Epilepsy

Throwback to when I pretended to be a worried parent whose child had just had a seizure for the mock clinical exams of the older year students. My performance was flawless.  I really enjoy pretending to be a patient, for some unexplainable reason. Even as a kid, I was always the patient. For this one, my son was playing videogames and then fell to the floor and started jerking for a few minutes. He lost consciousness and urinary continence, but there was no tongue biting.


Epilepsy

Definition: a recurrent tendency to spontaneous, intermittent, abnormal activity in part of the brain, manifesting as seizures (paroxysmal synchronised cortical discharges).

Convulsions are the motor signs of electrical discharges.

Aetiology/ risk factors:

Causes of epilepsy:

-2/3 are idiopathic (often familial)

Structural

-cortical scarring e.g. head injury years prior

-developmental e.g. dysembryoplastic neuroepithelial tumour or cortical dysgenesis

-space-occupying lesion, tumour

-stroke

-hippocampal sclerosis e.g. after a febrile convulsion

-vascular malformations

Other

-tuberous sclerosis

-sarcoidosis

-SLE (lupus)

Polyarteritis Nodosa (PAN)

There are non-epileptic causes of seizures and you want to exclude and treat these, mostly reversible causes:

-Trauma, stroke, haemorrhage, raised intracranial pressure

-alcohol or benzodiazepine withdrawal

-metabolic disturbances: hypo/hypernatraemia, hypocalcaemia, hypo/hyperglycaemia, uraemia, hypoxia (reflex anoxic convulsions due to syncope, may be difficult to distinguish)

-liver disease

-infection e.g. meningitis, encephalitis, syphilis, cysticercosis (from pork tapeworm), HIV

-pyrexia

-drugs e.g. tricyclics, cocaine, tramadol, theophylline

-pseudoseizures (all examinations and investigations normal)

Epidemiology: prevalence ≈ 1% of general population

-Peak onset is in early childhood or in the elderly

Symptoms & Signs:

⇒Take a collateral history, as well as talking to the patient

Seizures may take many forms, but tend to be stereotyped for each individual patient.

Seizure elements:

Prodrome- change in mood or behaviour, rarely precedes a seizure, lasts hours or days.

Triggers: e.g. alcohol, stress, fevers, certain sounds, flickering lights/TV, contrasting patterns, reading/writing? (TV induced fits rarely need drugs).

Aura- part of the seizure, may be a strange feeling in the gut, déjà vu, strange smells or flashing lights. This implies a partial/focal seizure from the temporal lobe (often, but, not necessarily from temporal).

Post-ictal (post-seizure)- may be headache, confusion, myalgia (muscle pain), and a sore tongue (from biting); or temporary weakness after a focal seizure in the motor cortex (Todd’s palsy); or dysphasia following a focal seizure in the temporal lobe.

Tongue biting and slow recovery are very suggestive of an epileptic seizure.

Types of seizure:

Partial/focal seizures = seizure begins with focal features (referable to a part of one hemisphere), even if it may rapidly generalise. Often seen with underlying structural disease.

Localising features

Temporal:

-automatisms- complex motor phenomena with impaired awareness and no later recollection e.g. oral- lip-smacking, chewing, swallowing; manual- fumbling, fiddling, grabbing; complex actions- singing, kissing, driving, violent acts.

-abdominal rising sensation or pain +/- ictal vomiting; rarely episodic fevers or D&V

-dysphasia- ictal or post-ictal

-memory phenomena- déjà vu, jamais vu

-emotional disturbance (hippocampus)- sudden terror, panic, anger, elation, derealization

-hallucinations of smell or taste and a dreamlike state (uncal involvement)

-complex auditory hallucinations (auditory cortex)

-delusional behaviour

Frontal:

-motor features- posturing, versive (forced, involuntary) movements of head and eyes, peddling movements of legs

-Jacksonian march- spreading focal motor seizure with retained awareness, often spasm starting with face or thumb

-motor arrest

-subtle behavioural disturbances

-dysphasia or speech arrest

-post-ictal Todd’s palsy (temporary post-ictal flaccid weakness)

Parietal: sensory disturbances- tingling, numbness, pain (rare)

                  motor symptoms

Occipital: visual phenomena- spots, lines, flashes

Simple partial = awareness unimpaired

focal motor, sensory (olfactory, visual etc.), autonomic or psychic symptoms

no post-ictal symptoms

Complex partial = awareness impaired

 may have simple partial onset (aura) or impaired awareness at onset

     most commonly arise from temporal lobe

     post-ictal confusion common with seizures arising from temporal

     rapid recovery after seizures from frontal lobe

Partial seizure with secondary generalisation = starts focally- either simple or complex partial seizure- and then spreads widely, causing a secondary generalised seizure, which is typically convulsive (in 2/3 of partial seizures).

Primary generalised seizures = simultaneous onset of electrical discharge throughout cortex, with no localising features.

Absence = brief- ≤10s pauses

e.g. suddenly stops talking in mid-sentence, staring into space, then carries on where left off

loss of consciousness but maintained posture

may experience blinking, rolling up of eyes or other repetitive motor actions e.g. chewing

no post-ictal phase

presents in childhood, often mistaken for daydreaming

Image result for absence seizure

Tonic-clonic = loss of consciousness

     limbs stiffen (tonic), then jerk (clonic)- may have just one

     post-ictal confusion and drowsiness

     this is your classic, TV seizure everyone thinks of with epilepsy

Image result for Jacksonian march-

Myoclonic = sudden jerk of a limb, face or trunk

patient may be thrown suddenly to the ground, or have a violently disobedient limb

Atonic = sudden loss of mucle tone causing a fall

  no loss of consciousness, patient just goes limp

Infantile spasms = commonly associated with tuberous sclerosis (rare multisystem genetic disease that causes benign tumours to grow in the brain and on other vital organs).

Investigations:

Look for organic causes of seizures.

Bloods- U&Es (electrolyte imbalances e.g. hyponatraemia?), ABG (hypoxia?), FBC (infection?), LFTs (liver disease?), glucose (hypo/hyper?), Ca2+ (hypo), Mg2+, toxicology screen, prolactin (transient rise shortly after true seizure)

Lumbar puncture-infection?

CT/MRI + enhancement- TB? structural lesions? space-occupying lesion? vascular lesion?

Electroencephalography (EEG)- cannot exclude or refute epilepsy completely but helps.

-Assists in classifying the epileptic syndrome.

-Usually performed between seizures and is often normal. Ictal EEGs are more useful but require adequate facilities.

-In first unprovoked seizures, unequivocal epileptiform activity on EEG helps assess risk of recurrence.

Drug levels- are they taking their anti-convulsants?

Magnetoencephalography (MEG), PET, Cognitive assessment, Ictal SPECT- may help localise epileptogenic focus when evaluating for epilepsy surgery.

Management:

-Advise about dangers e.g. swimming, driving, heights (after any fit until diagnosis known to be epilepsy)

-Counselling on employment, sports, insurance, conception (drugs = teratogenicity, breastfeeding transfer, affect OCP metabolism)

-Avoid driving until seizure-free for > 1 year, and ask them to contact the DVLA (UK driving authority)

-Relaxation training or aura interruption (e.g smelling a pleasant smell if the aura is a certain bad smell) may abort emotion-triggered seizures.

-Avoid triggers.

Epilepsy nurse specialists can be involved in patient management

Drugs (anti-convulsants)

-Not advised after one seizure, unless high risk of recurrence.

-Discuss drug options with patient after a second seizure. If seizures are infrequent, patient may choose to take risk.

-Drugs choice depends on seizure type, epilepsy syndromes, other medications, co-morbidities, plans for pregnancy, and patient preference.

-Monotherapy is the aim, building up dose until seizures are controlled, side effects intolerable or maximum dosage.

-Switch drugs if one is not working or not tolerated, by introducing it and only withdrawing the 1st drug once they are established on the 2nd.

-Dual therapy needed in < 10% of patients- if all appropriate drugs have been tried singly at the optimum dose.

-Consider drug withdrawal with patient after a few years seizure-free.

⇒Generalised tonic-clonic seizures = SODIUM VALPROATE or LAMOTRIGINE-1st line

CARBAMAZEPINE or TOPIRAMATE -2nd line

Others: levetiracetam, oxcarbazepine, clobazam

Tonic, atonic and myoclonic seizures = as above, but avoid:

carbamazepine and oxcarbazepine

-may worsen seizures

Absence seizures = SODIUM VALPROATE, LAMOTRIGINE, ETHOSUXIMIDE

Partial seizures +/- secondary generalisation = CARBAMAZEPINE- 1st line

2nd line: SODIUM VALPROATE, LAMOTRIGINE, OXCARBAZEPINE, TOPIRAMATE

Others: levetiracetam, gabapentin, tiagabine, phenytoin, clobazam

Surgery

-If drugs don’t work

-If a single epileptogenic focus identified e.g. hippocampal sclerosis, small low-grade tumour = Neurosurgical resection

-Risk of causing focal neurological deficits e.g. memory impairment, dysphasia, hemianopia

Vagal nerve stimulation- can reduce seizure frequency and severity in ∼33%

Complications:

Status epilepticus (see below)

-Bodily harm from seizures, fractures

-Behavioural problems

-Drug side effects

-Social stigma, unemployment, insurance difficulties, driving restrictions, inability to operate machinery

-Depression, fear

-Sudden unexpected death in epilepsy (SUDEP)- more common in uncontrolled epilepsy, may be related to nocturnal seizure-associated apnoea or asystole

3x mortality rate of controls

> 700 epilepsy related deaths recorded/ year (UK), up to 17% SUDEPs

mortality = 2 in 100,000/year

Prognosis:

-Provoked 1st seizures are less likely to recur = 3-10%, unless irreversible cause e.g. infarct or glioma.

-Unprovoked 1st seizure = 30-50% recurrence rates

(Provocation refers to organic causes like metabolic disturbances, infection, liver disease and raised ICP and most people would have a seizure given the provocation; whereas triggered attacks from e.g. TV or stress, tend to recur and suggest epilepsy.)

-Most patients are seizure-free within a few years of starting drugs, and more than 50% remain so when drugs are withdrawn.

-50% remission at 1 year


Status Epiletpicus

Definition: seizures lasting > 5 minutes, or repeated seizures without intervening consciousness. This is a medical emergency.

(It used to be 30 minutes, not that you would let it go on for that long without treatment anyway.)

Aetiology/ risk factors:

-Occurs in patients with known epilepsy

-If first presentation of epilepsy, chance of structural brain lesion is high (> 50%)

Symptoms & Signs:

Tonic-clonic status: limbs stiffen (tonic), then jerk (clonic)

Non-convulsive status may be more difficult to diagnose e.g:

Absence status

Continuous partial seizures with preservation of consciousness

They may present with confusion, impaired cognition/memory, odd behaviour, dreamy derealization.

Other features: aggression, psychosis +/- abnormalities of eye movement, eyelid myoclonus, and odd postures.

EEG can be helpful if uncertain- look for evidence of rhythmical discharges.

Investigations:

Bedside glucose

Once treatment started:

lab glucose, ABG, U&Es, Ca2+, FBC, ECG

pulse oximetry, cardiac monitor

Consider:

anticonvulsant levels, toxicology screen, lumbar puncture, blood and urine culture, EEG, CT, carbon monoxide level

Management:

-Aim to terminate seizures lasting more than a few minutes as soon as possible (< 20 minutes)

Basic life support- maintain airway, recovery position, oral/nasal airway, intubate if necessary

Oxygen, 100% + suction (as required)

IV access and take blood for investigations

Slow IV bolus phase to stop seizures: e.g. LORAZEPAM (2-4mg)

2nd dose if no response within 10 min

    Alternative = buccal MIDAZOLAM, IV/PR DIAZEPAM

Thiamine (250mg IV over 30min) if alcoholism or malnourishment suspected.

Glucose 50 mL 50% IV, unless glucose known to be normal.

-Treat acidosis if severe, correct hypotension with fluids.

IV infusion phaseif seizures continue, start PHENYTOIN (15-20 mg/kg IVI, rate ≤ 50mg/min; 100mg/6-8h maintenance dose). Monitor ECG, BP, and phenytoin levels.

Alternative = DIAZEPAM infusion (100mg in 500mL of 5% glucose, at ∼40mL/h)

General anaesthesia phase- continuos seizures require expert help with paralysis and ventilation with continuous EEG monitoring in ICU.

Once seizures controlled, start oral anticonvulsants and investigate the cause.

Complications:

-Respiratory arrest

-Hypotension, bradycardia, heart block (phenytoin)

-Death

Prognosis: mortality and the risk of permanent brain damage increase with the length of attack.

References: Cheese & Onion, Rapid Medicine

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s