Statistics and Surgery Success and Recurrence

There is no cure for Syringomyelia. Those words keep playing in my head. There is also no guarantee that Ella will no relapse after she has had an expensive surgery where they removed part of her skull and she spent months recovering from this procedure.  I knew that when I decided to take that chance.  It was the only chance I felt she had and if she was one of the ones that was not successful at least I did something.  I thought that would make me feel okay and I would worry about that later and figure something out then.  I just prayed that she would be one of the lucky ones.  I knew that surgery gave her time.  That was a given. It would at least relieve the pain but there is a possibility that when part of the skull is removed, scar tissue can form.  This will then cause relapse and dogs will require to have another operation.

Why has this been on my mind recently? There was a post on www.cavaliertalk.com with notes from Dr. Dewey who is a neurologist that pioneered foramen magnum decompression (FMD) surgery and spoke recently at the AVMA.  Someone took notes on what he said and his presentation was targeted to vets so most of it was not new information but reading again some of these statistics made me realize just how realistic relapse could be for Ella.  Dr. Dewey created a procedure using Titanium Mesh with the hope to reduce the rate of recurrence.  I knew about this procedure when deciding on Ella's surgery but it was more expensive, more dangerous, and at the time I did not know what the long term benefit would be.  I am going to copy from Dr. Clare Rusbridge's website who is the expert of SM and Cavaliers says in general about some surgery questions.

CM/SM – surgery





What surgical options are there?


The most common surgical management is cranial/cervical decompression (also described as foramen magnum or suboccipital decompression). The principle of this surgery is to allow CSF flow by removing the bone at the back of the skull (supraoccipital bone) and part of top of the first vertebrae. This may be combined with a durotomy (cutting the meninges) with or without patching with a suitable graft material.


A cranioplasty procedure used in human cranial/cervical decompression surgery has also been adapted for use in dogs. The procedure entails placement of a plate constructed of titanium mesh and polymethylmethacrylate (PMMA) on pre-placed titanium screws bordering the occipital bone defect (Dewey et al 2007).


An alternative method of managing syringomyelia is direct shunting of the cavity. In humans this is not a preferred technique as long term outcome is poor due to shunt obstruction and/or spinal cord tethering.




How successful is surgery?


Cranial/cervical decompression surgery is successful in reducing pain and improving neurological deficits in approximately 80% of cases and approximately 45% of cases may still have a satisfactory quality of life 2 years postoperatively (Rusbridge 2007). However surgery may not adequately address the factors leading to syringomyelia and the syrinx appears persistent in many cases (Rusbridge 2007). Much of the clinical improvement is probably attributable to improvement in CSF flow through the foramen magnum.


What is the recurrence rate after surgery?


In some cases scaring and fibrous tissue adhesions over the foramen magnum seem to result in re-obstruction and 25% to as many as 50% of cases can eventually deteriorate (Dewey et al 2005, Rusbridge 2007). This can be as early as 2 months postoperatively.


Dr. Dewey stated again about the 50% of "cases" and I hate to think of Ella as a case of relapse.  He stated that his procedure had a 7% relapse rate.  This is a big difference. 

I am constantly worrying about Ella getting worse.  I have days when she is better than ever but then there are the bad days and I see the signs that she had before she had surgery.  I am reliving everything over again.  I know it has only been 6 months and we still have a long way to go.  Every head shake, every stumble up the stairs, every time she hides under the bed, every time she flinches when I try to touch her head my stomach drops. I have these statistics in my mind. I will not be able to handle this again and she is just too young with too much to offer.  I know she has so many good days that to harp on the bad ones is not fair.

When I explained to her neurologist some of the things she had been doing, he seemed concerned and put her on some more medication. He mentioned doing another MRI and that was extremely scary for me. I know the more knowledge is better but if the MRI results are not good, then I am faced with the same thing as before. I worry but I have reason to worry because she has a 50% chance. One person told me to face the facts and that she is getting worse. To just adjust her medications and that is the answer. There are several articles you can read about statistics and dogs that are euthanized and success rates but it just makes me too sad. I am posting this to share my worries but I also know there are people that need hope. I also long for hope too and there is hope for many of them.  Ella is her own case. She is a special case and a special angel.