Juvenile Huntington disease exacerbated by methylphenidate: case report

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.

Psychiatric Treatment and Management of Psychiatric Comorbidities of Movement Disorders

Pediatric movement disorders may present with psychiatric symptoms at many points during the course of the disease. For the relatively common pediatric movement disorder, Tourette syndrome, psychiatric comorbidities are well-described and treatment is well-studied. Managing these comorbidities may be more effective than improving the movements themselves. For more uncommon movement disorders, such as juvenile-onset Huntington disease, treatment of psychiatric comorbidities is not well-characterized, and best-practice recommendations are not available. For the least common movement disorders, such as childhood neurodegeneration with brain iron accumulation, psychiatric features may be nonspecific so that underlying diagnosis may be apparent only after recognition of other symptoms. However, psychiatric medication, psychotherapy, and psychosocial support for these disorders may prove helpful to many children and adolescents.

Tics as an initial manifestation of juvenile Huntington's disease: case report and literature review

BACKGROUND

Huntington's disease (HD) is an autosomal dominant disorder, typically characterized by chorea due to a trinucleotide repeat expansion in the HTT gene, although the clinical manifestations of patients with juvenile HD (JHD) are atypical.

CASE PRESENTATION

A 17-year-old boy with initial presentation of tics attended our clinic and his DNA analysis demonstrated mutation in the HTT gene (49 CAG repeats). After treatment, his symptoms improved. Furthermore, we performed literature review through searching the databases and summarized clinical features in 33 JHD patients.

CONCLUSION

The most prevalent symptoms are ataxia, and two cases reported that tics as initial and prominent manifestation in JHD. Among them, 88% patients carried CAG repeats beyond 60 and most of them have family history. This case here illustrates the variable range of clinical symptoms of JHD and the necessity of testing for the HD mutation in young patients with tics with symptoms unable to be explained by Tourette's syndrome (TS).

Callosal Motor Impersistence: A Novel Disconnection Syndrome

Motor impersistence, an inability to sustain a certain position or movement, is a motor-intentional disorder, caused more often by right than left hemisphere lesions. Since the right hemisphere is dominant for mediating motor persistence, callosal lesions that disconnect the left hemisphere from the right may induce impersistence of the right upper and lower limbs. After an undiagnosed left callosal infarction, a 65-year-old right-handed man suddenly developed a transient loss of volitional movement of his left leg. Five days after onset, he was admitted to our hospital with signs of callosal disconnection: left-hand agraphia and apraxia, left-hand tactile anomia, failures on cross-replication of hand postures, and intermanual conflict. He had neither weakness nor ataxia of his upper or lower extremities, but when asked to keep his arms or legs extended he could not maintain his right arm and leg in the extended position, suggesting motor impersistence in his dominant limbs. When we examined him 3 months after onset, the motor impersistence had disappeared. In conclusion, motor impersistence of dominant limbs can result from isolated callosal injury that disconnects the left hemisphere from the right hemisphere's frontal-subcortical networks.

Ventricular fibrillation cardiac arrest produces a chronic striatal hyperdopaminergic state that is worsened by methylphenidate treatment

Cardiac arrest survival rates have improved with modern resuscitation techniques, but many survivors experience impairments associated with hypoxic-ischemic brain injury (HIBI). Currently, little is understood about chronic changes in striatal dopamine (DA) systems after HIBI. Given the common empiric clinical use of DA enhancing agents in neurorehabilitation, investigation evaluating dopaminergic alterations after cardiac arrest (CA) is necessary to optimize rehabilitation approaches. We hypothesized that striatal DA neurotransmission would be altered chronically after ventricular fibrillation cardiac arrest (VF-CA). Fast-scan cyclic voltammetry was used with median forebrain bundle (MFB) maximal electrical stimulations (60Hz, 10s) in rats to characterize presynaptic components of DA neurotransmission in the dorsal striatum (D-Str) and nucleus accumbens 14 days after a 5-min VF-CA when compared to Sham or Naïve. VF-CA increased D-Str-evoked overflow [DA], total [DA] released, and initial DA release rate versus controls, despite also increasing maximal velocity of DA reuptake (V_max ). Methylphenidate (10 mg/kg), a DA transporter inhibitor, was administered to VF-CA and Shams after establishing a baseline, pre-drug 60 Hz, 5 s stimulation response. Methylphenidate increased initial evoked overflow [DA] more-so in VF-CA versus Sham and reduced D-Str V_max in VF-CA but not Shams; these findings are consistent with upregulated striatal DA transporter in VF-CA versus Sham. Our work demonstrates that 5-min VF-CA increases electrically stimulated DA release with concomitant upregulation of DA reuptake 2 weeks after brief VF-CA insult. Future work should elucidate how CA insult duration, time after insult, and insult type influence striatal DA neurotransmission and related cognitive and motor functions.

Changes in mental state and behaviour in Huntington's disease

Changes in mental state and behaviour have been acknowledged in Huntington's disease since the original monograph in 1872 provided evidence of disinhibition and impaired social cognition. Behavioural problems can manifest before obvious motor symptoms and are frequently the most disabling part of the illness. Although pharmacological treatments are used routinely for psychiatric difficulties in Huntington's disease, the scientific evidence base for their use is somewhat sparse. Moreover, effective treatments for apathy and cognitive decline do not currently exist. Understanding the social cognitive impairments associated with Huntington's disease can assist management, but related therapeutic interventions are needed. Future research should aim to design rating scales for behaviour and mental state in Huntington's disease that can detect change in clinical trials. Generally, communication and understanding of behaviour and mental state in Huntington's would be enhanced by a clear conceptual framework that unifies ideas around movement, cognition, emotion, behaviour, and mental state, reflecting both the experience of the patient and their underlying neuropathology.

Acute dyskinetic reaction in a healthy toddler following methylphenidate ingestion

BACKGROUND

Acute dyskinetic or dystonic reactions are a long-recognized complication of medications that alter dopamine signaling. Most reactions occur following exposure to agents that block dopamine receptors (e.g., neuroleptics). However, agents that increase dopaminergic transmission (such as methylphenidate) can also trigger acute dyskinesias. This has been previously reported only in patients also taking dopamine antagonists or, less commonly, in children with developmental abnormalities.

CASE DESCRIPTION

The present report describes a previously healthy toddler who developed transient torticollis and orolingual dyskinesias following accidental exposure to methylphenidate. He had no preexisting movement disorder, central nervous system injury, or developmental abnormalities--in short, none of the previously reported risk factors for this side effect.

HYPOTHESIS AND CONCLUSIONS

The unique features of this case led to the hypothesis that developmental shifts in dopamine signaling were the basis for his particular sensitivity to methylphenidate. If confirmed, this hypothesis has implications for the treatment of common childhood attentional and behavioral disorders. The article includes a literature review of dyskinetic/dystonic reactions in children and the developmental regulation of dopamine metabolism.

Clinical features of Chinese patients with Huntington's disease carrying CAG repeats beyond 60 within HTT gene

Patients with Huntington's disease (HD) carrying CAG repeats beyond 60 are less frequently seen and clinical features of them have been rarely reported. We identified four unrelated patients carrying CAG repeats beyond 60 (84.0 ± 13.76, ranging from 74 to 104) from 119 Chinese HD patients via direct sequencing. These four were all early onset with a mean age at presenting symptom of 9.8 ± 1.71 years. Paternal transmission was found in three of them and the fourth was apparently sporadic. In addition, they had atypical onset symptoms including epilepsy, intellectual decline, tics and walking instability, which might lead the clinicians to make the wrong diagnosis in the early stage of disease. Our work explores clinical features of Chinese HD patients with an expanded CAG repeat over 60 and may help the clinicians make a correct diagnosis in the early stage of disease.

Huntington's disease in children

Huntington's disease (HD) is a dominantly inherited, fatal neurodegenerative disease. This incurable illness is characterized by a triad of a movement disorder, cognitive decline and psychiatric manifestations. Although most patients with HD have disease onset in the adult years, a small but significant proportion present with pediatric HD. It has been long known that patients with early-onset HD commonly exhibit prominent parkinsonism, known as the Westphal variant of HD. However, even among patients with pediatric HD there are differential clinical features depending on the age of onset, with younger patients frequently presenting diagnostic challenges. In his chapter, the characteristics of patients with childhood- and adolescence-onset HD are discussed, focusing on the differential clinical features that can aid the clinical reach a correct diagnosis, the indications and rational use of genetic testing and the currently available options for symptomatic treatment.

Hyperglycemic chorea-ballism or acute exacerbation of Huntington's chorea? Huntington's disease unmasked by diabetic ketoacidosis in type 1 diabetes mellitus

CONTENT

Hyperglycemic chorea-ballism is predominantly observed in older type 2 diabetic patients, and it is rare in type 1 diabetes and diabetic ketoacidosis (DKA). Huntington's disease (HD) is one of several genetic syndromes associated with diabetes, although the reported prevalence of the association varies. There are few opportunities for most physicians to diagnose early-stage HD.

OBJECTIVE

We describe bilateral hyperglycemic chorea-ballism in a 40-yr-old female type 1 diabetes patient with DKA and HD.

SETTING

The study was conducted in a tertiary care referral hospital.

RESULTS

On admission, the patient exhibited severe involuntary movement of bilateral extremities with DKA, and hyperglycemic chorea-ballism was diagnosed. She recovered from chorea-ballism with admission of fluids and insulin, but mild choreatic movement persisted in the upper extremities. Brain magnetic resonance imaging and DNA analysis revealed HD. Although it has been considered that depletion of striatal γ-aminobutyric acid (GABA) content is rare in DKA, it is largely decreased in HD. Therefore, it is probable that hyperglycemic chorea-ballism or exacerbation of Huntington's chorea resulted from transient depletion of GABA.

CONCLUSION

The present case provides important insights on the role of GABA in hyperglycemic chorea-ballism and on the clinical issues associated with HD diagnosis.

Treatment of Apathy in Huntington's Disease and Other Movement Disorders

OPINION STATEMENT

Apathy is one of the most prevalent neurobehavioral symptoms in Huntington's disease (HD), occurring in approximately 70% of the symptomatic HD population. Apathy scores in patients with HD are highly correlated with duration of illness, suggesting that apathy is an inevitable consequence of advanced disease. Although less distressing than symptoms like depression and less disruptive than irritability or aggression, apathy has a considerable adverse impact on those affected with HD because it leads to a decrease of the goal-directed behaviors that contribute much to the day-to-day quality of life. As a neuropsychiatric syndrome, apathy is also common in patients with other neuropsychiatric disorders such as Parkinson's disease, traumatic brain injury, cerebrovascular accident, dementia, and other neurodegenerative conditions. The nosologic status of apathy and lack of a clear definition has probably contributed to the paucity of therapeutic evidence in this area. Several different scales are available to measure apathy, including the Apathy Evaluation Scale, Apathy Inventory, Lilles Apathy Rating Scale, and the apathy items from the Unified HD Rating Scale, the Problem Behaviours Assessment for HD, and the Neuropsychiatric Inventory, but all are based on slightly different definitions of apathy, so the scores obtained may not be directly comparable. Assessment may also be complicated by overlap between the manifestations of apathy and other complications of HD such as depression, so the identification and treatment of these comorbid conditions is important. No adequate evidence currently supports any specific pharmacologic or psychological intervention for apathy in HD. Evidence can only be extrapolated from interventional studies done in other basal ganglia disorders such as Parkinson's disease or other neurodegenerative disorders such as dementia. The neurobiology of apathy points towards three areas of functional connectivity: connections between the dorsolateral prefrontal cortex (PFC) and basal ganglia, orbitomedial PFC and basal ganglia, and dorsomedial PFC and basal ganglia. Pharmacologic interventions such as cholinesterase inhibitors, the dopaminergic antidepressant bupropion, amantadine, levodopa, bromocriptine, methylphenidate, and atypical antipsychotics have all been tried in other neurodegenerative disorders, but not in HD. Psychosocial interventions such as cognitive stimulation therapy and multisensory stimulation, which have been used in patients with dementia, have not been properly studied in HD. Individualized treatment should be considered, using a combination of methods, as there is no evidence to support one particular type of treatment. Multidisciplinary input, environmental modifications, improved psychosocial support, and psychoeducation programs designed to help caregivers to understand and compensate for the deficits caused by this symptom may all have a role to play in the treatment of apathy.

Chorea caused by toxins

Chorea is uncommonly caused by toxins. Anecdotal evidence from cases of toxin-induced chorea assists in our understanding of neurodegenerative diseases associated with chorea. Beginning in medieval Europe with ergotism and the "fire that twisted people," spanning to crack dancing in contemporary times and the coexistence of alcohol abuse with chorea, toxins may exert direct effects to enhance mesolimbic dopamine transmission or indirect effects through gamma-aminobutyric acid modulation. The following chapter will discuss toxins associated with chorea and the presumed pathophysiology underlying the movement disorders in these case series.