Paroxysmal dyskinesias

Transcallosal conduction in paroxysmal kinesigenic dyskinesia

OBJECTIVES

Detecting whether a possible disequilibrium between the excitatory and inhibitory interhemispheric interactions in paroxysmal kinesigenic dyskinesia (PKD) exists.

METHODS

This study assessed measures of motor threshold, motor evoked potential latency, the cortical silent period, the ipsilateral silent period and the transcallosal conduction time (TCT) in PKD patients. Data were compared between the clinically affected hemisphere (aH) and the fellow hemisphere (fH).

RESULTS

The transcallosal conduction time from the aH to the fH was 11.8 ms (range = 2.3-20.7) and 13.6 ms (range = 2.8-67.7) from the fH to the aH. The difference in TCT in the affected side was significant (p = .019).

CONCLUSION

The findings demonstrated that, although inhibitory interneurons act normally and symmetrically between the motor cortices and transcallosal inhibition was normal and symmetrical between both sides, the onset of transcallosal inhibition was asymmetrical. The affected hemisphere's inhibition toward the unaffected hemisphere is faster compared to the inhibition provided by the fellow hemisphere. These results are consistent with an inhibitory deficit in the level of interhemispheric interactions.

SIGNIFICANCE

This study revealed a defect in inhibition of the motor axis could be responsible in the pathological mechanisms of kinesigenic dyskinesia.

Glucide metabolism disorders (excluding glycogen myopathies)

Glucide metabolism comprises pathways for transport, intermediate metabolism, utilization, and storage of carbohydrates. Defects affect multiple organs and present as systemic diseases. Neurological symptoms result from hypoglycemia, lactic acidosis, or inadequate storage of complex glucide molecules in neurological tissues. In glycogen storage disorders hypoglycemia indicates hepatic involvement, weakness and muscle cramps muscle involvement. Hypoglycemia is also the leading neurological symptom in disorders of gluconeogenesis. Disorders of galactose and fructose metabolism are rare, detectable by neonatal screening, and manifest following dietary intake of these sugars. Rare defects within the pentose metabolism constitute a new area of inborn metabolic disorders and may present with neurological symptoms. Treatment of these disorders involves the avoidance of fasting, dietary treatment eliminating specific carbohydrates, and enzyme replacement therapy in individual glycogen storage diseases.GLUT1 deficiency syndrome, a specific disorder of glucose transport into brain, results in global developmental delay, early-onset epilepsy, and a complex movement disorder. Treatment with a high-fat, low-carbohydrate ketogenic diet provides ketones as an alternative fuel to the brain and restores brain energy metabolism. Recently paroxysmal exertion-induced dyskinesia and stomatin-deficient cryohydrocytosis have been identified as an allelic disorder to GLUT1 deficiency equally responding to a ketogenic diet.

Genetic and phenotypic heterogeneity in sporadic and familial forms of paroxysmal dyskinesia

Paroxysmal dyskinesia (PxD) is a group of movement disorders characterized by recurrent episodes of involuntary movements. Familial paroxysmal kinesigenic dyskinesia (PKD) is caused by PRRT2 mutations, but a distinct etiology has been suggested for sporadic PKD. Here we describe a cohort of patients collected from our movement disorders outpatient clinic in the period 1996–2011. Fifteen patients with sporadic PxD and 23 subjects from three pedigrees with familial PKD were screened for mutations in candidate genes. PRRT2 mutations co-segregated with PKD in two families and occurred in two sporadic cases of PKD. No mutations were detected in patients with non-kinesigenic or exertion-induced dyskinesia, and none in other candidate genes including PNKD1 (MR-1) and SLC2A1 (GLUT1). Thus, PRRT2 mutations also cause sporadic PKD as might be expected given the variable expressivity and reduced penetrance observed in familial PKD. Further genetic heterogeneity is suggested by the absence of candidate gene mutations in both sporadic and familial PKD suggesting a contribution of other genes or non-coding regions.

Diagnosis and treatment of paroxysmal dyskinesias revisited

Paroxysmal dyskinesias (PDs) are a rare group of hyperkinetic movement disorders mainly characterized by their episodic nature. Neurological examination may be entirely normal between the attacks. Three main types of PDs can be distinguished based on their precipitating events - (i) paroxysmal kinesigenic dyskinesias (PKD), (ii) paroxysmal non-kinesigenic dyskinesias (PNKD) and (iii) paroxysmal exercise-induced (exertion-induced) dyskinesias (PED). The diagnosis of PDs is based on their clinical presentation and precipitating events. Substantial progress has been made in the field of genetics and PDs. Treatment options mainly include anticonvulsants and benefit of treatment is depending on the type of PD. Most important differential diagnosis are non-epileptic psychogenic, non-epileptic organic and epileptic attack disorders, especially nocturnal frontal lobe epilepsy.

Paroxysmal choreodystonic disorders

Paroxysmal choreodystonic disorders or paroxysmal dyskinesias are a heterogeneous group of movement disorders characterized by recurrent attacks of abnormal involuntary movements. They are classified into four categories according to the precipitant, duration of attacks, and etiology: (1) paroxysmal kinesigenic dyskinesia (PKD), in which attacks are brief and induced by sudden voluntary movements; (2) paroxysmal nonkinesigenic dyskinesia (PNKD), in which attacks occur spontaneously; (3) paroxysmal exertion-induced dyskinesia (PED), in which attacks are brought on by prolonged exercise; and (4) paroxysmal hypnogenic dyskinesia (PHD), in which attacks occur during sleep. Among them, PHD is currently known to be a form of mesial frontal-lobe epilepsy, and has been given the term "autosomal-dominant nocturnal frontal lobe epilepsy" (ANDFLE) in some familiar cases with an autosomal-dominant inheritance. The clinical, etiological and pathophysiological features of PKD, PNKD, and PED are reviewed.

Idiopathic paroxysmal kinesigenic dyskinesia in Malaysia, a multi-racial Southeast Asian country

Paroxysmal kinesigenic dyskinesia is a rare disorder, and there are few reports of Asian patients with this condition. We reviewed the clinical features of all patients with idiopathic paroxysmal kinesigenic dyskinesia (PKD) seen at a major neurological centre in Malaysia. The charts of 11 patients with idiopathic PKD seen between 1995 and 2008 were reviewed retrospectively. The male:female ratio was 9:2. Ten patients were of Chinese ethnicity, and one was Malay. Three patients (from two families) had a family history of PKD. The involuntary movement was dystonia in 73% of patients. In one patient, attacks were precipitated by vestibular stimulation. One patient had generalized epilepsy. Another patient who did not have epilepsy demonstrated epileptiform discharges. Only slightly over one-quarter of patients had a positive family history. Males, and people of Chinese ancestry, seem to be affected more frequently by PKD in certain Asian populations.

Bilateral deep brain stimulation for treatment of medically refractory paroxysmal nonkinesigenic dyskinesia

The authors present the case of a 26-year-old man with a 10-15-year history of worsening bilateral dystonia and baseline chorea occurring up to 20 times per day that was exacerbated by stress and anxiety and was refractory to medical management. Paroxysmal nonkinesigenic dyskinesia was diagnosed, which is a rare, hyperkinetic movement disorder that is episodic and does not respond to nonbenzodiazepine antiepileptics. The patient was significantly debilitated by his disease, lived in a group home, and suffered from frequent falls, necessitating the wearing of a protective helmet and face mask at all times. The patient underwent implantation of bilateral deep brain stimulation quadripolar electrodes in the globus pallidus internus with the aid of image-guided stereotactic neurosurgery and microelectrode recording without complication. At his 1-month postoperative follow-up, the patient reported a subjective 90% improvement in his symptoms; the only notable side effect was a slight increased slurring in his baseline dysarthria. Objective reporting and recording forms maintained by the patient's caretakers over the following 18 months suggested a significant and sustained improvement in his overall balance, ambulation, and gross motor function with a substantial decrease in the incidence of reported falls. The authors conclude that pallidal deep brain stimulation may be successfully applied to patients suffering from refractory paroxysmal nonkinesigenic dyskinesia with promising results. This treatment strategy deserves further prospective investigation, clinical consideration, and refinement.

Acute and chronic chorea in childhood

This review discusses diagnostic evaluation and management of chorea in childhood. Chorea is an involuntary, hyperkinetic movement disorder characterized by continuous, jerky, or flowing movement fragments, with irregular timing and direction. It tends to be enhanced by voluntary actions and generally causes interference with fine motor function. The diagnostic evaluation begins with accurate classification of the movement disorder followed by consideration of the time course. Most previously healthy children presenting with acute/subacute chorea have an autoimmune etiology. Chronic chorea usually occurs as part of encephalopathies or diseases causing more global neurologic symptoms. We review the management of acute/subacute and chronic choreas, with special emphasis on Sydenham chorea and benign hereditary chorea.