Typical and atypical forms of paroxysmal choreoathetosis

Phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS)

Glut1 deficiency syndrome (Glut1 DS) was originally described in 1991 as a developmental encephalopathy characterized by infantile onset refractory epilepsy, cognitive impairment, and mixed motor abnormalities including spasticity, ataxia, and dystonia. The clinical condition is caused by impaired glucose transport across the blood brain barrier. The past 5 years have seen a dramatic expansion in the range of clinical syndromes that are recognized to occur with Glut1 DS. In particular, there has been greater recognition of milder phenotypes. Absence epilepsy and other idiopathic generalized epilepsy syndromes may occur with seizure onset in childhood or adulthood. A number of patients present predominantly with movement disorders, sometimes without any accompanying seizures. In particular, paroxysmal exertional dyskinesia is now a well-documented clinical feature that occurs in individuals with Glut1 DS. A clue to the diagnosis in patients with paroxysmal symptoms may be the triggering of episodes during fasting or exercise. Intellectual impairment may range from severe to very mild. Awareness of the broad range of potential clinical phenotypes associated with Glut1 DS will facilitate earlier diagnosis of this treatable neurologic condition. The ketogenic diet is the mainstay of treatment and nourishes the starving symptomatic brain during development.

Paroxysmal dyskinesias

Paroxysmal movement disorders are a relatively rare and heterogenous group of conditions manifesting as episodic dyskinesia lasting a brief duration. Three forms are clearly recognized, namely, paroxysmal kinesigenic (PKD), nonkinisegenic (PNKD), and exercise induced (PED). There have been major advances in the understanding of the pathophysiological mechanisms and the genetics of these disorders, leading to better clinical definitions based on genotype-phenotype correlations in the familial idiopathic forms. PKD is genetically heterogenous, but there is linkage to chromosome 16 in a number of families. PNKD is due to mutations of the MR-1 gene. PED is genetically heterogenous, but a number of familial and sporadic cases may be due to GLUT-1 gene mutations. The GLUT1 gene-related form of PED may respond to a ketogenic diet. Potassium and calcium channel mutations underlie the 2 main forms of episodic ataxia (EA1 and EA2), whereas benign torticollis of infancy may also be a calcium channel disorder.

Paroxysmal dyskinesias

Paroxysmal dyskinesias are a rare group of movement disorders affecting both adults and children. Based on the events that precipitate the abnormal movements, they are subdivided into paroxysmal kinesigenic dyskinesia (PKD), precipitated by sudden voluntary movements; paroxysmal nonkinesigenic dyskinesia (PNKD), which occurs at rest; paroxysmal exertion-induced dyskinesia (PED), occurring after prolonged exercise; and paroxysmal hypnogenic dyskinesia (PHD), which occurs in sleep. Paroxysmal dyskinesias can be sporadic, familial (autosomal dominant inheritance), or secondary to other disorders. Recent genetic discoveries may aid us in elucidating the pathophysiology of these disorders. PKD has been linked to the pericentromeric region of chromosome 16, PNKD is associated with mutations in the myofibrillogenesis regulator 1 (MR-1) gene on the long arm of chromosome 2 (2q32-36 locus), and PED is associated with mutations in the glucose transporter gene, GLUT1, responsible for glucose transport across the blood-brain barrier. Lifestyle modification to avoid precipitating factors is important in the management of paroxysmal dyskinesias. Medical therapies have not been examined in controlled trials. Nevertheless, anticonvulsants have been found to be extremely effective in treating PKD and are sometimes useful in other types, suggesting that these disorders may indeed represent forms of channelopathies. Drugs such as acetazolamide, anticholinergics, levodopa, and tetrabenazine have been inconsistently successful. In rare cases with medically refractory symptoms, deep brain stimulation has also been employed. Development of successful treatments for the different paroxysmal dyskinesias rests on elucidating the pathophysiology and targeting therapy to treat the underlying perturbation.

Paroxysmal exercise-induced dyskinesia and epilepsy is due to mutations in SLC2A1, encoding the glucose transporter GLUT1

Paroxysmal exercise-induced dyskinesia (PED) can occur in isolation or in association with epilepsy, but the genetic causes and pathophysiological mechanisms are still poorly understood. We performed a clinical evaluation and genetic analysis in a five-generation family with co-occurrence of PED and epilepsy (n = 39), suggesting that this combination represents a clinical entity. Based on a whole genome linkage analysis we screened SLC2A1, encoding the glucose transporter of the blood-brain-barrier, GLUT1 and identified heterozygous missense and frameshift mutations segregating in this and three other nuclear families with a similar phenotype. PED was characterized by choreoathetosis, dystonia or both, affecting mainly the legs. Predominant epileptic seizure types were primary generalized. A median CSF/blood glucose ratio of 0.52 (normal >0.60) in the patients and a reduced glucose uptake by mutated transporters compared with the wild-type as determined in Xenopus oocytes confirmed a pathogenic role of these mutations. Functional imaging studies implicated alterations in glucose metabolism in the corticostriate pathways in the pathophysiology of PED and in the frontal lobe cortex in the pathophysiology of epileptic seizures. Three patients were successfully treated with a ketogenic diet. In conclusion, co-occurring PED and epilepsy can be due to autosomal dominant heterozygous SLC2A1 mutations, expanding the phenotypic spectrum associated with GLUT1 deficiency and providing a potential new treatment option for this clinical syndrome.

Moyamoya disease presenting with paroxysmal exercise-induced dyskinesia

We report a patient with moyamoya disease presenting with paroxysmal exercise-induced dyskinesia (PED). A 31-year-old lathe man developed recurrent attacks of paroxysmal hemichorea. The attacks always affected his left limbs and occurred either after several hours of working or while playing football. The duration of attacks ranged from 30 min to 4h. Attacks were not provoked by sudden movements, consumption of coffee or alcohol, hyperventilation, emotional stress, exposure to cold or passive movement. An MRI of the brain showed no parenchymal lesions. However, (99m)Tc-ethylcysteine dimer SPECT study showed hypoperfusion in the right striatum. Digital subtraction angiography showed stenosis of the right internal carotid and middle cerebral artery with prominent basal collaterals, which was compatible with moyamoya disease. Imaging studies of the cerebral arteries should be done in patients with clinical features of PED in order to detect possible cases of moyamoya disease.

Clinical characteristics of paroxysmal nonkinesigenic dyskinesia in serbian family withMyofibrillogenesis regulator 1 gene mutation

The aim of this study was to describe the clinical features of a large Serbian family with paroxysmal nonkinesigenic dyskinesia (PNKD) and one of the two previously described mutations in the Myofibrillogenesis regulator 1 gene (MR-1), which causes an alanine-to-valine substitution at position 9. In 5 examined out of 12 affected family members, attacks of dyskinesias appeared in the first 6 months of life. Both frequency and severity of attacks showed an age-dependent incremental-decremental pattern with a peak between 13 to 15 years of age. They were frequently precipitated by stress, caffeine, fever, hunger, tiredness, as well as abrupt changes in temperature. Three of our patients differentiated two types of attacks: mild (120-180 minutes), with a predominance of functionally insignificant choreoathetoid movements, and severe ( approximately 15-30 minutes), characterized by disabling dystonic and choreic movements of the extremities, trunk, and face. Sleep was the most reliable factor to discontinue an attack. This Serbian family further demonstrates that recurrent MR-1 mutations are associated with PNKD worldwide, which will affect genetic testing.

Channelopathy: hypothesis of a common pathophysiologic mechanism in different forms of paroxysmal dyskinesia

Paroxysmal dyskinesias are a rare heterogeneous group of neurologic disorders, characterized by transient sudden choreoathetoid or dystonic attacks without loss of consciousness. This study reports a family with six affected members in three generations, and two sporadic cases of paroxysmal dyskinesia. Familial cases of paroxysmal dyskinesia are affected by idiopathic long-lasting paroxysmal exertion-induced dyskinesia and the sporadic cases by idiopathic short-lasting paroxysmal kinesigenic dyskinesia. Familial cases also suffer from epilepsy, mainly of generalized type, with benign outcome; one sporadic case is affected by migraine. Results presented in this neurophysiologic study include electromyography, somatosensory evoked potentials by median nerve stimulation, somatosensory evoked potentials by posterior tibial nerve stimulation, motor evoked potentials by magnetic transcranial cortical stimulation, visual evoked potentials, brainstem auditory evoked potentials, blink reflex, reflex H, and electroencephalography. The clinical and neurophysiologic findings presented here suggest a condition of hyperexcitability at the muscular and brain level, perhaps as a result of an ion channel disorder, which is in agreement with reports in the literature.

Co-occurrence of infantile epileptic seizures and childhood paroxysmal choreoathetosis in one family: clinical, EEG, and SPECT characterization of episodic events

The co-occurrence of infantile convulsions and childhood paroxysmal choreoathetosis (ICCA syndrome) has recently been reported in several families. The pattern of familial clustering observed is consistent with a single locus mutation which has been mapped onto the pericentromeric region of chromosome 16. We studied the main clinical, electroencephalogram (EEG), and single photon emission computed tomography (SPECT) characteristics of episodic events in a new family presenting clinical features similar to that described in the ICCA syndrome. In the first year of life, a mother and her two daughters suffered from rare afebrile seizures lasting from 30 seconds to 15 minutes. Ictal EEG recording in one daughter at 7 months of age showed bilateral polyspikes with a posterior predominance. In the three patients, epileptic seizures regressed within a few weeks, and never reoccurred. At the age of 7 and 12 years, respectively, the two daughters presented daily brief (20 seconds to 1 minute) involuntary choreoathetotic episodes. In 10 of these attacks, EEG did not show any epileptiform abnormalities. In both sisters, an ictal SPECT was performed during a choreoathetotic episode. Subtracting the ictal SPECT from the interictal SPECT coregistered to magnetic resonance imaging (MRI) revealed significant modifications in the local cerebral perfusion in the sensorimotor cortex, the supplementary motor areas, and pallidum. Carbamazepine completely suppressed paroxysmal dyskinesias. These observations, together with literature data, suggest that in this syndrome, depending on brain maturation, the same genetic abnormality may result in different paroxysmal neurological symptoms.

Familial paroxysmal exercise-induced dyskinesia, epilepsy, and mental retardation in a family with autosomal dominant inheritance

Only few sporadic and familial cases of paroxysmal exercise-induced dyskinesia (PED) have been described in literature. PED associated with familial epilepsy has been rarely reported. We describe a family in which six members in different generations were affected by a long-lasting PED, with childhood onset in five cases. Fasting and stress were also precipitating factors. All the subjects, moreover, showed epileptic seizures during childhood and adolescence. In addition, in all cases a condition of mild mental retardation was also documented, associated in some cases, with irritable and impulsive behaviour. Clinical, neurophysiological, neuroimaging and neuropsychological findings were reported. The homogeneous recurrence of this particular clinical picture in members of three generations emphasised a common genetic basis. In our patients, PED is transmitted as an autosomal dominant trait, with age-dependent penetrance, without evidence of genetic anticipation. The neurophysiological findings suggest a condition of hyperexcitability in the muscular and brain membrane, due to a ion channels disorder.

A new family with paroxysmal exercise induced dystonia and migraine: a clinical and genetic study

OBJECTIVE

To characterise the phenotype of a family with paroxysmal exercise induced dystonia (PED) and migraine and establish whether it is linked to the paroxysmal non-kinesigenic dyskinesia (PNKD) locus on chromosome 2q33-35, the familial hemiplegic migraine (FHM) locus on chromosome 19p, or the familial infantile convulsions and paroxysmal choreoathetosis (ICCA syndrome) locus on chromosome 16.

METHODS

A family, comprising 30 members, was investigated. Fourteen family members in two generations including three spouses were examined. Haplotypes were reconstructed for all the available family members by typing several microsatellite markers spanning the PNKD, FHM, and ICCA loci. Additionally, the four exons containing the known FHM mutations were sequenced.

RESULTS

Of 14 members examined four were definitely affected and one member was affected by history. The transmission pattern in this family was autosomal dominant with reduced penetrance. Mean age of onset in affected members was 12 (range 9-15 years). Male to female ratio was 3:1. Attacks of PED in affected members were predominantly dystonic and lasted between 15 and 30 minutes. They were consistently precipitated by walking but could also occur after other exercise. Generalisation did not occur. Three of the affected members in the family also had migraine without aura. Linkage of the disease to the PNKD, FHM, or ICCA loci was excluded as no common haplotype was shared by all the affected members for each locus. In addition, direct DNA sequential analysis of the FHM gene (CACNL1A4) ruled out all known FHM point mutations.

CONCLUSIONS

This family presented with the classic phenotype of PED and is not linked to the PNKD, FHM, or ICCA loci. A new gene, possibly coding for an ion channel, is likely to be the underlying cause of the disease.

Reciprocal inhibition between the forearm muscles in patients with paroxysmal kinesigenic dyskinesia

We measured the changes of forearm flexor H reflexes produced by conditioning radial nerve stimulation at delays of -2, 0, 2, 4, 7.5, 10, 25 and 75 ms in 10 patients with PKD and six with generalized seizure disorder. We compared the results with 12 normal volunteers. In the patients with PKD, we compared the amounts of reciprocal inhibition between the severely and the asymptomatic or mildly affected sides of arms. Follow-up studies were done in eight PKD patients after they responded to the anticonvulsant treatment. At each delay, patients with seizure disorders showed comparable amounts of changes with controls. Patients with PKD showed paradoxical facilitation at a delay of 0 ms, enhanced facilitation between 2 to 7.5 ms delays and attenuated inhibition at a delay of 75 ms. There were no significant differences in the amount of reciprocal inhibition according to the severity of clinical symptoms. Follow-up studies showed no significant changes of reciprocal inhibition compared to the baseline data. In PKD, paradoxical facilitation and enhanced first relative facilitation period may be caused by defective spinal interneurons. In addition to the defective reciprocal inhibition, abnormalities of supraspinal inputs seem to be involved in the genesis of PKD.

Pleiotropic skeletal and ocular phenotypes of the mouse mutation congenital hydrocephalus (ch/Mf1) arise from a winged helix/forkhead transcriptionfactor gene

Congenital hydrocephalus is an etiologically diverse, poorly understood, but relatively common birth defect. Most human cases are sporadic with familial forms showing considerable phenotypic and etiologic heterogeneity. We have studied the autosomal recessive mouse mutation congenital hydrocephalus ( ch ) to identify candidate human hydrocephalus genes and their modifiers. ch mice have a congenital, lethal hydrocephalus in association with multiple developmental defects, notably skeletal defects, in tissues derived from the cephalic neural crest. We utilized positional cloning methods to map ch in the vicinity of D13Mit294 and confirm that the ch phenotype is caused by homozygosity for a nonsense mutation in a gene encoding a winged helix/forkhead transcription factor ( Mf1 ). Based on linked genetic markers, we performed detailed phenotypic characterization of mutant homozygotes and heterozygotes to demonstrate the pleiotropic effects of the mutant gene. Surprisingly, ch heterozygotes have the glaucoma-related distinct phenotype of multiple anterior segment defects resembling Axenfeld-Rieger anomaly. We also localized a second member of this gene family ( Hfh1 ), a candidate for other developmental defects, approximately 470 kb proximal to Mf1.

Autosomal recessive rolandic epilepsy with paroxysmal exercise-induced dystonia and writer's cramp: delineation of the syndrome and gene mapping to chromosome 16p12-11.2

We describe a pedigree in which 3 members in the same generation are affected by Rolandic epilepsy (RE), paroxysmal exercise-induced dystonia (PED), and writer's cramp (WC). Both the seizures and paroxysmal dystonia had a strong age-related expression that peaked during childhood, whereas the WC, also appearing in childhood, has been stable since diagnosis. Genome-wide linkage analysis performed under the assumption of recessive inheritance identified a common homozygous haplotype in a critical region spanning 6 cM between markers D16S3133 and D16S3131 on chromosome 16, cosegregating with the affected phenotype and producing a multipoint LOD score value of 3.68. Although its features are unique, this syndrome presents striking analogies with the autosomal dominant infantile convulsions and paroxysmal coreoathetosis (ICCA) syndrome, linked to a 10 cM region between D16S401 and D16S517, which entirely includes the 6 cM of the RE-PED-WC critical region. The same gene may be responsible for both RE-PED-WC and ICCA, with specific mutations explaining each of these Mendelian disorders. This report shows that idiopathic focal disorders such as epilepsy and dystonia, can be caused by the same genetic abnormality, may have a transient expression, and may be inherited as an autosomal recessive trait.

Paroxysmal kinesigenic choreoathetosis in Singapore and its relationship to epilepsy

OBJECTIVES

To study the clinical characteristics of paroxysmal kinesigenic choreoathetosis (PKC) in our local population and its relationship to epilepsy.

METHODS

We reviewed retrospectively 15 patients who were managed by neurologists in our department from 1982 to 1996. The literature was also reviewed to study the association between PKC and epilepsy.

RESULTS

In our study, all the cases were idiopathic. The male to female ratio was 14:1 with all major races represented. Sixty percent of our patients suffered dystonic posturing rather than chorea, during the attacks. Twenty-one percent had a family history of a similar disorder which appeared to be of autosomal dominant inheritance. The sporadic form (79%) predominated in Singapore. One had a history of febrile fits while two had a history of epilepsy. We reviewed the available literature and found five other patients with idiopathic PKC also suffering from epilepsy. Of the 83 patients reviewed, 8% had epilepsy. This further strengthens the relationship between the two conditions. All our patients responded well to phenytoin at doses between 100 and 400 mg/day.

CONCLUSION

PKC affected all three major races in our population with a high male to female ratio of 14:1. Seventy-nine percent of our cases were sporadic and 60% suffered dystonic posturing during attacks. Of the cases reviewed, 8% of patients with idiopathic PKC also had epilepsy.

Proton MR spectroscopic findings in paroxysmal kinesigenic dyskinesia

Although paroxysmal kinesigenic dyskinesia (PKD) has characteristic clinical features, the pathophysiology of PKD has remained unknown. The purpose of this study was to investigate the pathophysiology of idiopathic PKD by performing proton magnetic resonance spectroscopy (1H-MRS) in five patients with idiopathic PKD. Three patients were familial and two sporadic. Single-voxel 1H-MRS was performed on a GE 1.5-T SIGNA MR system. Localized 1H-MR spectra were obtained from the basal ganglia (n = 5), thalamus (n = 3), and supplementary motor area (SMA; n = 4) using STEAM sequence (stimulated echo acquisition mode; TR = 3.0 sec, TE = 30 msec, 64 AVG, volume = 8 mL) or PRESS (point resolved spectroscopy; TR = 3.0 sec, TE = 135 msec, volume = 4 mL). Peak ratios of Cho/Cr (Cho: choline, Cr: creatine) and mI/Cr (mI: myoinositol) were decreased significantly in the unilateral basal ganglia of two patients. In one, decreased peak ratio of mI/Cr in the unilateral basal ganglia was the only abnormality. In the remaining two, there was no significant abnormality. 1H-MR spectra obtained from the thalamus and SMA were all within normal limits. In conclusion, these results suggest that underlying pathophysiological mechanism of PKD may be at least partially associated with the dysfunction of cholinergic system in the basal ganglia.

Changes in perfusion pattern using ECD-SPECT indicate frontal lobe and cerebellar involvement in exercise-induced paroxysmal dystonia

The clinical features of exercise-induced paroxysmal dystonia (EPD) are delineated in a pedigree including two affected members (both male) showing an autosomal-dominant inheritance trait. Gait analysis using kinematic electromyography during the motor attacks revealed coactivation of antagonistic calf muscles characteristic of dystonia. In the interval, impaired muscular alternation was observed. To characterize further the pathophysiological basis of the condition, ictal and interictal cerebral perfusion SPECT studies using technetium 99m-ethyl cysteinate dimer (ECD) were performed to establish whether cortical hyperactivity indicative of epilepsy is present during the motor attacks and to identify regional changes in the ictal perfusion pattern that could indicate an anatomic structure relevant to the disease. During the motor attacks, decreased ictal perfusion of the frontal cortex was found in both patients. In contrast, increased cerebellar perfusion was observed. The perfusion of the basal ganglia also decreased. No cortical hyperperfusion indicative of an epileptic nature was seen. Cerebellar hyperactivity in connection with prominent frontal hypoactivity has also been described in both the idiopathic and the symptomatic forms of dystonia. Our findings therefore suggest that EPD represents a paroxysmal movement disorder rather than epilepsy. It is concluded that changes in frontal and in cerebellar function are relevant to the pathophysiology of EPD.

Paroxysmal exercise-induced dystonia: eight new sporadic cases and a review of the literature

We report eight new sporadic cases of paroxysmal dystonia induced by prolonged or sustained exercise and review an additional seven previously reported cases. The attacks in our patients lasted from a few minutes to up to 2 h, and patient age at onset ranged from 2 to 30 years. Four of the eight patients had hemidystonic attacks, both legs were involved in two other cases, and the remaining two patients had involvement of the right foot only. We propose that such cases should be classified as paroxysmal exercise-induced dystonia.

Paroxysmal dyskinesias: clinical features and classification

We studied 46 patients with paroxysmal dyskinesia and classified them according to phenomenology, duration of attacks, and etiology. There were 13 patients, 7 females, who had paroxysmal kinesigenic dyskinesia (PKD), 10 with attacks lasting 5 minutes or less (short lasting) and 3 with attacks lasting longer than 5 minutes (long lasting). Twenty-six patients, 18 females, had paroxysmal nonkinesigenic dyskinesia (PNKD), 9 with short-lasting and 17 with long-lasting PNKD. Five patients, 3 females, had paroxysmal exertion-induced dyskinesia (PED), 3 with short-lasting PED and the other 2 with long-lasting PED. In addition, there was 1 patient with paroxysmal hypnogenic dyskinesia (PHD) and 1 with paroxysmal superior oblique myokymia. Only 2 patients, 1 with PKD and 1 with PHD, had family history of paroxysmal dyskinesias. No specific cause could be identified in 21 patients; in the other 23 patients the etiologies included the following: psychogenic (9 patients), cerebrovascular diseases (4), multiple sclerosis (2), encephalitis (2), cerebral trauma (2), peripheral trauma (2), migraine (1), and kernicterus (1). Nine of 10 (90%) patients with PKD improved with medications, mostly anticonvulsants, compared with only 7 of 19 (37%) with PNKD. This new classification, based chiefly on precipitating events, allowed appropriate categorization of the attacks in all our patients with paroxysmal dyskinesias.

Concurrent nocturnal and diurnal paroxysmal dystonia

The authors describe a case of a 15-year-old girl who presented with a progressive sequence of nocturnal dystonic episodes, generalized seizures, and diurnal dystonic episodes. A diagnosis of nocturnal paroxysmal dystonia has been proposed in view of the association between nocturnal episodes and epileptic seizures, while the diurnal episodes are atypical. Neurophysiological data recorded during critical episodes are reported. A linkage between dystonic attacks and epilepsy is hypothesized.

Nonepileptic paroxysmal events in childhood

Seizures are the most commonly occurring paroxysmal events of childhood. There are a large number of other disorders, however, that present with discrete attacks separated by symptom-free intervals. The differentiation of these conditions from seizures depends on a willingness to consider alternate diagnoses and a thorough review of the history of the events. Laboratory tests, and especially the electroencephalogram, are aids to diagnosis, but reliance on laboratory data has many pitfalls. The clinical features of the important nonepileptic paroxysmal disorders of childhood are reviewed.