FIFTH STEP
What is the etiology of the syndrome?
- Symptomatic - known CNS disorder
- Idiopathic - no known cause
- Cryptogenic - presumed to be symptomatic but no known cause.
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In our experience, symptomatic constitutes 48% and idiopathic 52%. Incidence of symptomatic is higher as compared to figures from developed countries because of perinatal insult and CNS infections which are very common. Other causes of symptomatic epilepsy are tumors, intracranial granuloma, (ICG), A.V. malformations, trauma, vascular strokes, congenital malformations inborn error of metabolism etc. Since the advent of CT scan, ICG are more commonly diagnosed.
To diagnose a syndrome,
1. Thorough history of age of onset, developmental milestones, antenatal, perinatal events, family history of febrile convulsion and epilepsy, precipitating factors, trauma, intracranial infections, history of febrile and neonatal seizures, should be taken.
2. Detailed physical examinations :
CNS disorders :
- Anthropometry
- Size of the head (micro/macro)
- Dysmorphic features
- Congenetal malformations
- Chromosomal disorders
- Skin (Sturge Weber, tuberous sclerosis, neurofibromatosis)
- Intracranial bruit transillumination, cerebral palsy, abnormal movements.
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Non neurological disorders :
- Congenital cyanotic heart disease
- Renal and liver disease
- Hypoglycemia
- Hypertension
- Hypocalcemic states
- Organomegaly - storage diseases
- Eyes, fundus (for cherry red spots and storage disorders)
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History of dreamy states
- Learning disorders
- Attention deficits
- Cognitive impairment due to
*Seizures
*Previous CNS pathology
*AEDs
- Family problems
- School problems (Pseudo seizures)
- Determine IQ and DQ
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Hyperventilation for 3-5 minutes is a very simple bedside test to rule out absence because it precipitates seizures in majority or patients.
Investigations :
- Scalp EEG - is a very important non invasive gold standard in the investigation of epilepsy. First record is positive in 40-50% of cases and with repeated recordings it is positive in a majority. It is a supportive evidence and should always be correlated with the clinical picture.
It helps in classifying seizure types and diagnosis of various syndromes. EEG patterns in children are different from adults and newborn records are different from other older age group children. It requires a lot of experience to interpret children's EEGs. Sometimes the EEG is grossly abnormal without clinical seizures in some children with mental retardation. Such cases should not be treated with AEDs. EEG is also useful in structural lesions which shows focal delta bur neuroimaging is far superior in structural lesions.
Simultaneous video EEG recording is extremely useful in determining type of seizures, classification of syndromes, to rule out pseudoseizures and presurgical evaluation of patients. It can be normal in 2-3% of epilepsy particularly simple partial type.
Intracranial EEG recording is done for those cases which are likely candidates for surgery.
- Skull x-ray - does not help
- Neuroimaging - is very useful to rule out structural causes. MRI has replaced CT scan in epilepsy because focal cortical dysplasia, small angiomas, mesio temporal sclerosis, white matter disorders are better appreciated in MRI. Volumetric MRI is still better than conventional MRI. MRI may not diagnose calcified lesions where CT is indicated. Neuroimaging should be done in cases with focal epilepsy, focal CNS signs, focal EEG abnormality, mental retardation, intractable epilepsy etc.
In our country, intracranial granuloma is so common that neuroimaging is a must in children presenting with focal seizures who are otherwise asymptomatic.
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Radioisotope studies
SPECT studies can be done at few centres in India. Ictal SPECT is more useful than inter ictal. There is hyper metabolism during seizures and hypometabolism during inter ictal period.
PET is not done in India.
Are other investigations indicated routinely?
Skull x-ray, CBC, ESR, urine, LP, elecrolytes, urea, creatinine, serum calciums etc, have a very low yield and conditions are clinically obvious and should be done only when indicated. Various tests for inborn errors of metabolism and work up for mentally retarded children with epilepsy should be done when indicated.
SIXTH STEP
Treatment
After deciding the type of epileptic seizures and syndromes and ruling out pseudoseizures, the patient should be started with the first line of drugs e.g. CMZ, VPA, PHT or PB. Monotherapy is the rule and the minimum dose of the drug that is indicated is initiated and slowly increased till seizures are controlled. If seizures are not controlled then the drug level is estimated and the dose is increased till the therapeutic level is reached or side effects occur. If there is no control of seizures, a second drug is added and first drug is slowly tapered off. When first line drugs fail to control seizures, add-on drugs like acetozolamide, clonazepam, clobazam, pyriodxine are tried or newer AEDs like VGB, LTG, OTBP etc are added, If epilepsy becomes intractable, ketogenic diet is considered. When everything fails, patients should be referred for pre-surgical evaluation and epilepsy surgery.
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