Introduction

Epilepsy

Epilepsy is a term that has as little specificity as the word cancer. Just as cancer describes a large family of diseases all of which are linked by the occurrence of uncontrolled, abnormal cellular proliferation, epilepsy describes many diseases and disease states. In this case they are all linked by the occurrence of spontaneous seizures.

Seizures

A seizure is an abnormal synchronous discharge in a group of neurons that may or may not have clinical symptoms. Seizures generally have a sudden or paroxysmal onset, endure for seconds to minutes, and then end just as suddenly. Depending on the seizure, a patient may have residual transient symptoms following the end of the electrical discharge (what’s called the postictal state).

The symptom complex of a seizure, including the time course of symptom onset and evolution, is called its semiology. (This derives from the Greek σημεῖον meaning “sign.”)

Seizures are commonly understood by the lay population, and even by many physicians, as any kind of sudden and transient change. Any number of phenomena including syncopal collapse, shaking TIAs, conversion reactions, benign myoclonus, and paroxysmal dyskinesias may be construed by patients as seizures. It is most helpful if we insist on defining seizures strictly and choose less specific terms, such as spell, event, or the like to describe attacks of undetermined etiology.

Seizures are an abnormal brain state; they are necessarily a pathological phenomenon.

Spontaneity

Epilepsy is characterized by the occurrence of spontaneous seizures.

By spontaneous we mean seizures that do or may occur without an acute triggering injury.

When a patient sustains a traumatic brain injury, or endures a toxic-metabolic encephalopathy, etc, they may experience seizures as a direct response to the nervous system derangement. Seizures may result from acute withdrawal from alcohol or benzodiazepines. They may also occur in susceptible children with high-spiking fevers. Such seizures are often called provoked seizures.

Spontaneous seizures occur even in states of health or at times remote from an acute derangement. They still may be symptomatic insofar as there is a chronic lesion, but in these cases we view the lesions as causes of the underlying predisposition to seizures rather than of the individual seizures themselves.

Spontaneous seizures may still be triggerable. A small number of patients with primary generalized epilepsy or reflex epilepsy may have seizures in response to repetitive flashing lights. Absence epilepsies may be activated by hyperventilation. What makes seizures provoked is an acute pathological change to the brain.

Epilepsy again

Epilepsy is any disorder in which the patient has an enduring predisposition to spontaneous or unprovoked seizures along with the neurobiologic, cognitive, psychological, and social consequences thereof.

There is a clinical definition as well that operationalizes the enduring predisposition concept. Epilepsy is diagnosed when

  1. A patient has two or more unprovoked seizures at least 24 h apart.
  2. A patient has one unprovoked seizure along with clinical, physical, or diagnostic evidence of an increased risk (conventionally >60%) of future spontaneous seizures.
  3. A patient has one unprovoked seizures along with evidence of a well-described epileptic disorder.

Basic Epi

Epilepsy is one of the most common chronic neurologic illnesses. It affects 0.5–1.0% of the world population. Over lifetimes, 1 in 26 people will suffer from epilepsy.

The outlook is somewhat favorable. Around 2/3 of patients with epilepsy will be controlled using medications. Control in epilepsy means zero seizures. Phrasing such as “poorly-controlled” or “somewhat well-controlled” are meaningless; patients are either controlled or not.