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| Year : 2000 | Volume
: 48
| Issue : 1 | Page : 29-32 |
Usefulness of short term video-EEG monitoring in children with frequent intractable episodes.
Srikumar G, Bhatia M, Jain S, Maheshwari MC
Department of Neurology, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, 110029, India.
Correspondence Address:
Department of Neurology, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, 110029, India.
A prospective study was done to evaluate the role of short-term Video EEG (VEEG) recording in assessing the nature of clinical behaviour and in classification of seizures in children with frequent intractable seizure episodes. Forty five children upto 12 years of age with frequent intractable seizure episodes (> or =3/week) were included in the study. VEEG was done on an outpatient basis until an event was recorded or for a minimum period of 6 hours. The events were detected in 78% of cases. The seizures were classified in all children with recorded events and seizure classification was changed in 22%. Anti-epileptic drugs could be stopped or reduced in 11%. Short term VEEG monitoring was useful in characterising events and in classification of seizures in children with frequent, intractable seizure episodes. Use of this investigation as a screening procedure for diagnosis in children with frequent episodes is stressed, thereby reducing the cost associated with prolonged VEEG recordings and disability associated with misdiagnosis of epilepsy.
How to cite this article:
Srikumar G, Bhatia M, Jain S, Maheshwari M C. Usefulness of short term video-EEG monitoring in children with frequent intractable episodes. Neurol India 2000;48:29-32 |
How to cite this URL:
Srikumar G, Bhatia M, Jain S, Maheshwari M C. Usefulness of short term video-EEG monitoring in children with frequent intractable episodes. Neurol India [serial online] 2000 [cited 2023 Nov 29];48:29-32. Available from: https://www.neurologyindia.com/text.asp?2000/48/1/29/1479 |
Children with frequent seizures refractory to medical treatment constitute a special group. About 20% of these children may be having non-epileptic seizures (NES).[1] Recognition of these events is important as this can result in stopping unnecessary anti-epileptic treatment in these patients.[2] When NES occur along with epileptic seizures (ES), NES may inflate the seizure frequency and the physician may increase the dose or the number of anti-convulsants.[3] VEEG recording has become an established method for characterising the nature of events and for classification of seizures in children.[4] It helps in correlating clinical behaviour with EEG events,[5],[6] recognising pseudoseizures,[1],[2],[3] in seizure classification[5],[6] and is an essential work-up prior to epilepsy surgery.[7] While a number of studies have documented the usefulness of prolonged VEEG monitoring,[5],[6],[8] only a few studies have assessed the value of short-term VEEG recording in characterising events and seizure classification.[2],[9],[10] Short-term VEEG recording is economical and cost-effective since it does not require hospital admission and can reduce the cost of night time recording. This is especially important in developing countries like India, where the cost effectiveness of any investigative procedure is of particular concern.
This prospective study was aimed to assess the usefulness of short-term VEEG recording (upto 6 hours), in characterising the nature of clinical events and classification of the seizure disorder in children with intractable frequent seizure episodes (> 3/week).
All children less than 12 yrs, with intractable and frequent seizures (atleast 3 seizure episodes/week), who were referred to the neuro-electrophysiology services of the All India Institute of Medical Sciences, New Delhi, from June'95 to November'96, for VEEG were included in the study. The indications for VEEG recording were determining the nature of clinical events and seizure classification. A detailed history was obtained from each patient and the parents, including perinatal, development and family history. A complete neurological examination was done in each patient. Sedation was given to children who were not co-operative.
Routine l6 channel EEG recording was performed using the 10-20 International system. CT scan and MRI scan of the head were taken whenever clinically indicated. Metabolic screening was done in selected patients. VEEG monitoring was done using BMSI 4000 equipment. Seizure button was available to the patient or attendant to signal the occurrence of an event. One resident and one EEG technologist were always present during the recording. The record time ranged from 3-6 hours. The VEEG recording was done until an event occurred or until 6 hours. A patient or close relative was present during the recording and informed the resident if the events recorded were typical or not. The VEEG data were reviewed on a video-cassette recorder by a neurologist who had experience in analysing them. The seizures were identified, attempt was made to characterise them and the EEG correlate determined. The aim was to record atleast one event and determine by verification with the attendant that it was identical to the events described. However, as this group had high seizure frequency, > 2 events were recorded in 70%.
Electrical seizure was defined as a well-defined change in the EEG pattern with a clear onset and offset, showing evolution in amplitude frequency and morphology.[9] The following patterns were classified as electrical seizures.[9]
Electodecremental pattern with abrupt attenuation of ongoing electrical activity. Alteration of background with super-imposed fast activity (10-20 Hz). Attenuation of background with rhythmic slow activity. Generalized slow spikes and waves complexes followed by attenuation and / or suppression or superimposed activity. Focal or generalised recruiting rhythm, in the alpha or theta or beta frequency.
Seizures were classified according to the International classification.[11] Pseudoseizures or NES were defined according to the criterial laid down by Meierkord et al.[12] Simple partial seizues and psychic seizures, where ictal correlates may not be seen, were labelled as inconclusive.
Forty five patients were included in the study with a mean age of 7.9 ± 2.2 yrs (range 3-11 yrs). The mean duration of the disease was 2.7 ± 1.2 yrs. Sixty percent had more than one seizure / day. Eight children had delay in their motor or social milestones. Three children in this group had definite history of birth asphyxia. The inter-ictal EEG abnormalities included generalized slowing and spike and wave discharges in 12, focal slowing and spike and wave discharges in 8 and multifocal spike and wave discharges in 3 cases. Twenty two patients had normal inter-ictal EEG. CT scan was done in 32 patients and was found abnormal in 9. MRI brain was done in 9 children and was abnormal in 6. MRI detected abnormalities in 2 patients, in whom CT did not show any lesion (right frontal hamartoma in one and left parietal lobe gliosis in another).
Seven cases were referred to determine the nature of clinical behaviour, and 38 for seizure classification. Mean duration of the VEEG recording was 4.6 hours (range 3-6 hours). Thirty five patients (78%) had clinical events. Out of the seven cases referred as NES, five had spontaneous events and in the remaining two these were induced. In the other group, events were recorded in 28 out of 38 cases (74%). 21 patients were referred as complex partial seizures (CPS). The events were recorded in 16 cases, of which 10 were diagnosed to have NES. All events recorded were typical and known to be associated with EEG correlates. The relationship between clinical classification of seizures and classification of seizures after VEEG is given in [Table I]. AEDs were stopped in 5 of these 10 patients with no further seizure episodes. All 4 children referred with absence seizures had events with EEG correlates. It was possible to confirm the clinical diagnosis in all patients with absences and NES with the help of VEEG.
In the present study, short-term VEEG recorded an event in 78% of 45 children. 17 children (38%) had NES and 18 children (40%) ES. Seizures could be classified in 18 patients, which closely correlated with the clinical classification. Short-term VEEG altered the clinical diagnosis in 10 children (22%), who were referred for VEEG with a diagnosis of CPS. The antiepileptic drugs could be discontinued in five of them; and in the remaining 5, the drugs are being tapered off.
The rate of detection of events in this study is similar to the other studies of short-term VEEG recording.[9],[10] Connolly et al studied 43 children with intractable daily seizures using VEEG recording of 2-3 hours duration.[9] Event detection rate was 83% as compared to 77% in our series. However a classification was possible only in 60%. Rowan et al[10] studied day time monitoring for 6-8 hours, events were recorded in 55% of all patients and in 74% of patients who had daily episodes. Recordings of patients with known absences were successful in 83% and with known CPS in 38%.
The factors which influence success rate in VEEG recordings are the duration of recording, seizure frequency, and seizure type.[12] Clinical experience suggests that seizures often occur in clusters, in nonrandom distribution. The likelihood of recording a seizure does not necessarily increase with recording time. The point of diminishing returns appears to be reached by 24 hours, possibly by 8 hours.[12] Seizure frequency is another factor which can influence success rate of VEEG recording. A seizure frequency of 3-4/week corresponds to a 50% chance of recording an event.[12] The higher yield of events in short term recordings, including in our series, could be due to the inclusion of patients with frequent seizures. Seizure type also affects the success rate of VEEG recording. Absences, NES and CPS tend to be more frequent and hence have a higher event rate as compared to grand mal seizures. In our series, even though the number of patients in each group was small, we could record events in all patients with absences and NES. However, in diagnosing NES it is essential to confirm that the event identified was typical as sometimes atypical events may occur during the recording which can lead to a wrong diagnosis and subsequent sequelae. In case of any doubt, long term recordings with tapering off the anti-epileptic drugs is recommended to confirm the diagnosis, before discontinuing anticonvulsants.
In conclusion, short-term VEEG is a useful method for investigating children with epilepsy /NES who have frequent episodes. It is particularly helpful in confirming diagnosis of non-epileptic seizures in patients where clinical differentiation between complex partial seizures and NES is difficult. In the developing world where cost-effectiveness of any procedure is of utmost importance, short-term VEEG appears to be an ideal out-patient screening procedure for the diagnosis and classification of frequent (atleast 3/week) seizure episodes in children.
| 1. | Holmes GL, Sackellares JC, McKiernan J et al: Evaluation of childhood pseudoseizures using EEG telemetry and video tape monitoring. J Pediatrics 1980; 97: 554-558.  |
| 2. | Bhatia M, Jain S, Maheshwari MC: Video EEG monitoring in intractable attacks of uncertain aetiology. J Assoc Physi India 1996; 44: 393-394. |
| 3. | Devinsky O, Sanchez - Villasenor F, Vasques B et al: Clinical profile of patients with epileptic and non-epileptic seizures. Neurology 1996; 46: 1530-1533. |
| 4. | Mizrahi EM:Electroencephalographic; polygraphic video-9. Connolly MD, Wong PKH, Karim Y et al: Outpatient video monitoring in childhood epilepsy. J Pediatric 1984; 105: EEG monitoring in children. Epilepsia 1994; 35: 477-1-9. 481. |
| 5. | Binnie CD, Rowan AJ, Overweg J et al: Telemetric and 10. Rowan JA, Siegel M, Rosenbaum DH: Daytime intensive video EEG monitoring in epilepsy. Neurology 1981; 31: monitoring: Comparison with prolonged intensive and 298-303. ambulatory monitoring. Neurology 1987; 37: 481-484. |
| 6. | Pierelli F, Chatrian G, Erdly WE et al: Long term EEG-video audio monitoring detection of partial epileptic seizures and psychogenic episodes by 24 hours EEG record review. Epilepsia 1989; 30: 513 -523. |
| 7. | Commission on classification and Terminology of the International League Against Epilepsy. Proposal for revised clinical and electroencephalographic classification of epileptic seizure. Epilepsia 1981; 22: 489-501. |
| 8. | Theodore WH, Porter RJ, Penry JK: Complex partial 12. Meierkord H, Will R, Fish D et al: The clinical features and seizures: clinical characteristics and differential diagnosis. prognosis of pseudoseizures diagnosed using video EEG Neurology 1983; 33: 1115 - 1121. telemetry. Neurology 1991; 41: 1643-1646 |
| 9. | Penry JD, Porter FR, Dreifuss FE: Simultaneous recording of absence seizures with video tape and electroencephalography: a study of 374 seizures in 48 patients. Brain 1975; 98: 427-440. |
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