Epilepsy

Question 1

DEFINITIONS AND EPIDEMIOLOGY:

1. Seizure
2. Epilepsy
3. Epidemiology
4. Common associations

Answer 1

1. Paroxysmal neurological event due to abnormal discharge of neurones.
2. Tendency to recurrent seizure, ≥2 seizures.
3. • 5% of population
     - UK prevalence 0.5%
     - Peak onset in childhood/adolescence(usually congenital causes) and elderly(secondary to cerebrovascular/degenerative diseases)
     - associated with psychiatric illnesses
4. Cerebral palsy(about 30% have epilepsy), tuberous sclerosis, mitochondrial disease

Question 2

SEIZURE TYPES:

1. Focal
2. Generalised

Answer 2

1. a) Focal limb jerking
   b) Focal tingling
   c) Olfactory/gustatory hallucination
   d) Visual hallucination
   e) Limb posturing
   f) Swallowing/chewing movements
2. a) Tonic
   b) Clonic(repeated generalised jerking)
   c) Myoclonic(Intermittent symmetrical jerks)
   d) Absence with no focal symptoms.
   e) Atonic drop attacks

Question 3

GENERALISED EPILEPSY SYNDROMES:

• usually start in childhood/adolescence
• have good prognosis
• usually not associated with structural diseases
• increased risk among family members

1. Childhood absence epilepsy
2. Juvenile absence epilepsy
3. Juvenile myoclonic epilepsy
4. West syndrome
5. Lennox-Gastaut syndrome

Answer 3

1. • 3-12y, more common in girls, many absences per day, mimics daydreaming, rare convulsions. EEG: 3 Hz spike and wave, often photosensitive. Usually remits in teens. Tx: Ethosuximide/valproate
2. 7-17y, Less freq absences, convulsions common. EEG: 3 hz spike and wave, rarely photosensitive. Responsive to tx but may persist. Tx: valproate, lamotrigine, ethosuximide
3. 10-20y, myoclonic jerks within first few mins of waking and generalised tonic-clonic seizures in morning. absences occassionally. EEG: Polyspike and wave, sometimes photosensitive. Often persists, worsens with carbamazepine. Tx; Valproate, clonazepam, levetircetam
4. 3-7 months, flexor spasms followed by extension of arms(Salaam attack), tonic and atonic seizures, mental retardation usual. EEG: Hypsarrhythmia, mountains. Usually secondary to serious neurological abnormality ie tuberous sclerosis, encephalitis, birth asphyxia. Poor prognosis, very severe epilepsy. Tx: ACTH and vigabatrin
5. 2-9y, tonic and atonic seizures and atypical absences. EEG: slow spike, wave at 2-2.5 Hz. Epilepsy persistent, mental retardation common. Tx: carbamazepine, valproate, lamotrigine. ketogenic diet

Question 4

FOCAL EPILEPSY

• occurs at any age
• Poorer prognosis
• Usually associated with structural brain disease ie hippocampal sclerosis/developmental abnormalities in children OR trauma/cerebrovascular disease/tumours in adults
• focal seizure can progress to generalised one. If very rapid progression, may appear as generalised seizure.
• EEG to differentiate
• post-ictal confusional state with automatisms

1. Benign partial epilepsy with centrotemporal spikes(BECTS)

Answer 4

1. 3-13y, occassional unilateral motor seizures on face, spreads sometimes and usually nocturnal. EEG: centrotemporal spikes, esp in sleep, shift btw sides. remits by 20y. Tx: carbamazepine but often no tx required.

Question 5

STATUS EPILEPTICUS

• simple: consciousness retained
• complex: consciousness not retained

Answer 5

• Continuous/intermittent seizures for ≥30 mins without recovery
• 3 types: Convulsive status epilepticus, non-convulsive status epilepticus(simple, partial/focal), non-convulsive/ complex partial status epilepticus
• NICE recommends emergency medication started 5 mins after person first goes into prolonged seizure/≥3 seizures within 1h. Rescue medication with benzodiazepines ie diazepam PR/intranasally/under tongue.

Question 6

1. PURELY FOCAL EPILEPSIES:
2. PURELY GENERALISED EPILEPSIES:
3. SEIZURES TYPES THAT OCCUR IN BOTH:

Answer 6

1. Focal seizure onsets, Simple partial, Complex partial, Secondary generalised, Focal status epilepticus
2. Myoclonic seizures, photosensitive seizures
3. Tonic-clonic, tonic seizures, atonic seizures, absences, absence status epilepticus, convulsive status epilepticus

Question 7

INVESTIGATIONS:

Answer 7

1. EEG
   - characterises epilepsy type
   - cannot be used to exclude diagnosis of epilepsy
   - sleep deprivation increases yield
2. Head CT/MRI
   - MRI more sensitive but CT can exclude large lesions ie most tumours
   - Scan all >20y
   - If <20y, scan if focal seizure onset/seizures difficult to control

Question 8

SINGLE SEIZURES

Answer 8

• 60% recurrence rate within 1y

- More likely in focal seizures associated with congenital structural lesion/tumour

Question 9

ADVICE:

Answer 9

• Explain dangers of unpredictable loss of consciousness, eg: if go swimming, make sure accompanied by competent adults
• Ensure family, school, employers understand implications.
• Obliged to inform DVLA, likely cannot drive until 12 months seizure-free for epilepsy. More lenient with provoked seizures but still must be informed. Following seizure, cannot drive for 6 months.

Question 10

TREATMENT:

Answer 10

1. Tx if ≥2 seizures within 2y OR if after first seizure and presence of:
   - neurological deficit
   - structural abnormality on brain imaging
   - EEG shows unequivocal epileptic activity
   - patient/carers consider further risk of seizure unacceptable
2. 60% seizure-free for ≥2y with first-line tx. Recurrence rate 25-40% after stopping medication after 2y.
3. Measure drug levels in blood for checking compliance, optimising phenytoin(narrow TPI), carbamazepine and barbiturates, in patients on polytherapy.
4. Neurosurgical treatment.
   - Focal-onset seizures determined by detailed MRI and EEG beforehand.
   - Neuropsychological assessments to determine risk on cognition after operation.
   - Most effective in TL epilepsy with mesial temporal sclerosis and epilepsy due to foreign tissue lesions.

Question 11

DRUG CHOICES:

1. Focal epilepsies
2. Generalised epilepsies
3. Either
4. Other considerations:
5. Drug interactions

Answer 11

1. Carbamazepine(usually first-line, can exacerbate absence seizure), gabapentin, phenytoin, tiagabine, lacosamide
2. Ethosuximide, clonazepam, piracetam
3. Lamotrigine, valproate(usually first-line in generalised seizures), topiramate, levetiracetam, clobazam, phenobarbital, zonisamide
4. a) Age
   - valproate has lower risk of ataxia and falls so suitable for elderly.
   - Lamotrigine and carbamazepine have lower risk of teratogenicity. Advise to take folic acid 5 mg/day before pregnancy. Breastfeeding generally safe except for with barbiturates
   b) Switiching drugs
   - Drug has to be tried to max dose without adverse effects before deemed ineffective
5. • Carbamazepine, phenytoin and phenobarbital are liver-enzyme inducers hence increase elimination rate of contraceptive pill, warfarin and other antiepileptics
     - Lamotrigine most sensitive to effect of this
     - Gabapentin, topiramate, levetiracetam principally excreted renally.

Question 12

ADVERSE EFFECTS OF MEDICATIONS:

Answer 12

1. Sedation
   - most common
   - especially phenobarbital and benzodiazepines.
2. Diplopia and ataxia
   - Phenobarbital, phenytoin, carbamazepine, lamotrigine
3. Rash
   - Carbamazepine, lamotrigine, phenytoin
4. GI effects
   - Carbamazepine, sodium valproate
5. Weight gain
   - Sodium valproate, vigabatrin, gabapentin, pregabalin
6. Weight loss
   - Topiramate, zonisamide
7. Reversible hair loss
   - sodium valproate, vigabatrin
8. Teratogenic effects
   - carbamazepine(safest), phenytoin, phenobarbital, clobazam, sodium valproate, topiramate
9. Visual field loss
   - Vigabatrin

Question 13

PROGNOSIS:

Answer 13

1. Most generalised epilepsies remit in adolescence/early adulthood except juvenile myoclonic epilepsy
2. Partial epilepsies with congenital causes more persistent but 80% also achieve 3y remisison by 9y after onset
3. 3x increased mortality, usually due to seizure-related events/underlying cause of seizure. Sudden unexpected death in epilepsy(SUDEP) affect 0.5%/year

Question 14

MX OF STATUS EPILEPTICUS:

Answer 14

1. ABCDE Resus
2. Consider aetiology: metabolic dysfunction, drugs, intracranial mass lesions, haemorrhage, infections.
   - Investigate for metabolic disturbance
   - Urgent neuroimaging, CSF analysis(Can detect encephalitis) if imaging normal.
   - EEG
   - Check antiepileptic drug levels.
   - If presenting for first time, more likely to have underlying serious disease.
3. PR/IV diazepam OR IV Lorazepam. Add:
   - Phenytoin slow IVI, loading dose 10-15 mg/kg if not on antiepileptic.
   - Continue/restart previous antiepileptic.
4. If responds, regular review of medication and compliance. Check understanding.
5. If not responding, may need intubation with ventilation+thiopental. review causes and consider possibility of non-epileptic seizures/pseudoseizures

*EEG to help monitor control of seizures.

Question 15

OTHER COMMON CAUSES OF SEIZURES:

Answer 15

1. One-off seizures can be caused by infection, trauma, metabolic disturbances.
2. Febrile convulsions
   - aged 6 months - 5y
   - seizures usually generalised tonic/generalised tonic-clonic.
3. Alcohol withdrawal
   - Peak incidence 36h following cessation
   - benzodiazepines to reduce risk of this.
4. Psychogenic non-epileptic seizures(pseudoseizures)
   - epileptic-like seizures without abnormal electrical discharge.
   - associated with history of mental health problems/personality disorder