial screening tests, particularly to detect treatable causes. The main group of diseases that may cause acute ataxias discussed in this article are: stroke, infectious, toxic, immune-mediated, paraneoplastic, vitamin deficiency, structural lesions and metabolic diseases. This review focuses on the etiologic and diagnostic considerations for acute ataxia.

RESUMO A ataxia cerebelar é um achado comum na prática neurológica e tem uma grande variedade de causas, desde a degeneração cerebelar crônica e lentamente progressiva à lesão cerebelar aguda devido a infarto, edema ou hemorragia, configurando uma verdadeira emergência neurológica. Ataxia cerebelar aguda é uma síndrome que ocorre em menos de 72 horas em indivíduos previamente saudáveis. A ataxia aguda geralmente resulta em hospitalização e extensa investigação laboratorial. Os clínicos são frequentemente confrontados com a decisão sobre a extensão e o momento dos testes de rastreio iniciais, em particular para detectar as causas tratáveis. O principal grupo de doenças que podem causar ataxias agudas discutidas neste artigo são: acidente vascular cerebral, infecciosas, tóxicas, imunomediadas, paraneoplásicas, deficiência de vitaminas, lesões estruturais e doenças metabólicas. Esta revisão enfoca a etiologia e considerações diagnósticas para a ataxia aguda.

Clinical characteristics of patients with cerebellar ataxia associated with anti-GAD antibodies / Características clínicas de pacientes com ataxia cerebelar associada a anticorpos anti-GAD

ABSTRACT The enzyme glutamic acid decarboxylase (GAD), present in GABAergic neurons and in pancreatic beta cells, catalyzes the conversion of gamma-aminobutyric acid (GABA). The cerebellum is highly susceptible to immune-mediated mechanisms, with the potentially treatable autoimmune cerebellar ataxia associated with the GAD antibody (CA-GAD-ab) being a rare, albeit increasingly detected condition. Few cases of CA-GAD-ab have been described. Methods This retrospective and descriptive study evaluated the clinical characteristics and outcomes of patients with CA-GAD-ab. Result Three patients with cerebellar ataxia, high GAD-ab titers and autoimmune endocrine disease were identified. Patients 1 and 2 had classic stiff person syndrome and insidious-onset cerebellar ataxia, while Patient 3 had pure cerebellar ataxia with subacute onset. Patients received intravenous immunoglobulin therapy with no response in Patients 1 and 3 and partial recovery in Patient 2. Conclusion CA-GAD-ab is rare and its clinical presentation may hamper diagnosis. Clinicians should be able to recognize this potentially treatable autoimmune cerebellar ataxia.

RESUMO A enzima ácido glutâmico descarboxilase (GAD), presente nos neurônios GABAérgicos e células beta do pâncreas, catalisa a conversão do ácido gama-aminobutírico (GABA). O cerebelo é altamente susceptível a mecanismos imunomediados, sendo a ataxia cerebelar associada ao anticorpo anti-GAD (CA-GAD) uma doença potencialmente tratável. Embora rara, sua frequência é crescente, com poucos casos descritos. Métodos Estudo retrospectivo e descritivo avaliando características clínicas e desfechos da CA-GAD. Resultados Três pacientes com CA-GAD, altos títulos de anti-GAD e doença endócrina autoimune foram identificados. Os pacientes 1 e 2 tinham síndrome da pessoa rígida em forma clássica e apresentação insidiosa da ataxia cerebelar, enquanto o paciente 3 tinha ataxia cerebelar pura e apresentação subaguda. Os pacientes 1 e 3 não melhoraram com imunoglobulina intravenosa e o paciente 2 teve recuperação parcial. Conclusão A CA-GAD é rara e pode ter apresentação clínica desafiadora. Os médicos devem ser capazes de reconhecer essa forma potencialmente tratável de ataxia cerebelar autoimune.

Non-progressive cerebellar ataxia and previous undetermined acute cerebellar injury: a mysterious clinical condition / Ataxias cerebelares não-progressivas e lesão cerebelar aguda prévia indeterminada: uma condição clínica misteriosa

Cerebellar ataxias represent a wide group of neurological diseases secondary to dysfunctions of cerebellum or its associated pathways, rarely coursing with acute-onset acquired etiologies and chronic non-progressive presentation. We evaluated patients with acquired non-progressive cerebellar ataxia that presented previous acute or subacute onset. Clinical and neuroimaging characterization of adult patients with acquired non-progressive ataxia were performed. Five patients were identified with the phenotype of acquired non-progressive ataxia. Most patients presented with a juvenile to adult-onset acute to subacute appendicular and truncal cerebellar ataxia with mild to moderate cerebellar or olivopontocerebellar atrophy. Establishing the etiology of the acute triggering events of such ataxias is complex. Non-progressive ataxia in adults must be distinguished from hereditary ataxias.

Ataxias cerebelares representam um grupo amplo de doenças neurológicas secundárias a disfunções cerebelares ou das vias associadas, raramente cursando com etiologias adquiridas de início agudo e com evolução crônica não-progressiva. Nós avaliamos pacientes com ataxia cerebelar adquirida não-progressiva com apresentação prévia aguda ou subaguda. Foi realizada caracterização clínica e de neuroimagem de pacientes adultos com ataxia adquirida não-progressiva. Cinco pacientes foram identificados com o fenótipo clínico de ataxia adquirida não-progressiva. A maior parte dos pacientes apresentou início juvenil ou no adulto, de forma aguda ou subaguda, de ataxia cerebelar appendicular e de tronco com atrofia cerebelar ou olivopontocerebelar leve a moderada. Estabelecer a etiologia dos eventos agudos desencadeantes de tais ataxias é complexo. Ataxia não-progressiva em adultos deve ser diferenciada das ataxias hereditárias.

Ataxia, ophthalmoplegia and laryngeal stridor related to glutamic acid decarboxylase antibodies / Ataxia, oftalmoplegia e estridor laríngeo relacionados a anticorpos antidescarboxilase do ácido glutâmico

Glutamic acid decarboxylase (GAD) is the enzyme responsible for the conversion of glutamate to gamma-aminobutyric acid (GABA) in the central nervous system. The presence of anti-GAD antibody in cerebrospinal fluid and high levels in blood have been described in some neurological disorders, such as stiff person syndrome and cerebellar ataxia. It is postulated that African descent with anti-GAD may exhibit more severe neurological impairment. We report a case of a young adult African descent with cerebellar syndrome associ-ated with ophthalmoplegia and laryngeal stridor. We found in the literature relationship of ophthalmoplegia plus ataxia with anti-GAD, but no reports of these symptoms with laryngeal stridor, apparently being the first reported case.

Descarboxilase do ácido glutâmico (GAD) é a enzima responsável pela conversão do glutamato em ácido gama-aminobutírico (GABA) no sistema nervoso central. A presença do anticorpo anti-GAD no líquido cefalorraquidiano e em altos níveis no sangue tem sido descrita em alguns distúrbios neurológicos, tais como a síndrome da pessoa rígida e ataxia cerebelar. Postula-se que pacientes afrodescendentes podem apresentar comprometimento neurológico mais severo. Relatamos o caso de um adulto jovem afrodescendente com síndrome cerebelar associada a oftalmoplegia e estridor laríngeo. Encontramos na literatura relação entre a oftalmoplegia com ataxia e anti-GAD, mas nenhum relato desses sintomas com estridor laríngeo, sendo aparentemente o primeiro caso reportado.

Ataxia cerebelar idiopática de início tardio (ILOCA): um desafio diagnóstico / Idiopathic late onset cerebellar ataxia (ILOCA): diagnostic challenge

O diagnóstico diferencial das ataxias é complexo e a determinação etiológica um desafio. Quando se inicia após os 50 anos de idade, mesmo após extensa investigação, eventualmente não se estabelece a etiologia, podendo tratar-se de ataxia cerebelar idiopática de início tardio (ILOCA), uma das formas de ataxia esporádica neurodegenerativa. Relatamos o caso de uma mulher com quadro de ataxia e sinais piramidais com evolução de 14 anos, cuja causa, mesmo após extensa investigação, não foi possível de se identificar. Citamos, ainda, os diagnósticos diferenciais, assim como o estabelecido para a paciente em questão: ILOCA-plus , por causa da presença de sinais piramidais associados à ataxia.

The differential diagnosis of ataxia is complex and determining etiology is a diagnostic challenge. In some patients even after extensive investigation no etiology is determined and these cases could be classified as idiopathic late onset cerebellar ataxia (ILOCA), a cause of sporadic neurodegenerative ataxia. We report a case of a female patient with progressive ataxia (14 years of evolution) with pyramidal signs that even after extensive research has not been possible to determine the cause. We discuss the differential diagnosis and the diagnosis established for the patient: ILOCA-plus, due to presence of pyramidal signs associated with ataxia.

Adult onset sporadic ataxias: a diagnostic challenge / Ataxias esporadicas de inicio no adulto: um desafio diagnostico

Patients with adult onset non-familial progressive ataxia are classified in sporadic ataxia group. There are several disease categories that may manifest with sporadic ataxia: toxic causes, immune-mediated ataxias, vitamin deficiency, infectious diseases, degenerative disorders and even genetic conditions. Considering heterogeneity in the clinical spectrum of sporadic ataxias, the correct diagnosis remains a clinical challenge. In this review, the different disease categories that lead to sporadic ataxia with adult onset are discussed with special emphasis on their clinical and neuroimaging features, and diagnostic criteria.

Pacientes com ataxia progressiva que se inicia na idade adulta, e sem histórico familiar da doença, são classificados no grupo das ataxias esporádicas. Existem várias categorias de doenças que podem se manifestar com ataxia esporádica, tais como: causas tóxicas, ataxias imunomediadas, deficiência de vitaminas, doenças infecciosas, doenças degenerativas e até mesmo condições genéticas. Considerando a heterogeneidade no espectro clínico das ataxias esporádicas, a definição da etiologia constitui um desafio diagnóstico. Neste artigo de revisão, realizamos uma discussão sobre as diferentes categorias de doenças que causam ataxia com início na idade adulta sem histórico familiar, com ênfase nas características clínicas, aspectos de imagem e critérios diagnósticos.

Ataxia crónica en pediatría / [Chronic ataxia in childhood].

Chronic ataxias are an heterogeneous group of disorders that affect the child at different ages. Thus, the congenital forms, generally non progressive are observed from first months of life and are expressed by hypotonia and motor delay long before the ataxia became evident. The cerebral magnetic resonance images (MRI) may be diagnostic in some pictures like Joubert syndrome. The group of progressive hereditary ataxias, usually begin after the infant period. The clinical signs are gait instability and ocular apraxia that can be associated with oculocutaneous telangiectasias (ataxia-telangiesctasia) or with sensory neuropathy (Friedreich ataxia). In this review are briefly described congenital ataxias and in more detailed form the progressive hereditary ataxias autosomal recessive, autosomal dominants and mitochondrials. The importance of genetic study is emphasized, because it is the key to obtain the diagnosis in the majority of these diseases. Although now there are no treatments for the majority of progressive hereditary ataxias, some they have like Refsum disease, vitamine E deficiency, Coenzyme Q10 deficiency and others, thus the diagnosis in these cases is even more important. At present the diagnosis of childhood hereditary ataxia not yet treatable is fundamental to obtain suitable handling, determine a precise outcome and to give to the family an opportune genetic counseling.

Ataxias agudas en la infancia / [Acute cerebellar ataxia in childhood].

Acute cerebellar ataxia of childhood is the most frequent neurological complication of chickenpox virus infection. Acute cerebellar ataxia is categorized within the group of acute postinfectious complications. The aims of this study were: (I) to evaluate the clinical presentation, management, and follow-up of children hospitalized due to acute cerebellar ataxia in a tertiary pediatric hospital, where immunization for chickenpox is not available, and (II) to describe the differential diagnosis of acute postinfectious cerebellitis. We evaluated 95 patients with acute cerebellar ataxia. The diagnostic criteria for acute ataxia were: Acute-onset loss of coordination or gait difficulties, with or without nystagmus, lasting less than 48 hours in a previously healthy child. All children met the inclusion criteria, except those with drug-induced ataxia in whom duration should be less than 24 hours for inclusion in the study. The data were recorded in a clinical pediatrics and neurological chart. Among immunosuppressed patients acute cerebellar ataxia was most frequently due to chickenpox. Most of the patients were male. Age at presentation ranged from preschool to 5 years of age. Time lapse between presentation of the rash and hospital admission ranged from 1 to 3 days. CSF study was performed in 59.5

of the cases. Brain magnetic resonance imaging and computed tomography scan showed edema in 33.3

. Intravenous acyclovir was used in 23 patients, however, no significant differences were found in clinical manifestations and follow-up between treated and untreated patients. Ataxia was the first clinical manifestation. Mean hospital stay ranged from 2 to 11 days with a mean of 4 days.

Neurological disorders associated with glutamic acid decarboxylase antibodies: a Brazilian series / Distúrbios neurológicos associadas a anticorpos anti-GAD (descarboxilase do ácido glutâmico): uma série de casos brasileira

Neurological disorders associated with glutamic acid decarboxylase (GAD) antibodies are rare pleomorphic diseases of uncertain cause, of which stiff-person syndrome (SPS) is the best-known. Here, we described nine consecutive cases of neurological disorders associated with anti-GAD, including nine patients with SPS and three cases with cerebellar ataxia. Additionally, four had hypothyroidism, three epilepsy, two diabetes mellitus and two axial myoclonus.

Distúrbios neurológicos associados com anticorpos anti-GAD são doenças pleomórficas, raras, de causa incerta, das quais a rigidez muscular espasmódica (SPR) é a mais conhecida. Neste estudo, descrevemos nove casos consecutivos de distúrbios neurológicos associados com a presença de anticorpos anti-GAD, incluindo nove pacientes com SPR e três casos com ataxia cerebelar. Adicionalmente, foram encontrados quatro casos com hipotireoidismo, três com epilepsia, dois com diabetes mellitus e dois casos com mioclonia axial.

Cerebelite aguda com herniação tonsilar: relato de caso / Acute cerebellitis with tonsillar herniation: a case report

A cerebelite aguda é uma síndrome inflamatória rara frequentemente caracterizada por rápida disfunção cerebelar. Neste estudo relatamos os achados de imagem do caso de uma criança com cerebelite aguda, herniação tonsilar e hidrocefalia hipertensiva. O agente etiológico não foi descoberto. O tratamento foi conservador, com manitol e corticoide. A análise evolutiva por imagem demonstrou resolução do quadro clínico sem sequelas.

Acute cerebellitis is a rare inflammatory syndrome frequently characterized by fast onset of cerebellar dysfunction. The present case report describes imaging findings in a child with acute cerebellitis, tonsillar herniation and hypertensive hydrocephalus. The etiologic agent has not been determined. A conservative management was adopted, with corticoid and diuretic drugs. Imaging follow-up demonstrated resolution of the clinical condition with no sequela.

Rhombencephalosynapsis: association with single umbilical artery.

A 6-year-old girl who presented with developmental delay and non-progressive ataxia is described. MRI of brain showed agenesis of cerebellar vermis with fusion of cerebellar hemispheres and dentate nuclei. MRI findings were characteristic of rhombencephalosynapsis. Partial agenesis of corpus callosum and absent septum pellucidum were also seen. The child had also been noted to have a single umbilical artery at birth: a hitherto undescribed association.

Focal neurological manifestations in Legionellosis.

Legionnaires' disease is an atypical pneumonia with protean multisystem manifestations. Neurological involvement in legionellosis is rare and tends to be among the presenting manifestations. We report a previously healthy young lady who developed focal sensory deficits and cerebellar dysfunction after clinical recovery from Legionella pneumonia. The care is unusual for the delayed appearance of striking focal sensory abnormalities and cerebellar dysfunction.

A case of opsoclonus-myoclonus-ataxia with neuroblastoma.

A 2 year old boy presented with features of opsoclonus, myoclonus and ataxia. Routine investigations of blood, urine, x-ray chest, bone scan, EEG and MRI of brain, were normal. Urine for VMA was negative. A right suprarenal mass was detected at MRI of abdomen. The mass was resected completely and was found histologically to be of differentiating type of neuroblastoma. The child was treated initially with prednisolone for 6 weeks along with sodium valproate. He is still on sodium valproate for his neurological symptoms. His symptoms still persist though they have decreased in intensity.