Transient Generalized Chorea in Influenza A Encephalopathy

Differential diagnosis of chorea (guidelines of the German Neurological Society)

INTRODUCTION

Choreiform movement disorders are characterized by involuntary, rapid, irregular, and unpredictable movements of the limbs, face, neck, and trunk. These movements often initially go unnoticed by the affected individuals and may blend together with seemingly intended, random motions. Choreiform movements can occur both at rest and during voluntary movements. They typically increase in intensity with stress and physical activity and essentially cease during deep sleep stages. In particularly in advanced stages of Huntington disease (HD), choreiform hyperkinesia occurs alongside with dystonic postures of the limbs or trunk before they typically decrease in intensity. The differential diagnosis of HD can be complex. Here, the authors aim to provide guidance for the diagnostic process. This guidance was prepared for the German Neurological Society (DGN) for German-speaking countries.

RECOMMENDATIONS

Hereditary (inherited) and non-hereditary (non-inherited) forms of chorea can be distinguished. Therefore, the family history is crucial. However, even in conditions with autosomal-dominant transmission such as HD, unremarkable family histories do not necessarily rule out a hereditary form (e.g., in cases of early deceased or unknown parents, uncertainties in familial relationships, as well as in offspring of parents with CAG repeats in the expandable range (27-35 CAG repeats) which may display expansions into the pathogenic range).

CONCLUSIONS

The differential diagnosis of chorea can be challenging. This guidance prepared for the German Neurological Society (DGN) reflects the state of the art as of 2023.

Review of Hereditary and Acquired Rare Choreas

Background:

Movement disorders are often a prominent part of the phenotype of many neurologic rare diseases. In order to promote awareness and diagnosis of these rare diseases, the International Parkinson’s and Movement Disorders Society Rare Movement Disorders Study Group provides updates on rare movement disorders.

Methods:

In this narrative review, we discuss the differential diagnosis of the rare disorders that can cause chorea.

Results:

Although the most common causes of chorea are hereditary, it is critical to identify acquired or symptomatic choreas since these are potentially treatable conditions. Disorders of metabolism and mitochondrial cytopathies can also be associated with chorea.

Discussion:

The present review discusses clues to the diagnosis of chorea of various etiologies. Authors propose algorithms to help the clinician in the diagnosis of these rare disorders.

Treatment of Secondary Chorea: A Review of the Current Literature

Background

Chorea consists of involuntary movements affecting the limbs, trunk, neck or face, that can move from one body part to another. Chorea is conceptualized as being "primary" when it is attributed to Huntington's disease (HD) or other genetic etiologies, or "secondary" when it is related to infectious, pharmacologic, metabolic, autoimmune disorders, or paraneoplastic syndromes. The mainstay of the secondary chorea management is treating the underlying causative disorder; here we review the literature regarding secondary chorea. We also discuss the management of several non-HD genetic diseases in which chorea can be a feature, where metabolic targets may be amenable to intervention and chorea reduction.

Methods

A PubMed literature search was performed for articles relating to chorea and its medical and surgical management. We reviewed the articles and cross-references of pertinent articles to assess the current clinical practice, expert opinion, and evidence-based medicine to synthesize recommendations for the management of secondary chorea.

Results

There are very few double-blind randomized controlled trials assessing chorea treatments regardless of etiology. Most recommendations are based on small open-label studies, case reports, and expert opinion.

Discussion

Treatment of secondary chorea is currently based on expert opinion, clinical experience, and small case studies, with limited evidence-based medical data. When chorea is secondary to an underlying infection, medication, metabolic abnormality, autoimmune process, or paraneoplastic illness, the movements typically resolve following treatment of the underlying disease. Tardive dyskinesia is most rigorously studied secondary chorea with the best evidence-based medicine treatment guidelines recommending the use of pre-synaptic dopamine-depleting agents. Even though there is an insufficient pool of EBM, small clinical trials, case reports, and expert opinion are valuable for guiding treatment and improving the quality of life for patients with chorea.

Highlights

There is a dearth of well-controlled studies regarding the treatment of chorea. Expert opinion and clinical experiences are fundamental in guiding chorea management and determining successful treatment. In general, secondary chorea improves with treating the underlying medical abnormality; treatments include antibiotics, antivirals, immunosuppression, dopamine depleting agents, chelation, and supportive care.