Epilepsy AND Electroencephalography (EEG) : NEET PG Medicine
Apr 12, 2023
Epilepsy is a neurological disorder characterized by recurrent seizures, which can have a significant impact on an individual's quality of life. And, electroencephalography (EEG) is the diagnostic test that is commonly used to diagnose and monitor epilepsy. Understanding the clinical features, diagnostic workup, and management of epilepsy and EEG is essential for medical students.
In the NEET PG exam, there are often questions related to epilepsy and EEG, including the clinical features of different types of seizures, the indications and interpretation of EEG, and the management of epilepsy. Therefore, having a good understanding of epilepsy and EEG is crucial for success in the NEET PG exam.
EEG is invented by Hans Berger and it has 10 – 20 lead placement system
Alpha waves: seen when eyes are closed, drowsy, relaxed → 8 – 13 Hz
Beta waves: when person is awake Awake, eyes opened → 13 - 30 Hz
ϒ waves - 30-100 Hz(problem solving)
NREM 1 → Myoclonic jerk may occur.
Theta waves: 4- 7 Hz are seen
NREM 2 → longest phase of NREM
µ waves/ sleep spindles are present
12 - 14 Hz
NREM 3 → deepest phase of sleep/ most difficult to arouse
Delta waves: 0.5 – 4 Hz are seen
Slowest wave pattern
Maximum amplitude, least frequency
REM sleep: Decreased tone of muscles is seen
EEG shows Saw tooth pattern
Abnormal focus in the brain leading to abnormal electrical discharge.
Motor manifestation of the same is called convulsion.
Premonitory symptoms (general unwellness of the patient) are present
later on loss of consciousness, up rolling of the eye balls and during tonus there is ↑ in Tone of muscles & sudden contraction of muscles of expiration of vocal cord occurs, which lead to “Ictal Cry”.
→ Up rolling of eyes
Tonus → Pooling of secretions
(10-20 → Tongue bite +
Seconds) → Perioral cyanosis
→ ↑ HR, ↑ BP
GCSE: Convulsions > 5 min
Violent jerking of all limbs followed by post ictal deficit
Usual duration of both tonus and clonus: < 60 seconds
Postictal deficit - confusion, loss of orientation
Babinski sign is present and corneal reflex is absent in unconscious patients and vice versa at the time of regaining consciousness.
Epilepsy: If > 2 unprovoked seizures episodes are seen it is k/a Epilepsy
IMPORTANT INFORMATION To terminate Convulsion, Lorazepam is given intravenously. In case of failure to obtain intravenous access, rectal diazepam is used.
With intact awareness
Without intact awareness
Non motor (sensory symptom)
Evolution into GTCS
AURA is seen
Non – motor
Non – motor
Aura implies perception of stimulus like bright lights, unpleasant smell of burning rubber
Abnormal electrical activity in left motor cortex is seen
Right hand/face involuntary movements are seen
Jacksonian march: Abnormal movement starts from distal part and progresses to proximal part.
Todd’s palsy: Weakness persisting for hours to days after manifestation of focal seizures
Epilepsia partialis continua: Counterpart of GCSE and manifestation can persist for days & weeks.
Non motor manifestation
Paresthesia / vertigo is seen
Sensation of burning rubber
Micropsia or macropsia
Subjective events that cannot be observed by someone
AURA like bright lights, the smell of burning rubber etc.
Focal seizure without intact awareness
AURA is not a feature of GTCS (generalized tonic clonic seizures). It is a feature of focal seizure
It is a feature of focal seizure with impaired awareness
Uncontrollable laughter/ crying
Progression of focal seizure: AURA → Motionless stare → Automatism
There is presence of
Post ictal confusion
Transient neurological deficit in form of Aphasia
EEG can be normal during interictal period
The above EEG is showing Focal Seizures; possibly origin is from temporal lobe
GENERALIZED ONSET SEIZURES
Typical absence seizures
Transient loss of consciousness for 1-2 seconds
Seen in 4-10 yr child
Postural tone is maintained
Repeated blinking of eye is seen
Post ictal deficit is absent
Aka Day dreamers
Vacate stare spell is seen
EEG shows 3 per second spike & slow wave.
Ask the patient to first open the eye – alpha wave present, then close the eye – beta wave present. Ask the patient to hyperventilate or give a photic trigger resulting in 3 per second spike & slow wave.
T/t: Valproate/ ethosuximide (in younger child)
2. Atypical absence seizures
EEG < 2.5 Hz spike by slow wave pattern.
Lapse of consciousness is seen
Mental retardation is seen
Lennox gestaut syndrome
Loss of postural control for 1-2 sec
Loss of consciousness for 1-2 sec
Sudden onset of head nodding/dropping
Post ictal deficit is absent in Febrile seizure Absence seizure Atonic seizure
Progressive, subacute metal deterioration with typical signs like myoclonus
Periodic, stereotyped, high voltage discharges
Raised gamma globulin or oligoclonal pattern
RAISED Titre in serum (≥ 1:256) and /or cerebrospinal fluid (≥ 1:4)
Suggestive of pan encephalitis
Definitive: criteria 5 with three more criteria; probable: three of the five criteria.
PHAKOMATOSIS/ NEUROCUTANEOUS DISORDER
Tuberous sclerosis: AD
Family history is present
TSC1 (Chromosome 9) & TSC2 gene (Chromosome 16) involvement is seen
Adenoma sebaceum- Acne like lesion in butterfly distribution is seen
Shagreen patch: Irregular appearance of skin is seen
Subungual fibroma: fleshy growth from below the nail is seen
Earliest cutaneous manifestation
Ash- leaf macules: Hypopigmented macules on Trunk
< 1yr: Infantile spasm = Vigabatrin
> 1 yr : Focal/ seizures = Carbamazepine
On CT, Subependymal astrocytoma is seen
Lesion in Kidney: Angiomyolipoma (having fat, muscle and blood vessel together)
Bleeding in angiomyolipoma of Tuberous sclerosis is k/a Wunderlich syndrome
STURGE WEBER SYNDROME
Port wine stain
S – Seizure
T – Trigeminal Nerve distribution
U – U/L weakness
R – Mental Retardation
G – Glaucoma
E - Eye = Buphthalmos
CT scan head shows Tram Track Appearance
HOW TO REMEMBER STURGE
TRAM TRACK APPEARANCE on
CT scan head : Sturge weber syndrome
Chest X-ray : BRONCHIECTASIS
kidney Biopsy: MPGN
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