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Volume 24 |
April - June 2008 (Part-II) |
Number 3 |
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Published by : PROFESSIONAL MEDICAL PUBLICATIONS |
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Volume 24 |
April - June 2008 (Part-II) |
Number 3 |
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EEG findings in post stroke seizures:
An observational study
Maimoona Siddiqui1, Urooj Yaqoob2,
Asia Bano3, Abdul Malik4,
Farrukh Shohab Khan5, Khurram Siddiqui6
ABSTRACT
Objective: Stroke is an important cause of epilepsy especially in the elderly. We conducted an observational study in a tertiary referral center to describe different EEG findings in patients who developed seizures after stroke.
Methodology: We reviewed all EEGs that were performed for evaluation of seizures after stroke from January to December 2006 and retrospectively recorded demographic data, side of stroke, type of seizures and EEG findings. All this information was entered on a specially designed proforma.
Results: A total of 41 patients with post stroke seizures had EEG done at our laboratory that were reviewed and analyzed. Of these patients, 51.2% (n=21) were males (mean age 60.7; range 22-84 years) and 48.8% (n=20) were females (mean age 63; range 3-90 years). The commonest seizure semiology was generalized seizure in 56.1% (n=23), focal seizures in 36.6% (n=15) and focal with secondary generalization in 7.3% (n=3) patients.51.2% (n=21) had right hemispheric involvement, 26.8% (n=11) had left hemispheric involvement and in 22% (n=9) patients side of stroke was not identified. The commonest EEG finding was generalized slow waves seen in 39.0% (n=16) patients. Other abnormalities found were focal slowing in 19.5% (n=8), focal sharp and slow waves in 9.8% (n=4), focal spikes & slow waves in 4.9% (n=2), focal sharp waves in 4.9% (n=2) of the patients. Focal spike waves in 2.4% (n=1) and PLEDS were seen in 2.4% (n=1) patients. 17.1% (n=7) patients had normal EEG.
Conclusions: Generalized seizures and generalized slowing on EEG were the commonest findings in our patients who developed seizures after stroke. The commonest epileptiform discharges were focal sharp and slow waves seen in 9.8% of patients with post stroke seizures.
KEYWORDS: Post stroke seizures, EEG, Seizures.
Pak J Med Sci April - June 2008 (Part-II) Vol. 24 No. 3 386-389
How to cite this article:
Siddiqui M, Yaqoob U, Bano A, Malik A, Khan FS, Siddiqui K. EEG findings in post stroke seizures: an observational study. Pak J Med Sci 2008;24(3):386-9.
Authors
1. Maimoona Siddiqui,
2. Urooj Yaqoob,
3. Asia Bano,
4. Abdul Malik,
5. Farrukh Shohab Khan,
6. Khurram Siddiqui,
1-6: Department of Neurology,
Liaquat National Hospital,
Karachi – Pakistan.
Correspondence:
Dr. Maimoona Siddiqui
Department of Neurology,
Liaquat National Hospital,
Karachi – Pakistan.
Email: drmsid@gmail.com
* Received for Publication: November 17, 2007
* Revision Received: February 28, 2008
* 2nd Revision Received: March 26, 2008
* Final Revision Accepted: April 1, 2008
INTRODUCTION
Seizures after stroke have been described more than a century ago by John Hughling Jackson.
1 Even today stroke has been considered as an important cause of epilepsy especially in elderly.2-4 The reported incidence of seizures varies from 2–33%.5,6 From a community based register, patient with a first ever stroke had a 2% risk of having a seizure at stroke onset and an 11% risk of having a later seizure in the first 5 years of follow up. Patients with intracerebral and subarachnoid hemorrhage were at higher risk of seizure after stroke.3,4 Post stroke seizures have been classified according to their temporal relationship with the onset of stroke as immediately after (within 24h), early and late onset. Early onset seizures have been defined as occurring within one week or two week after stroke. Late onset seizures occur one or two weeks after stroke.7 When seizures occur after stroke they greatly increase the morbidity and mortality and further impair an already comprised quality of life. Early-onset seizures have a poor prognosis with a high in-hospital mortality rate.8 EEG can be helpful in identifying seizures type and localization of epileptic focus. Also some patterns of EEG are predictive of patients who can develop late onset seizures. We conducted an observational study in a tertiary referral center to describe different EEG findings in patients who developed seizures after stroke.METHODOLOGY
We reviewed all EEGs that were performed for evaluation of seizures after stroke from January to December 2006 and retrospectively recorded demographic data, side of stroke, type of seizures and EEG findings. All this information was entered on a specially designed proforma. EEG was done using Nicolet and Nihon Khoden digital EEG machines. EEG electrodes were placed according to the International 10-20% system. Activation procedures such as hyperventilation and photic stimulation were done.
RESULTS
A total of 41 patients with post stroke seizures had EEG done at our laboratory were reviewed and analyzed. Of these patients, 51.2% (n=21) were males, 48.8% (n=20) were females. Mean age was 61.8 years. 36.6% (n=15) patients were in awake state, 26.8% (n=11) were drowsy, 17.1% (n=7) were sedated, 4.9% (n=2) were semiconscious, 12.2% (n=5) were unconscious and 2.4% (n=1) was in asleep state. The commonest seizure semiology was generalized seizure in 56.1% (n=23), focal seizure in 36.6% (n=15) and focal with secondary generalization in 7.3% (n=3) patients. 51.2% (n=21) patients had right hemispheric involvement, 26.8% (n=11) had left hemispheric involvement and in 22% (n=9) of the patients, side of stroke was not identified. Table-I.
The commonest EEG finding was generalized slow waves seen in 39.0% (n=16) patients. Other abnormalities found were focal slowing in 19.5% (n=8), focal sharp and slow waves in 9.8% (n=4), focal spikes & slow waves in 4.9% (n=2), focal sharp waves in 4.9% (n=2) of the patients. Focal spike waves in 2.4% (n=1) and PLEDS were seen in 2.4% (n=1) patients. 17.1% (n=7) patients had normal EEG. Fig-1.
DISCUSSION
Despite their frequent occurrence especially in elderly age group, stroke related seizure is a topic that is mostly neglected. The most common seizure pattern seen in our cohort is generalized seizure in 56% followed by focal seizures in 36% of patients which is in contrast to what is reported by other authors.
7-10 Only one study has reported increase incidence of generalized seizures.11 This may be because the relatives do not notice the initial event or it was not properly mentioned in the files. Majority of our patients were elderly with mean age of 61 years similar to other studies.10 More than half of the patients had right hemispheric involvement.The commonest EEG finding was generalized slow waves (39%) while focal slowing was seen in 19%. Focal sharp and slow waves were seen in 9.8%. This is similar to other studies.
12 The EEG findings also correlate with the seizure semiology that generalized seizures were more common in our cohort. Many studies have reported that periodic lateralizing epileptiform discharges were associated with acute stroke and subsequent development of seizures.13 However in our cohort, PLEDS was seen in only one patient, that is similar to what is reported by Dhanuka and et al.14Limitations of the study: There are shortcomings in our study because of its retrospective nature. Further large, prospective, population based studies are needed to answer many questions regarding post stroke seizures that are still unanswered like pathophysiology, epidemiology, risk factors and treatment of post stroke seizures.
CONCLUSIONS
Generalized seizures and generalized slowing on EEG were the commonest findings in our patients who developed seizures after stroke. The commonest epileptiform discharges were focal sharp and slow waves seen in 9.8% of patients with post stroke seizures. Large prospective, observational studies are needed to define prognostic factors for post stroke seizures in specific stroke subtypes.
REFERENCES
1. Jackson JH. Epileptiform convulsions from cerebral disease In: Selected writings of John Hughlings Jackson on Epilepsy and epileptiform convulsions, Taylor J, Homes G, Walshe FMR. (Eds); Hodder and Stoughton Ltd., London, 1931;1:330-40.
2. Sitajayalakshmi S, Mani J, Borgohain R, Mohandas S. Post stroke epilepsy. Neurol India 2002;50 Suppl:S78-84.
3. Olsen TS. Post-stroke epilepsy. Curr Atheroscler Rep 2001;3(4):340-4.
4. John B, Martin D, John B, Peter S, Derick W, Charles W. Epileptic seizures after a first stroke: The Oxfordshire community stroke project. BMJ 1997;315:1582-7.
5. Osvaldo C, Larry BG. Seizures and Epilepsy after Ischemic Stroke. Stroke 2004;35:1769.
6. Myint PK, Staufenberg EFA, Sabanathan K. Post-stroke seizure and post-stroke epilepsy. Postgrad Med J 2006;82:568-72.
7. Kevin MK. Poststroke Seizures and Epilepsy: Clinical Studies and Animal Models. Epilepsy Curr 2002;2(6):173-7.
8. De Reuck JL. Stroke-related seizures and epilepsy. Neurol Neurochir Pol 2007;41(2):144-9.
9. Cheung CM, Tsoi TH, An-Yeung M. Epileptic seizures after stroke in Chinese patients. J Neurol 2003;250:839-43.
10. Lamy C, Domigo V, Semah F. Early and late seizures after cryptogenic ischemic stroke in young adults. Neurology 2003;60:400-4.
11. Arboix A, Comes E, Massons J, Garcia-Eroles L, Massons JB, Oliveres M, et al. Prognostic value of very early seizures for in-hospital mortality in atherothrombotic infarction. Eur Neurol 2003;50:78-84.
12. De Reuck J, Goethals M, Claeys I, Van Maele G, De Clerck M. EEG findings after a cerebral territorial infarct in patients who develop early- and late-onset seizures. Eur Neurol 2006;55(4):209-13.
13. Holmes G. The electroencephalogram as a predictor of seizure following cerebral infarction. Clin Electroencephalogr 1980;11:83-6.
14. Dhanuka AK, Misra UK, Kalita J. Seizures after stroke: A prospective clinical study. Neurol India 2001;49(1): 33-6.
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