Epilepsy

Fatigue | Mood | Cognition | Epilepsy

Epileptic seizures, in people with brain tumours, are due to episodes of “excessive activity” in a focal region of the brain (cerebral cortex) that contain nerve cells. Excessive activity will cause an excess of function in that focal area of the brain.

Video: What is a seizure?

The left side of the brain controls the right side of the body and vice versa.

Video: Types of seizures

Motor seizure in frontal lobe - A tumour in the area that controls movement in the arm, will cause over-activity, or involuntary jerking in the arm on the opposite side (rather than weakness). If the seizure focus was in the leg area of the brain, then the jerking would start in the opposite leg. If in the face or eye movement areas, then the face may jerk or eyes jerk to one side.

Sensory seizure in parietal lobe - Excessive activity in the area controlling sensation on the opposite side will cause burning, freezing, or tingling in that limb (rather than numbness).

Visual seizure in occipital lobe - A seizure in the visual cortex will cause a hallucination of vision e.g. colours or objects in the opposite visual field (rather than a loss of vision on the opposite side).

Psychomotor seizure in temporal lobe – will cause odd hallucinations of smell (burning, rotten smell) or taste (horrible taste) or memory (deja-vu – recurrent memories often difficult to describe), or a rising feeling coming up from the stomach like “butterflies” or heat.

The features that seizures generally have in common are that they are:

  • short lived (seconds to few minutes);

  • stereotyped (always the same onset and symptoms) and

  • non-situational (can come on at any time).

  • They settle spontaneously without treatment in the vast majority of cases within 2-3 minutes.

Sometimes seizures can be described as “minor” and occur without loss of awareness (simple seizures), or with loss of awareness (complex seizures) or alternatively there may be spread of symptoms to the other side with total loss of consciousness and stiffness then jerking on both sides of the body called a “major” convulsion or tonic-clonic seizure.

Rarely “minor” seizures can continue without stopping or be recurrent several within 20 minutes and this is called “partial (focal) status”. Sometimes “major convulsions can continue and not stop causing “convulsive (generalized) status”, which is a medical emergency.

Brain tumour-related epilepsy (BTRE) is a common complication of cerebral glioma. It has a serious impact on the patient’s confidence and quality of life and can be life threatening.

The risk of seizures occurring in patients with brain tumors depends on:

  • Location of the tumour (cortical > deep hemisphere)

  • Tumour cell type (oligodendroglioma > astrocytoma)

  • Grade (low grade > high grade glioma)


Prognosis
Most physicans agree that presentation with epilepsy is a good prognostic feature, independent of type or grade of malignancy. The better survival in people presenting with seizures may be due to earlier presentation, or that the tumour is cortically placed and therefore more accessible for surgical resection and less likely to be associated with neurological impairment (weakness, numbness or speech problems) and disability.

  • People with brain tumour related epilepsy (BTRE), are at high risk of seizure recurrence after a single seizure, and therefore treatment should be commenced after the first event.


  • Anti-epileptic drug (AED) with simple or complex partial epilepsy should be started at a low dose, with a slow subsequent increase in dose if seizures continue. The slow introduction reduces risk of side effects.


  • For major /generalized epilepsy drugs may have to be started more quickly to reduce the risk of recurrent major seizures. Sometimes this is done using AEDs into the vein (intra-venous) e.g. phenytoin, levetiracetam, valproate.


  • Major seizures are generally well controlled by AED medication, if it is taken regularly - >90% complete control.


  • Minor seizures are more difficult to control completely with medication and seizures can continue in about <50% of patients, but at reduced frequency.</li>