Movement Disorders Vol. 7, No. 1, 1992, pp. 3 M 2 0 1992 Movement Disorder Society
SUPPLEHEM
Is Nocturnal Paroxysmal Dystonia a Form of Frontal Lobe Epilepsy? H. Meierkord, D. R. Fish, S. J . M. Smith, C. A. Scott, S. D. Shorvon, and C. D. Marsden The University Department of Clinical Neurology, Institute of Neurology and The National Hospitals for Neurology and Neurosurgery, Queen Square, London, England
Summary: The sex ratio, age at onset, and ictal features of nine patients with nocturnal paroxysmal dystonia were compared with those of eight patients with daytime frontal lobe seizures and eight patients with nocturnal motor attacks of known epileptic origin. All patients underwent video electroencephalography telemetry. There were no clinical features that would allow distinction between the groups and no single phenomenon was uniquely seen in nocturnal paroxysmal dystonia. This study provides no evidence that nocturnal paroxysmal dystonia is a separate diagnostic entity. Key Words: Frontal lobe seizures-Nocturnal epileptic attacks-Nocturnal paroxysmal dystonia. -
apparent. Since the initial report, further cases have been described (Table 1,343). Recently the Bologna group has described two patients with nocturnal paroxysmal dystonia that were found on occasion to have attacks that progressed to secondary convulsive seizures with epileptiform scalp EEG changes (8), and they suggested that short nocturnal paroxysmal dystonic attacks were a form of mesialorbital frontal epilepsy. Nevertheless, in view of other previous reports it remains uncertain whether nocturnal paroxysmal dystonia is a distinct nosological entity or a form of nocturnal epilepsy. Certainly mesial frontal seizures may manifest as usually brief motor attacks without scalp EEG changes, but with epileptic activity confirmed on intracranial EEG studies (3,9). Futhermore, recent studies have emphasised that frontal seizures may be short, show prominent motor involvement with little if any alteration in awareness or postictal confusion, cluster at night, and be associated with normal interictal and ictal scalp EEGs (1&12). We have attempted in this study to resolve whether nocturnal paroxysmal dystonia is a distinct condition or a type of epilepsy, probably of frontal origin, by comparing the clinical and EEG features of patients who fulfilled the criteria for a diagnosis
In 1981, Lugaresi et al. (1) described a group of patients with brief nocturnal motor attacks during non-rapid eye movement (NREM) sleep. They suggested that they form a distinct nosological entity and called it hypnogenic paroxysmal dystonia and subsequently nocturnal paroxysmal dystonia (2). Characteristically, the patients had brief attacks, occurring in clusters almost every night, although occasional patients were included with longerlasting attacks. The main ictal phenomena were motor and included dystonic posturing, and ballistic or choreic dyskinesias, often accompanied by vocalisation. Consciousness was not obviously impaired, although this is difficult to assess on overnight studies of unattended subjects, and there were no epileptic electroencephalography (EEG) changes during the attacks. Interestingly, several patients had additional daytime convulsions and the nocturnal attacks often responded favourably to antiepileptic drugs. None had a positive family history and no aetiology was
A videotape segment accompanies this article. Address correspondence and reprint requests to Dr. D. R. Fish, The National Hospitals for Neurology and Neurosurgery, Queen Square, London WClN 3BG, England.
38
39
I S NOCTURNAL DYSTONIA EPILEPSY? TABLE 1. Previous studies on nocturnal paroxysmal disorders
Study Lugaresi and Cirignota, 1981 (1) Rajna et al., 1983 (3) Godbout et al., 1985 (4) Lee et al., 1985 (5) Crowell and Anders, 1985 (6) Lugaresi et al., 1986 (2) Lehkuniec et al., 1988 (7) Tinuper et al., 1990 (8)
No. of patients 5 1 1 3 I 12 1 3
Other epileptic seizures
Good response to AC
3 0 0 8 0
4 0 I 2 ? Allb I
2
2
1 ?
EEG abnormalities" 0 1 1 0 0 0 0 2
AC, anticonvulsant therapy, usually carbamazepine; ?, not known. " Electroencephalography (EEG) abnormalities refer to interictal or ictal epileptiform discharges. The authors state that all of those who tried carbamazepine responded favourably but the number of cases tried is not stated.
of nocturnal paroxysmal dystonia with patients having daytime frontal lobe seizures or nocturnal motor attacks of epileptic origin. PATIENTS AND METHODS Three groups of patients with brief motor attacks were identified from patients who had undergone diagnostic video telemetry at The National Hospitals for Neurology and Neurosurgery between 1987-90. Group 1: Nocturnal Paroxysmal Dystonia Nine patients met the diagnostic criteria described by Lugaresi et al. (1,2): brief nocturnal attacks with predominant dystonia or other dyskinetic movements arising from NREM sleep without obvious evidence of impaired consciousness or interictal or ictal epileptiform scalp EEG abnormalities. None of our patients in this group had known aetiologies or computed tomography (CT) abnormalities. Six of nine had a history of at least one daytime convulsion.
tal and/or ictal frontal EEG abnormalities and one had a frontal magnetic resonance imaging (MRI) lesion. The overnight recordings were performed using split-screen video telemetry (Telefactor) in a single room. Up to 24 bipolar channels of EEG were recorded using the 10/20 system of electrode placement and in some cases surface electromyography, electro-oculography , and superficial sphenoidal electrodes. The subsequent tapes were reviewed by one of us (H.M.) to assess the ictal features. RESULTS There were no significant differences between the three groups with respect to sex ratio, age at onset, and response to anticonvulsant treatment (Table 2). Attacks occurred with a similarly high frequency in all the groups and the duration of the episodes was less than 60 s in most patients (Fig. 1). All nocturnal TABLE 2. Characteristics of three groups with motor attacks Group I
Group 2: Nocturnal Epilepsy Eight patients had attacks that occurred mainly during sleep and for which there was evidence of an epileptic origin. Three had interictal and/or ictal frontal EEG abnormalities and one had a frontal CT lesion. The remaining cases did not have EEG or CT abnormalities but all had secondary generalised tonic-clonic seizures after some habitual nocturnal attacks, confirming an epileptic basis. Group 3: Daytime Frontal Lobe Epilepsy Eight patients had attacks during the daytime. Seven of the eight patients had interic-
W") F M Median age at onset, yr (range) Response to antiepileptic drugs present absent Frequency of attacks (recording period of 10 h) >15 10 < 20
Number of patients with ictal vocalisation
Group 2 WE)
Group 3 (DFE)
3
3
4
6
5
4
11 (3-38)
7 (4-17)
15 (3-39)
5 4
2 6
2 6
I
8
6
I
-
1
2
-
5
7
5
NPD, nocturnal paroxysmal dystonia; NE, nocturnal epilepsy; DFE, daytime frontal epilepsy.
Movement Disorders, Vol. 7 , N o . I , 1992
40
H . MEIERKORD ET AL.
. 70
-m u
KO
-
50
-
40
-
W
?L? 2
0 r(
+ d U 0
.. ..
..
30 -
.. *
..
20 -
10
.
..
I
I
I
1
2
3
FIG. 1. The duration of attacks in each patient. Group 1, nocturnal paroxysmal dystonia; group 2, nocturnal epilepsy; group 3, daytime frontal lobe epilepsy.
attacks arose from NREM sleep and often included vocalisations (Table 2). The character and distribution of ictal motor features identified during video telemetry showed considerable overlap between the groups. Dystonic posturing was the commonest type of ictal motor activity, while choreic, ballistic, myoclonic, tonic, or clonic activities were relatively rare. In most patients the ictal dyskinesias involved all four limbs to some extent (Table 3). In addition, review of the attacks recorded by telemetry failed to reveal any qualitative features that were unique to the nocturnal paroxysmal dystonia group. DISCUSSION
In their initial report of nocturnal paroxysmal dystonia, Lugaresi et al. (1) described five cases TABLE 3 . The ictal clinical features of attacks seen on video telemetry Nocturnal paroxysmal dystonia Dystonia 3 or 4 limbs 1 or 2 limbs axial Other dyskinesia
Nocturnal epilepsy
119 1 I9 519 519'
One myoclonic, one choreic, three ballistic. One chorea, one myoclonus, one clonic. One myoclonic, two ballistic, two tonic.
Movement Disorders, Vol. 7,No. 1 , 1992
Daytime frontal seizures 418 118
618 218 218
618
3iab
518'
that did not have evidence of epilepsy. In a subsequent series ( 2 ) , the majority of the cases (eight of 12) had either clinical or EEG evidence for additional epilepsy. Other reports highlight the difficulty of distinguishing nocturnal paroxysmal dystonia from epilepsy. The case of Rajna et al. (3) had tonic nocturnal seizures, and depth recordings revealed epileptiform abnormalities in the cingulate gyms. Godbout et al. (4) reported a case with frequent nocturnal attacks consisting of pronounced vocalisations and violent limb movements lasting less than a minute. The attacks started and stopped abruptly and there was no postictal confusion, but this patient had amnesia for the event and developed bizarre daytime attacks with repetitive complex automatisms. However, evidence for epilepsy is lacking in the three members of a family with nocturnal episodes consisting of tonic postures and laboured respiration reported by Lee et al. (5). Most of the reported cases had brief motor attacks, although Lugaresi et al. (2) suggested that occasional patients may have attacks lasting for many minutes. It remains to be established whether or not such long-lasting attacks form a truly separate entity. Motor involvement is a prominent feature of most frontal lobe epilepsies and may take dystonic, choreic, or ballistic forms as well as being clonic or myoclonic jerks (10-12). The seizures are usually brief, but may occur in clusters merging one into the next. The movements may be similar to the dyskinesias seen in extrapyramidal disease. Indeed, they may indicate participation of the basal ganglia in the motor expression of frontal epilepsy. Frontal lobe regions have intimate connections to the basal ganglia (13-20), and propagation of seizure activity from cortex to basal ganglia may occur in both human and experimental epilepsy (13). The clinical and ictal motor features did not allow a distinction between the three groups in this study (nocturnal paroxysmal dystonia, nocturnal epilepsy, and daytime frontal epilepsy). This leads us to question the existence of a separate syndrome of nocturnal paroxysmal dystonia and to postulate that these cases are examples of epilepsy, presumably of frontal lobe origin in which EEG abnormalities were not evident on the scalp. Many frontal regions that are capable of producing seizures are inaccessible to surface EEG recording (21). It may well be that paroxysmal nocturnal dystonia is an example of frontal lobe epilepsy arising from such hidden foci and careful screening for frontal lobe pathologic conditions is essential in patients with such noc-
41
I S NOCTURNAL D YSTONIA EPILEPSY?
turnal attacks. Wake and sleep scalp EEGs should be performed, with additional electrodes to increase frontal lobe sampling (e.g., supraorbital channels), and care should be taken to identify and differentiate central spikes from vertex sharp waves of sleep. Neuroimaging should include MRI scanning with particular reference to frontal lobe structures. In view of the earlier reports of a favourable response to antiepileptic medication, particularly carbamazepine, and the likely epileptic nature of the attacks, a trial of such therapy may be indicated in these patients. Acknowledgment:This work was supported by the Sir Jules Thorn Charitable Trust.
at 07: 19:32. Her left arm falls down over the edge of the bed and the right arm elevates and stiffens (in this attack partially hidden by the blankets). The right upper limb posturing is maintained for several seconds. When the right arm falls, dystonic posturing is seen in the right hand. She breathes deeply, whines, and the attack ends. Case 5: Nocturnal epilepsy with bilateral upper limb dystonia (recorded during a daytime nap). A 24-year-old woman has had nocturnal attacks since the age of 10 years. Interictal electroencephalography showed large-amplitude sharp waves maximum in the left central region. The patient awakens and the attack commences at 16:16:16 with bilateral upper limb dystonic posturing. The attack ends abruptly at 16:16:35.
LEGENDS TO VIDEOTAPE Case 1: Nocturnal paroxysmal dystonia with involvement of all four limbs. The 60-year-old woman has had nocturnal attacks since the age of 2 years. At 02:05:40 she awakens. The attack commences at 02:06:13 with jerky dystonic movements of all four limbs, altered respiration, and grimacing. The attack ends abruptly at 02:07:30 and she sits up on the bed. Case 2: Nocturnal paroxysmal dystonia affecting the left leg. A 24-year-old man has had nocturnal attacks since the age of 14 years. The onset of the attack awakens the patient at 21:29:04. There is stiffening of the left leg with flexion at the knee. He grunts and grimaces as if in pain. He cries out for help and swears. He sighs, and the attack ends at about 21:29:30. Case 3: Nocturnal paroxysmal dystonia showing ballism. A 32-year-old man has had nocturnal attacks since the age of 27 years. The patient awakens at 03:40:50 and the attack commences 7 s later with ballistic movements. The attack ends at 03:41:15, and the patient responds to the nurse. This patient was subsequently treated with highdose slow-release carbamazepine and became free of attacks. Case 4: Nocturnal epilepsy with dystonic posturing particularly evident in the upper limbs. A 24year-old woman has had nocturnal attacks since the age of 6 years. Sometimes these progressed to a generalised convulsion. She had a mild left-sided hemiparesis, and postictally this was worse. The patient awakens and the attack commences
REFERENCES 1. Lugaresi E, Cirignota F. Hypnogenic paroxysmal dystonia: epileptic seizure or a new syndrome? Sleep 1981;4:129-138. 2. Lugaresi E, Cirignotta F, Montagna P. Nocturnal paroxysmal dystonia. J Neurol Neurosurg Psychiatry 1986;49:375380. 3. Rajna P, Kundra 0, Halasz P. Vigilance level-dependent tonic seizures: epilepsy or sleep disorder? A case report. Epilepsia 1983;24:725-733. 4. Godbout R, Montplaisir J, Rouleau I. Hypnogenic paroxysmal dystonia: epilepsy or sleep disorder? A case report. CIin Electroencephalogr 1985;16:136-142. 5. Lee BI, Lesser RP, Pippenger GE, et al. Familial paroxysmal hypnogenic dystonia. Neurology 1985;35:1357-1360. 6 . Crowell JA, Anders TF. Hypnogenic paroxysmal dystonia. J Am Acad Child Psychiatry 1985;24:353-358. 7. Lehkuniec E, Micheli F, de Arbelaiz R, Torres M, Paradiso G . Concurrent hypnogenic and reflex paroxysmal dystonia. Move Disord 1988;3:290-294. 8. Tinuper P, Cerullo A, Cirignotta F, Cortelli P, Lugaresi E, Montagna P. Nocturnal paroxysmal dystonia with shortlasting attacks. Three cases with evidence for an epileptic frontal lobe origin of seizures. Epilepsia 1990;31:549-556. 9. Neidermyer E, Walker AE. Mesial frontal epilepsy. Electroencephalogr Clin Neurophysiol 1971;31:104-105. 10. Waterman K, Purves SJ, Kosaka B, Strauss E, Wada JA. An epileptic syndrome caused by mesial frontal lobe seizure foci. Neurology 1987;37:577-582. 11. Williamson PD, Spencer DD, Spencer SS, Novelly RA, Mattson RH. Complex partial seizures of frontal lobe origin. Ann Neurol 1985;18:497-504. 12. Moms HH, Dinner DS, Lueders H, Wyllie E, Kramer R. Supplementary motor seizures: clinical and electroencephalographic findings. Neurology 1988;38:1075-1082. 13. Walker EA. Pre-frontal lobe epilepsy. Int J Neurol 1966; 5:422-429. 14. Kemp JM, Powell TP. The cortico-striate projection in the monkey. Bruin 1970;93:525-546. 15, Kemp JM, Powell TP. The connexions of the striatum and globus pallidus: synthesis and speculation. Philos Trans R Soc Lond [Biol] 1971;262:441457.
Movement Disorders, Vol. 7, N o . 1 , 1992
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H . MEIERKORD ET AL.
16. Selemon LD, Goldman-Rakic PS. Longitudinal topography and interdigitation of corticostriatal projections in the rhesus monkey. J Neurosci 1985;5:77&794. 17. Wall PD, Glees P, Fulton JF. Corticofugal connexions of posterior orbital surface in rhesus monkey. Brain 1951; 74:66-71. 18. Leichnetz GR, Astruc J . The course of some prefrontal corticofugals to the pallidum, substantia innominata, and amygdaloid complex in monkeys. Exp Neurol 1977;54: 104109.
Movement Disorders, Vol. 7, N o . 1. 1992
19. Kuenzle H. An autoradiographic analysis of the efferent connections from premotor and adjacent prefrontal regions (areas 6 and 9) in Macaca fascicularis. Brain Behav Evol 1978;15:185-234. 20. Kanki S, Ban T. Cortico-fugal connections of frontal lobe in man. Med J Osaka Univ 1952;3:201-222. 21. Quesney LF, Constain P, Fish D, Rasmussen T. The clinical differentiation of seizures arising in the parasagittal and anterolateral dorsal frontal lobe convexities. Arch Neurol 1990;47:677479.
SUPPLEHEM
Is Nocturnal Paroxysmal Dystonia a Form of Frontal Lobe Epilepsy? H. Meierkord, D. R. Fish, S. J . M. Smith, C. A. Scott, S. D. Shorvon, and C. D. Marsden The University Department of Clinical Neurology, Institute of Neurology and The National Hospitals for Neurology and Neurosurgery, Queen Square, London, England
Summary: The sex ratio, age at onset, and ictal features of nine patients with nocturnal paroxysmal dystonia were compared with those of eight patients with daytime frontal lobe seizures and eight patients with nocturnal motor attacks of known epileptic origin. All patients underwent video electroencephalography telemetry. There were no clinical features that would allow distinction between the groups and no single phenomenon was uniquely seen in nocturnal paroxysmal dystonia. This study provides no evidence that nocturnal paroxysmal dystonia is a separate diagnostic entity. Key Words: Frontal lobe seizures-Nocturnal epileptic attacks-Nocturnal paroxysmal dystonia. -
apparent. Since the initial report, further cases have been described (Table 1,343). Recently the Bologna group has described two patients with nocturnal paroxysmal dystonia that were found on occasion to have attacks that progressed to secondary convulsive seizures with epileptiform scalp EEG changes (8), and they suggested that short nocturnal paroxysmal dystonic attacks were a form of mesialorbital frontal epilepsy. Nevertheless, in view of other previous reports it remains uncertain whether nocturnal paroxysmal dystonia is a distinct nosological entity or a form of nocturnal epilepsy. Certainly mesial frontal seizures may manifest as usually brief motor attacks without scalp EEG changes, but with epileptic activity confirmed on intracranial EEG studies (3,9). Futhermore, recent studies have emphasised that frontal seizures may be short, show prominent motor involvement with little if any alteration in awareness or postictal confusion, cluster at night, and be associated with normal interictal and ictal scalp EEGs (1&12). We have attempted in this study to resolve whether nocturnal paroxysmal dystonia is a distinct condition or a type of epilepsy, probably of frontal origin, by comparing the clinical and EEG features of patients who fulfilled the criteria for a diagnosis
In 1981, Lugaresi et al. (1) described a group of patients with brief nocturnal motor attacks during non-rapid eye movement (NREM) sleep. They suggested that they form a distinct nosological entity and called it hypnogenic paroxysmal dystonia and subsequently nocturnal paroxysmal dystonia (2). Characteristically, the patients had brief attacks, occurring in clusters almost every night, although occasional patients were included with longerlasting attacks. The main ictal phenomena were motor and included dystonic posturing, and ballistic or choreic dyskinesias, often accompanied by vocalisation. Consciousness was not obviously impaired, although this is difficult to assess on overnight studies of unattended subjects, and there were no epileptic electroencephalography (EEG) changes during the attacks. Interestingly, several patients had additional daytime convulsions and the nocturnal attacks often responded favourably to antiepileptic drugs. None had a positive family history and no aetiology was
A videotape segment accompanies this article. Address correspondence and reprint requests to Dr. D. R. Fish, The National Hospitals for Neurology and Neurosurgery, Queen Square, London WClN 3BG, England.
38
39
I S NOCTURNAL DYSTONIA EPILEPSY? TABLE 1. Previous studies on nocturnal paroxysmal disorders
Study Lugaresi and Cirignota, 1981 (1) Rajna et al., 1983 (3) Godbout et al., 1985 (4) Lee et al., 1985 (5) Crowell and Anders, 1985 (6) Lugaresi et al., 1986 (2) Lehkuniec et al., 1988 (7) Tinuper et al., 1990 (8)
No. of patients 5 1 1 3 I 12 1 3
Other epileptic seizures
Good response to AC
3 0 0 8 0
4 0 I 2 ? Allb I
2
2
1 ?
EEG abnormalities" 0 1 1 0 0 0 0 2
AC, anticonvulsant therapy, usually carbamazepine; ?, not known. " Electroencephalography (EEG) abnormalities refer to interictal or ictal epileptiform discharges. The authors state that all of those who tried carbamazepine responded favourably but the number of cases tried is not stated.
of nocturnal paroxysmal dystonia with patients having daytime frontal lobe seizures or nocturnal motor attacks of epileptic origin. PATIENTS AND METHODS Three groups of patients with brief motor attacks were identified from patients who had undergone diagnostic video telemetry at The National Hospitals for Neurology and Neurosurgery between 1987-90. Group 1: Nocturnal Paroxysmal Dystonia Nine patients met the diagnostic criteria described by Lugaresi et al. (1,2): brief nocturnal attacks with predominant dystonia or other dyskinetic movements arising from NREM sleep without obvious evidence of impaired consciousness or interictal or ictal epileptiform scalp EEG abnormalities. None of our patients in this group had known aetiologies or computed tomography (CT) abnormalities. Six of nine had a history of at least one daytime convulsion.
tal and/or ictal frontal EEG abnormalities and one had a frontal magnetic resonance imaging (MRI) lesion. The overnight recordings were performed using split-screen video telemetry (Telefactor) in a single room. Up to 24 bipolar channels of EEG were recorded using the 10/20 system of electrode placement and in some cases surface electromyography, electro-oculography , and superficial sphenoidal electrodes. The subsequent tapes were reviewed by one of us (H.M.) to assess the ictal features. RESULTS There were no significant differences between the three groups with respect to sex ratio, age at onset, and response to anticonvulsant treatment (Table 2). Attacks occurred with a similarly high frequency in all the groups and the duration of the episodes was less than 60 s in most patients (Fig. 1). All nocturnal TABLE 2. Characteristics of three groups with motor attacks Group I
Group 2: Nocturnal Epilepsy Eight patients had attacks that occurred mainly during sleep and for which there was evidence of an epileptic origin. Three had interictal and/or ictal frontal EEG abnormalities and one had a frontal CT lesion. The remaining cases did not have EEG or CT abnormalities but all had secondary generalised tonic-clonic seizures after some habitual nocturnal attacks, confirming an epileptic basis. Group 3: Daytime Frontal Lobe Epilepsy Eight patients had attacks during the daytime. Seven of the eight patients had interic-
W") F M Median age at onset, yr (range) Response to antiepileptic drugs present absent Frequency of attacks (recording period of 10 h) >15 10 < 20
Number of patients with ictal vocalisation
Group 2 WE)
Group 3 (DFE)
3
3
4
6
5
4
11 (3-38)
7 (4-17)
15 (3-39)
5 4
2 6
2 6
I
8
6
I
-
1
2
-
5
7
5
NPD, nocturnal paroxysmal dystonia; NE, nocturnal epilepsy; DFE, daytime frontal epilepsy.
Movement Disorders, Vol. 7 , N o . I , 1992
40
H . MEIERKORD ET AL.
. 70
-m u
KO
-
50
-
40
-
W
?L? 2
0 r(
+ d U 0
.. ..
..
30 -
.. *
..
20 -
10
.
..
I
I
I
1
2
3
FIG. 1. The duration of attacks in each patient. Group 1, nocturnal paroxysmal dystonia; group 2, nocturnal epilepsy; group 3, daytime frontal lobe epilepsy.
attacks arose from NREM sleep and often included vocalisations (Table 2). The character and distribution of ictal motor features identified during video telemetry showed considerable overlap between the groups. Dystonic posturing was the commonest type of ictal motor activity, while choreic, ballistic, myoclonic, tonic, or clonic activities were relatively rare. In most patients the ictal dyskinesias involved all four limbs to some extent (Table 3). In addition, review of the attacks recorded by telemetry failed to reveal any qualitative features that were unique to the nocturnal paroxysmal dystonia group. DISCUSSION
In their initial report of nocturnal paroxysmal dystonia, Lugaresi et al. (1) described five cases TABLE 3 . The ictal clinical features of attacks seen on video telemetry Nocturnal paroxysmal dystonia Dystonia 3 or 4 limbs 1 or 2 limbs axial Other dyskinesia
Nocturnal epilepsy
119 1 I9 519 519'
One myoclonic, one choreic, three ballistic. One chorea, one myoclonus, one clonic. One myoclonic, two ballistic, two tonic.
Movement Disorders, Vol. 7,No. 1 , 1992
Daytime frontal seizures 418 118
618 218 218
618
3iab
518'
that did not have evidence of epilepsy. In a subsequent series ( 2 ) , the majority of the cases (eight of 12) had either clinical or EEG evidence for additional epilepsy. Other reports highlight the difficulty of distinguishing nocturnal paroxysmal dystonia from epilepsy. The case of Rajna et al. (3) had tonic nocturnal seizures, and depth recordings revealed epileptiform abnormalities in the cingulate gyms. Godbout et al. (4) reported a case with frequent nocturnal attacks consisting of pronounced vocalisations and violent limb movements lasting less than a minute. The attacks started and stopped abruptly and there was no postictal confusion, but this patient had amnesia for the event and developed bizarre daytime attacks with repetitive complex automatisms. However, evidence for epilepsy is lacking in the three members of a family with nocturnal episodes consisting of tonic postures and laboured respiration reported by Lee et al. (5). Most of the reported cases had brief motor attacks, although Lugaresi et al. (2) suggested that occasional patients may have attacks lasting for many minutes. It remains to be established whether or not such long-lasting attacks form a truly separate entity. Motor involvement is a prominent feature of most frontal lobe epilepsies and may take dystonic, choreic, or ballistic forms as well as being clonic or myoclonic jerks (10-12). The seizures are usually brief, but may occur in clusters merging one into the next. The movements may be similar to the dyskinesias seen in extrapyramidal disease. Indeed, they may indicate participation of the basal ganglia in the motor expression of frontal epilepsy. Frontal lobe regions have intimate connections to the basal ganglia (13-20), and propagation of seizure activity from cortex to basal ganglia may occur in both human and experimental epilepsy (13). The clinical and ictal motor features did not allow a distinction between the three groups in this study (nocturnal paroxysmal dystonia, nocturnal epilepsy, and daytime frontal epilepsy). This leads us to question the existence of a separate syndrome of nocturnal paroxysmal dystonia and to postulate that these cases are examples of epilepsy, presumably of frontal lobe origin in which EEG abnormalities were not evident on the scalp. Many frontal regions that are capable of producing seizures are inaccessible to surface EEG recording (21). It may well be that paroxysmal nocturnal dystonia is an example of frontal lobe epilepsy arising from such hidden foci and careful screening for frontal lobe pathologic conditions is essential in patients with such noc-
41
I S NOCTURNAL D YSTONIA EPILEPSY?
turnal attacks. Wake and sleep scalp EEGs should be performed, with additional electrodes to increase frontal lobe sampling (e.g., supraorbital channels), and care should be taken to identify and differentiate central spikes from vertex sharp waves of sleep. Neuroimaging should include MRI scanning with particular reference to frontal lobe structures. In view of the earlier reports of a favourable response to antiepileptic medication, particularly carbamazepine, and the likely epileptic nature of the attacks, a trial of such therapy may be indicated in these patients. Acknowledgment:This work was supported by the Sir Jules Thorn Charitable Trust.
at 07: 19:32. Her left arm falls down over the edge of the bed and the right arm elevates and stiffens (in this attack partially hidden by the blankets). The right upper limb posturing is maintained for several seconds. When the right arm falls, dystonic posturing is seen in the right hand. She breathes deeply, whines, and the attack ends. Case 5: Nocturnal epilepsy with bilateral upper limb dystonia (recorded during a daytime nap). A 24-year-old woman has had nocturnal attacks since the age of 10 years. Interictal electroencephalography showed large-amplitude sharp waves maximum in the left central region. The patient awakens and the attack commences at 16:16:16 with bilateral upper limb dystonic posturing. The attack ends abruptly at 16:16:35.
LEGENDS TO VIDEOTAPE Case 1: Nocturnal paroxysmal dystonia with involvement of all four limbs. The 60-year-old woman has had nocturnal attacks since the age of 2 years. At 02:05:40 she awakens. The attack commences at 02:06:13 with jerky dystonic movements of all four limbs, altered respiration, and grimacing. The attack ends abruptly at 02:07:30 and she sits up on the bed. Case 2: Nocturnal paroxysmal dystonia affecting the left leg. A 24-year-old man has had nocturnal attacks since the age of 14 years. The onset of the attack awakens the patient at 21:29:04. There is stiffening of the left leg with flexion at the knee. He grunts and grimaces as if in pain. He cries out for help and swears. He sighs, and the attack ends at about 21:29:30. Case 3: Nocturnal paroxysmal dystonia showing ballism. A 32-year-old man has had nocturnal attacks since the age of 27 years. The patient awakens at 03:40:50 and the attack commences 7 s later with ballistic movements. The attack ends at 03:41:15, and the patient responds to the nurse. This patient was subsequently treated with highdose slow-release carbamazepine and became free of attacks. Case 4: Nocturnal epilepsy with dystonic posturing particularly evident in the upper limbs. A 24year-old woman has had nocturnal attacks since the age of 6 years. Sometimes these progressed to a generalised convulsion. She had a mild left-sided hemiparesis, and postictally this was worse. The patient awakens and the attack commences
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