Chorea and related disorders

Case Report: Chorea as a Rare Manifestation of Secondary Adrenal Insufficiency

The word "chorea" comes from the Latin word "choreus," which means dancing movement. Chorea is defined as a hyperkinetic movement disorder characterized by uncontrolled, unintended, jerky, brief, irregular, random movements involving the limbs or facial muscles. Here, we discuss the case of a 48-year-old male with hypothyroidism for two years, which is well-controlled with medication. He presented with behavioral disturbances for the past seven months and choreiform movements affecting all four limbs, his tongue, and his face for the past six months. Investigations revealed hyponatremia and low serum osmolality. An MRI of the brain showed the empty sella sign. Further investigations revealed low levels of adrenocorticotropic hormone (ACTH), prolactin, and testosterone. Considering the diagnosis of chorea with euvolemic hyponatremia due to secondary adrenal insufficiency, the patient was started on tetrabenazine, trihexyphenidyl, oral hydrocortisone, and gradual correction of sodium level. The patient's condition improved during the hospital stay, and he continues to do well in routine follow-ups.

Assessment and Treatment of Abnormal Involuntary Movements: A Clinically Focused Narrative Review

LEARNING OBJECTIVES

After participating in this CME activity, the psychiatrist should be better able to:• Categorize and describe different types of abnormal involuntary movements (AIMs).• Identify assessment tools and treatment options for AIMs.

ABSTRACT

Abnormal involuntary movements (AIMs) comprise a diverse group of movement disorders characterized by uncontrolled and unintended movements (e.g., tremors, tics, dystonia). AIMs can occur at any stage of life and pose significant challenges for clinicians. It is difficult to determine their underlying causes due to the complex neurobiological mechanisms involved. Therefore, it is crucial to quantify the severity and progression of AIMs using well-validated measurement scales, such as the Abnormal Involuntary Movement Scale (AIMS). By employing reliable assessment approaches, clinicians can objectively evaluate the motoric manifestations of AIMs and track them over time. Treatment of AIMs varies depending on their nature and etiology. While AIMs often respond to treatment, serious side effects can undermine treatment efficacy. In this clinically focused narrative review, we categorize different types of AIMs and discuss their neurobiological aspects. Further, we emphasize the importance of using well-validated measurement scales for accurate assessment and discuss available treatment modalities that target the specific AIMs manifestations. Additionally, we cover the need for comprehensive care to address the multifaceted nature of AIMs, accounting for their physical manifestations as well as their psychological, social, and functional toll on patients. By embracing a multidisciplinary approach, health care professionals can provide patient-centered care that promotes overall well-being and enhances the lives of patients coping with AIMs. Regular follow-up assessments are necessary to monitor treatment response, adjust medications when needed, and provide ongoing support for individuals affected by AIMs.

Impact of Clinical Examination and Gamma Knife Surgery in Stage IV Breast Cancer With Brain Metastasis

Metastatic breast cancer often presents with significant diagnostic and treatment challenges. This case report highlights the crucial role of thorough clinical examination and history-taking in diagnosing and managing a patient with metastatic breast cancer, mainly focusing on the successful integration of Gamma Knife radiosurgery (GKRS). We present a case of a 68-year-old postmenopausal woman with metastatic breast cancer, initially presenting with a primary tumour in the left breast and later developing a solitary brain metastasis (BM) in the left temporal lobe. Following neoadjuvant chemotherapy and left mastectomy, the patient experienced involuntary movements in the right arm, leading to the discovery of the brain lesion. Critical to this diagnosis was a detailed clinical examination emphasising the importance of vigilant monitoring in cancer management. The patient underwent GKRS, offering a focused and less invasive treatment approach with favourable outcomes. This case underscores the value of clinical vigilance in managing complex breast cancer cases. The integration of GKRS as a targeted treatment modality for BM represents a pivotal aspect of modern oncological care, especially for patients with multiple treatment modalities. This report emphasizes the importance of clinical examination in the early detection of complications such as BM in breast cancer patients. Furthermore, it demonstrates the effectiveness of GKRS in managing such metastases, reinforcing its role as a valuable tool in the multidisciplinary treatment approach for advanced breast cancer.

Diagnostic Uncertainties: Chorea

Chorea is a hyperkinetic movement disorder with a multitude of potential etiologies, both acquired and inherited. Although the differential diagnosis for new-onset chorea is extensive, there are often clues in the history, exam, and basic testing that can help to narrow the options. Evaluation for treatable or reversible causes should take priority, as rapid diagnosis can lead to more favorable outcomes. While Huntington's disease is most common genetic cause of chorea, multiple phenocopies also exist and should be considered if Huntington gene testing is negative. The decision of what additional genetic testing to pursue should be based on both clinical and epidemiological factors. The following review provides an overview of the many possible etiologies as well as a practical approach for a patient presenting with new-onset chorea.

A Kinematic Data-Driven Approach to Differentiate Involuntary Choreic Movements in Individuals With Neurological Conditions

OBJECTIVE

The ability to differentiate similar choreic involuntary movements could lay the groundwork for the development of a minimally-invasive screening tool for their etiology and provide in-depth understandings of pathophysiology. As a first step, we investigate kinematic differences between Huntington's disease (HD) chorea and Parkinson's disease (PD) choreic levodopa-induced dyskinesia (LID), which have distinct pathological causes yet share a great kinematic resemblance.

METHODS

Twenty subjects with HD and ten subjects with PD stood with both upper limbs in front of them for approximately 60 seconds. The three-dimensional velocity time-series of involuntary movements of both hands were segmented into one-dimensional sub-movements abutted by velocity zero-crossings. A combination of unsupervised and supervised machine learning algorithms was employed to automatically select data features extracted from sub-movements and distinguish the two types of involuntary choreic movements.

RESULTS

The trained model was able to accurately classify chorea vs. LID with an Area Under the Receiver Operating Characteristic Curve of 99.5%. A set of important features contributing to the construction of the classification model were identified and investigated.

CONCLUSION

The trained model may serve as a tool for the automatic identification of different types of involuntary choreic movements, enabling continuous monitoring and personalized treatment for patients in various clinical settings.

SIGNIFICANCE

The results provide insights into kinematic characteristics of HD chorea and PD LID, which is the first step towards an improved general understanding of involuntary choreic movements.

Dystonia, chorea, hemiballismus and other dyskinesias

Hyperkinesias are heterogeneous involuntary movements that significantly differ in terms of clinical and semeiological manifestations, including rhythm, regularity, speed, duration, and other factors that determine their appearance or suppression. Hyperkinesias are due to complex, variable, and largely undefined pathophysiological mechanisms that may involve different brain areas. In this chapter, we specifically focus on dystonia, chorea and hemiballismus, and other dyskinesias, specifically, levodopa-induced, tardive, and cranial dyskinesia. We address the role of neurophysiological studies aimed at explaining the pathophysiology of these conditions. We mainly refer to human studies using surface and invasive in-depth recordings, as well as spinal, brainstem, and transcortical reflexology and non-invasive brain stimulation techniques. We discuss the extent to which the neurophysiological abnormalities observed in hyperkinesias may be explained by pathophysiological models. We highlight the most relevant issues that deserve future research efforts. The potential role of neurophysiological assessment in the clinical context of hyperkinesia is also discussed.

Therapeutic aspects of Sydenham's Chorea: an update

Sydenham’s Chorea (SC) is a hyperkinetic movement disorder associated with neuropsychiatric manifestations. It is believed to be caused by the autoimmune response following a group A beta-hemolytic streptococcal (GABHS) pharyngitis, and it is one of the major diagnostic criteria for Acute Rheumatic Fever (ARF) diagnosis. Despite having been known and studied for centuries, there are still no standardized therapies or official guidelines for SC treatment, so that it is necessarily left to physicians’ clinical experience. Antibiotic treatment, symptomatic therapies, and immunomodulatory treatment are the three pillars upon which SC patients’ management is currently based, but they still lack a solid scientific basis. The aim of this writing is precisely to review the state of the art of SC’s treatment, with an overview of the advances made in the last 5 years. However, since the therapeutic uncertainties are a mere reflection of the severe gap of knowledge that concerns SC’s pathogenesis and manifestations, the importance of high-quality research studies based on homogenized methodologies, instruments, and measured outcomes will also be stressed. (www.actabiomedica.it)

Hyperkinetic Choreiform Movements Secondary to Basal Ganglia Calcification and Underlying Developmental Venous Anomaly

Chorea is irregular, involuntary movements that are associated with a variety of conditions and can encompass a wide differential. Unilateral hyperkinetic choreiform movements represent a rare subset characterized by the acute and sudden onset of progressive, uncontrollable body movements. We present a patient presenting with left-sided arm and leg arrhythmic movements caused by right-sided basal ganglia calcifications associated with an underlying developmental venous anomaly (DVA). To the author’s knowledge, this is only the second reported case of such a presentation, and it should be on the differential in patients presenting with unilateral movement abnormalities.

Hyperglycemic hemichorea due to diabetic striatopathy: case-based review

Diabetic Striatopathy (DS) is a rare complication of diabetes mellitus (DM) with poor glycemic control and typical neuroimaging findings. DS predominantly leads to a unilateral reversible injury of the basal ganglia resulting in various movement disorders such as hemichorea and hemibalismus. We present a rare case of DS with left-sided hemichorea as a first presentation for a newly diagnosed Diabetes Mellitus (DM) type II and to make a thorough review of this disorder and to provide a practical approach to its management. A 63-year-old female was admitted to the neurology ward with symptoms of involuntary hyperkinetic movements for the left limbs and the left half of the face. The blood samples revealed random serum glucose of 30.8 mmol/l and an HbA1c of 15.13%. The computed tomography of the brain showed asymmetric, unilateral hyperdensity in the right basal ganglia (BG) - the putamen and nucleus caudatus. The patient was managed with Insulin and Haloperidol as the symptoms entirely resolved on the tenth day. In conclusion (DS) is a condition with a good prognosis and reversible clinical and neuroimaging findings after a prompt diagnosis and management. DS should be considered a possible differential diagnosis in patients with abrupt onset of hyperkinetic movement disorders.

Combining Literature Review With a Ground Truth Approach for Diagnosing Huntington's Disease Phenocopy

One percent of patients with a Huntington's disease (HD) phenotype do not have the Huntington (HTT) gene mutation. These are known as HD phenocopies. Their diagnosis is still a challenge. Our objective is to provide a diagnostic approach to HD phenocopies based on medical expertise and a review of the literature. We employed two complementary approaches sequentially: a review of the literature and two surveys analyzing the daily clinical practice of physicians who are experts in movement disorders. The review of the literature was conducted from 1993 to 2020, by extracting articles about chorea or HD-like disorders from the database Pubmed, yielding 51 articles, and analyzing 20 articles in depth to establish the surveys. Twenty-eight physicians responded to the first survey exploring the red flags suggestive of specific disease entities. Thirty-three physicians completed the second survey which asked for the classification of paraclinical tests according to their diagnostic significance. The analysis of the results of the second survey used four different clustering algorithms and the density-based clustering algorithm DBSCAN to classify the paraclinical tests into 1st, 2nd, and 3rd-line recommendations. In addition, we included suggestions from members of the European Reference Network-Rare Neurological Diseases (ERN-RND Chorea & Huntington disease group). Finally, we propose guidance that integrate the detection of clinical red flags with a classification of paraclinical testing options to improve the diagnosis of HD phenocopies.

Hemichorea: A Rare Neurological Complication of Diabetes Mellitus

Diabetes mellitus is a prevalent metabolic disorder that has a wide range of complications. Neurological complications are common and include stroke and peripheral neuropathy. However, hemichorea is a very rare manifestation of diabetes mellitus. Chorea can be due to primary inherited conditions or secondary to other disorders. Careful evaluation of patients with chorea is crucial since secondary chorea can be managed with the treatment of the underlying cause. We report the case of a 51-year-old man who presented to the emergency department with a two-week history of sudden involuntary and random-appearing movements of the right upper and lower extremities. These movements were non-suppressible and disappeared during sleep. Further, the movements were not associated with any neurological symptoms, including headache, dizziness, weakness, sensory deficits, or loss of consciousness. The patient had a longstanding history of hypertension and diabetes mellitus. He reported that he was not compliant with his medications. Laboratory investigation revealed a very high level of blood glucose (580 mg/dL) with associated pseudohyponatreamia (127 mEq/L). Head computed tomography scan showed increased density in right caudate nuclei and putamen with no surrounding edema or mass effect. The findings were suggestive of non-ketotic hyperglycemic hemichorea based on the clinical, laboratory, and radiological laboratory findings. The patient received insulin therapy according to sliding-scale protocol. The chorea movements gradually improved and completely disappeared after the fourth day of admission with the normalization of glucose level. In view of this, emergency medicine physicians should consider non-ketotic hyperglycemia as a potential underlying etiology of acute hemichorea.

Cryptococcal Meningitis Causing Refractory Hemichorea-Hemiballismus Treated With Pallidotomy

We report a case of a 31-year-old immunocompetent male who presented with altered mental status and agitation requiring intubation. As sedation was weaned, he demonstrated choreiform movements with associated hemiballismus of the right upper and lower extremities, and he was ultimately diagnosed with cryptococcal meningitis. The patient’s chorea did not terminate after the completion of induction antifungal therapy and all pharmacologic options for the management of chorea were ineffective. He underwent a successful unilateral pallidotomy using standard stereotactic methodology targeting the posterior-ventral pallidum, and his choreiform movements dramatically improved post-operatively within 48 hours.

Hemichorea due to ipsilateral thalamic infarction: A case report

BACKGROUND

Hemichorea usually results from vascular lesions of the basal ganglia. Most often, the lesion is contralateral to the affected limb but rarely, it may be ipsilateral. The pathophysiology of ipsilateral hemichorea is still poorly understood. We review the literature on hemichorea due to ipsilateral cerebral infarction and explore possible mechanisms for its occurrence.

CASE SUMMARY

A 72-year-old woman presented with complaints of involuntary movements of the muscles of the left side of the face and mild weakness of the right limbs. Her symptoms had started suddenly 1 d earlier. After admission to the hospital, the involuntary movements spread to involve the left limbs also. Magnetic resonance imaging revealed a left thalamic infarction. The patient’s hemichorea subsided after treatment with haloperidol (2 mg per time, 3 times/d) for 3 d; the hemiparesis resolved with rehabilitation physiotherapy. She is presently symptom free and on treatment for prevention of secondary stroke. We review the literature on the occurrence of ipsilateral hemichorea following thalamic infarction and discuss the possible pathomechanisms of this unusual presentation.

CONCLUSION

Ipsilateral hemichorea following a thalamic stroke is rare but it can be explained by structure of the extrapyramidal system. The thalamus is a relay station that exerts a bilateral control of motor function.

State-of-the-art pharmacological approaches to reduce chorea in Huntington's disease

Introduction Chorea is a common motor manifestation of Huntington's disease (HD). Two vesicular monoamine transporter type 2 (VMAT-2) inhibitors have been approved by the FDA for treatment of HD chorea, and a third is currently being assessed in a phase 3 trial. Antipsychotic therapies are used off-label for treatment of chorea and can treat comorbid psychiatric symptoms. There is considerable clinical equipoise regarding the safe and effective treatment of chorea and comorbid symptoms in HD.Areas covered: The authors review existing medications used to treat HD chorea in the United States of America (USA). Implications for common comorbid symptoms (e.g. psychiatric, metabolic) are also discussed. Available therapies vary widely in cost, dosing frequency, and off -target effects, both beneficial or negative.Expert opinion: Treatment considerations for chorea should account for patient comorbidities. The authors recommend prospective, observational clinical effectiveness studies which can evaluate the long-term comparative effectiveness and safety of VMAT-2 inhibitors and antipsychotics in HD. Data regarding safety of dual therapy is another critical need. This is especially timely given the changing landscape of HD therapies which may increase cost burden and possibly extend both asymptomatic and symptomatic years for HD patients.

Clinical Spectrum of Movement Disorders in Neurology Inpatients in a Tertiary Care Centre

Background  Little data are available on the spectrum of movement disorders in inpatients, particularly those admitted in neurology specialty. This may be related to the fact that patients presenting with movement disorders are usually evaluated from outpatient clinics.

Objective  The aim of this study is to provide data on the pattern of movement disorders in neurology inpatients.

Materials and Methods  Patients admitted through emergency department or neurology clinic with complaints of movement abnormalities were recruited in this study from October 2019 to September 2020. Cases were subjected to proforma-based detailed history, examination, and appropriate investigations.

Statistical Analysis  Descriptive statistics using SPSS 20.

Results and Conclusion  Bradykinesia with or without tremor was the most common movement disorder (28.3%), followed by ataxia and dystonia (24.5% each) and hemifacial spasm and myoclonus (7.5% each). Chorea, tic disorder, and hemiballismus were also reported. Etiologies included Parkinson disease, Wilson’s disease, subacute sclerosing panencephalitis (SSPE), drugs, stroke, spinocerebellar ataxia, Huntington’s disease, neuroacanthocytosis, and others. Dystonia represented the most common disorder in the younger age group (44.4%), whereas bradykinesia and/or tremor represented the most common movement disorder in the older age group (46.4%).

This study demonstrates the characteristic distribution of movement disorders in neurology inpatients.

On the hunt for a cure: A guide to Huntington disease

ABSTRACT

Huntington disease is a rare genetic disorder characterized by motor, cognitive, and psychiatric impairments. Although the typical patient has a positive family history and initially presents with chorea between ages 30 and 50 years, some patients do not have a typical presentation. Healthcare providers should know when to refer patients to neurology for testing for Huntington disease. The earlier the diagnosis is made, the earlier the patient and patient's family can receive education about the expected disease trajectory. A multidisciplinary approach is required to mitigate symptoms as the disease progresses. Although no cure exists, ongoing research is targeting genotypic abnormalities in hopes of finding a permanent treatment for Huntington disease.

Systematic Review: Quantitative Susceptibility Mapping (QSM) of Brain Iron Profile in Neurodegenerative Diseases

Iron has been increasingly implicated in the pathology of neurodegenerative diseases. In the past decade, development of the new magnetic resonance imaging technique, quantitative susceptibility mapping (QSM), has enabled for the more comprehensive investigation of iron distribution in the brain. The aim of this systematic review was to provide a synthesis of the findings from existing QSM studies in neurodegenerative diseases. We identified 80 records by searching MEDLINE, Embase, Scopus, and PsycInfo databases. The disorders investigated in these studies included Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Wilson's disease, Huntington's disease, Friedreich's ataxia, spinocerebellar ataxia, Fabry disease, myotonic dystrophy, pantothenate-kinase-associated neurodegeneration, and mitochondrial membrane protein-associated neurodegeneration. As a general pattern, QSM revealed increased magnetic susceptibility (suggestive of increased iron content) in the brain regions associated with the pathology of each disorder, such as the amygdala and caudate nucleus in Alzheimer's disease, the substantia nigra in Parkinson's disease, motor cortex in amyotrophic lateral sclerosis, basal ganglia in Huntington's disease, and cerebellar dentate nucleus in Friedreich's ataxia. Furthermore, the increased magnetic susceptibility correlated with disease duration and severity of clinical features in some disorders. Although the number of studies is still limited in most of the neurodegenerative diseases, the existing evidence suggests that QSM can be a promising tool in the investigation of neurodegeneration.

Advances and Future Directions of Neuromodulation in Neurologic Disorders

"Deep brain stimulation is a safe and effective therapy for the management of a variety of neurologic conditions with Food and Drug Administration or humanitarian exception approval for Parkinson disease, dystonia, tremor, and obsessive-compulsive disorder. Advances in neurophysiology, neuroimaging, and technology have driven increasing interest in the potential benefits of neurostimulation in other neuropsychiatric conditions including dementia, depression, pain, Tourette syndrome, and epilepsy, among others. New anatomic or combined targets are being investigated in these conditions to improve symptoms refractory to medications or standard stimulation."

Hemichorea-hemiballismus as the initial manifestation of symptomatic middle cerebral artery dissection: A case report

INTRODUCTION

Hemichorea-hemiballismus, which spans a spectrum of involuntary, continuous, nonpatterned movement involving one side of the body, can emerge as the initial manifestation of acute ischemic stroke. However, because of its rarity in the community, the diagnosis and treatment are often delayed.

PATIENT CONCERNS

We report a unique case of a 47-year-old female who presented with acute onset hemichorea-hemiballismus. No obvious focal sign apart from involuntary, continuous, nonpatterned movement of her left arm and leg was presented.

DIAGNOSIS

Initial diffusion-weighted magnetic resonance imaging (MRI) was negative but significant increase of blood flow velocity in the right middle cerebral artery (MCA) stem was revealed by transcranial doppler sonography. Repeated MRI showed acute infarction in the contralateral globus pallidus. Isolated dissection of the right MCA typified by intimal flap with double lumen was identified by digital subtraction angiography and high-resolution magnetic resonance imaging (HR-MRI).

INTERVENTIONS

The patient was initially treated with dual antiplatelet agents but the uncontrollable movement deteriorated during hospitalization. Antithrombotic therapy was then intensified with combination of tirofiban and low-molecular-weight heparin. Other symptomatic treatment included volume expansion with colloidal fluid to improve cerebral perfusion. Her involuntary movement gradually diminished and the patient was discharged with rivaroxaban 15 mg/daily.

OUTCOMES

The patient had recovered with significant reduction in her hemichorea-hemiballismus. Three-month follow-up HR-MRI showed complete resolution of the MCA dissection lesions.

CONCLUSION

Prompt recognition of acute onset hemichorea-hemiballismus as the manifestation of acute ischemic stroke in appropriate clinical setting may reduce diagnostic delay. Multiple imaging techniques including cerebral digital subtraction angiography and HR-MRI can be applied to diagnosis and further clarify the mechanism of stroke, which facilitate in selection of secondary prevention therapies.

Quantifying Postural Control in Premanifest and Manifest Huntington Disease Using Wearable Sensors

Background. Impairments in postural control in Huntington disease (HD) have important consequences for daily functioning. This observational study systematically examined baseline postural control and the effect of sensory attenuation and sensory enhancement on postural control across the spectrum of HD. Methods. Participants (n = 39) included healthy controls and individuals in premanifest (pHD) and manifest stages (mHD) of HD. Using wearable sensors, postural control was assessed according to (1) postural set (sit vs stand), (2) sensory attenuation using clinical test of sensory integration, and (3) sensory enhancement with gaze fixation. Outcomes included sway smoothness, amplitude, and frequency. Results. Based on postural set, pHD reduced postural sway in sitting relative to standing, whereas mHD had pronounced sway in standing and sitting, highlighting a baseline postural deficit. During sensory attenuation, postural control in pHD deteriorated relative to controls when proprioceptive demands were high (eyes closed on foam), whereas mHD had significant deterioration of postural control when proprioception was attenuated (eyes open and closed on foam). Finally, gaze fixation improved sway smoothness, amplitude, and frequency in pHD; however, no benefit was observed in mHD. Conclusions. Systematic examination of postural control revealed a fundamental postural deficit in mHD, which further deteriorates when proprioception is challenged. Meanwhile, postural deficits in pHD are detectable when proprioceptive challenge is high. Sensory enhancing strategies using gaze fixation to benefit posture may be useful when introduced well before motor diagnosis. These findings encourage further examination of wearable sensors as part of routine clinical assessments in HD.

Reversible Choreoathetosis in a Patient with End-stage Renal Disease from Administration of Ceftriaxone

A wide spectrum of neurological manifestations may be induced in patients with impaired renal function when receiving beta-lactam antibiotics due to the altered pharmacokinetics. Beta-lactam antibiotics is commonly chosen for treatment in patients with end-stage renal disease due to its good penetration into the cerebrospinal fluid and long half-life.

Here, we present a case of a 73-year-old Malay lady with end-stage renal disease who was admitted for treatment of gastroenteritis. She presented with acute onset of diarrhoea and vomiting for two days. She was febrile during admission and was prescribed intravenous ceftriaxone 2 grams daily for coverage of bacterial gastroenteritis. Among the investigations done, white cell count were raised together with the C-reactive protein. Stool and blood cultures were also sent for further investigations. Over a three-day period, her general condition improved and she was discharged home. The onset of clinical manifestation of choreoathetosis was noticed by her caregiver on the same day of discharge. She was brought back to the emergency department and was readmitted for further workup of the new presenting complain of abnormal movement and disorientation. Haemodialysis was arranged and immediately commenced during her admission. The renal nurses reported that her neurological symptoms were noticeably improved after completion of the initial dialysis without any treatment.

Ceftriaxone including other beta lactam antibiotics penetrates the blood-brain barrier and induces glutamate in excess in the striatum and cerebral cortex, resulting in neurological hyper excitability disorders despite appropriate renal adjusted dosage for end-stage renal disease patients on haemodialysis.

Hemichorea associated with cavernous angioma and a small errhysis: A case report and literature review

RATIONALE

Chorea is a movement disorder characterized by randomly appearing involuntary movements of the face, neck, limbs, or trunk. Hemichorea is unilateral, involving one side of the body. Hemichorea is commonly caused by non-ketotic hyperglycemia and/or cerebrovascular injury to the contralateral basal ganglia.

PATIENT CONCERNS

Here, we report the case of a patient diagnosed with hemichorea who had diabetes, cavernous angioma, and a small intracranial errhysis. Routine testing showed the patient's blood glucose level was slightly higher than the normal range.

INTERVENTIONS

The errhysis was too small to be treated.

DIAGNOSES

Brain magnetic resonance imaging showed a cavernous angioma with a small errhysis in the right putamen.

OUTCOMES

Hemichorea was completely resolved after 4 months.

LESSONS

If diabetes is well controlled and imaging indicates brain lesions suggestive of a recent stroke, a diagnosis of post-stroke hemichorea should be considered.

Movement disorders in mitochondrial disease

Mitochondrial disease presents with a wide spectrum of clinical manifestations that may appear at any age and cause multisystem dysfunction. A broad spectrum of movement disorders can manifest in mitochondrial diseases including ataxia, Parkinsonism, myoclonus, dystonia, choreoathetosis, spasticity, tremor, tic disorders and restless legs syndrome. There is marked heterogeneity of movement disorder phenotypes, even in patients with the same genetic mutation. Moreover, the advent of new technologies, such as next-generation sequencing, is likely to identify novel causative genes, expand the phenotype of known disease genes and improve the genetic diagnosis in these patients. Identification of the underlying genetic basis of the movement disorder is also a crucial step to allow for targeted therapies to be implemented as well as provide the basis for a better understanding of the molecular pathophysiology of the disease process. The aim of this review is to discuss the spectrum of movement disorders associated with mitochondrial disease.

[Antipsychotic-induced tardive syndromes]

Tardive dyskinesia (TD) remains a relevant clinical problem despite the increasing use of new-generation antipsychotics. Antipsychotic-induced tardive syndromes are difficult to treat and have a low tendency of remission. Therefore, prophylaxis is of utmost importance, with the responsible use of antipsychotics as a prime desideratum. With respect to managing tardive dyskinesia, discontinuing the antipsychotic, if possible, albeit not backed up by unequivocal evidence, is still the main recommendation. If this is not possible, the switch to an antipsychotic with a lower TD risk is the next-preferred option. Other symptomatic treatments have been explored, but clinical trials have provided inhomogeneous results and only very few compounds are approved for the treatment of tardive dyskinesia. This manuscript summarizes the current evidence with respect to the phenomenology, course, prevention and treatment of tardive syndromes.

Movement Disorders Following Cerebrovascular Lesion in the Basal Ganglia Circuit

Movement disorders are primarily associated with the basal ganglia and the thalamus; therefore, movement disorders are more frequently manifest after stroke compared with neurological injuries associated with other structures of the brain. Overall clinical features, such as types of movement disorder, the time of onset and prognosis, are similar with movement disorders after stroke in other structures. Dystonia and chorea are commonly occurring post-stroke movement disorders in basal ganglia circuit, and these disorders rarely present with tremor. Rarer movement disorders, including tic, restless leg syndrome, and blepharospasm, can also develop following a stroke. Although the precise mechanisms underlying the pathogenesis of these conditions have not been fully characterized, disruptions in the crosstalk between the inhibitory and excitatory circuits resulting from vascular insult are proposed to be the underlying cause. The GABA (gamma-aminobutyric acid)ergic and dopaminergic systems play key roles in post-stroke movement disorders. This review summarizes movement disorders induced by basal ganglia and thalamic stroke according to the anatomical regions in which they manifest.

Abnormal movements in critical care patients with brain injury: a diagnostic approach

Abnormal movements are frequently encountered in patients with brain injury hospitalized in intensive care units (ICUs), yet characterization of these movements and their underlying pathophysiology is difficult due to the comatose or uncooperative state of the patient. In addition, the available diagnostic approaches are largely derived from outpatients with neurodegenerative or developmental disorders frequently encountered in the outpatient setting, thereby limiting the applicability to inpatients with acute brain injuries. Thus, we reviewed the available literature regarding abnormal movements encountered in acutely ill patients with brain injuries. We classified the brain injury into the following categories: anoxic, vascular, infectious, inflammatory, traumatic, toxic-metabolic, tumor-related and seizures. Then, we identified the abnormal movements seen in each category as well as their epidemiologic, semiologic and clinicopathologic correlates. We propose a practical paradigm that can be applied at the bedside for diagnosing abnormal movements in the ICU. This model seeks to classify observed abnormal movements in light of various patient-specific factors. It begins with classifying the patient’s level of consciousness. Then, it integrates the frequency and type of each movement with the availability of ancillary diagnostic tests and the specific etiology of brain injury.

Drug-induced movement disorders

INTRODUCTION

Drug-induced movement disorders (DIMDs) can be elicited by several kinds of pharmaceutical agents. The major groups of offending drugs include antidepressants, antipsychotics, antiepileptics, antimicrobials, antiarrhythmics, mood stabilisers and gastrointestinal drugs among others.

AREAS COVERED

This paper reviews literature covering each movement disorder induced by commercially available pharmaceuticals. Considering the magnitude of the topic, only the most prominent examples of offending agents were reported in each paragraph paying a special attention to the brief description of the pathomechanism and therapeutic options if available.

EXPERT OPINION

As the treatment of some DIMDs is quite challenging, a preventive approach is preferable. Accordingly, the use of the offending agents should be strictly limited to appropriate indications and they should be applied in as low doses and as short duration as the patient's condition allows. As most of DIMDs are related to an unspecific adverse action of medications in the basal ganglia and the cerebellum, future research should focus on better characterisation of the neurochemical profile of the affected functional systems, in addition to the development of drugs with higher selectivity and better side-effect profile.

Chorea associated with high titers of antiphospholipid antibodies in the absence of antiphospholipid antibody syndrome

Background

Chorea associated with high titers of antiphospholipid antibodies in the absence of antiphospholipid antibody syndrome has been seldom reported.

Case report

An 89-year-old female developed persistent right side chorea associated with high titers of anticardiolipin antibody (antiphospholipid antibosies immunoglobulin (Ig)M, 45 MPL and 112 IgM aCL (MPL) after 3 months) but normal lupus anticoagulants. Her magnetic resonance imaging (MRI) showed no abnormality, but positron emission tomography (PET) demonstrated increased bilateral striatal metabolic activity, more on the left side. Her MRI showed no cause for chorea. The PET scan demonstrated a marked increase in the metabolic activity of the left basal ganglia.

Discussion

Her chorea remained unchanged over a 9-month follow-up period. The literature on chorea associated with high titers of antiphospholipid antibodies in the absence of antiphospholipid syndrome is reviewed.

Clinical and Neuroimaging Findings of Sydenham's Chorea

OBJECTIVE

Sydenham's chorea (SC) is thought to be an autoimmune disorder. MRI is generally used to exclude other causes of chorea. There are no typically defined MRI features of SC. In this study we aimed to determine clinical and neuroimaging findings of SC.

METHODS

In this study 17 patients with acute SC were retrospectively evaluated. Sydenham's chorea was diagnosed according to the 1992 revision of the Jones criteria. The other causes of chorea were excluded. Cranial MRI was performed in all patients during the acute phase of SC. Walking, speech and swallowing disorders, muscle weakness, behavioral disorders, treatment, symptom recovery time and recurrence were evaluated. Findings : The patients' mean age was 11.2 years. Behavioral changes, muscle weakness and dysphagia occurred in 70%, 64% and 23% of the patients, respectively. Nonspecific signal hyperintensities were observed in the white matter, brain stem and caudate nucleus in 47% of patients. Two patients who had chorea paralytica were treated successfully with a high dose of intravenous methylprednisolone.

CONCLUSION

Nonspecific hyperintense white matter abnormalities may be due to the inflammatory process associated with a longer duration of clinical signs. To explain the MRI findings and the pathogenesis of SC, comprehensive studies are needed.

Successful deep brain stimulation surgery with intraoperative magnetic resonance imaging on a difficult neuroacanthocytosis case: case report

BACKGROUND AND IMPORTANCE

Chorea acanthocytosis is a progressive hereditary neurodegenerative disorder characterized by hyperkinetic movements, seizures, and acanthocytosis in the absence of any lipid abnormality. Medical treatment is typically limited and disappointing.

CLINICAL PRESENTATION

We report on a 32-year-old patient with chorea acanthocytosis with a failed attempt at awake deep brain stimulation (DBS) surgery due to intraoperative seizures and postoperative intracranial hematoma. He then underwent a second DBS operation, but under general anesthesia and with intraoperative magnetic resonance imaging guidance. Marked improvement in his dystonia, chorea, and overall quality of life was noted 2 and 8 months postoperatively.

CONCLUSION

DBS surgery of the bilateral globus pallidus pars interna may be useful in controlling the hyperkinetic movements in neuroacanthocytosis. Because of the high propensity for seizures in this disorder, DBS performed under general anesthesia, with intraoperative magnetic resonance imaging guidance, may allow successful implantation while maintaining accurate target localization.

What's the role of topiramate in the management of patients with hyperkinetic movement disorders?

Topiramate (TPM) is an O-alkyl sulfamate derivative of the naturally occurring monosaccharide D-fructose with an epileptic activity. However, it has been suggested that, in addition to its use in epilepsy, TPM could also be used in the treatment of neurological disorders, psychiatric conditions and hyperkinetic movement disorders. The clinical applications of TPM in hyperkinetic movement disorders is consistent with the multiple pharmacodynamic mechanisms e.g., the modulation of both γ-aminobutyric acidergic or glutamatergic neurotransmission and the modulation of voltage-gated ion channels or intracellular signalling pathways. The purpose of the present review is to describe the mechanisms of action of TPM and its clinical efficacy in patients with hyperkinetic movement disorders.

Post-stroke Movement Disorders: Clinical Manifestations and Pharmacological Management

Involuntary abnormal movements have been reported after ischaemic and haemorrhagic stroke. Post stroke movement disorders can appear as acute or delayed sequel. At the moment, for many of these disorders the knowledge of pharmacological treatment is still inadequate. Dopaminergic and GABAergic systems may be mainly involved in post-stroke movement disorders. This article provides a review on drugs commonly used in post-stroke movement disorders, given that some post-stroke movement disorders have shown a partial benefit with pharmacological approach.

Deep brain stimulation in the treatment of chorea

Deep brain stimulation has been used as a means of reducing dyskinesias in various conditions, including Parkinson's disease and dystonia for many years. Recently, owing to the clinical similarities between L-dopa induced dyskinesia and chorea, deep brain stimulation has now been implemented as a novel treatment method in both Huntington's disease and neuroacanthocytosis, and a paucity of case studies exist reporting its efficacy. This review will summarize the case studies of deep brain stimulation in both Huntington's disease and neuroacanthocytosis, and discuss the possible implications and limitations associated with these reports. As both these disorders are often refractory to medication and difficult to treat, deep brain stimulation may be a useful treatment option in the future.

Oromandibular dyskinesia as the initial manifestation of late-onset huntington disease

Huntington's disease (HD) is a neurodegenerative disorder characterized by a triad of choreoathetosis, dementia and dominant inheritance. The cause of HD is an expansion of CAG trinucleotide repeats in the HD gene. Typical age at onset of symptoms is in the 40s, but the disorder can manifest at any time. Late-onset (≥ 60 years) HD is clinically different from other adult or juvenile onset HD and characterized by mild motor problem as the initial symptoms, shorter disease duration, frequent lack of family history, and relatively low CAG repeats expansion. We report a case of an 80-year-old female with oromandibular dyskinesia as an initial manifestation of HD and 40 CAG repeats.

Phenotypic disruption to orofacial movement topography in conditional mutants with generalized CamKIIa/Cre D1Tox versus striatal-specific DARPP-32/Cre D1Tox ablation of D1 dopamine receptor-expressing cells

Orofacial movements were quantified in (a) DARPP-32/Cre D1Tox mutants, having progressive loss of D1 dopamine receptor expressing striatal medium spiny neurons and (b) CamKIIa/Cre D1Tox mutants, having progressive, generalized loss of forebrain D1 receptor expressing cells. Horizontal jaw movements and tongue protrusions were reduced in DARPP-32/Cre but not in CamKIIa/Cre mutants; head and vibrissae movements were increased in DARPP-32/Cre but decreased in CamKIIa/Cre mutants. In drug challenge studies, tongue protrusions were increased in CamKIIa/Cre mutants following vehicle, suggesting a stress-related phenotype. These findings indicate that mice with progressive loss of striatal-specific D1 receptor expressing cells have an orofacial phenotype that may be modulated by the loss of extrastriatal D1 receptor expressing cells. As progressive loss of D1 dopamine receptor-expressing cells is a hallmark feature of Huntington's disease (HD), these findings may inform the functional role of loss of this cell population in the overall pathobiology of HD.

Sydenham's chorea in a family with Huntington's disease: case report and review of the literature

CONTEXT

Sydenham's chorea affects almost 30% of patients with acute rheumatic fever. It is more frequent in females and is rare in the first decade of life, and genetic vulnerability underlies it. Because of easy access to antibiotics, it is now rare in so-called developed countries.

CASE REPORT

A 6-year-old boy with a family history of Huntington's disease, who was the only child of an unscreened and asymptomatic mother, was brought for a consultation because of migratory arthralgia, depressed mood, and rapid, abrupt and unintentional movements of his right arm and leg, that had evolved over a three-week period. On physical examination, he presented a grade III/VI systolic heart murmur and right-side choreic movements, giving rise to a deficit of active mobilization. Laboratory tests revealed elevated erythrocyte sedimentation rate (63 mm/h), C-reactive protein (25 mg/l) and antistreptolysin O titer (1,824 U/ml). Cardiovascular evaluation showed mild aortic insufficiency, moderate mitral insufficiency and a prolonged PR interval. A clinical diagnosis of Sydenham's chorea/acute rheumatic fever was made, and therapy consisting of penicillin, haloperidol, captopril and furosemide was instituted, with excellent results.

CONCLUSION

In developed countries, Sydenham's chorea seems forgotten and, because of this, little is known about its clinical course and controversy surrounds the therapeutic options available. This occurrence of rheumatic chorea in a family with Huntington's disease highlights the importance of the differential diagnosis for the different forms of chorea.

Reversible choreoathetosis after the administration of ceftriaxone sodium in patients with end-stage renal disease

Neurologic manifestations, such as myoclonus, asterixis, seizures and altered level of consciousness, may be induced in patients with impaired renal function receiving β-lactam antibiotics, which stem in part from drug accumulation because of altered pharmacokinetics. Because of its long half-life and easy penetration into the cerebrospinal fluid, the third generation cephalosporin, ceftriaxone (CTRX), is often chosen to treat patients with end-stage renal disease (ESRD). Here, the authors describe 4 patients with ESRD complicated with bacterial infection and choreoathetosis after the administration of CTRX. Choreoathetosis disappeared without leaving sequelae after CTRX therapy was withdrawn, although the severity and symptom duration varied. To our knowledge, there are few reports on choreoathetosis associated with β-lactam antibiotic administration in patients with kidney diseases. To prevent delayed diagnosis, one should bear in mind that choreoathetosis might occur in patients with ESRD treated with CTRX, when it is given in high or even regular doses.

Use of antiepileptic drugs for hyperkinetic movement disorders

Many studies investigated the use of antiepileptic drugs (AEDs) in several neurological diseases other than epilepsy. These neurological disorders, usually, involve neuronal excitability through the modulating of ion channels, receptors and intracellular signaling pathways, and are the targets of the AEDs. This article provides a review of the clinical efficacy of both conventional and newer AEDs in hyperkinetic movement disorders. Some of these indications for AEDs have been established, while others are under investigation. The modulation of GABAergic transmission may explain the neuronal hyper-excitability that underlies some forms of hyperkinetic movement disorders. So, AEDs able to increase GABAergic neurotransmission may play a role in hyperkinetic movement disorders treatment. Therefore, AEDs could represent a useful therapeutic option in the management of hyperkinetic movement disorders where the available treatments are ineffective.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.

Acute and long-term response of dopamine nigrostriatal synapses to a single, low-dose episode of 3-nitropropionic acid-mediated chemical hypoxia

The goal of the present investigation was to determine the persistence of striatal (DA) dopaminergic dysfunction after a mild chemically induced hypoxic event in Fisher 344 rats. To this end, we gave a single injection of the mitochondrial complex II inhibitor 3-nitropropionic acid (3-NP; 16.5 mg/kg, i.p.) to 2-month old male F344 rats and measured various indices of striatal DA functioning and lipid peroxidation over a 3-month span. Separate groups of rats were used to measure rod walking, evoked DA release, DA content, malondialdehyde (MDA) accumulation, DA receptor binding, and tyrosine hydroxylase (TH) activity. The results showed that 3-NP exposure reduced most measures of DA functioning including motoric ability, DA release, and D(2) receptor densities for 1 to 3 months postdrug administration. Interestingly, DA content was reduced 1 week after 3-NP exposure, but rose to 147% of control values 1 month after 3-NP treatment. MDA accumulation, a measure of lipid peroxidation activity, was increased 24 h and 1 month after 3-NP treatment. 3-NP did not affect TH activity, suggesting that alterations in DA functioning were not the result of nigrostriatal terminal loss. These data demonstrate that a brief mild hypoxic episode caused by 3-NP exposure has long-term detrimental effects on the functioning of the nigrostriatal DA system.

Sydenham's chorea: a practical overview of the current literature

Sydenham's chorea is characterized by uncoordinated movements, emotional instability, and hypotonia. It can occur up to several months after group A beta-hemolytic Streptococcus infection. A diagnosis of Sydenham's chorea in a patient with acute chorea involves an application of the Jones criteria and the exclusion of other causes of chorea. In patients with an atypical history or hemichorea, cranial magnetic resonance imaging is indicated to exclude other cerebral pathologies. A pathogenesis has not been elucidated, and therapy has not been investigated in placebo-controlled trials. Antibiotic treatment and a 2-week or 3-week schedule of antibiotic prophylaxis are recommended. If the chorea is severe, valproate or carbamazepine can be effective. In more severely affected patients, dopamine receptor blocking agents or corticosteroids can be used.

Sydenham's chorea as a presentation of Moyamoya disease

A seven year-old male presented to his pediatrician with choreiform movements and a recent history of sore throat. He was diagnosed with Sydenham's chorea based on clinical criteria and laboratory evidence. Worsening symptoms prompted a magnetic resonance imaging (MRI) of the brain which demonstrated evidence of Moyamoya disease. Sydenham's chorea is a common and well-documented complication of post-streptococcal infection, but has not been previously reported in association with Moyamoya disease. This case raises the quandary of causality of chorea in this patient and the need for neuroimaging in children with movement disorders.

Schizophrenieforme Symptomatik bei Chorea minor

Die Chorea minor (Sydenham), die häufigste erworbene Ursache für Bewegungsstörungen im Kindesalter, ist gekennzeichnet durch unwillkürliche und abrupte Bewegungsmuster. Bei einem Teil der Patienten treten zusätzlich neuropsychologische Dysfunktionen und psychiatrische Störungsbilder wie Angst-, Zwangs-, und Tic-Störungen auf. Psychotische Symptome wurden dabei bisher nur selten beschrieben (n = 4, davon zwei Fallberichte sowie eine prospektive und eine retrospektive Studie). Wir berichten von einer 12-jährigen Patientin mit akuter paranoid-halluzinatorischer Symptomatik und choreatiformer Bewegungsstörung. Die Kombination der im Hinblick auf die paranoid-halluzinatorische Symptomatik wirksamen antipsychotischen Therapie mit hochdosiertem Prednisolon verbesserte die weiterbestehende Negativ-Symptomatik und führte zu einer vollständigen Remission der Bewegungsstörung. Nach Reduktion der Steroide traten eine Verschlechterung der Negativ-Symptomatik und ein Rezidiv der Bewegungsstörung ein. Ursächlich für die Schizophrenie wird eine Funktionsstörung des Corpus Striatum vermutet, welche sekundär das Arbeitsgedächtnis und den für kognitive Flexibilität bedeutsamen präfrontalen Kortex beeinträchtigt. Als Ursache der Chorea minor gilt eine postinfektiöse autoimmun-mediierte Störung der Basalganglienfunktion, ausgelöst durch einen vorausgegangenen Streptokokken-Infekt. Der Morbus Huntington und der Morbus Wilson sind Bewegungsstörungen, die auf einer Basalgangliendysfunktion beruhen und zudem häufig mit psychotischen Symptomen assoziiert sind. Ähnlich könnte die Kombination aus psychotischer und choreatiformer Symptomatik unserer Patientin auf einer Basalgangliendysfunktion beruhen. Die Negativ-Symptomatik wäre durch eine sekundäre Störung präfrontal kortikaler Strukturen erklärbar.

Meige's syndrome and hemichorea associated with hyperthyroidism

Movement disorders are known to be associated with hyperthyroidism. However, the association of Meige's syndrome and hemichorea with hyperthyroidism has not been reported. We describe a young Chinese woman with hyperthyroidism, who presented with a unique combination of Meige's syndrome and hemichorea in the left limbs. Both neurologic manifestations were preceded by symptoms of hyperthyroidism, and resolved following treatment with methimazole for hyperthyroidism. Nevertheless, the neurologic symptoms recurred when she stopped taking methimazole, but abated when she returned to a euthyroid state after additional treatment with methimazole. The evolution of her clinical course indicated that the involuntary movements were in association with hyperthyroidism. This case is the first report of Meige's syndrome and hemichorea in a patient with hyperthyroidism, which raises the likelihood that hyperthyroidism may be a cause of Meige's syndrome and hemichorea. Furthermore, it emphasizes the need for greater attention to thyroid function in those afflicted with involuntary movements in order to optimize clinical management.

A case of vascular hemichorea responding to topiramate

Although vascular chorea often comes into remission spontaneously, a few patients may remain with persistent movement disorder. Most movements respond well to neuroleptics as well as other antidopaminergic drugs, but some patients show poor responses to those neuroleptics. Topiramate is a widely used of broad-spectrum anticonvulsant possessing a complex mechanism of action. It has been proven to enhance gamma-aminobutyrate acid activity and to be effective in the control of other movement disorders. We describe a 63-year-old woman with intractable vascular hemichorea which was controlled with anti-convulsant, topiramate.

Age-related behavioural phenotype and cellular characterisation of mice with progressive ablation of D1 dopamine receptor-expressing cells

In this study we characterize the behavioural and cellular phenotype of mutant (MUT) mice with progressive loss of D1 dopamine receptor (Drd1a)-expressing cells. Adult [14-19 weeks] MUT mice showed intact working memory in the spontaneous alternation test but evidenced anxiety-like behaviour in the elevated plus maze and the light-dark test. The ethogram of mature adult MUT [average age 22 weeks] was compared with that of young adult MUT mice [average age 12 weeks]. While MUT mice evidenced hyperactivity over initial exploration at both time points, the topography of hyperactivity shifted. Moreover, initial hyperactivity was sustained over habituation at 12 weeks, but not at 22 weeks. Thus, by 22 weeks MUT mice evidenced shifts in, and mitigation of, these early phenotypic effects. However, orofacial behaviours of chewing and sifting were reduced similarly at 12 and 22 weeks. These data support the hypothesis that aspects of the mutant phenotype change with time. Quantitative autoradiography at 20 weeks revealed loss of D1-like dopamine receptor binding in the entire basal ganglia, with upregulated D2-like binding. There appear to be topographically specific interactions between normal maturational processes and compensatory mechanisms evoked subsequent to targeted ablation of D1 dopamine receptor-expressing cells. Understanding the mechanistic bases of mitigation vs persistence of individual phenotypes in relation to neural adaptation consequent to cell loss may lead to novel therapeutic strategies for basal ganglia disorders.