Neurology

Epilepsy

Definition

  • Epilepsy is defined as "the recurring tendency to have seizures" which begs the question of what is a seizure ?
  • A seizure is an abnormal paroxysmal discharge of cerebral neurons resulting in a clinical event.
  • You need to have 2 or more seizures to have epilepsy.
Incidence
  • Epilepsy is seen in 1% of the UK population with bimodal peaks in both young and the elderly.
  • One must always remember that under provoking circumstances we all have the tendency to fit (seizure), it's all a matter of threshold levels.

Terminology

  • A simple rather than complex seizure means that during the seizure that consciousness is unimpaired and memory of the event is unaffected. The patient remains awake and aware of the seizure in progress.
  • A complex seizure suggests impaired memory or consciousness or both.
  • Seizures can also be focal - localised to one area of the brain e.g. a motor or sensory seizure causing symptoms in a limb, or be generalised such as with generalised tonic-clonic seizure.
Driving
  • Remember that a single seizure does not equal epilepsy. Many have a single seizure with no recurrence. However all patients must avoid driving after even a single seizure and should be informed to inform the DVLA. Taht is the doctor's responsibility and you must document it in the notes.
  • The driving license may be suspended for 6-12 months post seizure in the UK. It is the doctor's job to advise and to record that in the notes. It is the responsibility of the driver to inform the DVLA.
  • It is recommended in the UK that all new diagnoses of seizure should be reviewed by a neurologist or physician with appropriate expertise.
  • In many patients ongoing care can be through general practitioners but some patients may require more ongoing specialist support.
  • This is especially true in young patients where issues around compliance, pregnancy, driving, lifestyle can be complex. There is increased awareness of the need to discuss SUDEP.

Aetiology

  • The aetiology of epilepsy is complex. It may be considered as structural (focal) or non structural. At neuronal synaptic level neurons receive both inhibitory and excitatory inputs.
  • If the excitatory Post synaptic potentials far exceeds inhibitory post synaptic potentials this can lead to a paroxysmal depolarisation shift detected as a spike and wave pattern.
  • Intrinsic to this are localised Ca2+/Na+/K+ ion exchanges and the neurotransmitters such as the excitatory - glutamate and inhibitory - GABA.
  • In some patients there is an obvious focus however in younger patients with idiopathic epilepsy cell membrane and ion pump disorders are suspected.

Risks and precipitants

  • Epilepsy is more common following SAH, in the presence of an AVM, Brain injury - surgery, trauma, stroke, meningitis, encephalitis, tumour, hypoxia, Congenital lesions. It is also associated with drug overdosage of cocaine and theophyllines and drug withdrawal of alcohol, benzodiazepines, barbiturates and AEDS. It is classically seen with Eclampsia. It is commoner in Alzheimer's disease. Seizures may be triggered by tiredness, menstruation, drugs, alcohol excess or withdrawal and poor compliance with AEDs. Be sure to look for precipitants and risk factors.
  • Clinically as mentioned already one can use the following terms to describe a seizure. Simple (Consciousness unaffected), Complex (consciousness affected or amnesia). A seizure can start focal and go on to be generalised. The key to diagnosis of a new event of suspected seizure is the eye witness account. This is the key to the diagnosis and every step must be made to get an accurate second by second account (I have rung friends and relations in the clinic to get the information). With repeated seizures patients or their partners should keep a seizure diary. Beware the early misdiagnosis of seizure especially in cases of syncope. Even a simple vasovagal faint can be accompanied by abnormal jerky movements but recovery should be rapid. Fainters too can have urinary incontinence.
  • Findings suggestive of a generalised seizure rather than syncope are tongue bite usually side of tongue, Urine/Faecal incontinence, Shoulder dislocation, Bruising, Post ictal drowsiness for several hours and headache. A precipitant or family history should also be sought.

Investigations

  • FBC, U&E, LFT, Blood glucose, Calcium. Never miss Hypoglycaemia.
  • CT Brain is useful for the first seziure to exclude haemorrhage or fracture or other underlying cause. later an MRI may be done and is the imaging modality of choice which can be done following discharge.
  • Toxicology screen may be useful in selected cases. CK and Prolactin elevated post fit but have limited usefulness and there may be also positives - most who lie on the floor for several hours have a raised CK. There are many other causes of a raised prolactin.
  • EEG - If assessed during attack (it may be normal between attacks) may show changes. Simple motor seizures show focal epileptic activity. Simple sensory seizures show spike or sharp discharges. Generalised tonic clinic show generalised spike and wave and absence seizures show 3-s spike and wave pattern. Temporal lobe show spokes or sharp waves over temporal lobes. If the EEG is normal then provoke with sleep deprivation. In difficult cases Video with EEG monitoring is helpful.

Management

  • Management is focused around ensuring the diagnosis is correct, encouraging a normal life as much as possible, reducing seizure incidence, establishing a mutually agreed anti epileptic drug (AED) once options are discussed.
  • AED use only occurs after the second seizure or with a single seizure with a high risk of recurrence. Discuss risks and benefits with patient/parent. Explore expectations. Maximise dose of one AED before adding a second. Beware interactions between drugs especially the contraceptive pill which can have reduced effects as many of the drugs induce liver enzymes. If seizures not initially controlled on a therapeutic dose then switch to another drug by withdrawing and staring with an overlap period of 3-4 weeks.
  • However this is the remit of the neurologists and all patients should see a specialist at least initially to review diagnosis and therapy.
  • Refractory cases consider add on therapy - Lamotrigine, Topiramate, Tiagabine, Gabapentin, Levitiracetam.
  • Surgery: Rarely patients may benefit from surgery such as resection of a lesion, Modified temporal lobectomy for Mesial temporal lobe sclerosis or Vagal nerve stimulation implant.
  • Driving advice must be given and documented as mentionned above and advise against dangerous situations e.g. swimming alone, cycling, ladders, avoid locking doors, bathing, handling dangerous equipment where a loss of awareness could cause injury to patient or others
  • Sudden Unexpected Death in Epilepsy (SUDEP) is a rare event with no cause identified. It should be discussed with patients and should underlie the emphasis on good drug compliance, good seizure control and avoidance of seizure precipitants as this may reduce the risk of SUDEP.

Complex partial seizures

Introduction
  • About 60% of Epilepsy suffer amnesia or a loss of consciousness which makes a partial seizure into a complex partial seizure CPS.
  • These most commonly originate in the temporal lobe. They can secondarily generalise into a tonic clonic seizure.
Clinical
  • Patients may recall an odd perhaps or unpleasant Smell or taste, feeling in stomach and other visceral sensations.
  • Some describe deja vu, loss of speech, automatism e.g. lip smacking or simply stare into space for a few seconds.
Investigations
  • An MRI should be done in addition to basic investigations to exclude a structural lesion such as mesial temporal sclerosis or grey matter heterotopia. An EEG - If assessed during attack (EEG may be normal between attacks) Partial motor seizures may show spikes or sharp waves over the temporal lobes.
Management
  • Patients with complex partial seizures respond best to drugs such as Valproic acid, Ethosuximide, Gabapentin, Topiramate.
  • Mesial temporal sclerosis may be treated by neurosurgical resection where medication is ineffective.

Primary Generalised seizures

Approximately 30% of Epilepsy are primary Generalised - both hemispheres involved from the onset rather than sSecondary generalised from a partial seizure. In these patients evidence suggests no structural abnormality but possible a possible genetic cell level ion channel disorder as the substrate in many patients.

Clinical there may be an aura and then a tonic phase which lasts 10-20 seconds and the patient falls to ground often followed by a clonic phase generalised bilateral muscle movements, tongue biting and urinary or even faecal incontinence. The clonic phases typically lasts up to 5 minutes and after the patient is comatose and there is post ictal confusion

Investigations include basic bloods and CT acutely if any conerns or new episode or concerns over head trauma. AN EEG and MRI may be considered in follow up especially if any suggestion of CPS

Management of primary generalised seizures is either Phenytoin, Valproic acid, Lamotrigine or Carbamazepine. Phenytoin is used less and less nowadays and really only for acute IV administration.

Simple Partial (Focal) seizures

With these there is no altered consciousness or amnesia they however can secondarily generalise. Clinically they can be partial motor affecting the motor cortex and can pass from mouth to hand to arm along motor homunculus. Occasionally can leave a temporary paralysis called Todd's paresis. Typically turning of head to opposite side, twitching of hand to arm or to face "jacksonian march" . Similarly if the senosry cortex is affected there can be partial Sensory (sensory cortex) seizures if there is tingling or paraesthesia or even warmth over one side of body, May spread from leg to arm to face or vice versa. Spread is over 20-60 seconds and not instant as with TIA.

Investigations again include CT initially with first presentation to look for focal disease and then EEG and MRI should be considered to exclude focal lesion e.g. tumour, stroke

Management for focal seizures with generalisation - Phenytoin, Carbamazepine, Vigabatrin, Valproic acid

Pseudoseizures

Introduction
  • These can fool and challenge even the most experienced. Patients can end up intubated, paralysed and ventilated.
  • More complex as may be seen in those with pre-existing epilepsy and psychiatric disorders.
  • May be difficult to diagnose and manage as initially seen by juniors and non specialist who treat as seizure.

Clinical

  • Fits invariably occur in a public area with witnesses, flailing and the patient may resist opening of eyes, Incontinence and tongue biting may be seen.
  • Tip of tongue rather than side of tongue which is more common with seizures. There is a lack of post fit drowsiness those this can be feigned.

Investigations

  • Prolactin and CK may be normal which is useful but if elevated doesn't necessarily make the diagnosis.

Management

  • Psychological support and usually difficult and holistic. Involve general practitioner who may be in the best place to manage.

Status epilepticus

Definition
  • This is ongoing seizure activity without return to consciousness for over 30 minutes (most would consider 5 minutes too long)
  • It is potentially life threatening as it leads to high metabolic activity and Untreated can lead to death.

Causes

  • Changes in AEDs or failure to take them
  • Hypoglycaemia, cocaine and alcohol
  • Tiredness, Trauma, Late pregnancy (eclampsia)
  • Encephalitis, Liver failure, Uraemia
  • Hypocalcaemia, Low magnesium

Clinical

  • Ongoing generalised seizure, High tone tonic phase, Followed by clonus, Impaired consciousness.
  • Fits recur or persists despite treatment. Can take many hours to wake up even after fitting has ceased.
  • Be aware of Sudden unexplained death in epilepsy (SUDEP) due to a seizure related cardiac arrhythmia

Investigations

  • Include blood sugar, calcium, CXR. Look for signs of infection, head trauma and drugs - urine toxicology.
  • CT scan may be needed acutely to exclude pathology.
  • Lumbar puncture may be needed to exclude meningitis or encephalitis or SAH bleed.

Management

  • ABC + DEFG (Don't ever forget glucose) - High flow Oxygen and manage airway and circulation needs. Watch the clock to see how long fitting continues and escalate
  • Manage with IV fluids. Exclude hypoglycaemia and if unsure or if any doubt at all give IV glucose.
  • If there is any concern about Meningococcal meningitis e.g. blanching, fever, neck stiffness then treat also.
  • Get IV access and protect it. Slow IV lorazepam 1-4 mg. Diazepam rectally is useful if no access.
  • Once lorazepam made up and given and fits continue prepare IV phenytoin or fosphenytoin with ECG monitoring.
  • Get ITU help early which may mean paralysis and ventilation

Juvenile myoclonic epilepsy

An interesting form of idiopathic generalised epilepsy. Presumed genetic basis. It is seen in young adults where there may be generalised tonic clonic fits precipitated by sleep deprivation, classic Myoclonic jerks typically in mornings "cornflake epilepsy". Investigations show a normal MRI and EEG shows polyspike pattern. Management is lifelong AED therapy with sodium valproate. Withdrawal universally leads to relapse

Absence seizures

These are typically seen in children but may occur rarely in adults. Clinically the patient has a loss of awareness 5-10 seconds whilst eyes are open. Patient remains standing but unresponsive

Investigations such as EEG shows 3-s spike and wave. Management is that they responds best to valproate

West syndrome

These are seen in infants and usually caused by developmental and other disorders. Commonest in 1st year of life and those affected can have up to 100 attacks per hour where the baby flexes forwards with arms outstretched. Myoclonic jerks are seen

Investigations such as EEG show high amplitude slow waves with sharp waves and spikes at varying locations (hypsarrhythmia)

Prognosis is poor. Treated with ACTH over several weeks and anti epilepsy drugs