Types of seizures: a question and an answer

One of the readers of my blog sent me this question.  Thank you for the same. My answer follows.

 

QUESTION

I experienced something a few days ago. Without any warning as I was getting out of my chair, I hit the floor hard. I woke up after a few seconds and I was in a cold sweat, shaking and confused. I tried to get up, but, I couldn’t move for another few seconds. I am under a Neurologist’s care and he suspects complex partial seizures due to an abnormality on an EEG, but, he is not too sure. I went to the ER and everything seemed normal. I had another episode a few days later, the same thing, except this time I was just walking from one room to another and it happened. I have no idea what this could be. I have been accused of “spacing out” and I have callouses on my left finger knuckles. I never realized I was rubbing my fingers enough to get callouses. Is this seizure or just passing out? So confused!!

ANSWER

Dear so confused,

thank you for writing in. The episodes do sound suspicious for seizures though as my post indicates there is a broad differential of sudden unexplained loss of consciousness. Broadly speaking there can be three types of seizures:

1. Generalized seizures: as the name suggests in primary generalized seizures, the seizure starts off from the entire brain at the same time. So for example if you were to suffer a generalized seizure while the EEG is running, the EEG will show abrupt onset of epileptiform activity from the entire brain (both the hemispheres). Primary generalized tonic clonic seizures (at times referred to as grand mal seizures) are quite dramatic. If the person is standing when the seizure strikes, he shall suffer loss of body tone and fall down. Patients usually strike the ground hard and may suffer craniofacial injury as a result. There is complete loss of consciousness (so the patient shall be amnestic for the seizure). There is an initial tonic phase where in the body stiffens. This is soon followed by a clonic phase where in rhythmic inphase jerks of the limbs are observed. The patient may suffer a tongue bite or may suffer loss of bladder control during the ictus. The seizure itself lasts for about a minute or two and is followed by a more prolonged post ictal phase during which the patient has stopped shaking but is somnolent and difficult to arouse. The past ictal phase may last for about an hour with slow recovery to complete consciousness and a return to baseline. Of note the staring spells seen in children (also called Absence Epilepsy) is a type of generalized epilepsy.

2. Focal seizures/ partial seizures: as the name suggests these are seizures which arise from a focal area in the brain. Focal seizures are not accompanied by a complete loss of consciousness. Rather there is impairment in the level of consciousness/ awareness. Let me explain further. Let us assume that you are right handed. In people who are right handed, the left hemisphere is the dominant hemisphere and in the left temporal lobe is the speech center. Let us assume you suffer a focal seizure arising from the left temporal lobe. There shall be a sudden arrest in your behavior and you may stop speaking (since the left temporal lobe is now misfiring). If I speak to you at this time, you shall not reply back to me and you may not recall that I had spoken to you later. That said unlike a generalized seizure, you do not fall down and do not convulsive. Patients do display some non purposeful movements such as lip smacking and picking at the clothes. This is referred to an automatisms.  Prior to the onset of the seizure, patients may report an aura. The typical auras which are reported including an unpleasant smell (burning rubber), rising sensation in the tummy, a spinning sensation, unpleasant taste, psychic phenomena such as fear and so forth. This type of seizure is what we doctors refer to as a complex partial seizure (complex because awareness is impaired).

3. Focal seizure with secondary generalization: I think this is simple to understand now. The seizure starts off as a focal seizure but then spreads and crosses over to the other side of the brain and very soon (in a matter of milliseconds) the entire brain is showing the epileptiform activity. So initially you have a behavioral arrest and cannot speak but then very soon your entire body tenses up and you start convulsing.

There are other types of seizures some of which occur in the pediatric age group. At present I shall not dwell on them.

I hope I have been able to explain seizures to you in very simple terms. Follow up with your doctor. My very best to you.

Personal Regards,

Nitin Sethi, MD

Complex partial seizures/ temporal lobe epilepsy

One of the most common type of seizures seen in the adult population is what are called complex partial seizures. As the name suggests these are partial seizures  meaning that only a part of the brain has the seizure (remember in generalized seizures the whole brain has the seizure and hence the patient clinically has a convulsion, read my posts on epilepsy and seizures at http://braindiseases.info). Complex partial seizures differ from simple partial seizures. While in simple partial seizures there is no disturbance in the patient’s level of consciousness (the patient is awake and alert), in complex partial seizures there is an impairment in the level of consciousness. The patient may have his or her eyes open but usually is unable to respond or communicate. He may or may not comprehend if you try to speak to him during a seizure episode.

As many of the complex partial seizures arise from the temporal lobes in the brain, epilepsy of this kind is also referred to as temporal lobe epilepsy (TLE). That said and done complex partial seizures may also arise from the frontal lobes. Seizures arising from the frontal lobes can present with bizzare clinical manifestations, patient may become hyperactive during the seizure and have strange bicycling like movements of the legs. Complex partial seizures are at times associated with an aura. A simple way to define aura is what happens usually before the seizure. Prior to the onset of a seizure, the patient may experience gustatory or olfactory auras (smell of burning rubber, metallic taste in the mouth are the different classical auras mentioned in the textbooks of neurology). Other patients may mention they “feel wierd” or “dizzy”. Others mention a rising sensation in the stomach.

During the seizure apart from impairment in the level of consciousness, patients frequently exhibit what we refer to as automatisms. These are semi-purposeful movements. Examples include lip-smacking, chewing movements, tongue protusion, picking at the clothes (semi-purposeful movements of the hands). These patients may or may not have a “convulsion”. If the seizure spreads and becomes generalized then they go into a convulsion (such seizures are referred to as partial with secondary generalization).

If an adult presents with a new onset complex partial seizure, neuroimaging is warranted. This is because a new onset complex partial seizure raises the suspicion for an underlying structural lesion in the brain such as a cyst or a tumor (though I want to emphasize here that the most common cause of new onset seizures in the elderly is vascular, meaning a previous stroke).

Work-up for TLE includes an EEG, if needed a long term EEG recording (we call this a video-EEG study), imaging studies like CT scan (though the study of choice is what is called a MRI scan of the brain done under the epilepsy protocol). Thin slices are taken to look at the temporal lobes and hippocampus to make sure there is no structural lesion there nor is there any evidence for mesial temporal sclerosis (MTS).

There are many effective drugs for complex partial seizures/TLE. The most commonly used are carbamazepine (Tegretol) and oxcarbazepine (trileptal). If the seizures are refractory to medications, these patients can be worked up for epilepsy surgery (see my post on epilepsy surgery at http://braindiseases.info).

Nitin Sethi, MD