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Integrated Diagnostics – A Unique Epilepsy Approach
Dr. Rama KrishnanDr. Rama Krishnan
Consultant Radiologist
Medall Health Care Private Limited
Chennai
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Next 20 minutes…
Basic introduction to epilepsy and the burden of disease in society and the need for investigations.
Imaging modalities - MRI
Clinico-radiologic images.
Integrated Neuro diagnostics.
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Seizure & Epilepsy
Seizure - Definite event of altered cerebral function due to excessive and abnormal electrical discharge from brain cells.
Greek word - epilepsia “taking hold of or seizing”
Chronic neurologic disorder
Spontaneous recurrent seizures
First seizure ever 4% of population
Epilepsy 1% of population
Uncontrollable epi 0.4% of population
80% has epileptogenic focuson dedicated MRI
Imaging can be normal
Fever, drugs, dehydration & sleep deprivation
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50 million sufferers in the world today, 85% of whom live in the developing countries
2.4 million new cases each year
50% cases begin in childhood/adolescents
70-80% of people with epilepsy could lead normal lives if properly diagnosed and treated
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Impact to society
Physical hazards due to unpredictability of seizures
Social exclusion because of negative attitudes of others towards epilepsy
20-30 % of people with epilepsy and physically able to work are unemployed
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How is epilepsy treated?
Long term pharmacotherapy - Drugs
Neurosurgery – when removal of epileptogenic focus is possible without unacceptable neurologic deficit
Uncontrollable epi 0.4% of population
80% has epileptogenic focuson dedicated MRI
Lesion resection can lead to seizure freedom in many patients
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Role of neuroimaging
To identify underlying structural abnormalities that require specific treatment
Determine functional areas
To aid in formulating a syndromic or etiologic diagnosis
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CTEmergency settings
(status epilepticus )
Calcification-Sturge -Weber
Useful as a screening tool
SOL and granulomas
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CT – PITFALLS
Sensitivity not more than 30%
Poor resolution in the temporal fossa – not helpful in the diagnosis of MTS
Fails to detect abnormalities upto 50% of patients
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ILAE RECOMMENDATIONS
CT can be the diagnostic imaging of choice in patients with epilepsy if MRI is not available
Patients who have intractable seizures should have an MRI study even if CT is normal
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MRI
Imaging procedure of choice
Identifies and localizes structural abnormalities like MTS
Surgical planning
Covers both anatomic and physiologic aspects
Post-operative imaging
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Epilepsy Protocol MRI(Medall)
1.5 T magnet Axial, coronal and sagittal T1 and T2 weighted images FLAIR Oblique coronal perpendicular to the long axis of hippocampus 3D Isotropic T1 sequence Susceptibility weighted imaging Spectroscopy if needed Contrast if needed
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PATHOLOGIC SUBSTRATES
Hippocampal sclerosisMalformations of cortical
developmentNeoplasmsVascular malformationsGliosis & miscellaneous
abnormalities
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Hippocampal sclerosis
Complex partial seizures – MC cause in adults
Most common entity in pts undergoing surgery
H/o complicated childhood febrile seizures, complicated delivery and developmental process
Surgical removal of visible MRI changes associated with unilateral mesial temporal sclerosis leads to seizure freedom in up to 80% of cases.
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MR Hippocampal Volumetry
Visual analysis – 80-90% accuracy
Volumetric analysis – 90-95%
B/l HS without visually appreciable signal changes
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Epilepsy associated tumors
Ganglioglioma – MC tumor of temporal lobe epilepsy
DNET
Pleomorphic xanthoastrocytoma
Hypothalamic hamartoma
MR has 100% sensitivity
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Ganglioglioma
Cyst with enhancing mural nodule.
Calcification – common – distinguishing factor.
Mural nodule
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AVM
-Ischemia from steal phenomenon.-Gliosis and hemosiderin deposition
due to subclinical hemorrhages
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a b n o r m a l n e u r o n a lp r o l i f e r a t i o n
a b n o r m a l n e u r o n a lm i g r a t i o n
a b n o r m a l n e u r o n a lo r g a n i z a t i o n
d e v e l o p m e n t a la b n o r m a l i t i e s
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Focal cortical dysplasia
Cortical or subcortical hyperintensities
Blurred interface between grey and white matter
Transmantle sign
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HeterotopiaAgyria / pachygyria Lissencephaly
Schizencephaly
Malformations of cortical development
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Gliosis
Focal – trauma, infection, infarction
Diffuse – Rasmussen’s encephalitis, sturge weber syndrome, perinatal insults
Encephalomalacia with Porencephalic cyst
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Tuberous sclerosis
Cortical hamartomasSubependymal tubersSubependymal GCA
White matter abnormalities
Epilepsy, adenoma sebaceum, mental retardation
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Functional MRI (fMRI) Demonstrates alterations in blood oxygenation
Before cranial surgery to map with high accuracy functional areas such as language, motor, and visual cortices
Speech paradigm
Astrocytoma
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Nuclear medicine imaging in epilepsy
Perfusion changes, metabolic changes and neurotransmission abnormalities.
Ictal spect and Inter-ictal PET.
PET lateralizion and localization in cases of non-lesional epilepsy, in cases of multiple lesions visible on MRI and can guide intracranial electrode placement.
Ictal
Inter-ictal
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Lab tests
Metabolic and genetic abnormalities may manifest as seizures without any structural abnormality.
MRI = Normal in early infection.
CBC and the blood chemistry panel.
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Complete blood count
Infections
Allergies
Other abnormalities that may affect the choice of appropriate anticonvulsant drugs
Help monitor the possible drug-induced side effects in the future.
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Chemistry panel
Sodium, potassium, and blood sugar levels.
RFT & LFT = Complete metabolic panel.
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to conclude…
MRI is excellent tool for imaging and for surgical planning.
Integrated neurodiagnostic approach is the most efficient method for evaluating patients with epilepsy.
Recommended