Sunday, January 27, 2013

Is it really Anterior Interosseous Nerve syndrome, or just a more rare type of Neuralgic Amyotrophy?


PTS/NA can cause symptoms that are exactly like Anterior Interosseous Nerve syndrome (AINS). I know this because I had this diagnosis originally. When my fingers suddenly could not flex to make the traditional “OK” finger gesture, it followed a month or so of arm pain and weakness. At the time, I was told I had a textbook case of AINS. But during all of my exams, no one could tell me why I had AINS.  They kept asking me about the pain in my forearm, which I did not have.  I kept telling them I had pain in my upper arm and a bit in my shoulder. At the time I had checked the known causes of AINS, and found that none of them seemed to match my case.  But, what else could it be?

 Eventually, the other shoe dropped and my diagnosis was altered to PTS/NA and I realized that nerve damage that PTS causes can be misdiagnosed as AINS. That had originally been the reason for this post. I had recently noticed some who had been diagnosed with PTS/NA reporting that they had now also been diagnosed with AINS and now have to worry about two rare diseases. And in some cases surgery had been suggested as a cure.  I had found this article which designates the names of at least some of the nerves impacted by NA.  Notice in the anatomy section the mention of the anterior interosseous nerve

http://wiki.cns.org/wiki/index.php/Neuralgic_Amyotrophy

“Description
Neuralgic amyotrophy is also called Parsonage-Turner syndrome, brachial neuritis, and brachial plexitis. In response to bodily stress (e.g., surgery, flu, unusually excessive exercise, post-vaccination), the brachial plexus, branches of the brachial plexus, or other upper (rarely lower) extremity nerves may develop idiopathic inflammation. The exact cause is unknown. This inflammation is quite painful, which limits use of the arm. As the pain slowly resolves over a few days or weeks, the patient now notices paralysis and a variable degree of numbness in the shoulder and arm. The amount of paralysis varies, with unusually severe cases having complete arm paralysis. Weakness and numbness slowly resolves over time. This may take many months, or even 1-3 years. Although most people improve, the arm may not return to normal and remain partially paralyzed. Brachial plexitis may involve nerves controlling almost any muscle; however, nerves to the shoulder, scapula, and forearm are more commonly affected.

Anatomy
The following nerves may be affected (unilateral or bilateral): brachial plexus, long thoracic nerve, anterior interosseous nerve, posterior interosseous nerve, suprascapular nerve, lumbosacral plexus, and others).”

I hate to see anyone go through surgery that would possibly not be needed or even be an answer for the problem being experienced if there were a viable alternative that may help, namely just to wait it out.  If you have a case as AINS, and do not have the typical causes in your history, it may be caused by PTS/NA.

Well, then I just found this suggesting that maybe doctors have realized that inflammation of the nerves can cause AINS in a similar way as PTS.  See the link here:

http://en.wikipedia.org/wiki/Anterior_interosseous_syndrome

“Most cases of AIN syndrome are due to a transient neuritis, although compression of the AIN can happen. Trauma to the median nerve have also been reported as a cause of AIN syndrome.
Although there is still controversy among upper extremity surgeons, AIN syndrome is now regarded as a neuritis (inflammation of the nerve) in most cases; this is similar to parsonage-turner syndrome. Although the exact etiology is unknown, there is evidence that it is caused by an immune mediated response.
Studies are limited, and no randomized controlled trials have been performed regarding the treatment of AIN syndrome. While the natural history of AIN syndrome is not fully understood, studies following patients who have been treated without surgery show that symptoms can resolve starting as late as one year after onset. Other retrospective studies have shown that there is no difference in outcome in surgically versus nonsurgically treated patients. Surgical decompression is rarely indicated in AIN syndrome. Indications for considering surgery include a known space-occupying lesion that is compressing the nerve (a mass) and persistent symptoms beyond 1 year of conservative treatment.”

Notice it says in most cases it says that surgery would not be indicated for most AINS cases now a days, and outcome for surgery rarely improves the outcome of just waiting.  Unless they can be relatively sure there is something to decompress, you may be better off just waiting.

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