Paroxysmal dyskinesias as a paradigm of paroxysmal movement disorders

Oxcarbazepine-responsive paroxysmal kinesigenic dyskinesia in Wilson disease

A 22-year-old man presented with a 2-year history of tremor of the upper limbs associated to behavioral disorders. A magnetic resonance imaging of the brain showed hyperintensity in the right frontoparietal region, basal ganglia, particularly in the caudate nucleus, midbrain, and pons in T2 sequences, fluid-attenuated inversion recovery, and diffusion. Serum ceruloplasmin levels were 4 mg/dL (range, 20-45 mg/dL), and 24-hour urine cooper excretion was increased up to 223 µg (10-40 µg/24 hours). Slit lamp examination demonstrated the presence of a Kayser-Fleischer ring and penicillamine treatment started. Four months later, he developed episodes of paroxysmal dystonic posturing of his left arm, which increased in frequency reaching 2 or 3 attacks per hour. They were triggered by voluntary movements and forced him to adopt an abnormal flexion of the left forearm over the left bicep and were preceded by a tightening sensation of the left forearm muscles. Episodes completely remitted with oxcarbazepine.

Neuroacanthocytosis and carbamazepine responsive paroxysmal dyskinesias

Neuroacanthocytosis (NA) comprises a genetically heterogeneous group of disorders characterized by dysfunction of the erythrocyte membrane, presenting with acanthocytes and several neurological manifestations. We report the case of a 42-year-old woman with NA who in addition had episodes consistent with paroxysmal dyskinesias. She was diagnosed with NA featuring mild chorea, weakness of the right lower extremity and myoclonic jerks. However, one year after onset she presented attacks of paroxysmal abnormal movements, consistent with paroxysmal kinesigenic dyskinesias. Carbamazepine markedly reduced the frequency and severity of the attacks. Our case illustrates that paroxysmal dyskinesias can be a hitherto unrecognized manifestation of neuroacanthocytosis responsive to carbamazepine.

Paroxysmal nonepileptic events of childhood

The paroxysmal nonepileptic events of childhood are a group of disorders, syndromes, and phenomena that mimic true epileptic seizures. Clinical experience and a clear description of the event in question will usually lead to a correct categorization. They span in age from neonate to young adult and are apt to be the most common diagnostic challenges clinicians face regularly. The key to diagnosis is a detailed history and careful observation. Despite the large number of discrete entities enumerated herein, common principles in clinical approach are successful and described. Each entity can pose a significant clinical challenge in identification, etiologic pathophysiology, genetics, and management. A simple division is offered here separating those episodes that are associated with an altered mental status or occurring during sleep and those without an altered mental status or occurring while awake.

Interictal myoclonus with paroxysmal kinesigenic dyskinesia

We report a new association between interictal myoclonus and paroxysmal kinesigenic dyskinesia (PKD) in 2 patients. By definition, PKD is transient, but the overexcitability of the neuronal system that induces these attacks may be permanent. Interictal myoclonus could be a manifestation of permanent overexcitability.

[A family with exercise-induced paroxysmal dystonia and childhood absence epilepsy]

INTRODUCTION

The boundary between epilepsy and paroxysmal dyskinesia appears to be less easy to delineate than previously believed. Reports of families showing both phenomena suggest a shared pathophysiology.

PATIENTS AND METHOD

A new family with autosomal dominant exercise-induced paroxysmal dystonia is reported.

RESULTS

Two family members also had childhood absence epilepsy, and one of them suffered from acute transient hemiplegia at age 10.

CONCLUSION

The association of epilepsy and paroxysmal dyskinesia has been rarely reported in the literature, and several loci have been identified. Absence epilepsy and exercise-induced paroxysmal dystonia appear to be very uncommon, although some reports mentioned the association in sporadic and familial cases. The involvement of ion channel genes in several transient neurological disorders supports the hypothesis of a common pathophysiological process underlying both the childhood absence seizure and the later paroxysmal dystonia.

The approach to patients with "non-epileptic seizures"

Up to one fifth of patients who present to specialist clinics with seizures do not have epilepsy. The majority of such patients suffer from psychologically mediated episodes; dissociative seizures, often referred to as "non-epileptic seizures". This paper describes the diagnostic evaluation of seizure disorders, including clinical assessment and the role of special investigations. The organic and psychiatric imitators of epilepsy are outlined and findings on psychiatric assessment are reviewed. This group of patients often proves difficult to engage in appropriate treatment and an approach to explaining the diagnosis is described. As yet there are no controlled trials of treatment in this disorder but preliminary evidence suggests cognitive behavioural therapy is both a rational and promising way forward.

Chorea as manifestation of epilepsia partialis continua in a child

The authors present a case of a child with epilepsy who developed choreoathetotic movements coinciding with the development of epilepsia partialis continua. His abnormal movements and seizures resolved after successful management of his epilepsia partialis continua with intravenous immunoglobulin and steroid therapy. The authors propose that the chorea was an unusual manifestation of epilepsia partialis continua.

[Movement disorders in childhood: classification and genetic update]

Abnormal movements are not unusual in childhood. Recent genetic progresses provide a new approach of childhood movement disorders. Several loci have been identified in paroxysmal dyskinesia, or in Gilles de la Tourette syndrome. A gene has been cloned in Hallervorden-Spatz syndrome, and a gene has recently been implicated in benign hereditary chorea. Considerable advances concern the genetic of dystonic syndromes: several chromosomal localizations have been identified, and several genes have been cloned. Genetic advances allow nosographic reclassification of some entities and offer new molecular tools for a more appropriate diagnosis. The increasing wealth of genetic knowledge will provide further insight in the understanding of abnormal movement disorders in childhood.

Paroxysmal Dyskinesias in Children

Paroxysmal dyskinesias are rare movement disorders. The onset of paroxysmal dyskinesias in childhood are typically idiopathic (sporadic or familial), whereas those in adulthood are usually secondary to an identifiable cause. Paroxysmal dyskinesias are classified according to precipitating factors, and these include paroxysmal kinesigenic dyskinesia, paroxysmal nonkinesigenic dyskinesia, paroxysmal exertion-induced dyskinesia, and paroxysmal hypnogenic dyskinesia. The pathophysiology remains unknown; however, there is increasing evidence that channelopathies may play a role, which explains the response to anticonvulsant medications in certain kindreds. Pharmacologic treatment with anticonvulsant medications, clonazepam, tetrabenazine, trihexyphenidyl, or levodopa is reviewed herewith. Paroxysmal dyskinesias go by many names, but a rational classification does exist. Of those that respond to medications, the majority of paroxysmal dyskenesias respond to anticonvulsant medications. Channelopathies have been implemented as a cause in paroxysmal dyskinesias.

Ataxia and paroxysmal dyskinesia in mice lacking axonally transported FGF14

Fibroblast growth factor 14 (FGF14) belongs to a distinct subclass of FGFs that is expressed in the developing and adult CNS. We disrupted the Fgf14 gene and introduced an Fgf14(N-beta-Gal) allele that abolished Fgf14 expression and generated a fusion protein (FGF14N-beta-gal) containing the first exon of FGF14 and beta-galactosidase. Fgf14-deficient mice were viable, fertile, and anatomically normal, but developed ataxia and a paroxysmal hyperkinetic movement disorder. Neuropharmacological studies showed that Fgf14-deficient mice have reduced responses to dopamine agonists. The paroxysmal hyperkinetic movement disorder phenocopies a form of dystonia, a disease often associated with dysfunction of the putamen. Strikingly, the FGF14N-beta-gal chimeric protein was efficiently transported into neuronal processes in the basal ganglia and cerebellum. Together, these studies identify a novel function for FGF14 in neuronal signaling and implicate FGF14 in axonal trafficking and synaptosomal function.

Post-streptococcal autoimmune neuropsychiatric disease presenting as paroxysmal dystonic choreoathetosis

Paroxysmal dystonic choreoathetosis (PDC) is an episodic, non-kinesogenic, extrapyramidal movement disorder. It is postulated that PDC is an ion channel disorder. We describe a sporadic case of paroxysmal dystonic choreoathetosis occurring after streptococcal pharyngitis. The episodes were characterized by abrupt-onset dystonic posturing, choreoathetosis, visual hallucinations and behavioral disturbance. Each episode lasted between 10 minutes and 4 hours, and occurred up to 4 times per day. In between attacks, examination was normal. The episodes waxed and waned in frequency during a 6-month illness. Magnetic resonance imaging of the brain was normal. Post-streptococcal neuropsychiatric disease has a proposed autoimmune etiology, which is supported by the presence of serum antibasal ganglia antibodies. Western immunoblotting of this case's serum demonstrated antibody binding to a basal ganglia antigens of molecular weight 80 kDa and 95 kDa. Immunohistochemistry examination demonstrated specific antibody binding to large striatal neurones. We propose that autoantibodies produced in post-streptococcal neuropsychiatric disease cause alteration in neurotransmission, possibly secondary to ion channel binding.