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Brain Functioning In the Period Between Seizures

Last night I  attended a fascinating lecture sponsored by the NYU Comprehensive Epilepsy Center entitled: "The Impact of Epilepsy on Memory and Thinking" which was given by Dr. Arthur C. Grant, M.D. PhD.

Brain functioning during seizures and the period of time between seizures, known as the interictal period is an area receiving a great deal of attention by epilepsy researchers.  It is now realized that epilepsy and seizures impacts on the functions of the brain even during the periods between seizures.

Here is some of the interesting information that I learned last night:

It is no surprise that during a seizure itself, the portions of the brain that are seizing are not functioning properly. In the last several years, what happens to the brain between seizures has been extensively studied.

Frequent complaints especially from those suffering from temporal lobe epilepsy are reports of memory problems in the periods between seizures. Their most common memory complaints are the failure to remember names followed by general short term memory loss and difficulties in attention and concentration.

Epilepsy specialists have studied the EEG tracings of these individuals in the interictal period and have found that they frequently show short spikes, lasting no more then seconds.  These spikes are not considered to be seizures and are instead called Interictal electrical discharges (IED). Careful neuropsychological testing has shown that when these discharges occur, brain function may be affected.   Additionally activities of the brain that are centered in the area of the seizure focus (where the seizure starts) are prone to be affected in this in between period.

It has also been theorized that the metabolism in the area of the brain is also impaired in the brain regions connected to the seizure focus.  This can be seen in PET scans and SPECT scans which are studies of brain metabolism. 

The cognitive impairments that occur during the discharges are called "Transient Cognitive Impairment"  Studies have shown that approximately 50% of patients who experience these interectial discharges will have transient cognitive impairments which will interfere with reading, driving, memory and response times.

The transient impairments that occur correlate with the region of the brain where these intermittent discharge activity takes place.  Thus, it can affect memory, attention, concentration, balance, speaking, sight, etc., if this is that area of the brain where the discharge is taking place.  It is important the remember that these discharges ARE NOT seizures, but it is still abnormal activity involving a small number of brain cells even in individuals who have well controlled seizures.

Unfortunately, these transient discharges are extremely difficult to suppress even with the use of common seizure medications that control seizure activity.  At this time, there is no reliable way of suppressing these discharges.

This information has important implications to brain injury lawyers who attempt to prove cognitive impairments and their causes including traumatically induced epilepsy and seizure disorder in courts of law.  Lawyers who are representing clients suffering from post traumatic epilepsy need to focus their attention on this interictal period and the cognitive dysfunctions that occur. 

Scalp electrodes may not be able to record these discharges since they occur deep within the brain and do not spread to the surface regions which are recorded by typical EEG studies. A patient with temporal lobe epilepsy can have thousands of these discharges that are not recordable in scalp  EEG's but are recordable if electrodes are placed in regions deep within the brain.

More information on this and other seizure disorders can be obtained by going to the NYU Comprehensive Epilepsy Center site.

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