Neuro Flashcards
What are the indications for MRI following a seizure?
MRI is indicated in those:
who develop epilepsy before the age of 2years or in adulthood
who have any suggestion of a focal onset on history, examination or EEG (unless clear evidence of benign focal epilepsy)
in whom seizures continue in spite of first-line medication.
It should be used to identify structural abnormalities that cause certain epilepsies.
MRI should be the imaging investigation of choice in people with epilepsy if indicated.
CT can be used if MRI is not available or contraindicated
What are the side effects and drug interactions of antiepileptics?
Common adverse effects include:
Cognitive: Slowed cognition, memory problems, reduced concentration, fatigue and drowsiness
Psychological: Mood and behavioural changes. The risk of death due to suicide is reported to be greater on anticonvulsant drugs.
Balance: Unsteadiness, ataxia, reduced coordination and vertigo
Dermatological: Skin reactions are common with anticonvulsant drugs. Severe reactions (E.g. Stevens Johnson Syndrome, Toxic Epidermal Necrolysis, and DRESS syndrome) are much less common but occur more frequently with carbamazepine, phenytoin and lamotrigine.
Gastrointestinal: problems such as diarrhoea, nausea or vomiting are commonly reported.
Hypoatraemia: common with older drugs (e.g. valproate, phenytoin, carbamazepine)
Osteoporosis: Bone loss/osteoporosis is reported as a long-term side effect of anticonvulsants.
Drug interactions
Interactions between anticonvulsants and other medications are common. Most interactions are related to changes in hepatic metabolism causing increased or decreased effective drug levels.
Hepatic CYP inducers: carbemazepine and phenytoin. Increase clearance of other drugs e.g. COCP, reducing their efficacy.
Drugs that increase clearance of AEDs (more seizure risk): doxycycline
Drugs that decrease clearance of AEDs (more side effect/toxicity): erythromycin and clarithromycin
Similar interactions between different anticonvulsants make management of patients on more than one anticonvulsant drug particularly challenging
These can be helpful in managing dosing. Drug levels vary over time – so taking samples at a particular time point after dosing or at least knowledge of when the last dose was taken is often important in interpretation.
They are particularly helpful in patients on phenytoin where dosing is particularly challenging. Phenytoin has first-order pharmacokinetics (i.e. a fixed percentage of drug is eliminated per unit time) at lower levels, and zero order kinetics at higher levels (i.e. a fixed amount is eliminated per unit time). The practical consequence is that at higher doses serum drug levels increase to a much greater extent for a small increment in dose than at lower doses.
Drug levels are more useful when considering whether a patient’s symptoms might be due to drug toxicity. In this setting it is important to remember, however, that some patients can develop adverse effects at relatively low drug levels, and that any “therapeutic range” quoted on the laboratory report is more guidance than absolute truth.
Finally, levels may be used in patients who continue to have seizures whilst on medication. Again, levels should be interpreted cautiously and in clinical context but may offer some help in deciding whether to increase drug doses further or further investigate a patient’s concordance with their prescription.
What contraception can be used with epileptics?
There are certain restrictions with certain anti epileptic meds – can reduce effectiveness of contraception
For women treated with a non-enzyme inducing antiepileptic drug (except lamotrigine)- their contraceptive options are the same as women without epilepsy.
For women treated with enzyme-inducing antiepileptic drugs they can reduce the effectiveness of oral contraceptives (COCP, progestogen-only pills), transdermal patches, the vaginal ring, and progestogen-only implants. Therefore an alternative contraceptive method is recommended.
Methods unaffected by enzyme-inducing drugs are:
medroxyprogesterone acetate injections
intrauterine method (copper intrauterine device or the levonorgestrel-releasing intrauterine system).
For women taking lamotrigine:
Oestrogen-containing contraceptivesmay reduce the effectiveness of lamotriginebecause of a reduction in circulating lamotrigine levels which may result in increased seizure activity.
Progestogen-only contraceptives can be used without restriction, butthe woman should report any symptoms or signs of lamotrigine toxicity.
Emergency contraception – Copper intrauterine device is preferred as there is potential interactions with oral emergency contraceptions.
All women of child bearing potential should be given 5mg of folic acid before possibility of pregnancy
What can you do if s patient on anti-epileptics want to get pregnant?
So what should you do?
Discuss with her the risk of AEDs causing malformations and possible neurodevelopmental impairments in an unborn child especially Sodium Valproate.
Valproate is contraindicated in pregnancy due tothe risk of birth defects and developmental disordersand should only be used in girls and women of childbearing potential when no alternative is available and a pregnancy prevention programme is in place.
In women who take valproate while pregnant, around 1 in 10 babies will have a birth defect. They include spina bifida, facial and skull malformations and malformation of the limbs, heart, kidney, urinary tract and sexual organs
Refer the woman to an epilepsy specialist for pre-conceptual counselling, especially if she is taking antiepileptic drugs.
Advise her to continue using effective contraceptionuntil she has been assessed by a specialist and to continue her antiepileptic drugs while waiting for appointment
If an unplanned pregnancy is discovered it is usually too late for changes to be made to the treatment regimen; the risk of harm to the mother and fetus from convulsive seizures outweighs the risk of continued therapy. For such case an urgent consultation is required to reconsider the benefits and risks of valproate therapy
Prescribe high-dose folic acid 5mg daily to reduce the risk of neural tube defects.This should be given before pregnancy and continued throughout the first trimester of pregnancy.
How to manage status epilepticus?
ABCDE approach:
Secure the airway
Give high-concentration oxygen
Assess cardiac and respiratory function
Check blood glucose levels
Gain intravenous access (insert a cannula)
IVlorazepam(or IV diazepam or buccal midazolam if no IV access), repeated after 10 minutes if the seizure continues (max 2 doses including pre hospital treatment)
If seizures persist: IVphenobarbitalorphenytoin
If still persists after 30 mins (refractory status) -> transfer to ICU to be managed under GA
How are absence seizures diagnosed and managed?EEG patterN?
bsence seizures/ Petit Mal Seizure.
Age at onset: range (3−9 years) and peak (4−7 years).
More common in girls: approximately 3:1 (possibly slightly higher).
Family history of epilepsy: more often than not because this is a genetic epilepsy.
manifest by frequent (as many as 100 times per day or more) episodes of brief staring spells (lasting 5-12 seconds at a time). The child ceases what he or she is doing, stares, looks a little pale and may flutter the eyelids.
Sometimes more extensive bodily movements occur (such as dropping the head forwards) and there may be a few clonic movements of the arms.
Child are unaware of the attacks, and may be the parents for some time after onset, assuming that the child is just day-dreaming.
About one third of all children with petit-mal will have one or more tonic-clonic convulsions.
EEG: characteristic pattern with 3 Hz (cycles per second) generalised spike and slow-wave discharges – seen during an absence seizure; this activity may also be seen between absences.
treatment
Prescribe anti-epileptic medications of choice: ethosuximide (if the child has only ever had absence seizures) or sodium valproate if the child has had tonic−clonic seizures and absence seizures. Lamotrigine is another option but is less effective . Response to anti-epileptic medication: approximately 70% will become seizure-free on medication.
Development : children do not usually have any associated learning difficulties or behaviour problems if diagnosed and treated quickly.
Long-term outcome: approximately 70% of children will remit spontaneously. There is a low risk (< 10%) of the person developing tonic−clonic seizures in early adulthood even if the absence seizures have entered remission and the child is off anti-epileptic medication
How do temporal lobe seizures present?
Aura occurs in the majority of temporal lobe seizures.
last a very short period - seconds or 1 to 2 minutes.
may cause sensory, autonomic or psychic symptoms:
Olfactory, auditory and gustatory illusions and hallucinations may occur.
Patients may report distortions of shape, size and distance of objects.
Psychic phenomena: Feeling of déjà vu (familiarity) or jamais vu (unfamiliarity).
Depersonalisation (ie feeling of detachment from oneself) or derealisation (surroundings appear unreal).
Sensations rising up the body
What is the first line treatment for focal seizures?
First-line medication for focal epilepsy is carbamazepine or lamotrigine. If these are not suitable, alternatives include oxcarbazepine, valproate or levetiracetam.
Who gets Juvenile myclonal eplilepsy
Occurs in the teen years
The defining seizure is myoclonic - Early morning sudden myoclonic jerks, especially of the arms and shoulders but may affect any muscle
Often later develop generalised tonic-clonic (GTC) seizures after a few years.
Sometimes develop absence seizures. A variant of this form of epilepsy is atonic seizure where the patient suddenly loses body tone and falls to the floor.
Epileptogeneic photosensitivity occurs in at least half of patients with JME.
Treatment:
sodium valproate - controls all the seizure types in about 90% of children with juvenile myoclonic epilepsy
lamotrigine - This treatment option may be preferable in adolescent girls, in whom menstrual irregularities, transient hair loss, and weight gain may troublesome side effects of sodium valproate therapy
Spontaneous remission before puberty occurs in fewer than 20% of children with juvenile myoclonic epilepsy. Also drug withdrawal is often unsuccessful even after 2 or more years of seizure-freedom, with at least 70% of patients relapsing. Often lifelong treatment will be required to ensure seizure-freedom.
What are the first line treatment of different seizures?
Generalised tonic clones
First line: sodium valproate
second line: lamotrigine, carbamazepine
Absence
First lline: ethosuximide or sodium valproate (if co-existent tonic-clonic seizures)
Myoclonic
Second line: lamotrigine
First line: sodium valproate
Second line: levetiracetam, topiramate
Focal
First line: carbamazepine or lamotrigine
second line: levetiracetam, oxcarbazepine or sodium valproate
Atonic or tonic
First line: sodium valproate
Second line: lamotrigine
Most patients are effectively treated with drugs. However, patients whose epilepsy remains poorly controlled over a period of 2 years or more despite two drugs, are less likely to gain control. In these patients there are a number of surgical options are possible. In simple terms these involve electrically isolating or removing an identified focus of seizure activity.
Benefits and risks depend greatly on the nature of the provoking epileptogenic lesion, and on the extensiveness of the surgery required. In carefully selected patients control in previously uncontrolled patients improves over the year from intervention from 40% (in controls) to 90% in those who have surgery.
Why is an ABG done after a collapse or seizure?
Initial presentation with a first seizure requires careful work-up. The importance of a clear seizure history, with a witness account if possible, cannot be understated.
At the time of seizure bloods should be taken to look for any electrolyte/metabolic abnormalities triggering the seizure. An ABG is often taken during a seizure, a raised lactate is supportive of the diagnosis of seizure, as the cell start to respire anaerobically.
What are the complications following seizures?
Potential complications of epilepsy include:
Sudden Unexpected Death in Epilepsy (SUDEP): Occurs in approximately 1:1000 patient years with epilepsy. Patients with a diagnosis of epilepsy need to be counselled about this risk.
Status epilepticus: defined as a seizure that persists for more than 30 minutes. This is associated with a mortality of 15-20% - due to hypoxia and metabolic disturbances occurring during the seizure.
Injuries sustained during a seizure or in the post-seizure period. Accidental injuries of some degree are estimated to occur in 6.5% of patients with epilepsy over 2 years. Injuries are partly culturally determined; e.g. severe injuries from burns sustained when falling into an open fire are particularly common in cultures where open fires are used for cooking and heating.
Mood disorders and anxiety are common – occurring in a third to a half of patients with epilepsy.
Cognitive impairment is common, and usually due either to the underlying brain disease of which seizures are a manifestation, or drug side effects.
Cardiovascular and respiratory disease are more common in patients with epilepsy.
Most antidepressant drugs increase the risk of seizures, so there will be a balance to be struck between the beneficial effects of these drugs on mood and potential worsening of control of seizures.
What factors determine the reocurrance and prognosis if seizures?
Prognosis is usually quantified in terms of risk of recurrent seizures.
Single unprovoked seizure:risk of recurrence is 40-50% within 2 years – and, if there are going to be recurrent seizures then these occur within 2 years in 80-90% of patients.
Two unprovoked seizures (>48hours apart):Higher risk of recurrence. Even with anticonvulsant treatment this is 75% at 4 years, and without treatment recurrent seizure is even more likely.
Single provoked seizure:Risk of recurrence is low if a seizure has a known provoked cause e.g. in context of a medical illness, metabolic abnormality or within 1 week of an acute stroke.
The risk of recurrence even after a single seizure is increased twofold if the patient has
- Persistently abnormal neurological examination
- Focal area of change on the MRI (e.g. previous stroke) acting as a focus to generate seizures. These would be termed “remote symptomatic seizures”.
- Epileptiform abnormalities on EEG
- A seizure that occurred during sleep
What complications can occur during pregnancy for someone with epilepsy?
Women with epilepsy have increased risks during pregnancy including
preeclampsia premature delivery hemorrhage fetal growth restriction stillbirth maternal mortality The causes for these are unclear, but they are probably reduced by optimal management of both epilepsy and of the pregnancy.
Having seizures increases risk to both mother and foetus, so maintaining the lowest risk of seizures is important. About half of women have no change in seizure frequency during pregnancy, but some may have increased siezures during this period which require changes in management.
Drug management can be challenging - partly because pregnancy changes the clearance and half life of many anticonvulsant drugs. Monitoring of drug levels can be helpful in maintaining effective levels and altering doses.
When is reduced red desaturation seen?
optic neuritis
