Expert: Ricardo Scott. R.T.R(ARRT), B.A.,J.D. - 9/7/2009

Question
My husband has been experiencing Diplopia for two weeks, without any other symptoms (i.e. no eye crossing), but has complained of light headedness for about a month prior to the onset of Diplopia.  He has a history of Adenoid Cystic Carcinoma diagnosed in April, 2009 in which a 3.5 cm tumor was removed from the parotid gland that showed extensive perineural invasion.  He completed 35 treatments of radiation in June, 2009.  A Neurologist did a MRI with and without contrast of his brain.  Findings:  High resolution thin section pre-and postgadolinium imaging of the cranial nerves and brain stem demonstrates a focal small area of increased signal on T2 and FLAIR sequences with the dorsal margin of the left side of the pons abutting the inferior aspect of the fourth ventricle.  This lesion also shows focal enchancement after gadolinium adminstration.  Its location is too low to represent a lesion of the left trochlear nerve which typically arises higher.  This lesion may involve 1 of the nuclei and the pons.  The remainder of the pons shows no abnormality.  The cranial nerves themselves show no abnormal enhancement.  The internal auditory canals show no abnormal enhancement.  Impression: Focal abnormal signal and enhancement at the dorsal margin of the left pons at the inferior left 4th ventricle that may represent focal inflammatory or infection or demyelinating lesion.  Focal neoplasm is considered less likely, but is difficult to exclude.  He is now being told to go to John Hopkins because of his history of ACC.  I need someone to explain to us in laymen terms what the findings mean, as well as what questions should we ask and should we even seek a second/third opinion?

Thank you.

Answer
Hello D Tornillo, Thanks for your question and concerns. Let me begin by saying that it is always good to get a second or a third opinion on issues such as this. Johns Hopkins is still considered one of the best hospitals to go. Now from reading the report, here is what the breakdown looks like as to what seems to be happening. You mentioned that your husband recently completed a course of radiation treatments(35 in June 2009). There is what is called-Radiation/Chemotherapy induced Brain(CNS) abnormalties. This means that the effects of the radiation treatments will show up. There is the possibilities for several things showing up after this toxic treatment for his diagnosed cancer. Some patients often present with blindness. The MRI readings showing increased signals on T2 and flair could be attributed to the radiation he has had. When patients ubdergo radiation or chemotherapy treatments you might have acute as well as chronic changes manifesting. Acute changes will occur during or immediately after the course of treatments, whereas chronic changes occuring between 6-8 months after nonfractionated therapy. Some changes may then become permanent, and focal demyelination(membrane covering the nerves "peels off") is one of the pathology seen. The radiologist was not sure as to this or an infection taking place in the area of the left pons(a lower part of the brain-stem). He/she said that a focal lesion is less likely. They are not sure. This reading can be attributed to the often seen post radiation treatment of patients, hence it is not too alarming or surprising.
Another thing they may be considering is what is known as CPM ( Central Pontine Myelinolysis), the exact reason for this occuring is at the moment unknown. What they do see however is that it is non-inflammatory, often symmetrical, and is the demyelination of the same pons area. In MRI what is seen is hyperintensity on T2W images. In spite of all these findings the cranial nerves appear normal. This is a good sign. Surely there is need for follow-up in all this so I would say again to get the neurological experts at Hopkins to help you along. All the best.