For the diagnosis of epilepsy, is a PET scan mandatory?

Q. Is PET scan necessary for epilepsy diagnosis?

Answered by
Dr. Lalit R. Bansal
and medically reviewed by Dr. Sneha Kannan
This is a premium question & answer published on Mar 07, 2016 and last reviewed on: Aug 02, 2023

Hi doctor,

My four year old son, weighing 35.27 lb is taking medicine for benign childhood epilepsy. Medicines he is taking are namely Topamac 100 mg a day in two divided doses and Lobazam 15 mg a day (5-0-10). His magnetic resonance imaging (MRI) for epilepsy protocol is normal without abnormalities. I would like to know whether he is taking overdosed medication. Does anti-epileptic drug cause lot of side effect? Doctor suggested positron emission tomography (PET) scan. Is PET scan required for epilepsy diagnosis? Please suggest.



Welcome to For benign childhood epilepsy (BCE) your child is on 6.25 mg/kg/day of tablet Topiramate (anticonvulsant) which is a medium dose and is fine. Side effect to look from Topamac is dehydration. For dehydration, he needs to drink at least 700-1000 mL water daily. He can get tingling in finger which usually responds to taking high potassium diet like banana or raisin. Occasional side effects are kidney stones and word finding difficulty. All anti-epileptic medication comes with some side effects and one has to choose between them and benefit one can have with control of seizures. PET scan is performed in epilepsy patients for surgical evaluation in refractory cases. Is your child still having seizures after taking these two medicines? Also, has he been tried on other medicines before?

Hi doctor,

Thank you for the detailed explanation. His seizure is of focal type. He will get jerks in his left leg (5-7 seconds) and he will be conscious at that time. His seizure will be in control most of the time. Sometimes, it will get triggered due to unknown reason and symptoms go off within a day or two. Is surgery safe in long term?



Welcome back to He hassimple focal motor seizures. I would not call this as benign childhood seizures unless I have more information. Yes, surgery is a cure for epilepsy. But, it depends on where the focus is and it is safe to remove it without leaving any deficit.

Hi doctor,

I have enclosed magnetic resonance imaging (MRI) report for your reference. For last four months along with Topiramate he is having Lobazam 15 mg. His treating neurologist is suspecting for some scar, but it is not identified in MRI. If he is fine with medication and his seizure is in control, is surgery required?



Welcome back to It is not uncommon to find normal magnetic resonance imaging (MRI) brain in patients with epilepsy. MRI report (attachment removed to protect patient identity) is normal but it has to be looked in accordance with area of EEG (electroencephalogram) findings. Sometimes, small lesions are missed and only detected on repeat MRI. You do not need a repeat MRI as his seizures are controlled. As long as he is on two medicines and well controlled on medication, he does not need surgery. If he fails on two medications after full optimization of each medicine, then topic of surgery comes into play. Getting an evaluation of surgery does not mean one would have a surgery. It is a process of month of data collection and discussion before making a final recommendation. I think your neurologist is doing his evaluation and collecting information for future. If he fails with medication, then this would help in discussion over next available options.

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