Seizures and Epilepsy Flashcards
Intracranial causes of LOC
- trauma e.g. haematoma (extradural, subdural, intracerebral)
- tumour
- epilepsy
- hydrocephalus
- SAH
- intracerebral haematoma
- stroke + shift
- brainstem infarction or haemorrhage
- meningitis/encephalitis
- abscess
Extracranial causes of LOC
- electrolyte imbalances
- DKA/hypoglycaemia
- lactic acidosis
- hypo/hyperthremia
- hepatic failure
- hypercapnia
- hypoxia
- any endocrine disturbance
- anaemia
- blood loss
- vasovagal attack
- valvular disease
- MI
- arrhtyhmia
- hypotensive drugs
- sedatives
- opiates
- alcohol
- CO poisoning
Features of history that help identify a cause for LOC
Trauma prior to admission Previous head injury - chronic subdural Sudden collapse - SAH or stroke Limb twitching, incontinence - epilepsy/postictal state Gradual development of symptoms - mass lesion, metabolic or infective cause Previous illness - diabetes - epilepsy - psychiatric illness (overdose) - alcoholism or drug abuse (drug toxicity) - viral infection (encephalits) - malignancy (mets)
Definition of seizures and epilepsy
A seizure or epileptic attack is the consequence of a paroxysmal uncontrolled discharge of neurons within the central nervous system
- clinical manifestations range from a major motor convulsion to a brief period of lack of awareness
Classifcations of types of seizures
1) partial (focal, localisation related) seizure
- A: simple, partial complex seizures with preserved conciseness
- B: complex partial seizure accompanied by any degree of impaired conscious level
- C: partial seizures evolving to tonic/clonic convulsion
2) generalised seizures (convulsive or non-convulsive)
- A: absences
- B: myoclonic seizures
- C: clonic seizures
- D: tonic seizures
- E: tonic/clonic seizures
- F: atonic seizures
3) unclassified seizures - if insufficient information
Investigations for patients with loss of conciousness
Bloods - FBC, TFTs, U&Es, LFTs, CK, prolocatin, calcium
Blood cultures
Drug screen
VBG
Blood glucose - hypo/hyperglycaemia
Urine dipstick - glucose or infective causes
ECG and 24-hour ECG - cardiac arrhythmia
CT head - trauma or suspected rasied ICP
- LP and CSF examination if negative (meningitis)
Echo - cardiomyopathy
EEG - may reveal a focal or generalised disturbance (epilepsy)
CT/MRI
- structural brain lesions
- indicated in late onset, partial seizures and abnormal clinical signs
Medical management long-term epilepsy
Idiopathic generalised epilepsy
- 1st line: sodium valporate or lamotrigine
- 2nd line: topiramate, levetiracetam or carbamazepine
Partial/focal epilespy
- 1st line: lamotrigine or carbamazepine
- 2nd line: sodium valporate, phenobarbitone or levetiracetam
Absence seizures
- 1st line: sodium valporate or ethosuximide
- 2nd line: lamotrigine
What should you be wary of when prescribing anti-epileptics
Teratogenicity
- risk highest with sodium valporate and polytherapy
- lamotrigine and carbamazepine considered safe
Interactions
- many anti-epileptics induce liver enzymes to increase the metabolism of other drugs (OCP, warfarin and other anti-epileptics) e.g. carbamazepine, phenytoin, phenobarbitone
- valporate inhibits liver enzymes
Blood levels
- useful in phenytoin due to the difficult pharmacokinetics
- in case of toxicity
What are the main adverse effects with the main anti-epileptics
Lamotrigine - rash (SJS risk) drowsiness
Carbamazepine - rash, drowsiness, ataxia, diploplia, hyponatraemia and thrombocytopenia
Sodium valporate - abdominal pain, hair loss, weight gain, tremor and thrombocytopenia
Phenytoin - gum hypertrophy, acne, ataxia, diploplia, skin thickening and neuropathy
Phenobarbitone - sedation, behavioural changes and withdrawal seizures
Gabapentin/pregabalin - drowsiness, ataxia and weight gain
Topiramate - drowsiness, weight loss, renal stones and parasthesiae
Levetiracetam - irritability and weight loss
What are the possible surgical interventions for epilepsy?
Extra-temporal cortical resection Anterior temporal lobectomy Corpus callosal section Hemispherectomy/otomy Selective amygdalo-hippocampectomy Vagal nerve stimulation
What is status epilepticus
A succession of tonic/clonic convulsions, one after the other with a gap between each = serial epilepsy
When consciousness doesn’t return between attacks = status epilepticus
- may be life threatening with the development of pyrexia, deepening come and circulatory collapse
Causes of status epilepticus
Frontal lobe lesions Following head injury Reducing drug therapy - esp. phenobarbitone Alcohol or other sedation withdrawal Drug intoxications - TCA Infections Metabolic disturbances e.g. hyponatraemia Pregnancy
Management of status epilepticus
Pre-hospital
- diazepam rectally, or midazolam buccally (short term efficacy)
Early status
- lorazepam IV (beware of respiratory distress)
Established status
- phenytoin or phenobarbitone IV and cardiac monitoring
- status should be controlled and oral maintainance therapy resumed
Refractory status
- GA with propofol or thiopentone - bolus followed by continuous infusion
- administered under EEG control to induce and maintain a ‘burst suppression’ pattern
Considerations of seizures developing during pregnancy
Mostly idiopathic
- tumours and AVM may enlarge during pregnancy and produce such seizures
In late pregnancy seizures occur often in association with hypertension and proteinuria as eclampsia
- emergency, immediate delivery required
Post-partum
- consider cortical venous thrombus
Considerations of patients with established epilepsy during pregnancy
Risks of teratogenicity from anticonvulsants
- discuss with all women of childbearing age before they become pregnant
- avoid sodium valporate, phenytoin and polytherapy
Patients offered early, detailed scans
>90% of women deliver a normal child
Most drugs present in breast milk
- except carbamazepine and valporate
- lamotrigine not harmful to the infant
