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July2005 Vol.42 Issue:      2 Table of Contents
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Video-EEG Monitoring for The Diagnosis of Epileptic and Non-epileptic Paroxysmal Events in Children

Hassan Elwanl, Ann Ali Abd Alkader2, Sadek Helmy1Ibtesam Fahmy1, Mona Mohammad Nada2, Dalia Labib1, Mona T. El-Ghoneimy3
Departments of Neurology1, Clinical Neurophysiology2, Neurosurgery3 , Cairo University

ABSTRACT

Purpose: This study aimed to establish, a proper diagnosis of the type of paroxysmal disorders, and to assess the value of short term video. EG monitoring in differentiating epileptic from non-epileptic events. Subjects: 36 children were studied, age ranged from 3 months to 15 years. According to the main clinical complaint, they were divided into: epileptic (group I, n=26) and non-epileptic (group II, n=10) groups. Results: Clinical events were observed in 14/26 patients of group I and 7/10 patients of group II. In group I, epileptic seizures were confirmed in 4/9 (44.4%) patients and reclassified in 5/9 (55.6%) patients. 5 patients presented with non-epileptic events and 12 patients did not present clinical events during monitoring. In group II; non-epileptic events were confirmed in 6/7 (85.7%) patients. 1 patient presented epileptic seizures and 3 patients did not present clinical events during monitoring. Video-EEG monitoring enabled major modification of therapeutic approach in 5 patients. Conclusion: In children with paroxysmal disorders, short term video-EEG monitoring allows proper classification of epileptic syndromes and diagnosis of non-epileptic events, promoting introduction of appropriate treatment with a relatively low cost.

(Egypt J. Neurol. Psychiat. Neurosurg., 2005, 42(2): 475-483).

 




INTRODUCTION

 

Human beings have been aware of the presence of epilepsy for at least 2500 years, references from Egyptian Babylonian and Greek have identified this illness reliably.1

The range of clinical events suspected of being seizures in pediatric population is quite different from those in adult. Also in childhood, it is age specific. Betts and Boden2, defined non-epileptic seizures (NES) as a sudden disruptive change in a person's behaviour, which has a clinical symptomatology that may resemble an epileptic seizure. It does not have the characteristic electrophysiological changes in the brain detected by electroencephalogram (EEG), which accompany true epileptic seizures, NES present as "convulsive" and "non-convulsive" events. Patients with NES had 85% non-convulsive event.3 The overall incidence of childhood epilepsy from birth to 16 years is approximately 40 in 100.000 children per year.4,5 NES are commonly encountered in pediatric neurology clinics; up to 25% of children referred to pediatric neurologist have NES.6

It is difficult to reach a precise diagnosis in many cases of seizures or seizure-like episodes. In others, the inclusion into a certain epileptic syndrome is difficult. In these cases, the direct observation of the episodes is necessary and this can be achieved with the available video-EEG monitoring.7,8 Long duration synchronized video-EEG is essentially done both whilst awake and sleep when there is doubt as to whether the motor disorders are of cerebral origin or not.9 Use of this investigation as a screening procedure for diagnosis in children with frequent episodes is stressed as it is expensive, thereby short term monitoring reduces the cost associated with prolonged video-EEG recordings and disability associated with misdiagnosis of epilepsy on routine EEG10 and making the introduction of appropriate treatment possible.11 Most authors in literature described short term video-EEG monitoring as less than 12 hour.12,13,14 Recently it was described as less than 24 hours.15

 

PATIENTS AND METHODS

 

The study was carried out between June 2003 and February 2004. 36 children with paroxysmal events were selected from Kasr El-Aini epilepsy out patients clinic. They were 21 males and 15 females with age range from 3 months to 15 years.

According to their clinical diagnosis, they were divided into epileptic group and non-epileptic group. The epileptic group included 26 children (9 females and 17 males) with age range between 3 months and 15 years, the non-epileptic group included 10 children (6 females and 4 males) with age range between 10 months and 15 years.

 

Methods:

A detailed clinical history was taken from the patients and their parents, with special stress on family history prenatal, natal and postnatal history, developmental milestones, age of onset of symptoms, frequency, associated symptoms and signs, and the treatment.

A general and neurological examination was carried out to all patients, intelligence quotient (IQ) testing was performed in Kasr El-Aini psychiatry out-patient clinic.

 

Electrophysiological evaluation:

A day time short term video-EEG monitoring was performed for 2-6 hours (mean 3.7 hrs) depending on the number of events, without any reduction of the AEDs. If no spontaneous events occurred, provocation (in the form of sleep deprivation) was carried out. Infants were given oral chloral hydrate before starting the recording.

The apparatus used was Dantec paperless EEG equipment, version 5.1, a Panasonic video and a digital video-camera so as to record the EEG signals and the patient's clinical picture simultaneously and both being time-locked.

EEG electrodes were placed according to the 10-20 system using an electrogel cap. Recording parameters were:

Time constant: 0.3 sec                         Speed: 3.0 cm/sec

Filter: 75 Hz                           Gain: 70 µv/cm

 

The parameters could be changed during the display in order to minimize movement and other artifacts, so as to be able to interpret the EEG correctly. EEG abnormalities were coded as follows:

1.             Focal epileptiform discharges.

2.             Multifocal epileptiform discharges.

3.             Generalized epileptiform discharges.

4.             Background disturbance.

 

The EEG results were reviewed for clinical correlation and the international League Against Epilepsy (ILAB) diagnostic criteria were used for the diagnosis of epileptic syndromes.

 

Laboratory evaluation:

Were carried out in the chemical pathology unit of Kasr EL-Aini hospital. They include: liver function tests, kidney function tests, random blood sugar, electrolytes including Na+, K+, Ca+ and Mg++, to exclude metabolic causes of seizures.

 

Magnetic resonance imaging (MRI):

MRI studies of the brain were performed for the definition of symptomatic, cryptogenic and idiopathic epilepsy.

 

RESULTS

 

The study included 36 children, 15 females and 21 males, the age ranged from 3 months to 15 years (mean = 7.4 yrs ± 5.5 SD). They were divided clinically into two groups (age and sex matched):

-     Group I: non-epileptic (including 10 children).

-     Group II: epileptic (including 26 children).

 

Positive family history of epilepsy was found in 5 children (13.9%), a mother of one child (2.8%) had a prenatal history of vaginal bleeding, mothers of 5 children (13.9%) had a history of obstructed labour and 2 children (5.6%) had a history of postnatal jaundice and febrile convulsions. There was no statistical significant difference between the two groups. The type of epileptic and non- epileptic events among groups under study is shown in Table (1).

20 children (76.9%) of the epileptic group were receiving anti epileptic treatment either monotherapy or polytherapy. 12 children (46.2%) were on monotherapy and 8 children (30.7%) were on polytherapy.

Neurological examination was abnormal in only one child of the epileptic group (3.9%) in the form of increased deep reflexes and positive planter reflex over the right side of the body. The laboratory investigations were normal in all patients (100%).

 

MRI results:

8 children (22.2%) had detectable abnormalities in MRI brain, these are shown in table (2).

 

 

 

Video-EEG monitoring results:

The recording lasted 2-6 hours (mean 3.7 hours), clinical events were recorded in 21 of 36 children (58.3%) others were suggested to do long term video-EEG monitoring.

Among 26 children diagnosed as epileptic: 14 children had recorded events. Among them, 6 had epileptiform ictal discharges and 8 had no ictal EEG changes.

Among the 8 children who had no epileptiform ictal EEG changes: in 3 children, the diagnosis of epilepsy was not changed because they had typical epileptic clinical events and postictal EEG slowing inspite of absence of epileptiform ictal discharges. In the other 5 children the diagnosis was changed from epileptic to non-epileptic paroxysmal events.

Hence, among the epileptic group, diagnosis of epilepsy was confirmed in 9 (64.3%) out of 14 children who had recorded events, with confirming seizures classification in 5 children (Table 3).

Among the non-epileptic group, diagnosis of non-epileptic events was confirmed in 6 (85.7%) out of 7 children who had recorded events. In one child (14.3%) the diagnosis was changed from non-epileptic to epileptic paroxysmal events, as shown in table (4).


Table 1. Showing the type of epileptic and non-epileptic events among groups under study.

 

Items

Epileptic (n=26)

 

Non-epileptic (n=10)

No

%

No

%

Simple partial seizures

5

(19.3%)

Movement disorders

5

(50%)

complex partial seizure

3

(11.5%)

Sleep disorder

2

(20%)

with 2ry generalization

3

(11.5%)

Syncope

1

(10%)

 

 

 

Pseudoseizures

2

(20%)

GTCs

9

(34.6%)

 

 

 

myoclonic jerks

1

(3.9%)

 

 

 

absence

2

(7.7%)

 

 

 

combination

3

(11.5)

 

 

 

 

Table 2. MRI results among groups under study .

 

Item

Epileptic

(n=26)

Nonepileptic

(n=1 0)

Total

(n=36)

U

P

No

%

No

%

No

%

Abnormal MRI

6

23.1

2

20

8

22.2

0.9

> 0.05

NS

Normal MRI

20

76.9

8

80

28

77.8

 

Table 3. Comparison between clinical diagnosis before and after VEEG recording among epileptic group under study.

 

Items

Diagnosis before

VEEG

Diagnosis after

VEEG

Epileptic

diagnosis

Syndromic

classification

Case (1)

Epileptic (GTCs)

Epileptic

Confirmed

Focal onset with

2ry generalization

Case (2)

Epileptic (complex

partial seizure with

2ry generalization)

Epileptic

Confirmed

Herpetic encephalitis with symptomatic generalized epilepsy

Case (3)

Epileptic (GTCs)

Epileptic

Confirmed

Symptomatic generalized

epilepsy

Case (4)

Epileptic (simple

partial seizure)

Non-epileptic

Changed

Nocturnal paroxysmal

arousals with motor-behaviors

Case (5)

Epileptic (complex

partial seizure)

Epileptic

Confirmed

Complex partial

seizure

Case (6)

Epileptic (simple

partial seizure)

Epileptic

Confirmed

Complex partial

seizure

Case (7)

Epileptic (complex

partial seizure)

Non- epileptic

Changed

Nocturnal paroxysmal

arousals with motor behaviors

Case (8)

Epileptic (absence)

Epileptic

Confirmed

Childhood absence epilepsy

Case (9)

Epileptic (generalized

epilepsies)

Epileptic

Confirmed

Lennox Gastaut

syndrome

Case (10)

Epileptic (generalized

epilepsies)

Epileptic

Confirmed

Lennox Gastaut

syndrome

Case (11)

Epileptic (simple

partial seizure)

Non- epileptic

Changed

Generalized dystonia

Case (12)

Epileptic (complex

partial seizure)

Non- epileptic

Confirmed

Juvenile absence

epilepsy

Case (13)

Epileptic (simple

partial seizure)

Non- epileptic

Changed

Nocturnal paroxysmal

arousals with motor behaviors

Case (14)

Epileptic (simple

partial seizure)

Non- epileptic

Changed

Nocturnal paroxysmal

arousals with motor behaviors

Table 4. Comparison between clinical diagnosis before and after VEEG recording among non-epileptic group under study.

 

Item

Diagnosis before

VEEG

Diagnosis after

VEEG

Non-epileptic

diagnosis

Case (1)

Non-epileptic (sleep terror)

Non-epileptic

Confirmed

Case (2)

Non-epileptic (pseudoseizures)

Non-epileptic

Confirmed

Case (3)

Non-epileptic (tremors)

Non-epileptic

Confirmed

Case (4)

Non-epileptic (pseudoseizures)

Epileptic (Juvenile myoclonic epilepsy)

Confirmed

Case (5)

Non-epileptic (tremors)

Non-epileptic

Confirmed

Case (6)

Non-epileptic (Tics)

Non-epileptic

Confirmed

Case (7)

Non-epileptic (Syncope)

Non-epileptic

Confirmed

 

 

 

 

Fig. (1): Right hemispherical spike and were discharges, ictal changes of case 2 of the epileptic group.

 

 

Fig. (2): Paroxysm of subcortical spike and wave, ictal changes of cases 4 of the non epileptic group.

 

 


DISCUSSION

 

Differentiating epileptic from non-epileptic events is frequently challenging in children manifesting repetitive, stereotypic behaviour. An incorrect diagnosis of epilepsy was made in about 20-30% of children having episodes of abnormal behaviours.16 Routine EEG interpretation is complicated by nonspecific findings which may occur in 15% of asymptomatic children. Continuous EEG monitoring techniques offer an attempt to resolve some routine EEG inadequacies.17

Short term outpatient video EEG monitoring had a relatively good  rate of event detection-especially in patients with frequent seizures- compared with other studies with longer durations of video EEG monitoring.15,18 There is little published data on the diagnostic value of short duration outpatients video EEG monitoring (less than 12 hours) in children. There are also variations regarding studied populations and the type of complaint, consequently, estimated event detection rate differs greatly from one study to another (55-83%).12,18,19

In our study, patients were evaluated to differentiate epileptic from non-epileptic events. Patients proved to be epileptic were evaluated for a better definition of their seizure type. Similar studies and categorization were done by Folly et al.14, Freitas et al.15 and Valente et al.18. As in Valente et al., mothers were present during the recording sessions to recognize and confirm that recorded events were similar to those presented at home. 15

Our video EEG monitoring was done as a daytime procedure (mean = 3.7 hours), clinical events were recorded in 21 of 36 children (58.3%). In agreement with previous reports, lower rates of detection seem to occur mostly in studies with shorter duration.12,20 On the contrary, in another study, a higher event detection rate (83%) was reported during 2-3 hours outpatient video EEG monitoring in 43 children with frequent seizures and this might be attributed to the higher frequency rate of their clinical events.21

Our study showed that short term video EEG monitoring was well tolerated by children especially in school age (5-12 years). Infants and toddlers (in whom events were not captured) were suggested to do long term video EEG monitoring to record and diagnose the type of the paroxysmal events.

Although video EEG monitoring with concomitant drug reduction or withdrawal may potentially increase diagnostic yield, these solutions were not recommended in our study as well as other studies, as the patient may develop status epilepticus if they had truly epileptic events.18,22

In our study, the preliminary diagnosis as epileptic or non-epileptic events was confirmed in 15/21 children (71.4%) and the diagnosis was changed in 6/12 children (28.6%). In our epileptic group, paroxysmal events were confirmed as epileptic in 9 out of 14 patients (64.3%).

It is also striking that the diagnosis of epilepsy was wrong in 5 patients out of 14 (35.7%) of our epileptic group. In those 5 wrongly treated patients, we recommended the gradual withdrawal of antiepileptic drugs (AED) similar results were obtained by Paolicchi23.

We recorded one patient, case no. (2) of the epileptic group, aged 18 months presented with fever, drowsiness, and recurrent attacks of sudden onset of jerky movements of right upper limb followed by both lower limbs with deviation of both eyes to the right side without urination or frothy secretion. This patient was diagnosed as encephalitis. The evidence of diffuse delta waves (1-2 C/S- and poor sleep spindles, as well as the evidence of an ictal right hemispherical brief spikes and wave discharges that accompany the brief synchronous myoclonic jerks, was diagnostic of herpes simplex encephalitis (Fig. 1)

Two of our patients with refractory seizures (cases no.5,6) of the epileptic group had been diagnosed as partial seizures (Frontal lobe epilepsy and temporal lobe epilepsy) on video-EEG monitoring, inspite of absence of recorded ictal discharges. As extracranial or scalp EEG may not record potentially epileptiform discharges in patients with sequestered areas of epileptogenesis (e.g. amygdala and mesial frontal lobe).24 Also the absence of extra-cranial EEG changes may occur in patients with auras or simple partial seizures.

Also one of our patients, case no. (12) of the epileptic group, had a history of generalized tonic-clonic seizures with age of onset at 14 years. There was a normal EEG background activity with the emergence of 2.5 to 3.5 c/sec generalized spike and wave discharges. Hence, the type of epileptic seizure was reclassified after short term video-EEG from complex partial seizures to juvenile absence epilepsy, also the AEDs were changed according to the final diagnosis.

Case no. (4) of the non-epileptic group was diagnosed as pseudoseizures. After video EEG monitoring, the diagnosis was changed to Juvenile Myoclonic epilepsy (JME). She had a normal interictal EEG backgroup activity with ictal generalized spike and wave discharges that accompany the brief synchronous myoclonic jerks involving upper limbs without loss of consciousness (Fig. 2).17

The present work showed 11 patients (52.4%) out of 21 patients who had recorded non-epileptic events. This goes well with previous studies that demonstrated 12-40% of paroxysmal events being non- epileptic in children admitted for diagnostic video EEG monitoring.26

                In agreement with other studies, we found that the mean duration of non-epileptic seizures was longer than that of epileptic seizure.27

Different sleep disorders recorded by us were nocturnal paroxysmal arousals with motor behaviours in cases (4, 7, 13 & 14) of the epileptic group, and sleep terrors in case no. (1) of the non-epileptic group. The most important differential diagnosis of arousals is nocturnal frontal lobe epilepsy, so long term polysomnographic monitoring was recommended for such cases.

As a conclusion, video EEG monitoring resulted in an alteration of clinical management in 23% of our patients. This finding goes well with

other studies.27,28

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