Cannot have MRI

[ericaa]

I have been experiencing headaches and dizziness over the past weeks. I also discovered that my pupils were different sizes with variable see-saw aniscoria (alternates eyes and occasionally same size). I was seen by an opthamologist who measured 1mm difference in my pupils and referred me to a neuro-opthamologist. I was evaluated by a neuro-opthamologist and the day I saw him my eyes were normal with no difference in pupil size. I was told that I had physiologic aniscoria and no further evaluation was neccessary. In light of my other symptoms, I am still going to get a CAT scan. I am concerned, however, because I have a defibrillator and am unable to have MRIs. It is my understanding that the CAT scan can not pick up certain things and I am concernd about a tumor being missed because I can not obtain an MRI. Can you please comment on the differences between a CAT scan and an MRI and how concerned I should be about not being able to obtain an MRI? Can you suggest the best way to proceed with getting a diagnosis given the complications of having a defibrillator?

Thank in advance,
Erica

[engjcosta]

Hi hi had the same symptons pupil dilated 1mm in the side of the headache problems come and go eye stuck and red pain in neck, pupil and vision bad in the side that is dilated, done CAT and MRI no problem nothing wrong no MS. So it´s likely to be a migrane or a muscular deacese, but if your blood is normal.

Cat scan is not the best exame, but if there´s a tumor or something the cat scan will not be normal.  Don´t worry its almost impossible to miss. MRI is a better exame indeed and could exclud MS and other kind of things, but tumor will apear in cat scan, and then they will advance to MRI.

In your case we hope that tou live long and no tumors just migrane :D

[Neuro Forum]

Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.

Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.

You are correct in stating that an MRI can not be done for patients with a variety of implanted electronics including defibrillators. Hopefully in the future these will be MRI compatible, and that MRI machines can be made that will not affect these implanted devices, but for the time being this is unfortunately the case.

Pupillary asymmetry does not necessarily imply a neurologic problem; over 20% of the general population can have a difference in pupillary size, and a 1 mm difference is usually what is termed physiologic anisocoria, or pupillary asymmetry that is not considered pathologic or reflective of an underlying problem.

There are several causes of headaches. Headaches can be divided into primary and secondary. Primary headache disorders are headaches without a direct cause. These are diagnosed after secondary causes have been excluded. Secondary headache disorders are due to an underlying problem, there are many many causes but some include medication side effects, systemic illness, nervous system infection, tumors, bleeds in the brain or clots in the veins of the brain, and others.

Imaging of the brain is as you mention necessary when someone starts having new headaches. A CT scan is best for detecting skull (bone) problems and for detecting blood (even better than MRI for detecting blood). CT scans also detect calcium well. MRI scan is better for soft tissues, including tumors. However, CT scans done in combination with intravenous dye (give through a vein), a CT scan with contrast, will often show an abnormality such as a tumor. A CT scan, combined with a good neurologic physical examination by a neurologist, should be able to suggest or exclude whether or not there is an abnormality such as a tumor, because most tumors as associated with other neurologic signs on examination. However as with anything, a tumor may not be able to be excluded definitively. A tumor can very rarely even not be detected with MRI. The key is to have continued follow-up with a neurologist, particularly if symptoms persist or worsen, because if the symptoms change and the neurologic examination changes, this will be more of an indicator of brain pathology, and other testing can then be pursued.

Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.