Post traumatic epilepsy: a question and an answer

One of the readers of my blog asked me a question regarding her son. I am reproducing her question here. My answer to it follows.

V

my son was involved in a car crash 3 years ago aged 17 years and required brain surgery to remove a bloodclot. He recovered well with no ill effects. He had his first fit in November 2009. He had another 2 that same month. CT and MRI scans clear but eeg showed slight abnomal waves over area of surgery. Neuroligist said our choice if wanted to be on medication. Last fit was 27th November 2009 but he has just had another on 8th February whilst flying to holiday Do you thnk meds should be started to prevent further fits.

Dear V,

                    thank you for writing in to me. Your son’s condition is consistent with what is called post traumatic epilepsy. Let me attempt to explain this a little further. Your son obviously was not born with a seizure disorder (epilepsy). He was apparently well till he was involved in a motor vehicle accident (MVA). As a result of the MVA, he suffered head injury and from what you decribe an intracranial hematoma (blood clot) which required evacuation (removal of the blood clot surgically). He had an uneventful recovery but soon there-after had his first convulsion (you do not mention the time interval between the head trauma and the first convulsion).

As the name suggests post traumatic epilepsy refers to epilepsy/ seizure disorder which occurs after head trauma. Usually for post traumatic epilepsy to occur, the head trauma has to be significant such as a motor vehicle accident with significant intracranial hemorrhage or head injuries sustained in the battle field. Many of our soldiers returning from the battlefields of Afghanistan and Iraq suffer bullet shot injuries to the head (these as you can imagine are penetrating head injuries and cause significant brain damage as the high velocity bullet traverses through the skull). IED (improvised explosive devices) related blast injuries cause closed but still significant head trauma and are the signature injury of these two wars. Many of these brave men and women later develop post traumatic seizure disorder/ epilepsy. In other words minor bumps to the head (example you walk into a door) do not cause post-traumatic epilepsy.

There are three types of post traumatic epilepsy. Immediate, early and delayed. Let me explain this at length. Let us assume you are involved in an accident. Your head strikes the ground or steering wheel hard. You have a seizure soon after the impact. This is called immediate or impact seizure. This type of seizure does not lead to seizures later in life and hence such a patient does not warrant to be on long term anti-convulsant therapy.

Early post traumatic seizures are those which occur within 6 months of injury while late post traumatic seizures are those which occur after 6 months. Remember you can have your first post traumatic seizure as long as 5 years after the head injury. In other words if 18 months go by and the person has not had a seizure then likely he shall not have seizures as a result of head trauma. Patients who have early and late post traumatic epilepsy may warrant treatment with anti-convulsants. This is because the brain has suffered a scar (as a result of the head injury) and it is this scar tissue (consisting of damaged brain tissue) which then misfires and acts as a seizure focus (point in the brain where the seizure originates from).

In the case of your son, since he has suffered multiple convulsions since his head injury, he likely needs to be on an anti-convulsant. This decision though shall be made by his neurologist after consideration of factors which I mentioned earlier in my post. EEG may or may not be helpful in this regard (a normal EEG does not rule out seizure disorder and vice versa not every patient with a seizure disorder has an abnormal EEG).

I hope this is helpful to you. I wish him my very best.

Personal Regards,

Nitin Sethi, MD

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