Characteristic head drops and axial extension in advanced chorea-acanthocytosis

A Man With Progressive Chorea and Abnormal Trunk Movements

Neuroacanthocytosis (NA) syndromes are a group of rare genetic disorders characterized by the presence of abnormally shaped red blood cells (acanthocytes) and the progressive degeneration of the basal ganglia, leading to various neurological and systemic symptoms. The "rubber man" gait, characterized by distinctive flexions of the neck (manifesting as head drops) and the trunk, is seen in advanced chorea-acanthocytosis. A 35-year-old male patient presented with progressive abnormal movements affecting his limbs and face, along with dysphagia resulting from involuntary protrusion of the tongue and biting of the cheeks and lips over the past three years. He used to place the food on the back of his tongue and throw his head back to begin swallowing. He also kept a towel in his mouth to absorb saliva and prevent cheek and lip biting. The neurologic examination revealed generalized chorea, severe orolingual dystonia (eating dystonia), and sudden loss of tone while walking, resulting in flexion of the trunk followed by extension. We believe that these features could serve as definitive clinical indicators for chorea-acanthocytosis, providing valuable diagnostic insights, especially when accompanied by self-mutilatory mouth movements or feeding-related tongue dystonia.

Non-Status Epilepticus female rats show seizure-like behaviors in the chronic phase of Pilocarpine experimental model

Abstract Only few studies have focus on animals that received Pilocarpine (Pilo) and did not develop behavioral status epilepticus (SE) and, whether they may become epileptic in the model’s chronic phase. Previews works observed mossy fiber sprouting in the hippocampus of Non-SE (NSE) rats, while others observed spontaneous and recurrent seizures (SRS) 6 - 8 months after animals received Pilo. It is known that neuronal excitability is influenced by female hormones, as well as, the occurrence of SE in castrated and non-castrated female rats. However, it is not known whether females that received Pilo and did not show SE, may have SRS. The aim of this work was to investigate whether castrated and non-castrated female rats that did not show behavioral SE after Pilo, will develop SRS in the following one-year. For that, animals received 360 mg/kg of Pilo and were video monitored for 12 months. SE females from castrated and non-castrated groups became epileptic since the first month after drug injection. Epileptic behaviors were identified watching video monitoring recordings in the fast speed. Castrated and Non-castrated NSE animals showed behaviors resembling seizures described by Racine Scale stages 1 - 3. Motor alterations showed by NSE groups could be observed only when recordings were analyzed in slow speed. In addition, behavioral manifestations as, rhythmic head movements, sudden head movements, whole body movements and immobility were also observed in both, SE and NSE groups. We concluded that NSE female rats may have become epileptic. Adding to it, slow speed analysis of motor alterations was essential for the observation of NSE findings, which suggests that possibly many motor alterations have been underestimated in epilepsy experimental research.

PhenoExam: gene set analyses through integration of different phenotype databases

BACKGROUND

Gene set enrichment analysis (detecting phenotypic terms that emerge as significant in a set of genes) plays an important role in bioinformatics focused on diseases of genetic basis. To facilitate phenotype-oriented gene set analysis, we developed PhenoExam, a freely available R package for tool developers and a web interface for users, which performs: (1) phenotype and disease enrichment analysis on a gene set; (2) measures statistically significant phenotype similarities between gene sets and (3) detects significant differential phenotypes or disease terms across different databases.

RESULTS

PhenoExam generates sensitive and accurate phenotype enrichment analyses. It is also effective in segregating gene sets or Mendelian diseases with very similar phenotypes. We tested the tool with two similar diseases (Parkinson and dystonia), to show phenotype-level similarities but also potentially interesting differences. Moreover, we used PhenoExam to validate computationally predicted new genes potentially associated with epilepsy.

CONCLUSIONS

We developed PhenoExam, a freely available R package and Web application, which performs phenotype enrichment and disease enrichment analysis on gene set G, measures statistically significant phenotype similarities between pairs of gene sets G and G' and detects statistically significant exclusive phenotypes or disease terms, across different databases. We proved with simulations and real cases that it is useful to distinguish between gene sets or diseases with very similar phenotypes. Github R package URL is https://github.com/alexcis95/PhenoExam . Shiny App URL is https://alejandrocisterna.shinyapps.io/phenoexamweb/ .

Pallidus Stimulation for Chorea-Acanthocytosis: A Systematic Review and Meta-Analysis of Individual Data

A significant proportion of patients with chorea-acanthocytosis (ChAc) fail to respond to standard therapies. Recent evidence suggests that globus pallidus internus (GPi) deep brain stimulation (DBS) is a promising treatment option; however, reports are few and limited by sample sizes. We conducted a systematic literature review to evaluate the clinical outcome of GPi-DBS for ChAc. PubMed, Embase, and Cochrane Library databases were searched for relevant articles published before August 2021. The improvement of multiple motor and nonmotor symptoms was qualitatively presented. Improvements in the Unified Huntington’s Disease Rating Scale motor score (UHDRS-MS) were also analyzed during different follow-up periods. A multivariate linear regression analysis was conducted to identify potential predictors of clinical outcomes. Twenty articles, including 27 patients, were eligible. Ninety-six percent of patients with oromandibular dystonia reported significant improvement. GPi-DBS significantly improved the UHDRS-motor score at < 6 months (p < 0.001) and ≥ 6 months (p < 0.001). The UHDRS-motor score improvement rate was over 25% in 75% (15/20 cases) of patients at long-term follow-up (≥ 6 months). The multiple linear regression analysis showed that sex, age at onset, course of disease, and preoperative movement score had no linear relationship with motor improvement at long-term follow-up (p > 0.05). GPi-DBS is an effective and safe treatment in most patients with ChAc, but no reliable predictor of efficacy has been found. Oromandibular dystonia-dominant patients might be the best candidates for GPi-DBS.

Deep brain stimulation for chorea-acanthocytosis: a systematic review

Deep brain stimulation (DBS) is a reversible treatment for chorea-acanthocytosis (ChAc). Its safety and efficacy remain elusive due to the low prevalence of ChAc. We aimed to investigate the safety and efficacy of DBS for ChAc by systematically reviewing literature through PubMed and EMBASE. Inclusion criteria were reports on the efficacy or safety of DBS for ChAc and English language articles, and exclusion criteria were other movement disorders, non-human subjects, and studies without original data. Most studies were published as case reports, and we therefore pooled these cases in one cohort. Twenty studies with 34 patients were included. The mean age of symptom onset was 29.3 years (range, 17-48). The median follow-up was 12 months (range, 2-84). Twenty-nine patients underwent GPi-DBS, two received STN-DBS, and one underwent Vop-DBS. Electrodes were implanted into the ventralis oralis complex of the thalamus and the pallidal in two patients. Symptoms seemed to be easier relieved in chorea (88.5%) and dystonia (76.9%) but dysarthria of most patients (85.7%) was no response after DBS. The Unified Huntington's Disease Rating Scale-Motor Score was used to assess the efficacy of DBS in 25 patients; the mean score decreased from 43.2 to 22.3 and the median improvement rate was 46.7%. Of 24 patients with data on adverse events, complications occurred in 9 patients (37.5%; mostly transient and mild events). DBS is a promising treatment for ChAc with satisfactory efficacy and safety based on the review. Pallidal and thalamic DBS have been applied in ChAc; GPi-DBS seems to be more widely used.

[Case-report of neuroacanthocytosis associated with a compound mutation in the VPS13A gene]

Neuroacanthocytosis is a group of neurodegenerative diseases manifested by a combition of neurological symptoms (most often choreic hyperkinesis) and the presence of an increased number of acanthocytes (erythrocytes with horns) in the peripheral blood. This group includes chorea-acanthocytosis, MacLeod's syndrome, pantothenate kinase-associated neurodegeneration, Huntington-like disease type 2, and some other very rare diseases. This article presents a genetically confirmed clinical case of chorea-acanthocytosis associated with a compound mutation in the VPS13A gene, discusses in detail the stages of a diagnostic search, presents an algorithm for examining patients with chorea.

Movement Disorders and Liver Disease

The association of movement disorders with structural or functional hepatic disease occurs in three principal scenarios: (1) combined involvement of both organ systems from a single disease entity, (2) nervous system dysfunction resulting from exposure to toxic compounds in the setting of defective hepatic clearance, or (3) hepatic and/or neurological injury secondary to exposure to exogenous drugs or toxins. An important early step in the workup of any patient with combined movement disorders and liver disease is the exclusion of Wilson's disease. Diagnostic delay remains common for this treatable disorder, and this has major implications for patient outcomes. Thereafter, a structured approach integrating variables such as age of onset, tempo of progression, nature and severity of liver involvement, movement disorder phenomenology, exposure to drugs/toxins and laboratory/neuroimaging findings is key to ensuring timely diagnosis and disease‐specific therapy. Herein, we provide an overview of disorders which may manifest with a combination of movement disorders and liver disease, structured under the three headings as detailed above. In each section, the most common disorders are discussed, along with important clinical pearls, suggested diagnostic workup, differential diagnoses and where appropriate, treatment considerations.

Phasic Knee Bending Dystonic and Parkinsonian Gait: A Characteristic Finding in X-Linked Dystonia Parkinsonism

Background

X-linked dystonia parkinsonism (XDP) is a rare disorder characterized by adult-onset, progressive dystonia that, over time, is combined with or replaced by features of parkinsonism. Gait impairment is common.

Methods

Case series of 4 XDP patients with a unique gait disorder.

Results

The patients displayed a characteristic gait disorder with combined dystonic and parkinsonian gait features, with phasic knee bending. Of these patients, all had parkinsonism and three-quarters had prominent dystonic features, but 1 had predominant parkinsonism and subtle dystonic features.

Conclusion

Although XDP is a classic form of dystonia parkinsonism, some cases can mimic idiopathic Parkinson's disease. We describe a gait disorder which appears unique to XDP, involving phasic dystonic knee bending superimposed on parkinsonian shuffling, and may help clinically differentiate one of our parkinsonian-predominant patients from more-common forms of parkinsonism. The gait is distinct from other complex dystonic disorders with gait involvement.

Chorea

PURPOSE OF REVIEW

This article provides an overview of the approach to chorea in clinical practice, beginning with a discussion of the phenomenologic features of chorea and how to differentiate it from other movement disorders. The diagnostic approach, clinical features of important acquired and genetic choreas, and therapeutic principles are also discussed. Practical clinical points and caveats are included.

RECENT FINDINGS

C9orf72 disease is the most common Huntington disease phenocopy, according to studies in the European population. Anti-IgLON5 disease can present with chorea. The role of immunotherapies in Sydenham chorea has increased, and further clinical studies may be useful. Benign hereditary chorea is a syndrome or phenotype due to mutations in several genes, including NKX2-1, ADCY5, GNAO1, and PDE10A. New-generation presynaptic dopamine-depleting agents provide more options for symptomatic treatment of chorea with fewer adverse effects. Deep brain stimulation has been performed in several choreic disorders, but features other than chorea and the neurodegenerative nature should be taken into consideration. Studies on genetic interventions for Huntington disease are ongoing.

SUMMARY

Clinical features remain crucial in guiding the differential diagnosis and appropriate investigations in chorea. Given the complexity of most choreic disorders, treating only the chorea is not sufficient. A comprehensive and multidisciplinary approach is required.

Criminal Behaviour Associated with a Novel Mutation in the VPS13A-Gene Causing Chorea-Acanthocytosis

Heralded by obsessive-compulsive disorder and anxiety, chorea-acanthocytosis may initially present in a psychiatric setting. As insidious onset of involuntary movements is commonly precipitated by dopamine blocking agents, this may not prompt further neurological investigation until symptoms progress after withdrawal of the suspected offending drug. Oromandibular dystonia and frontal disinhibition should call for early neurologic evaluation.

Subcortical neurodegeneration in chorea: Similarities and differences between chorea-acanthocytosis and Huntington's disease

INTRODUCTION

Chorea-acanthocytosis (ChAc) and Huntington's disease (HD) are neurodegenerative conditions that share clinical and neuropathological features, despite their distinct genetic etiologies.

METHODS

In order to compare these neuropathologies, serial gallocyanin-stained brain sections from three subjects with ChAc were analyzed and compared with our previous studies of eight HD cases, in addition to three hemispheres from two male controls.

RESULTS

Astrogliosis was much greater in the ChAc striatum, as compared to that found in HD, with dramatic increase in total striatal glia numbers and the number of glia per striatal neuron. Striatal astrocytes are most likely derived from the striatal subependymal layer in ChAc, which showed massive proliferation. The thalamic centromedian-parafascicular complex is reciprocally connected to the striatum and is more heavily affected in HD than in ChAc.

CONCLUSION

The distinct patterns of selective vulnerability and gliosis observed in HD and ChAc challenge simplistic views on the pathogenesis of these two diseases with rather similar clinical signs. The particular roles played by astroglia in ChAc and in HD clearly need to be elucidated in more detail.

Axial Sensory Tricks in Chorea-Acanthocytosis: Insights into Phenomenology

Background

Trunk flexion and axial extension are characteristic symptoms of chorea–acanthocytosis (ChAc).

Phenomenology Shown

A 41-year-old male with ChAc (confirmed by VPS13A mutations) reported that his involuntary axial movements were significantly ameliorated by either folding his arms over his chest or putting his hands behind his head.

Educational Value

These apparent “sensory tricks” suggest a dystonic pathophysiology, and also merit further study to analyze their potential for symptom control in ChAc.

Functional neuroimaging and chorea: a systematic review

Chorea is a hyperkinetic movement disorder consisting of involuntary irregular, flowing movements of the trunk, neck or face. Although Huntington’s disease is the most common cause of chorea in adults, chorea can also result from many other neurodegenerative, metabolic, and autoimmune conditions. While the pathophysiology of these different conditions is quite variable, recent advances in functional imaging have enabled the development of new methods for analysis of brain activity and neuronal dysfunction. In this paper we review the growing body of functional imaging data that has been performed in chorea syndromes and identify particular trends, which can be used to better understand the underlying network changes within the basal ganglia. While it can be challenging to identify whether changes are primary, secondary, or compensatory, identification of these trends can ultimately be useful in diagnostic testing and treatment in many of the conditions that cause chorea.

A Video Report of Brain-Lung-Thyroid Syndrome in a Japanese Female With a Novel Frameshift Mutation of the NKX2-1 Gene

Benign hereditary chorea is a rare autosomal-dominant disorder that is characterized by childhood-onset nonprogressive chorea and normal cognitive function. Defects in NKX2-1 on chromosome 14q13, which encodes thyroid transcription factor 1, produce a concurrent clinical manifestation of chorea, respiratory distress, and hypothyroidism known as “brain–lung–thyroid syndrome.” Here, the authors describe a video report of benign hereditary chorea in a Japanese female with a novel frameshift mutation of NKX2-1 (c.915_916insC) (p.Ala303ArgfsX132) that was initially misdiagnosed as ataxic cerebral palsy. In early infancy, especially before the appearance of chorea, benign hereditary chorea can be misdiagnosed as ataxic and dyskinetic cerebral palsy due to shared clinical features including motor delay, hypotonia, ataxic gait, and dystonia.

ADCY5-related movement disorders: Frequency, disease course and phenotypic variability in a cohort of paediatric patients

Introduction

ADCY5 mutations have been recently identified as an important cause of early-onset hyperkinetic movement disorders. The phenotypic spectrum associated with mutations in this gene is expanding. However, the ADCY5 mutational frequency in cohorts of paediatric patients with hyperkinetic movement disorders has not been evaluated.

Methods

We performed a screening of the entire ADCY5 coding sequence in 44 unrelated subjects with genetically undiagnosed childhood-onset hyperkinetic movement disorders, featuring chorea alone or in combination with myoclonus and dystonia. All patients had normal CSF analysis and brain imaging and were regularly followed-up in tertiary centers for paediatric movement disorders.

Results

We identified five unrelated subjects with ADCY5 mutations (11% of the cohort). Three carried the p. R418W mutation, one the p. R418Q and one the p. R418G mutation. Mutations arose de novo in four cases, while one patient inherited the mutation from his similarly affected father. All patients had delayed motor and/or language milestones with or without axial hypotonia and showed generalized chorea and dystonia, with prominent myoclonic jerks in one case. Episodic exacerbations of the baseline movement disorder were observed in most cases, being the first disease manifestation in two patients. The disease course was variable, from stability to spontaneous improvement during adolescence.

Conclusion

Mutations in ADCY5 are responsible for a hyperkinetic movement disorder that can be preceded by episodic attacks before the movement disorder becomes persistent and is frequently misdiagnosed as dyskinetic cerebral palsy. A residual degree of neck hypotonia and a myopathy-like facial appearance are frequently observed in patients with ADCY5 mutations.

•

ADCY5 mutational frequency in paediatric patients is unknown.

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5/44 (11%) subjects in our cohort carried pathogenic ADCY5 mutations.

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Chorea-dystonia, exacerbations and developmental delay are often observed together.

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Disease course and clinical features are variable among patients with ADCY5 mutations.

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Residual cervical hypotonia and a myopathy-like face are additional diagnostic clues.

Chorea

PURPOSE OF REVIEW

This article reviews the clinical approach to the diagnosis of adult patients presenting with chorea, using Huntington disease (HD) as a point of reference, and presents the clinical elements that help in the diagnostic workup. Principles of management for chorea and some of the associated features of other choreic syndromes are also described.

RECENT FINDINGS

Mutations in the C9orf72 gene, previously identified in families with a history of frontotemporal dementia, amyotrophic lateral sclerosis, or both, have been recognized as one of the most prevalent causes of HD phenocopies in the white population.

SUMMARY

The diagnosis of chorea in adult patients is challenging. A varied number of associated causes require a physician to prioritize the investigations, and a detailed history of chorea and associated findings will help. For chorea presenting as part of a neurodegenerative syndrome, the consideration of a mutation in the C9orf72 gene is a new recommendation after excluding HD. There are no new treatment options for chorea, aside from dopamine blockers and tetrabenazine. There are no disease-modifying treatments for HD or other neurodegenerative choreic syndromes.

Intermittent head drops: the differential spectrum

Intermittent Head Drops are episodic head flexion movements that can occur in a number of conditions. Typically, the term has mainly been related to epileptic episodes, but the spectrum of clinical conditions associated with this feature is wide-ranging even if never discussed in detail. By searching the electronic database, we may find that apart from the epileptic conditions, Intermittent Head Drops have been in fact reported in the setting of movement disorders, sleep disorders and even internal medicine disorders, such as Sandifer syndrome. We render an in-depth description of this characteristic phenomenon in different diseases, describing the clinical clues and neurophysiological patterns that may help the clinician to distinguish between the different settings of occurrence.

Chorea-acanthocytosis: a case report

Neuroacanthocytosis is a group of rare disorders. We report a 36-year-old right-handed female who presented with gradually progressive abnormal facial movements, generalized weakness, and lower-lip biting starting 4 years ago. On examination, she had lower-lip ulcer, orofacial dyskinesias, and peripheral neuropathy. Her peripheral blood smears showed acanthocytosis and magnetic resonance imaging revealed atrophied head of caudate nuclei and putaminal hyperintensities on T2-weighted and fluid attenuated inversion recovery images. Work-up for autoimmune and metabolic causes was negative. She was diagnosed with chorea-acanthocytosis, an entity under neuroacanthocytosis syndrome and the patient was offered symptomatic treatment.

Huntington's Disease, Huntington's Disease Look-Alikes‎, and Benign Hereditary Chorea: What's New?

Background

The differential diagnosis of chorea syndromes is complex. It includes inherited forms, the most common of which is autosomal dominant Huntington's disease (HD). In addition, there are disorders mimicking HD, the so-called HD-like (HDL) syndromes.

Methods and Results

Here we review main clinical, genetic, and pathophysiological characteristics of HD and the rare HD phenocopies in order to familiarize clinicians with them. Molecular studies have shown that HD phenocopies account for about 1% of suspected HD cases, most commonly due to mutations in C9orf72 (also the main cause of frontotemporal dementia and amyotrophic lateral sclerosis syndromes), TATA box-binding protein (spinocerebellar ataxia type 17 [SCA17]/HDL4), and JPH3 (HDL2). Systematic screening studies also revealed mutations in PRNP (prion disease), VPS13A (chorea-acanthocytosis), ATXN8OS-ATXN8 (SCA8), and FXN (late-onset Friedreich's Ataxia) in single cases. Further differential diagnoses to consider in patients presenting with a clinical diagnosis consistent with HD, but without the HD expansion, include dentatorubral-pallidoluysian atrophy and benign hereditary chorea (TITF1), as well as the recently described form of ADCY5-associated neurodegeneration. Lastly, biallelic mutations in RNF216 and FRRS1L have recently been reported as autosomal recessive phenocopies of HD.

Conclusion

There is a growing list of genes associated with chorea, yet a substantial percentage of patients remain undiagnosed. It is likely that more genes will be discovered in the future and that the clinical spectrum of the described disorders will broaden.

Late Emergence of Parkinsonian Phenotype and Abnormal Dopamine Transporter Scan in Chorea-Acanthocytosis

Chorea-acanthocytosis (ChAc) is a neurodegenerative condition predominantly manifesting with chorea and often acanthocytes on peripheral blood film. Abnormal appearances with ¹²³I-FP-CIT single-photon emission computed tomography (SPECT) have not previously been reported in ChAc. We describe 2 cases with typical presentations of ChAc and late development of parkinsonism with asymmetric reduction in presynaptic striatal uptake on ¹²³I-FP-CIT SPECT. Case 1, a 50-year-old male, developed micrographia and limb bradykinesia 14 years after initial presentation at the age of 30. Case 2, a 42-year-old female presenting with vocal tics and generalized dystonia at the age of 25, developed tremor, bradykinesia, and rigidity 11 years into the disease course. These cases represent the best description to date of the natural history of ChAc, in which the early hyperkinetic clinical syndromes give way to a parkinsonian phenotype. This is consistent with a gradual deterioration of presynaptic nigrostriatal projections, reflected in the clinical parkinsonism and abnormal ¹²³I FP-CIT SPECT.

Differential diagnosis of Huntington's disease: what the clinician should know

Huntington's disease (HD), an autosomal-dominant illness caused by an expansion of the CAG repeats on the short arm of chromosome 4, is clinically characterized by a combination of movement disorders, cognitive decline and behavioral changes. HD accounts for 90-99% of patients who present with this clinical picture. The remaining patients that are negative for the HD genetic mutation are said to have HD phenocopies. Autosomal-dominant diseases that can mimic HD are HD-like 2, C9orf72 mutations, spinocerebellar ataxia type 2, spinocerebellar ataxia type 17 (HD-like 4), benign hereditary chorea, neuroferritinopathy (neurodegeneration with brain iron accumulation type 3), dentatorubropallidoluysian atrophy and HD-like 1. There are also autosomal-recessive choreas that can be HD phenocopies: Friedreich's ataxia, neuroacanthocytosis, several forms of neurodegeneration with brain iron accumulation, ataxia telangiectasia, HD-like 3 and ataxia with oculomotor apraxia. Among X‑linked conditions, McLeod syndrome can mimic the clinical features of HD. Although less frequently, sporadic conditions, such as tardive dyskinesia and non-Wilsonian hepatolenticular degeneration, can also mimic HD.

Huntington's disease and Huntington's disease-like syndromes: an overview

PURPOSE OF REVIEW

The differential diagnosis of chorea syndromes may be complex and includes various genetic disorders such as Huntington's disease and mimicking disorders called Huntington's disease-like (HDL) phenotypes. To familiarize clinicians with these (in some cases very rare) conditions we will summarize the main characteristics.

RECENT FINDINGS

HDL disorders are rare and account for about 1% of cases presenting with a Huntington's disease phenotype. They share overlapping clinical features, so making the diagnosis purely on clinical grounds may be challenging, however presence of certain characteristics may be a clue (e.g. prominent orofacial involvement in neuroferritinopathy etc.), Information of ethnic descent will also guide genetic work-up [HDL2 in Black Africans; dentatorubral-pallidoluysian atrophy (DRPLA) in Japanese etc.], Huntington's disease, the classical HDL disorders (except HDL3) and DRPLA are repeat disorders with anticipation effect and age-dependent phenotype in some, but genetic underpinnings may be more complicated in the other chorea syndromes.

SUMMARY

With advances in genetics more and more rare diseases are disentangled, allowing molecular diagnoses in a growing number of choreic patients. Hopefully, with better understanding of their pathophysiology we are moving towards mechanistic therapies.

Short and long term outcome of bilateral pallidal stimulation in chorea-acanthocytosis

Background

Chorea-acanthocytosis (ChAc) is a neuroacanthocytosis syndrome presenting with severe movement disorders poorly responsive to drug therapy. Case reports suggest that bilateral deep brain stimulation (DBS) of the ventro-postero-lateral internal globus pallidus (GPi) may benefit these patients. To explore this issue, the present multicentre (n=12) retrospective study collected the short and long term outcome of 15 patients who underwent DBS.

Methods

Data were collected in a standardized way 2-6 months preoperatively, 1-5 months (early) and 6 months or more (late) after surgery at the last follow-up visit (mean follow-up: 29.5 months).

Results

Motor severity, assessed by the Unified Huntington’s Disease Rating Scale-Motor Score, UHDRS-MS), was significantly reduced at both early and late post-surgery time points (mean improvement 54.3% and 44.1%, respectively). Functional capacity (UHDRS-Functional Capacity Score) was also significantly improved at both post-surgery time points (mean 75.5% and 73.3%, respectively), whereas incapacity (UHDRS-Independence Score) improvement reached significance at early post-surgery only (mean 37.3%). Long term significant improvement of motor symptom severity (≥20 % from baseline) was observed in 61.5 % of the patients. Chorea and dystonia improved, whereas effects on dysarthria and swallowing were variable. Parkinsonism did not improve. Linear regression analysis showed that preoperative motor severity predicted motor improvement at both post-surgery time points. The most serious adverse event was device infection and cerebral abscess, and one patient died suddenly of unclear cause, 4 years after surgery.

Conclusion

This study shows that bilateral DBS of the GPi effectively reduces the severity of drug-resistant hyperkinetic movement disorders such as present in ChAc.

The differential diagnosis of Huntington's disease-like syndromes: 'red flags' for the clinician

A growing number of progressive heredodegenerative conditions mimic the presentation of Huntington's disease (HD). Differentiating among these HD-like syndromes is necessary when a patient with a combination of movement disorders, cognitive decline, behavioural abnormalities and progressive disease course proves negative to the genetic testing for HD causative mutations, that is, IT15 gene trinucleotide-repeat expansion. The differential diagnosis of HD-like syndromes is complex and may lead to unnecessary and costly investigations. We propose here a guide to this differential diagnosis focusing on a limited number of clinical features ('red flags') that can be identified through accurate clinical examination, collection of historical data and a few routine ancillary investigations. These features include the ethnic background of the patient, the involvement of the facio-bucco-lingual and cervical district by the movement disorder, the co-occurrence of cerebellar features and seizures, the presence of peculiar gait patterns and eye movement abnormalities, and an atypical progression of illness. Additional help may derive from the cognitive-behavioural presentation of the patient, as well as by a restricted number of ancillary investigations, mainly MRI and routine blood tests. These red flags should be constantly updated as the phenotypic characterisation and identification of more reliable diagnostic markers for HD-like syndromes progress over the following years.

Neuroacanthocytosis syndromes

Neuroacanthocytosis (NA) syndromes are a group of genetically defined diseases characterized by the association of red blood cell acanthocytosis and progressive degeneration of the basal ganglia. NA syndromes are exceptionally rare with an estimated prevalence of less than 1 to 5 per 1'000'000 inhabitants for each disorder. The core NA syndromes include autosomal recessive chorea-acanthocytosis and X-linked McLeod syndrome which have a Huntington´s disease-like phenotype consisting of a choreatic movement disorder, psychiatric manifestations and cognitive decline, and additional multi-system features including myopathy and axonal neuropathy. In addition, cardiomyopathy may occur in McLeod syndrome. Acanthocytes are also found in a proportion of patients with autosomal dominant Huntington's disease-like 2, autosomal recessive pantothenate kinase-associated neurodegeneration and several inherited disorders of lipoprotein metabolism, namely abetalipoproteinemia (Bassen-Kornzweig syndrome) and hypobetalipoproteinemia leading to vitamin E malabsorption. The latter disorders are characterized by a peripheral neuropathy and sensory ataxia due to dorsal column degeneration, but movement disorders and cognitive impairment are not present. NA syndromes are caused by disease-specific genetic mutations. The mechanism by which these mutations cause neurodegeneration is not known. The association of the acanthocytic membrane abnormality with selective degeneration of the basal ganglia, however, suggests a common pathogenetic pathway. Laboratory tests include blood smears to detect acanthocytosis and determination of serum creatine kinase. Cerebral magnetic resonance imaging may demonstrate striatal atrophy. Kell and Kx blood group antigens are reduced or absent in McLeod syndrome. Western blot for chorein demonstrates absence of this protein in red blood cells of chorea-acanthocytosis patients. Specific genetic testing is possible in all NA syndromes. Differential diagnoses include Huntington disease and other causes of progressive hyperkinetic movement disorders. There are no curative therapies for NA syndromes. Regular cardiologic studies and avoidance of transfusion complications are mandatory in McLeod syndrome. The hyperkinetic movement disorder may be treated as in Huntington disease. Other symptoms including psychiatric manifestations should be managed in a symptom-oriented manner. NA syndromes have a relentlessly progressive course usually over two to three decades.

Bilateral temporal lobe epilepsy confirmed with intracranial EEG in chorea-acanthocytosis

Chorea-acanthocytosis (ChAc) is an uncommon basal ganglia disorder, in which the movement disorder element may be obscured by the predominance of seizures. We report a pertinent case of a patient who had undergone extensive evaluation for epilepsy, including intracranial EEG before finally the diagnosis of ChAc was made and confirmed by Western blot. We suggest that in patients with epilepsy, particularly of temporal lobe origin and with onset in the third decade with inconclusive findings on clinical examination and neuroimaging such as dyskinesias, dystonia and basal ganglia involvement, ChAc should be considered.