(August 5, 2008 - Insidermedicine) Welcome to Insidermedicine's If I Had, where we get a chance to ask an expert what they would do if they had a medical condition.
On a recent trip to Washington, we caught up with Dr. Raymond Sze, MD, who is a Radiologist in the Center for Hospital-Based Specialties at Children's National Medical Center. An active researcher, Dr. Sze focuses on both craniofacial abnormalities and pediatric brain cancer imaging.
What should I do if my child has seizures and needs medical imaging?
Let me start by saying as a radiologist that it is truly important to have a strong clinician, whether it’s a neurologist or a very strong general practitioner, evaluate the child first. There is a tendency in medicine, because of the power of imaging, to rely on it to the exclusion of the history and physical. Point being that within the differential of seizures there are easily one hundred things, both from very bland and benign to clearly very aggressive and malignant. As a perfect example, an infant with a high fever who has a first febrile seizure. Honestly one should do as little as possible. That is not the person who should get a multi-million dollar workup. On the other hand there are patient groups that should, repeat seizures not in the context of febrile seizures, because the differential or the possibilities include everything from a mass, to a developmental malformation, to an intracranial hemorrhage. Imaging is critical for these situations. Clearly we cant palpate or trans-illuminate a skull.
What kind of imaging should be expected?
Let me just briefly talk about CT and MRI examinations. Why you should have one, the differences, as well as their different strengths and weaknesses. CAT scan or CT is extremely fast. It uses ionizing radiation. It’s extremely good for bone and acute hemorrhage. In essence it takes seconds. Its very rare now-a-days for us to require sedation for young children. Those are its strengths. The ionizing radiation is certainly a concern, but we do minimize dose for that usage. So the short of it is in emergency situations, where we are worried about trauma, or a bleed, or a mass, or something that is going to require immediate surgical intervention, CT or CAT scan is definitely the way to go. MRI on the other hand used a combination of a high field magnet and radio frequency pulses. It can take upwards of forty-five minutes to an hour depending on how many sequences are done. Do we just need the brain? Do we need the spine as well? Are there functional questions? Do we need to look at the individual fiber tracts? Do we want to pull out the metabolites? If can be very very intense. It is never a short process. In general if you are less than eight years old or so, there is not a child who can sit through that long in a relatively claustrophobic. Environment. So it does require sedation. But MRI has the additional advantage of not requiring ionizing radiation. It gives you a lot more soft tissue and allows you to have functional as well as neurologically specific information.
What are the most common abnormalities related to seizures found using medical imaging?
For imaging, again there are a lot of conditions where imagine is not required such as the febrile seizure for example, but the big three would certainly be Tumor, and there are a whole host of tumors, and frankly almost every tumor can first express itself as a seizure. Number two would probably be developmental malformation. There are a host of thing that came go wrong during the complex developmental cycle of the brain. It there are little islands of brain tissue that don’t belong at that particular location, they can act as a little focus for seizures. The third one that comes easily to mind is vascular malformation. Things like aneurisms or other twisted knots of abnormally formed arteriovenous tissue, and those can bleed of intrinsically lead to seizures. For al three of these imaging is exquisitely sensitive and specific for making the correct diagnosis.
If I had a child who had a seizure…
If my child had a seizure the good news it this protocol is pretty much been worked out, it’s a common disease. What you should expect and what generally will happen is after a thorough and well documented physical as well as history, basically a CT examination is almost always done. Again looking for those emergency procedures that need to be emergently addressed by the surgeon or such. After that you can usually expect typically within one to two weeks to be scheduled for an MRI examination. That is one of the things that stressful for parents in the sense that because of the high demand as well as the limited availability of MRI examinations sometimes we have to make our patients wait. I think its important to understand that if there truly is an emergency that it will always get done. But in general a one to two week to better tease out the specific white matter tracts or metabolites of the brain is not something that needs to be done within twenty-four or forty-eight hours. But again the sequence is, thorough examination, CT examination to rule out emergencies, then MRI to better understand the intrinsic anatomy and physiology of the brain.