Epilepsy

Epilepsy

·        Epilepsy in Childhood, Benign Febrile Convulsions and Anoxic Seizures

·        1:200 

·        Onset after age 20 Þ 10% chance of tumour

·        Symptoms:

o  Abrupt onset, brief duration, rapid recovery, and stereotypical recurrence

o  Not just fits: focal signs depending on where in the brain it arises

·        Very long list of differentials to epileptic seizure: See Other Spells,

·        Is it epileptiform:

o   Pseudo-seizure (or Non-Epileptic Seizure): either factitious disorder (are deliberately faking) or conversion disorder (they think it‟s real)

o   Hard to differentiate: going blue, frothing at mouth and incontinence can happen in pseudo-seizure. Epiletics may not have post-ictal phase

o   Gold standard is EEG: but can‟t do this in A&E. Fall back is checking whether the person is in any way aware (then it can‟t be generalised) – eg localising to pain (sternal rub, squeeze thumb nail), drop their hand onto their face

o   Check history: evidence of brain injury, infection, on anticonvulsant meds

o   Pseudo seizure more common in women (10:1) and those with a medical connection (eg doctor/nurse in family, someone with epilepsy)

·        Epileptic seizures happen more if: tired, ill, fever, stressed, not taking medication (but these are not classified as „provoked‟ as they wouldn‟t provoke a seizure in a normal person)

Seizure Types

·        Generalised: bilaterally symmetrical without local onset

o   Tonic-clonic (Grand mal) seizures:  Tonic phase: 10 – 20 secs – extension phase then tremour 

o   begins – repetitive relaxation of tonic contraction. Clonic phase: usually 30 seconds, random movements, tongue often bitten 

o   Absence (Petit Mal) Seizures: Characteristic type of absence attack. Childhood or adolescent onset, associated with 3/sec spike and wave on the EEG. Blank stare and unresponsive for 5 – 15 seconds. No post-ictal confusion or sleepiness. May also have automatisms and mild clonic motion (usually eyelids at 3 Hz). May be induced by hyperventilation. 80% have no further seizures after 20 years old. Can also have atypical absence seizures. Treat with ethosuximide or sodium valproate 

o   Atonic: complete, sudden loss of tone – completely collapse, may injure themselves

o   Tonic: sustained contraction, maybe with fine tremour

o   Myoclonic: Sudden, very brief jerk but still generalised

o   Clonic: rhythmic jerking

o   Infantile spasms:

§  Sudden bilateral symmetrical jerk, extensor or flexor.  Can be subtle, come in clusters

§  Usually around 3 – 6 months, boys > girls

§  Grow out of the spasms

§  Bad prognosis: cerebral palsy, retardation, etc

§  Medical emergency: try to urgently get them under control

·        Partial: Begin locally

o   In simple partial seizures consciousness is preserved. 

o   Complex partial seizures are focal seizures in which consciousness is altered (eg blank unresponsiveness followed by automatisms, eg lip smacking, other semipurposeful activity) – usually temporal lobe but may be frontal. Can go on for minutes. Aware it is coming (cf absence which is sudden) 

o   Partial seizure secondarily generalised: they have an awareness first

o   Localising it:

§  Preceding aura: olfactory, visceral, auditory, visual, déjà vu

§  Dystonic posturing: contraction of agonist and antagonist muscles 

§  Post-ictal Todd‟s Syndrome: if they have one area of weakness after a seizures (ie one hand weaker than the other) then it started locally

·        Automatic behaviour usually seen in complex partial seizures: but can be in absence (petit mal) seizures. Eg Oral or manual automatisms

·        Seizure location: 

o   Frontal: focal tonic or clonic motor activity, posturing, prominent motor automatisms but no orofacial or experiential automatisms

o   Central: focal clonic seizures with preservation of awareness

o   Temporal: experiential, gustatory or olfactory hallucination.  Motion arrest, automatisms

o   Parietal: exclusively somatosensory manifestations

o   Posterior: polymodal sensory, visual, auditory or somatosensory hallucinations

·        Sorting out type of seizure:

o   When do the seizures occur

o   Does patient know they‟re going to have a seizure

·        What can the patient recall

·        Detailed description from observers:

o   Are they aware – will they respond

o   Are their automatisms

o   Is there dystonic posturing

o   How long did it last

·        After the seizure: are they confused, can they speak, any post-ictal Todd‟s

Treatment

·        Diagnosis is clinical. EEG helps with severity, classification, to localise a surgically remediable abnormality (eg hippocampal sclerosis), and to differentiate pseudo-seizures

·        Don‟t treat until you‟re sure it‟s epilepsy

·        Anticonvulsants suppress seizure activity in 80%

·        Principles of drug treatment: 

o  When to treat: often wait for second seizure – although treatment after the first ® ¯occurrence, but no long term change in outcome 

o  Use only one drug

o  Tailor drug to seizure type

o  Introduce slowly.  Takes about 5 days to stabilise a change in dose 

o  Monitor drug level: for other than phenytoin, this is to check compliance. Beware – plasma level at which seizure control is obtained is variable

o  Consider withdrawal of drugs after 2 years without seizure, slowly over 6 months

·        Mode of action unknown – but may ¯GABA breakdown, as well as modifying flux of Na, K and Ca ions

·        Usual drugs:

o  Idiot‟s guide: carbamazepine for partial seizures and Valproate for generalised

·        Conventional drugs have hepatic clearance

·        Side Effects: 

o  General lethargy, ¯concentration, unsteadiness, dizziness

o  ­LFTs: but serious hepatotoxicity rare.  Especially Valproate

o  Rarely bone marrow suppression

o  Pregnancy:

§  Epilepsy often worsens during pregnancy

§  Plasma concentration of drugs falls due to pharmokinetic changes and ¯compliance 

§  Teratogenic: 3% risk of malformation on 1 drug (also, epilepsy itself can be teratogenic - ?hypoxia during seizure) 

§  % in breast milk varies by drug

o  Specific drugs:

§  Carbamazepine: enzyme inducer 

§  Phenytoin: Dose-dependent kinetics ® small ­ in dose may ® ­­ in plasma concentration,

§  SE: ataxia, peripheral neuropathy, gingivitis

·        Must be seizure free (with or without treatment) for 12 months before you can drive.  Obliged to tell

·        LTSA on diagnosis if the patient won‟t and continues to drive

Status Epilepticus

·        Repeated seizures without regaining consciousness

·        No one knows how long is too long: but after 10 minutes ­risk of damage

·        If not sure whether it‟s epileptiform then must still treat for status

·        Treatment:

o   Protect and maintain airway, insert oral airway

o   Prevent injury

o   100% oxygen 

o   Diazepam 10 – 20 mgs iv, not exceeding 2 – 5 mgs per minute. If no iv access give rectally with 10 – 20 ml normal saline. Duration is brief and another anticonvulsant is required. Avoid repeating diazepam ® cardiorespiratory collapse. If no response give clonazepam 1 – 4 mg iv

o   Phenytoin 50 mg/min iv (25 mg/min in cardiovascular disease), usual adult dose 1250 mg in 100 mls saline over no more than 20 minutes. Monitor BP and heart rate

o   If established, give phenobarbitone

o   If refractory, then anaesthesia with propofol or thiopentone.  Taper after 12 – 24 hours

Other Spells

·        Commonly misdiagnosed as seizures

·        Paroxysmal non-epileptic events without altered consciousness: Jitteriness, migraine with focal aura, hyperventilation, acute paroxysmal vertigo, shuddering attacks, anxiety states (eg panic attack), psychosis, drug induced dystonias, masturbation, tics, etc

·        Paroxysmal non-epileptic events with altered consciousness: Day dreaming, breath holding spells, reflex syncope, TIAs, psychosis, pseudo-seizures, delirium, metabolic disorders, other brain insult (infection, haemorrhage), ritualistic movements, migraine, arrhythmias, drugs substance abuse

·        Paroxysmal non-epileptic events related to sleep: benign sleep myoclonus of infancy, head banging, night terrors, hypnogogic jerks, sleep walking, sleep apnoea