The basics - Epilepsy

Dr Anna Cumisky reviews the essential elements of this neuronal disorder.

Epilepsy can be defined as 'a sudden and transient alteration in behaviour caused by abnormal, excessive neuronal discharge in the cerebral cortex'.1

SPECT scans of axial sections through the brain of a two year old during an epileptic seizure (SPL)

The abnormal neuronal discharge may manifest as loss of consciousness, abnormal motor phenomena, psychic, sensory or autonomic disturbances. A single episode is termed a seizure and epilepsy generally describes recurrent seizures.

Causes
Any individual would undergo a seizure if put into the correct sort of environment. Metabolic disturbances, patterns of bright lights, head trauma or similar insult could trigger such an event in an otherwise normal person.

Those who suffer epileptiform seizures on a more regular basis have a lower threshold for this. Threshold lowering may be secondary to structural changes of the neurological system, such as trauma, infective collections or space-occupying lesions, chemically-induced changes, for instance metabolic change or secondary to alcohol or recreational drugs, or idiopathic, where the cause is unknown.

In the majority of cases no cause is found and a diagnosis of idiopathic epilepsy is made.

Understanding the label
Epilepsy is commonly classified according to the areas involved. Both idiopathic and secondary types can be subdivided into partial and generalised varieties.

Partial seizures begin in one part of the brain, whereas generalised seizures have their onset simultaneously in both cerebral hemispheres. Partial seizures can be subdivided into simple, complex or secondarily generalised varieties.

Simple partial seizures remain localised to one region of the brain and consciousness is retained, whereas in complex partial and secondarily generalised cases there is propagation of the initial seizure focus causing impairment or loss of consciousness. In generalised seizures, consciousness is lost.

Differential Diagnoses
  • Vasovagal episode
  • Situation syncope eg cough, effort, micturition, carotid sinus massage induced
  • Adams-Stokes attack
  • Stroke or TIA
  • Hypoglycaemia
  • Drop attacks
  • Choking
  • Hyperventilation and anxiety
  • Pseudoseizures/hysteria

History taking
Many people will have an episode of transient loss of consciousness at some stage in their lives but very few will be diagnosed with epilepsy. Careful history taking is key in diagnosing between faints, fits and other causes for impaired consciousness.

In any seizure, and especially the first, careful history taking is vital and a witness statement invaluable. That said, be cautious regarding details.

Rhythmical movements are frequently noted but can be a misleading sign and may be confused by a witness with twitching movements seen during vasovagal collapses.

Urinary incontinence can similarly lead to a false positive diagnosis. Tongue biting is usually more reliable and should certainly raise suspicion of epilepsy.

History taking should focus on pre-seizure, during seizure and post-seizure events. Enquiring about abnormal sensations such as smells or auditory impulses prior to a seizure may identify an aura. Triggers for a seizure may include flashing lights, computer games or television programmes.

A witness can help describe the seizure itself, although individuals can usually recall themselves whether urinary incontinence or tongue biting featured. Post seizure there is normally a classical post-ictal state when a person feels exhausted, sometimes with headache.

This can last some hours, although examination is usually unremarkable apart from a possible tongue lesion.

Persistent focal signs, concurrent severe illness or similar red flags should trigger an emergency admission.

Hyperplasia of the upper gum as a side-effect of long-term phenytoin treatment

Management
Classical seizure-type behaviour should raise suspicion of epilepsy and warrants referral, but a formal diagnosis is best left to a specialist.

The speed of referral will depend on the likely cause of the seizures, the clinical state and age of the patient. Certainly not all patients require emergency admission after an initial seizure. However, it is important to be familiar with the red flags to ensure such circumstances are dealt with appropriately.

A diagnosis of epilepsy has important repercussions for any patient, with implications for employment, insurance and driving. The speed of referral does not preclude the need for any patient suffering a seizure to be advised not to drive pending specialist assessment. Care should be taken to document that this discussion has taken place. Other considerations, for instance safety issues regarding bathing alone should also be discussed.

Anticonvulsant medications can have unpleasant side-effects and should be initiated by a specialist unless in the case of emergency, such a status epilepticus. Regular medication is rarely started after an initial event.

Status epilepticus
Status epilepticus describes recurrent seizure activity for more than 30 minutes. It is a medical emergency and requires a 999 ambulance call.

Until the ambulance arrives, ensure the patient is given safe space to fit and administer rectal diazepam to help bring about the end of the fit. Avoid any temptation to insert airways or hold down the patient.

Epilepsy in children
Epileptiform seizures in children can also be generalised or partial. Generalised seizures tend to show one of four patterns. In a grand mal seizure, individuals stiffen visibly and subsequently start to rhythmically jerk forcefully (tonic-clonic seizure).

Absence seizures describe brief pauses that can occur at any time, including during speaking or eating. The child is unaware of the brief loss of consciousness.

Infantile spasms tend to affect babies around five months of age. A baby is observed to jerk forward with arms flexed and hands extended repeatedly every two to three seconds.

Myoclonic fits are when a young child is seemingly thrown to the floor. Partial seizures can also affect children and may or may not involve impaired consciousness (simple or complex).

The main differential diagnosis in children is that of a febrile fit. This is diagnosed if tonic-clonic seizure activity occurs during a normally developing child as fever rises rapidly during a concurrent illness not affecting the CNS. The seizure itself is brief (less than five minutes) and self-limiting.

Of the 3 per cent of all children who have a febrile fit only 1 per cent will go on to develop epilepsy. The susceptibility of a febrile fit is increased in other family members.

Management should focus on ensuring the child is in a safe environment by removing objects that may cause injury from the vicinity of the fitting child and placing the child prone in the recovery position after a seizure has ended.

Fever reduction used to be NICE recommended but current guidelines state that while analgesics are used to help symptoms of associated febrile illness they do not reduce seizure activity.

Some children will require rectal diazepam to terminate seizure activity. Parents tend to attend A&E or the GP with the initial event and education is vital. Support groups and advice leaflets are valuable.

Consider giving rectal diazepam tubes to keep at home for future attacks.

A diagnosis of epilepsy can be extremely frightening for all concerned.

Good support is vital and various websites and support groups are available, such as www.epilepsysupportcentre.com and www.epilepsy.org.uk.

  • Dr Cumisky is a GP locum in Bath
Red Flags
  •  Onset >30 years
  • Persistent focal neurology
  • Recent history of head/neck trauma
  • Seizure in immunosuppressed patient
  • Seizure with known drug use or alcohol dependency
  • Seizures in patients with cancer diagnosis
  • Seizures following new medication initiation
  • Seizure in clinically unwell patient eg symptoms of infection, meningism, dehydration
  • Crescendo seizures in chronic epileptics
  • Status epilepticus (continued seizures >30 minutes


Reference
1. Rakel R E, Bope E T. Conn's Current Therapy 2009. Saunders Elsevier,
2009.

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