My plea to you guys

Specific Illnesses & Conditions VM/MAV
1

Hi all— I’ve been off the forum for a while because my diagnosis was changed to Superior Canal Dehiscence. I know that there has been some talk on this forum about SCD, but I feel so strongly to bring it up again so maybe someone----anyone----can get pointed in the right direction. MAV and SCD are sooooohhhh closely married in symptoms, some doctors (like mine) will not touch an SCD diagnosis until you show failure on migraine meds. Although I hated the months on the meds, I’m grateful that my doctor was conservative at first. Also, keep in mind that SCD was only discovered a mere 13 years ago-----many people were and still are misdiagnosed with Meniere’s, MAV, Enodlymphatic Hydrops, fistulas, etc. The key in proper diagnoses is so complex! It requires the right doctor who knows alot about SCD AND the right hi-res CT scan. About 25% of people have to get more than one CT before getting the right SCD diagnosis. There really are only a handful of dcotors around the country who are doing this work and surgery to correct SCD.

I was diagnosed with MAV last Fall after a hi-resolution CT said that myleft superior canal was just fine and my right one was “thinned.” (Keep in mind, it was my LEFT side that had all of the fullness, crackling, and hearing my eyes move.) So, I tried 3 different migraine meds…only side effects, but no relief. So, my doctor ordered another hi-resolution CT, but this time he called the neuroradiologist (I highly recommend this over a “plain” radiologist) and told him specifically what angles and specs he wanted the CT done at. Low and behold, the LEFT side DOES have a dehiscence and the right side is not only thinned, but “abnormally thin—suspected dehiscence.” Also, on the left side, an “Encephalocele” showed up (hole in temporal bone with brain matter spilling into ear canal.)

So, on May 4th, I am having a surgery to repair the left side----it’s full-blown brain surgery, they cut a 3" x 3" sqaure in your skull to access the area that they need to repair. I thought long and hard about this surgery, but it’s my only chance to feel better.

I have all sorts of info. to pass along if anyone is interested. My doctor thinks that soon there will start to emerge evidence of the SCD/migraine connection-----it hasn’t happened yet though. I wouldn’t be surprised if it turns out that one causes the other. As of now, how do you get SCD??? Only 2% of the population is born with thinned skull and head bones that just don’t finish forming properly. Either you have a head trauma OR normal wear and tear starts to break these already compromised bones down and ta-dah…a Superior Canal Dehiscence. Your symptoms get worse with age----hence more wear and tear. There is no cure other than the risky surgery.

I hope this encourages some of you to ask (demand) a proper hi-res CT just to rule out SCD. I can provide the hi-res CT specs that are needed for SCD detection.

Linda

2

One of my doctors think I have MAV or SCD, she wants my new doc to do a scan of my temporal bone, so we will wait and see! People can develope this from pushing (life child birth) and very heavy lifting…Will be very intertesting to see how everything turns out for you! PLEASE keep us updated!!
Donna

3

Donna-

Good luck with the CT. Here is the exact info. needed to get the EXACT hi-resolution CT needed to detect SCD.
**A CT scan of the temporal bone should generally be obtained in persons with sound or pressure sensitivity. CT of the temporal bone is supposedly very accurate in identifying canal fistulae (Fuse et al, 1996), although as there is really no other good way to identify canal fistulae, it is hard to be sure that it is picking them all up. As SCD is a type of canal fistula and it is moderately common, the main reason for this procedure is to check for SCD. CT should be done of the temporal bone with at 0.6 mm resolution or better (lower is better). It may be impossible to get a CT scan with a resolution < 0.6 mm. This is generally OK, but don’t accept lower resolution (i.e. 1 mm is not good enough). Conventional CT scans of are nearly always useless to diagnose SCD as their cut resolution is 8-10mm – this is almost as big as the entire inner ear ! There is also a trade-off between radiation and resolution. One might argue that the tiny lesions that can be discovered with 0.1 mm cuts are not worth the radiation load. This issue is presently unclear.

Direct coronal scans are the best protocol for SCD – in our opinion, reformatted images (from axial cuts) are not nearly as good. At this writing (2011) all University hospitals should be able to do a direct coronal CT. It is very important to insist on this – radiology technicians have been known to do reformatting, figuring that it doesn’t matter. It does matter ! Usually you only get one shot at this, so make sure it is done right the first time.

Reformatted sagittal views are not conventional, but some radiologists feel that they are essential. If there is a bony defect in the tegman or superior semicircular canal in the coronal view, it should be supported and confirmed with sagittal views. This is due to the fact that the sloping of the tegmen and the appearance of the arcuate eminence may result in a partial volume effect, mimicking a dehiscent canal or tegmen. In these cases, the finding on direct coronal is not supported by the sagittal images.

In our opinion, this is what your test prescription should say:

CT scan of the temporal bone, with high resolution (0.6 mm or less). You must do direct coronals, using a bone dedicated window (width 1600 HU and center at 400 HU). If you are unable to do this protocol, do NOT proceed with the scan.

Axial cuts are not necessary to diagnose SCD. Nevertheless the radiologists often do them anyway. We suspect that they do this largely because radiologists are more familiar with axial views and also because radiologists seem often to be fond of using 3D reconstructions. One could also argue that without axial cuts, the very rare PCD syndrome might go undiagnosed. On the other hand, one could also argue that the axial cuts are generally not necessary, and add financal cost and biological cost (radiation) to the patient experience.

Radiologists often take matters into their own hands and add temporal bone CT protocols that were not authorized by the treating physician. For temporal bone CT – x-rays of the most dense bone in the body – this seems to us to be a very bad idea. We are particularly perturbed by the radiation cost, as we think that it would be best for all concerned to just do the minimal procedure needed to confirm or rule out SCD.

We are also very unenthused in general about radiologists deciding, on their own, to add expensive and intrinsically damaging procedures to a patient’s test repertoire. Radiologists typically do not have enough knowledge about the patient to make independent decisions concerning medical testing. They don’t examine the patient, or know details concerning patient clinical history. They are simply not the patient’s doctor. We would not allow a car repairman instructed to fix a headlight, to replace the muffler too, without permission from the car owner. Similarly, we think that radiologists should generally not be allowed to add procedures without clearance from the patient’s overseeing physician.

An MRI is useful to exclude potentially confounding entities such as cholesteatoma or tumor. MRI is not a test for dehiscence because it doesn’t show the bone and resolution is not as good as CT scan. However, MRI is the best way of showing other possibly confounding problems such as acoustic tumors, cholesteatoma, or multiple sclerosis plaques.**

And, it’s not the pushing or heavy lifting that actually causes the SCD-----one is born wih the thinner bones that sets them up for the bones to break easier later on either by trauma (pushing or lifting or an accident) or normal wear and tear!

Linda

4

Right, I have heard that not all people can do the test right! what were your symtomps of scd?

5

Hi-
My symptoms are constant dizziness, I can hear my eyeballs move in one ear—I can hear my heartbeat in the other, fatigue, light and sound intolerance, ear fullness in one ear, increased headaches—including migraines, general brain fog and spacey feeliing. I feel like I did when I was diagnosed with MAV, but now I have SCD. I failed on the migraine meds…in fact I feel like the meds aggrivated the SCD symptoms.

I brought this post up because I know that most everybody on this site has had all of the usual ear and balance tests, MRI’s, and CT’s. But, **UNLESS THE SPECIAL HI-RES CT IS ORDERED WITH THE SPECIFIC SPECIFICATIONS, ANY OHTER CT IS A WASTE.**Hope this helps at least one person. Let me know if I can provide more info. on doctors who know about this, etc.

Linda

6

Good luck with the surgery.

I felt very lucky to have been diagnosed MAV when I went for a second opinion on the much-more-minor meniere’s surgery!