ELECTROENCEPHALOGRAPHY (EEG)

Brain waves were discovered by Hans Berger in Germany in the 1920's and although fond hopes of reading thoughts or finding the snipe of "mental illness" never materialized, the humble and "old-fashioned" EEG remains the ONLY objective test, however limited, for epilepsy and an invaluable clinical tool for distinguishing organic brain syndrome from the extremes of pyschological variation. No matter how bizarre someone's behavior, if the EEG is perfecly normal it is most unlikely that the behavior is inovluntary.

Basically, an EEG can be too slow or too fast.

If the background activity during wakefulness is below the 8 cycles per second (or Herz abbreviated Hz), the lower limit of normal Alpha, then one may expect to see an organic brain syndrome (OBS), that is, confusion perhaps, or stupor or coma. The cause of any particular patient's OBS is rarely implied by an EEG and may be structural e.g. hydrocephalus, brain swelling (cerebral edema), or toxic/metabolic e.g. liver or kidney failure, drug overdose, low thyroid etc.

If the background activity contains excessive fast and/or spiky-irregular activity it is also abnormal and might be compatible with seizures.

SEIZURE CLASSIFICATION

Many systems of seizure classification have come and gone but the types listed below are basic:

Petit Mal activity

(3 per second rhythmic spike and wave, abrupt on/off)

Complex partial

(irregular dysrhythmic spike or polyspike/wave temporal lobe, stuttering on/of)

Grand Mal, interictal

Loma Prieta Quake

The EEG test itself is quite benign: no energy is imparted to the patient. Naturally occurring electrical activity is picked up with surface electrodes, amplified and printed out for analysis.

An EEG is approximately one fourth the cost of an MRI which is by far the better test for structural abnormalities.

But for functional disturbances, slowing or seizure activity, the EEG can pick up problems the MRI will miss.

For example, most patients with epilepsy have normal MRI's and while many patients with epilepsy also have a normal EEG, most do not. While in no way infallible, the electroencephalogram is the only test which can "see" epilepsy.

Thus, the MRI and the EEG complement each other as form complements function.

Electroconvulsiuve therapy (ECT) AND THE EEG

ECT produces changes in the EEG which may last for 6 months.

ECT AND EPILEPSY

"We reviewed all documented cases of spontaneous seizures that followed convulsive therapy. 19 studies provided information in 81 cases.....A longer latency to first seizure was associated with greater likelihood of seizure recurrence, a relationship also observed in postttraumatic epilepsy." Seizures after convulsive therapy: a retrospective case survey. Devinsky O and Duchowny M. Neurology V 33 p 921. July, 1983.

For an annotated, chronological bibliography of ECT "kindled" seizure disorders, stimulate here:

for more Electroshock

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