Diagnosing Epilepsy

Some of this information has been presented in various posts below, but I wanted to add it here in the context of diagnosing epilepsy.

Epilepsy is diagnosed upon having more than one unprovoked seizure. Identifying the type of seizure is critical in deciding the appropriate treatment. It is a good idea to see an epileptologist to increase the likelihood of accurate diagnosis and treatment.

Types of Epilepsy

Symptomatic Epilepsy
Approximately 30-40% of patients with epilepsy have “symptomatic” seizures. These are seizures associated with a specific structural abnormality in the brain. Such abnormalities can include tumours, brain injury, infections, scars, and blood vessel malformations (Browne & Holmes, 2001). Symptomatic epilepsies are the hardest to treat and are often drug-resistant (Kwan & Brodie, 2000).

Idiopathic Epilepsy
Sixty to seventy percent of patients with epilepsy have “idiopathic” seizures. These are seizures that occur in an apparently normal brain. Idiopathic seizures are thought to be caused by a subtle biochemical or ionic imbalance, probably inherited. These seizures tend to respond favourably to anticonvulsant drugs.


Types of Seizure
Seizures are classified as “partial” (focal, local) or “generalized” (global).

Partial Seizures
Partial seizures, initially, involve only a portion of the brain. The three forms of partial seizures are simple partial, complex-partial and partial seizures that secondarily generalize.

Simple partial seizures are usually non-motor seizures that involve certain sensations (e.g. flashing lights, odd smells, strong anxiety). Those who experience a simple partial seizure remain conscious and alert throughout the seizure. These seizures typically last less than two minutes. Simple partial seizures may secondarily generalize (spread) to other brain structures.

Complex-partial seizures begin as a focal or “partial” seizures and spread to become partially generalized, which causes impairment of consciousness. The patient is not unconscious, but is unaware of the environment around him. Impairment of consciousness is what makes the seizure “complex”. Complex-partial seizures are often preceded by an “aura”, that warns the patient the seizure is going to occur. The aura is actually the simple partial seizure that triggers the complex-partial attack. During the seizure, “automatisms” may occur. These non-reflex movements can involve oral automatisms (e.g. chewing, lip smacking, and swallowing) or “ambulatory automatisms” (e.g. rubbing or picking hand movements, running or walking). Patients have no memory for the period of the seizure. Complex-partial seizures typically last between 30 seconds and 2 minutes but can leave the patient mentally hazy or confused for hours.

Generalized Seizures

Generalized seizures involve the entire brain. There are various types of generalized seizures, including absence seizures, myoclonic seizures and tonic-clonic seizures.

Absence seizures are characterized, behaviourally, by a sudden loss of consciousness accompanied by brief staring spells. Electrographically (ie, the pattern you see on the EEG), absence seizures are characterized by a three-per-second spike and wave discharge. Absence seizures tend to be very short (3-10 seconds) and they can occur many times in a day.

Myoclonic seizures involve a sudden jerking movement of the body. These seizures only tend to last a second or two but can recur frequently.

Tonic-clonic seizures are what many people think of when they hear the word “epilepsy”. They are seizures where the individual is unconsciousness and experiencing a convulsions (full body involuntary motor movements). The words “tonus” and “clonus” apply to the muscle actions involved in the convulsions. Clonus refers to a rapid succession of muscle contraction and relaxation, leading to jerking-like movements. Tonus refers to a constant state of contraction. This usually causes the limbs to stiffen and to flex or extend. Tonic-clonic seizures tend to last between one and two minutes, although they may last longer.

What Does This Mean for You?

It is important that you continually seek consults, tests, etc. until you can answer these three questions with confidence:

1) What type of epilepsy do I have? (partial seizures, absence seizures, etc.) If this is unclear, then the type of drug you need is unclear. This question can be answered through careful description of your seizures combined with EEG. Other tests may also be required.

2) What are the appropriate/best drugs for this seizure type? The first treatment option is almost always drug therapy. It is important to be prescribed the correct drug for your seizure type. Some drugs can make your seizures worse.

3) Are you a candidate for neurosurgery? This is the only potentially curative treatment. It is important to know if you may be a candidate. The test to determine this is admission to an EMU (epilepsy monitoring unit). You will be hospitalized and hooked up to an EEG and monitored daily until you have a seizure.

Things have been really busy, so I haven't been posting as much lately. Nonetheless, I'll continue to try and get something up every week or so.

Have a good one.
Kirk.