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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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Is investigation really needed?

What is the most effective method?

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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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Modalities of neuroimaging

Structural Functional

CT f MRI

MRI MRS

MEG

SPECT

PET

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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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HS

Hyperintense signal on T2WI

Atrophy

Loss of internal architecture

FLAIR

T2

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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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Vascular malformations

AVMCavernous angioma

MR has 100% sensitivity

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AVM

-Ischemia from steal phenomenon.-Gliosis and hemosiderin deposition

due to subclinical hemorrhages

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Cavernoma

Popcorn ball appearance with complete hemosiderin rim.

Blooms on GRE.

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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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DTI With Fiber Tractography

Decreased fiber connections

AXIAL T2

AXIAL FT IMAGE

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MR Spectroscopy = Chemical

Choline peak

Lipid peak

TB

Glioma

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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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PET MRI MRI = Anatomy

PET = Function

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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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Integrated Neuro diagnostics

EEG MRI LAB

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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.

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