Evolution of Movement Disorders in Patients With CLN2-Batten Disease Treated With Enzyme Replacement Therapy.

OBJECTIVES: Neuronal ceroid lipofuscinosis type 2 (CLN2-disease) is an inherited childhood-onset neurodegenerative condition, with classical early features of speech delay, epilepsy, myoclonus, ataxia, and motor regression. This study aimed to better characterize the spectrum of movement disorders in CLN2-disease in a cohort of children receiving enzyme replacement therapy (ERT). METHODS: A cohort of 18 children attending a single center for treatment with cerliponase alfa ERT was systematically assessed using a standardized structured history and a double-scored, video-recorded examination using the Unified Batten Disease Rating Scale (UBDRS) and Abnormal Involuntary Movement Scale. RESULTS: Noncanonical movement disorders are common: while ataxia (89%) and myoclonus (83%) were near-universal, spasticity and dystonia were experienced by over half (61% each), with children having a median of 4 distinct movement disorder phenotypes. This progression was stereotyped with initial ataxia/myoclonus, then hyperkinesia/spasticity, and later hypokinesia. ERT slows progression of movement disorders, as measured by the UBDRS physical subscale, with 1.45 points-per-month progression before diagnosis and 0.44 points-per-month while on treatment (p = 0.019). DISCUSSION: Movement disorders are a core feature of CLN2-disease and follow a typical pattern of progression which is slowed by ERT. Identifying and treating movement disorders should become standard, especially given increased patient survival.

The natural history of progressive myoclonus ataxia.

Progressive myoclonus ataxia (PMA) is a rare clinical syndrome characterized by the presence of progressive myoclonus and ataxia, and can be accompanied by mild cognitive impairment and infrequent epileptic seizures. This is the first study to describe the natural history of PMA and identify clinical, electrophysiological, and genetic features explaining the variability in disease progression. A Dutch cohort of consecutive patients meeting the criteria of the refined definition of PMA was included. The current phenotype was assessed during in-person consultation by movement disorders experts, and retrospective data was collected to describe disease presentation and progression, including brain imaging and therapy efficacy. Extensive genetic and electrophysiological tests were performed. The presence of cortical hyperexcitability was determined, by either the identification of a cortical correlate of myoclonic jerks with simultaneous electromyography-electroencephalography or a giant somatosensory evoked potential. We included 34 patients with PMA with a median disease duration of 15 years and a clear progressive course in most patients (76%). A molecular etiology was identified in 82% patients: ATM, CAMTA1, DHDDS, EBF3, GOSR2, ITPR1, KCNC3, NUS1, POLR1A, PRKCG, SEMA6B, SPTBN2, TPP1, ZMYND11, and a 12p13.32 deletion. The natural history is a rather homogenous onset of ataxia in the first two years of life followed by myoclonus in the first 5 years of life. Main accompanying neurological dysfunctions included cognitive impairment (62%), epilepsy (38%), autism spectrum disorder (27%), and behavioral problems (18%). Disease progression showed large variability ranging from an epilepsy free PMA phenotype (62%) to evolution towards a progressive myoclonus epilepsy (PME) phenotype (18%): the existence of a PMA-PME spectrum. Cortical hyperexcitability could be tested in 17 patients, and was present in 11 patients and supported cortical myoclonus. Interestingly, post-hoc analysis showed that an absence of cortical hyperexcitability, suggesting non-cortical myoclonus, was associated with the PMA-end of the spectrum with no epilepsy and milder myoclonus, independent of disease duration. An association between the underlying genetic defects and progression on the PMA-PME spectrum was observed. By describing the natural history of the largest cohort of published patients with PMA so far, we see a homogeneous onset with variable disease progression, in which phenotypic evolution to PME occurs in the minority. Genetic and electrophysiological features may be of prognostic value, especially the determination of cortical hyperexcitability. Furthermore, the identification of cortical and non-cortical myoclonus in PMA helps us gain insight in the underlying pathophysiology of myoclonus.

Myoclonus: an update.

PURPOSE OF REVIEW: Myoclonus, a common hyperkinetic movement disorder, can be disabling for patients. It is important to identify and classify myoclonus correctly to ensure appropriate workup and treatment. While the clinical history, examination, and process of classifying myoclonus remain largely unchanged, new causes and triggers for myoclonus are being elucidated, and new genetic causes have been found. Treatment can be challenging, though preliminary data about new options has been promising. RECENT FINDINGS: In this article, we will briefly outline the process of classifying and treating myoclonus. We will then discuss three specific scenarios where myoclonus has been identified: myoclonus associated with SARS-CoV-2 infections, spinal myoclonus following surgery or anesthesia of the spine, and auricular myoclonus. We will also discuss new genetic findings associated with myoclonus-dystonia, and promising results regarding the use of perampanel in treating myoclonus. SUMMARY: The process of describing unique scenarios associated with myoclonus has helped us build our understanding of the causes, genetic background, expected prognosis, and effective treatment of specific types of myoclonus. We hope that further studies on this topic will help tailor treatment.

Myoclonus and Dystonia as Recurrent Presenting Features in Patients with the SCA21-Associated TMEM240 p.Pro170Leu Variant.

Background: Spinocerebellar ataxia 21 (SCA21) is a rare neurological disorder caused by heterozygous variants in TMEM240. A growing, yet still limited number of reports suggested that hyperkinetic movements should be considered a defining component of the disease. Case Series: We describe two newly identified families harboring the recurrent pathogenic TMEM240 p.Pro170Leu variant. Both index patients and the mother of the first proband developed movement disorders, manifesting as myoclonic dystonia and action-induced dystonia without co-occurring ataxia in one case, and pancerebellar syndrome complicated by action-induced dystonia in the other. We reviewed the literature on TMEM240 variants linked to hyperkinetic disorders, comparing our cases to described phenotypes. Discussion: Adding to prior preliminary observations, our series highlights the relevance of hyperkinetic movements as clinically meaningful features of SCA21. TMEM240 mutation should be included in the differential diagnosis of myoclonic dystonia and ataxia-dystonia syndromes.

The genetics of the dystonias – a review based on the new classification of the dystonias / A genética das distonias – uma revisão baseada na nova classificação das distonias

The definition and classification of the dystonias was recently revisited. In the new 2013 classification, the dystonias are subdivided in terms of their etiology according to whether they are the result of pathological changes or structural damage, have acquired causes or are inherited. As hereditary dystonias are clinically and genetically heterogeneous, we sought to classify them according to the new recently defined criteria. We observed that although the new classification is still the subject of much debate and controversy, it is easy to use in a logical and objective manner with the inherited dystonias. With the discovery of new genes, however, it remains to be seen whether the new classification will continue to be effective.

O conceito e a classificação das distonias foram recentemente revisados. Na nova classificação de 2013, quanto à etiologia, as distonias podem ser subdividas em relação às alterações patológicas, aos danos estruturais, às causas adquiridas e à hereditariedade. Como as distonias hereditárias são clínica e geneticamente heterogêneas, buscamos classifica-las segundo os novos critérios estabelecidos recentemente. Observamos que apesar da nova classificação das distonias ainda ser objeto de discussões e controvérsias, ela pode usada com facilidade, de uma maneira lógica e objetiva, no contexto das distonias hereditárias. Com a descoberta de novos genes poderemos observar se essa classificação continuará sendo efetiva.

Mioclonia essencial hereditária com distonia e resposta favoravél ao álcool: estudo clínico de 6 pacientes / Hereditary essential myoclonus with dystonia and alcohol: clinical study of 6 patients

Mioclonia essencial hereditária é uma entidade rara caracterizada por uma síndrome mioclônica de curso variável, com início nas 1a ou 2a décadas, homens e mulheres afetados igualmente, padrÝo de herança dominante com gravidade variável, ausência de outros déficits neurológicos e EEG normal. Um subgrupo de pacientes com estas características, também apresentam distonia e resposta à ingestÝo de álcool. Isto tem levado à muita confusÝo na literatura na definiçÝo e terminologia. O objetivo de nosso trabalho é mostrar o perfil clínico deste grupo de pacientes e classificá-los no contexto das mioclonias essenciais. Foram selecionados 6 pacientes pertencentes a 4 famílias, sendo 4 do sexo masculino e 2 do sexo feminino com mioclonias localizadas preferencialmente em membros superiores, e durante a açÝo destes, eram desencadeados movimentos semelhantes da regiÝo cefálica. Associava-se a presença de movimentos distônicos dos membros superiores e à açÝo. Os movimentos involuntários apresentavam melhora acentuada à ingestÝo de bebida alcoólica. A investigaçÝo laboratorial mostrou EEG normais. O potencial evocado somato sensitivo, CT de crânio e RNM embora nÝo realizados em todos, foram normais. A ENMG realizada em 3 pacientes, mostrou a presença de surtos com duraçÝo que variou de 30 a 112 ms. Em um deles houve o registro de um padrÝo trifásico (agonista-antagonista-agonista) do tipo balísco. Este grupo de pacientes pode ser representativo de uma expressÝo clínica dentro das mioclonias essenciais

Mioclonia essencial hereditária: relato de uma família / Hereditary essencial myoclonus: report of a family

Tem sido descrita na literatura ocorrência de movimentos mioclônicos e distônicos como expressäo isolada de uma condiçäo neurológica de caráter hereditário. Para essa entidade alguns autores propöem a denominaçäo "distonia mioclônica hereditária", enquanto outros preconizam o uso da expressäo "mioclonia essencial hereditária". O presente relato refere-se a uma família em que essa peculiar associaçäo de movimentos anormais acometia diversos membros em três geraçöes. O propósito é uma paciente de 14 anos com movimentos distônicos instalados aos 7 anos e miocloniais aos 13 anos, com evoluçäo lenta e tendendo à estabilizaçäo. Näo havia referência a melhora sob açäo do álcool (paciente abstêmia). A história familiar mostrava outros casos semelhantes. A investigaçäo complementar (dosagem sericas de cobre, ceruloplasmina, T3, T4, TSH; pesquisa de acantócitos; exame do LCR; tomografia e ressonância do segmento cefálico) näo revelou anormalidades. O quadro foi satisfatoriamente controlado com clonazepam na dose de 3 mg/dia