Introduction
t
has long been recognized that in some individuals a wide variety of external
stimuli can precipitate epileptic seizures. Today these kinds of epilepsies are
known as reflex epilepsies.1,2 Nearly 5% of adult and 10% of pediatric
epilepsies are reflex epilepsies.3
Visual stimuli are the most common triggers of reflex
epilepsies, which induce photosensitive epilepsies.2,4 Epileptic
events have been reported to be induced by watching movies since 1900 and by watching
television (TV) since the 1950,s.5,6 TV epilepsy is known to be the
most frequent type of photosensitive epilepsy.7 Simple visual
stimuli such as light or patterns,8 or complex visual excitations
such as TV programs or video games may trigger visually-provoked seizures in
susceptible subjects.9
Genetic factors are described to play a role in the
incidence of TV epilepsy. In nearly 10% of patients, family history of TV
epilepsy is positive.10
There are many reports on seizures induced by TV
program contents,11–13 however, there are controversies over the
frequency and some characteristics of the disease.14 In a study from
Srilanka the frequency of photosensitive epilepsy has been reported as the
least common among the other kinds of reflex epilepsies,15 and TV
epilepsy was not the most common type of photosensitive epilepsy in contrast to
previous studies. Other studies from India and Srilanka reported that the
frequency of photosensitive epilepsy was lower in these areas than other parts of
the world and genetic factors were thought to be responsible for this
difference.15,16
There are some studies on TV epilepsy in children,17
but there are no reports about TV epilepsy in children from Iran considering
the increasing rate of using TV, video games, and computers specially among
children who are the most frequent population using these devices in recent
years. As a result this survey was designed to study children (<12 years old)
with TV epilepsy and their seizure characteristics in Iran where the flicker
of the raster scan of TV screens is 50 Hz and genetic differences exist in
comparison with the other parts of the world.
Materials and Methods
Patients who were diagnosed as having TV epilepsy with
an age less than 12 years were recruited from outpatient neurology clinics in Isfahan, Iran, from December 2002 through December 2006.
The diagnosis of TV epilepsy was made by a neurologist according to patient's
history of epilepsy triggered by watching TV, electroencephalographic (EEG)
findings, and patient's presentation of photoparoxysmal response (PPR) to
intermittent photic stimulation (IPS).
The standard IPS test was done according to the
protocol of the European expert panel.18 After the patients have
been placed in 30 cm distance from the photic stimulator, separate 10-second
trains of flashes were given for each frequency with intervals of at least seven
seconds between stimulus trains. The eyes were open for the first five seconds
of each train of flashes and closed for another five seconds. Generally the
frequencies of one, two, four, six 10, 12, 14, 16, 18, and 20 flashes/second
and 60, 50, 40, 30, and 25 flashes/second were tried. PPR was defined in accordance with the subclassification of Waltz et al.19
The responses were categorized into focal and generalized spikes. For
each patient age, sex, family history of epilepsy, co-existence of other types
of seizure, EEG findings, and neuroimaging findings were recorded. The seizures
were categorized into different types according to classification and
terminology of International League Against Epilepsy (ILAE) and the epileptic
syndromes were classified according to the revised ILAE classification.20,21
After the confirmation of diagnosis, treatments were
started for the patients based on the neurologist’s decision, and the results
of treatment were recorded. Each patient was followed at least for two years
after initiation of the treatment using serial EEGs with the standardized
protocol of Kasteleijn-Nolst Trenité et al.18 EEG recording was done
with an 18-channel bipolar
and referential recording set according to the international 10 – 20 system.
Results
In our study, of 1705 patients with epilepsy attending
the clinics, 30 (1.76%) patients under 12 years old were diagnosed as having TV
epilepsy. Of them, 17 (56.7%) were females and 13 (43.3%) were males with a
female to male ratio of 1.31:1. The mean age of the children at the time of
diagnosis of seizure was 9.9±2.1 (9.8±2.1 in males, 9.9±2.2 in females) with a
range from six to 12 years.
Only one female patient had a positive family history
of TV epilepsy (3.3% of all the patients). In addition eight patients (26.7%)
had a family history of other kinds of epilepsy including seven females (41.2%
of female patients and 23.3% of all) and one male patient (7.7% of male
patients and 3.3% of all). Types of seizure of the patients are presented in Table
1.
|
Table 1. Types of seizure among the studied
patients.
|
|
Type of seizure
|
Male
|
Female
|
Total
|
|
Generalized
tonic-clonic
|
12
(40%)
|
16
(53.3%)
|
28
(93.3%)
|
|
Absence
|
1(3.3%)
|
-
(0%)
|
1
(3.3%)
|
|
Myoclonic
|
-
(0%)
|
1
(3.3%)
|
1
(3.3%)
|
|
Pure TV epilepsy
|
7
(23.3%)
|
10
(33.3%)
|
17(56.7%)
|
|
TV
epilepsy+other types of generalized seizure
|
6
(20%)
|
7
(23.3%)
|
13
(43.3%)
|
|
TV:
television.
|
|
|
|
Twenty-three patients (76.7%) showed generalized
spikes on their EEG including 13 females (43.3%) and 10 males (33.3%),while
only two males showed focal spikes (6.7%) and five patients (16.7%) had normal
EEG findings without photic stimulation (interictal epileptiform discharges)
including one male (3.3%) and four females (13.3%).
Twenty-seven patients (90%) showed general-ized spikes
on EEG in response to IPSs including 16 females (53.3%) and 11 males (36.7%).
One female and two males (10%) had focal spikes in response to IPSs on their
EEG recordings.
Twenty-nine patients had normal imaging findings
(96.7%), and only one female patient (3.3%) showed generalized brain atrophy on
magnetic resonance imaging (MRI).
Carbamazepine was prescribed for 17 (56.6%) patients
while valproic acid was prescribed for 13 (43.3%) patients alone or in
combination with the other drugs. All the patients were seizure free at most one
year after initiation of treatments. Details of drug administration for these
patients are shown in Table 2.
|
Table 2. Anticonvulsant
medications that were prescribed for the patients.
|
|
Anticonvulsant
medication
|
Number of treated patients
|
|
Carbamazepine
|
13
(43.3%)
|
|
Valproic
acid
|
7(23.3%)
|
|
Phenobarbital
|
2
(6.7%)
|
|
Carbamazepine+valproic
acid
|
2
(6.7%)
|
|
Carbamazepine+phenobarbital
|
2
(6.7%)
|
|
Valproic
acid+ethosuximide
|
1
(3.3%)
|
|
Valproic
acid+lamotrigine
|
3
(10%)
|
Discussion
In our study, TV epilepsy was more
prevalent in females than males (1.31:1) and this is in line with previous
studies on photosensitivity and TV epilepsy, which have reported a female
preponderance of 1.69 to 1.7,22 However, there are some studies that
have reported a male preponderance specially in video-game epilepsy.23,24 These
differences in sex distribution maybe due to genotype and phenotype variability
among different subgroups of visually-induced seizures or may be because boys
play video games more than girls.
Previous studies showed that genetic transmission and
positive family history played an important role in TV epilepsy.10,25,26 In our study, just 3.3% of the patients had a positive
family history of TV epilepsy and 26.7% had a positive family history of any
other kinds of epilepsy.
Previously it was thought that seizures induced by
visual stimuli were almost exclusively generalized,27–29 but
there are studies that have discussed partial seizure as visual stimuli-induced
seizure.30,31 Most of the patients in our study had generalized
tonic-clonic seizure (43.3%), and absence and myoclonic were other types of
seizure (each 3.3%). These findings are in line with previous studies that have reported the most common types of seizures
are generalized tonic-clonic, followed by myoclonic and absence seizures.28,29
The strong association of TV epilepsy with idiopathic
generalized epilepsy has been reported in previous studies as well.32–34 In
our study, 43.3% of the patients had associated epileptic syndromes all with generalized
idiopathic epilepsy and 56.7% of the patients had pure TV epilepsy. This is in
contrast to other reports, in which the frequency of pure TV epilepsy was
reported less than epilepsy associated with other epileptic syndromes (26.1% vs.
73.9%).29
In a recent study, interictal epileptiform discharges
were reported in 83.6%, which were generalized in 74%.34 In our
study, 83.4% of the patients had interictal epileptiform discharges. Of them
76.7% had generalized spikes and 6.7% had focal spikes. In addition, 16.7% had
normal EEG recordings without photic stimulation (interictal epileptiform
discharges).
In previous studies, paroxysmal epileptiform
discharges elicited by standard intermittent photic stimulation were reported
in two-third of patients as generalized spikes and in the remaining as focal
spikes.34 In our study, 90% of the patients had generalized spikes
and 10% had focal spikes in response to IPS on their EEGs and there were no
normal EEG findings during IPS. It can be concluded that children with normal
EEGs can be sensitive just to photic stimulations as previous studies had
shown.35–37 It was interesting that children with normal EEG
findings during interictal period without IPSs were those with pure TV
epilepsy. Other studies had shown that 50% of patients had normal EEG recording
without any photic stimulation.37 But we found lower frequencies and
one may conclude that there is a significant correlation between abnormal EEG
findings and TV epilepsy.
The choice for drug treatment depends on many factors such
as the type of stimulus which triggers patient’s seizures, the environment of
patient's home and office, frequency and severity of seizures, and the type of
epileptic syndrome.38 Sodium valproate is suggested as first choice
drug for children with TV epilepsy in many studies as monotherapy.22,38,39
Different studies have suggested many other drugs as second choices such as clobazam,
carbamazepine, lamotrigine, topiramate, ethosuximide, and levetiracetam. But
there is no consensus on them in different studies.38 We used sodium
valproate, lamotrigine, phenobarbital, carbamazepine, clonazepam, and ethosuximide
alone or in combination with each other, and the response to treatment appeared
to be beneficial in all cases. In our study, carbamazepine successfully
prevented seizures in 43.3% of the patients with TV epilepsy.
The clinical and demographic differences of our
patients compared with other reports are probably due to genetic differences.
In our study, carbamazepine alone or in combination with other drugs has
successfully terminated seizures in 56.6% of the patients. This demonstrates
that carbamazepine can be used in children with TV epilepsy.
References
1
Gowers WR.
Epilepsy and other Chronic Convulsive Disease: their Causes, Symptoms, and Treatment.
2nd ed. New York: Wood; 1901.
2
Bickford
RG, Klass DW. Sensory precipitation and reflex mechanisms. In: Jasper HH, Ward
AA Jr, Pope A, eds. Basic Mechanisms of the Epilepsies. Boston: Little, Brown;
1969: 543 – 573.
3
Parra J,
Kalitzin SN, Iriarte J, Blanes W, Velis DN, Lopes da Silva FH. Gamma-band phase
clustering and photosensitivity: is there an underlying mechanism common to photosensitive
epilepsy and visual perception? Brain. 126; 5: 1164 – 1172.
4
Klass DW, Fischer-Willams
M. Sensory stmulation, sleep, and sleep deprivation. In: Remond A, ed. Handbook
of Electroencephalography and Clinical Neurophysiology. Vol 3(part D). Amsterdam:
Elsevier; 1976: 5 – 73.
5
Kerson TS,
Kerson LA. Implacable images: why epileptiform events continue to be
featured in film and television. Epileptic Disord. 2006; 8: 103 –
113.
6
Livingston
S. Comments on the study of light-induced epilepsy in children. Am J Dis
Child. 1952; 83: 409.
7
Quirk JA,
Fish DR, Smith SJ, Sander JW, Shorvon SD, Allen PJ. First seizure associated
with playing electronic screen games: a community-based study in Great Britain.
Ann Neurol. 1995; 37: 733 – 737.
8
Klass DW. Pattern
activation of seizures. In: Luders HO, Noachtar S, eds. Epileptic Seizures:
Phatophysiology and Clinical Semiology. New York: Cherchill Livingstone; 2000:
598 – 608.
9
Funatsuka M, Fujita M, Shirakawa
S, Oguni H, Osawa M. Study on photo-pattern sensitivity in patients
with electronic screen game-induced seizures (ESGS): effects of spectial
resolution, brightness, and pattern movement. Epilepsia. 2001; 42:
1185 – 1197.
10
Doose H, Gordon
H. On the genetics of EEG anomalies in childhood TV photoconvulsive reaction. Neuropediatric.
1973; 4: 162 – 171.
11
Zifkin BG, Kasteleijn-Nolst
Trenité D. Reflex epilepsy and reflex seizures of the visual system:
a clinical review. Epileptic Disord. 2000; 2: 129 – 136.
12
Harding
GF, Harding PF. Televised material and photosensitive epilepsy. Epilepsia.
1999; 40 (suppl 4):
65 – 69.
13
Binnie CD,
Jaevons PM. Photosensitive epilepsies. In: Roger J, Bureau M, Dravet CH, et al,
eds. Epileptic Syndromes in Infancy, Childhood, and Adolescence. London:
John Libbey; 1992: 299 – 305.
14
Fisher RS,
Harding G, Erba G, Barkley GL, Wilkins A. Epilepsy Foundation of America
Working Group. Photic- and pattern-induced seizures: a review for the Epilepsy
Foundation of America Working Group. Epilepsia. 2005; 46: 1426 – 1441.
15
Senanayake
N. Reflex epilepsies: experience in Sri Lanka. Ceylon Med J. 1994; 39:
67 – 74.
16
Saleem SM,
Thomas M, Maheshwary MC. Incidence of photosensitive epilepsy in unselected
Indian epileptic population. Acta Neurol Scand. 1994; 89: 5 – 8.
17
Stroink H,
Dekker E, Trenité DG. Television, children, and epilepsy. Ned Tijdschr
Geneeskd. 2002; 146: 1065 – 1068.
18
Kasteleijn-Nolst
Trenité D, Binnie CD, Harding GF, Wilkins A. Photic stimulation: standardization
of screening methods. Epilepsia. 1999; 40 (suppl 4):
75 – 79.
19
Waltz S,
Christen HJ, Doose H. The different patterns of the photo-paroxysmal response:
a genetic study. Electroencephalogr Clin Neurophysiol. 1992; 83: 138
– 145.
20
Commission
on classification and terminology of the International League against Epilepsia.
Proposal for revised clinical and electroencephalographic classification of
epileptic seizures. Epilepsia.1981; 22: 489 – 501.
21
Commission
on classification and terminology of the International League against Epilepsia.
Proposal for revised classification of epilepsies and epileptic syndromes. Epilepsia.
1989; 30: 389 – 399.
22
Jeavons PM,
Harding GFA. Photosensitive Epilepsy. London: William Heinmann; 1975.
23
Graf WD,
Chatrian GE, Glass ST, Knauss TA. Video game-related seizures: a report on 10
patients and a review of the literature. Pediatrics. 1994; 93: 551
– 556.
24
Fylan F,
Harding GF, Edson AS, Webb RM. Mechanisms of video-game epilepsy. Epilepsia.
1999; 40 (suppl 4): 28 – 30.
25
Davidson
S, Watson CW. Hereditary light-sensitive epilepsy. Neurology. 1956; 6:
235 – 261.
26
Doose H, Gerken
H, Hein-Voelpel KF, Voelzke E. Genetics of photosensitive epilepsy. Neuropaediatrie.
1969; 1: 56 – 73.
27
Takahashi
T. Photoconvulsive response and disposition. Folia Psychiatr Neurol Jpn.
1976; 30: 349 – 356.
28
Covanis A. Photosensitivity in idiopathic
generalized epilepsies. Epilepsia. 2005; 46
(suppl 9): 67 – 72.
29
Petrukhin
AS, Mukhin KIu, Kolpachki LM, Glyzova KI, Volchenkova MM. Television epilepsy
[in Russian]. Zh Nevrol Psikhiatr Im S S Korsakova. 1997; 97: 13
– 16.
30
Zifkin BG,
Inoue U. Visual reflex seizures induced by complex stimuli. Epilepsia.
2004; 45 (suppl 1): 27 – 29.
31
Hennessy
M, Binnie CD. Photogenic partial seizures. Epilepsia. 2000; 41: 59
– 64.
32
Wolf P, Goosses
R. Relation of photosensitivity to epileptic syndromes. J Neurol Neurosurg
Psychiatry. 1986; 49: 1386 – 1391.
33
Guerrini
R, Genton P. Epileptic syndromes and visually- induced seizures. J Neurol
Neurosurg Psychiatry. 1994; 57: 925 – 931.
34
Radhakrishnan K, St Louis EK,
Johnson JA, McClelland RL, Westmoreland BF, Klass DW. Pattern -sensitive
epilepsy: electroclinical characteristics, natural history, and delineation of
epileptic syndrome. Epilepsia. 2005; 46: 48 – 58.
35
So EL, Ruggles
KH, Ahmann PA, Olson KA. Prognosis of photoparoxysmal response in nonepileptic
patients. Neurology. 1993; 43: 1719 – 1722.
36
Verrotti
A, Basciani F, Trotta D, Cutarella R, Salladini C, Morgese G, et al. Photoparoxysmal
responses in nonepileptic children in long-term follow-up. Acta Neurol Scand. 2002; 105: 400 – 402.
37
Zifkin B, Andermann
F. Epilepsy with reflex seizure. In: Wylie E, ed. The Treatment of Epilepsy:
Principles and Practice. 2nd ed. Baltimore: Williams &Wilkins; 1996: 575
– 557.
38
Covanis A,
Stodieck SR, Wilkins AJ. Treatment of photosensitivity. Epilepsia. 2004;
45 (suppl 1): 40 – 45.
39
Harding
GFS, Herrick CE, Jeavons PM. A controlled trial of sodium valproate on
photosensitive epilepsy and its prognosis. Epilepsia. 1994; 19: 555
– 556.
AIM Home
| Table of Contents
