Epileptic Disorders
MENUPanayiotopoulos syndrome: video‐EEG illustration of a typical seizure Volume 6, numéro 2, June 2004
Auteur(s) : Veysi Demirbilek, Aysin Dervent
Istanbul University, Cerrahpasa Medical Faculty, Department of Neurology, Division of Child Neurology, Istanbul, Turkey
Received July 16, 2003; Accepted December 18, 2003Although the prevalence of Panayiotopoulos syndrome (PS) is reported as 13% in three-six year-old children with seizures [1], some features of this syndrome, such as the infrequency of seizures, their syncope-like characteristics, predominating autonomic phenomena, lack of major motor manifestations, and others, may well lead to misdiagnosis. Initial seizures with recognizable motor manifestations may suggest acute, symptomatic epileptic conditions such as CNS intoxication or encephalitis when long-lasting autonomic symptoms and confusional episodes complicate the picture; these patients may only be evaluated and treated for the acute picture. Motion sickness, which is not a very rare condition, has been a misdiagnosis in our experience when seizures have occurred during or soon after travelling.
The infrequent seizures of this benign syndrome include mainly
autonomic phenomena with nausea, retching and frequently vomiting,
along with unilateral deviation of the eyes. Mild
cardio-respiratory, and gastro-intestinal, as well as pupillary
changes, urination and defecation may occur. Prolonged periods of
alterations in consciousness, more conventional seizure
manifestations and headache may also occur. The duration is
generally long and nearly half of the cases had episodes of
‘autonomic status epilepticus’ as described by Panayiotopoulos in
his comprehensive book on the subject [1]. It has been suggested
that PS be classified as a benign childhood seizure susceptibility
syndrome (BCSSS)’ along with benign rolandic epilepsy’ (BRE) and
febrile seizures [1] instead of ‘early-onset benign ‘childhood
occipital epilepsy’ under idiopathic childhood occipital
epilepsies’ as was cited in the new classification scheme proposed
by the ILAE Task Force [2]. Panayiotopoulos states that seizures in
PS may not be always occipital in origin; the only possible
occipital symptom, that is, the eye-deviation, is not usually the
first clinical event and the ictal EEG may start from the frontal
regions [1]. Accumulation of ictal data may thus contribute not
only to theoretical considerations, but may also serve as practical
purposes for diagnosis and management.
Here, we present video-EEG documentation of a seizure in an
otherwise healthy patient diagnosed as having PS due to his seizure
characteristics and inter-ictal EEG features.
Case report
B.U. is a six year-old boy with normal development. His first
seizure was at three years of age. It took place half an hour after
falling asleep; he opened his eyes, fixed his gaze and was
drooling. He seemed attentive but unresponsive, and started
retching and vomiting. He was soon taken to a hospital. He became
sleepy and hypotonic after IR diazepam, but intermittent staring
and episodes of vomiting lasted around 90 minutes, followed by
four hours of sleep; he then woke up and neurological examination
was normal. He underwent blood and CSF examinations and cranial MRI
with normal results. His EEG the next day, revealed single or
repetitive spike-and-waves with left occipital localization and a
normal background activity. History of a few seizures in four adult
members on the paternal side, one with a single febrile seizure
during smallpox, was present, and they all had ended by five years
of age. No detailed descriptions of these seizures were
available.
B.U’s condition was diagnosed as PS after his first seizure and
has been followed up to the present. He has had six more seizures
since then. One of the later seizures happened during a long
journey by car, after about four hours; another accompanied an
upper respiratory tract infection and high fever. Two of the later
seizures were similar to the initial one, but they were not as
long, about 10-15 minutes; they were all accompanied by
vomiting. The other three seizures included awakening, staring,
deviation of the eyes to the left, followed by clonic jerking of
the left leg. They lasted less than five minutes. All of the
seizures happened during sleep, the last one was during a video-EEG
recording in June 2002, at five years of age. He has been
seizure-free since then and has been taking carbamazepine 200mg
BID, for the last two years. His repeated inter-ictal EEGs revealed
frequent right, infrequent left occipital and parieto-occipital
spike-and-wave discharges enhanced during sleep. Background
activities during waking and NREM were always normal.
The present seizure took place during a routine’ control video-EEG. He had a shorter-than-usual sleep the night before which might have had a precipitating effect. The seizure took place about 10 minutes after the onset of sleep (pre-ictal NREM see figure 1a). It continued for four minutes and ended spontaneously while IR diazepam was just about to be introduced.
As seen in the video, the initial manifestations of the seizure are awakening and staring. A dystonic movement of the right foot is followed by a slow eye-deviation to the left for 30 seconds and was repeated as a down-left deviation (figure 2b) after a short period of apparently normal gaze. A dystonic movement of the right hand is evident at that time. Two episodes of vomiting occur approximately two and three minutes after initial awakening. IR diazepam was given by the end of the 4th minute, but the seizure terminated just before the drug was took effect. The child returned to sleep within a few minutes. There was mild hypotonia on the left side of the body during the seizure. The patient was unresponsive during the seizure.
While asleep, ictal spiking on the EEG started in the right occipital (figure 1b) region nearly four minutes before the awakening and four and a half minutes before the onset of eye-deviation to the left. The onset of the ictal activity appeared as repetitive spikes and sharp-waves of mixed voltage, later transforming to 2 Hz., multiple spike-and-slow waves. More or less regular alternating sequences take place during the seizure activity. Initial ictal changes limited to the right occipital region showed a subsequent propagation to an adjacent posterior temporal area within a few seconds. Involvement of symmetrical regions of the left hemisphere developed about three minutes later in a similar order, at the same time as the right parietal leads (figure 1c).
There was ictal spiking in the right posterior area and slow activity in the same regions of the left hemisphere, at the time when the patient opened his eyes (figure 2a). Although bilateral slowing took place in the EEG, focal spiking was predominant in the right occipital region throughout the seizure. Enhancement of spike-waves was seen in the left occipital region post-ictally (figure 2c), and the background of NREM activity returned to normal immediately after the patient went back to sleep.
The ECG channel revealed an increase in the pulse rate from a pre-ictal average 94 to ictal 108 during sleep, and to 120 beats per minute after eye opening. No irregularity in the pulse occurred during the seizure.
Discussion
Data on the ictal video-EEG of patients may be of use for a
better understanding of the origin and propagation of seizure
discharges in PS. In the literature, three ictal recordings from
the onset of the seizures are reported one of which was a video
EEG. Two of these patients had unilateral occipital seizure onset
in their EEG [3, 4], the third one apparently had a frontal origin
[5]. Sudden awakening, staring, eye-deviation and retching/vomiting
were symptoms common to them and the present case. A unique feature
of our case was the long latency between the onset of EEG and
clinical seizure activity, which was four minutes. The first
symptom of the seizure was apparently related to nausea when the
ictal spikes were still unilateral and restricted to the right
occipito-temporal leads. Slowing in the same regions of the left
hemisphere had already started as the initial clinical symptom,
which was, during awakening. However, ictal spiking was
consistently localized in the right posterior leads during the
whole seizure, including the autonomic manifestations and
apparently no diffuse involvement took place in any sequence.
Although a precise localization of the ictogenic neurons can not
be determined by scalp EEG only, this case may favor an occipital
onset in a seizure with initial clinical symptoms other than
eye-deviation. Clinical onset of the present seizure took place
after a considerable latency following the EEG onset, and after the
abnormal discharges became bilateral. Thus, any subjective
sensation leading to awakening (one of which may be nausea in this
case, since the patient had a slight retching movement before
awakening), might be triggered by the propagation of ictal
discharges to other sites before clinical signs of occipital
involvement were visible. Spread of ictal discharges to lateral
temporal convexity has previously been shown to coincide with ictal
vomiting in a group of patients studied using subdural electrodes
[6].
To summarize, it is suggested that documentation of video EEGs of
seizures in benign epileptic syndromes may provide a better
understanding of the nature of age-related, so-called,
seizure-susceptibility, as it may also enable the positioning of
possible sub-groups within this context. n