Dr. Julius Birnbaum: Neurological Complications of Sjogren's Syndrome

Do you deal with the difficult symptoms that arise from Sjogren's induced neuropathy? I know that I do. I deal with shooting pains and burning in my feet as well as restless leg syndrome; and a bizarre sensation that all of my leg muscles are quivering even though they are still.

So thanks to Dr. Sarah Schafer for reminding me of this excellent article found on the Johns Hopkins Jerome L. Greene Sjogren's Syndrome Center website. Entitled 'Neurologic Complications - A Primer on the Neurological  Complications of Sjogren's' and written by By Julius Birnbaum, MD Johns Hopkins Neurology-Rheumatology Clinic; it is a thorough discussion of all things neurologic pertaining to Sjogren's:

Introduction to the nervous system

The nervous system is divided into two anatomic compartments:

1. The “Central Nervous System” – or CNS – includes the brain and the spinal cord;
2. The “Peripheral Nervous System” – or PNS – includes larger and smaller nerves, connecting muscles to the spinal cord.

Sjögren’s syndrome can cause inflammation and damage to both the CNS and PNS.

Peripheral neuropathy of Sjögren’s syndromes

What is neuropathy?

Neuropathy, which means inflammation and/or damage to the peripheral nerves, can be affect patients with Sjögren’s. Neuropathy can cause various symptoms, from “numbness,” to “coldness;” in its most severe, neuropathy has been described as “burning,” “lancinating” or “feeling like my skin is on fire”. Neuropathy can also cause weakness and clumsiness.

How does my doctor diagnose neuropathy?

The first step is to take a careful history and do a physical examination. The pattern and description of symptoms, which may include pain and weakness, may suggest damage to the peripheral nerves. A neurological examination is crucial in providing objective evidence of peripheral neuropathy. Weakness may be present, which is typically greater in the toes and fingers, than in the larger muscle groups of the arms and legs. Your physician may test your reflexes. Whereas a reflex hammer should elicit emphatic lurches of arms and legs, patients with neuropathy may not have any reflexes. Lastly, your physician may test your ability to appreciate temperature, a sharp pin, and vibration. If the neurological examination confirms a peripheral neuropathy, then you may have a nerve-conduction test, looking at the integrity of nerves and muscles.

Why is neuropathy under-diagnosed or under-treated in Sjögren’s syndrome?

1. Sjögren’s may uniquely target nerves which are not tested on normal nerve-conduction tests.

Neuropathy can target nerves either of larger or smaller caliber, respectively referred to as a “large-fiber” neuropathy anda “small-fiber” neuropathy. Symptoms of large-fiber neuropathy include weakness and poorly localizable numbness and are associated with abnormalities on nerve-conduction tests.  In contrast, patients with small-fiber neuropathy may have symptoms of pain, burning, and prickling, even without weakness. The nerve-conduction test is only sensitive to damage in the large-fiber nerves. and does not detect abnormalities in the smallest-caliber nerves.

At Johns Hopkins we obtain skin biopsies when patients with symptoms of small-fiber neuropathy have normal nerve-conduction tests. The skin biopsy allows the clinician to assess damage to the small sensory nerve fibers that innervate the skin, an excellent marker of a small sensory fiber neuropathy, common in Sjogren’s patients.

2. The lack of any definitive blood tests

Sjögren’s syndrome is an example of an autoimmune syndrome. In autoimmune disorders, the immune system, which normally protects the body from infection and cancers, may cause injury to the body’s own tissues. In addition to the nervous system, organs which may be targeted in Sjögren’s syndrome include the eye, the lung, the heart, the kidney, and the joints. Many patients with Sjögren’s syndrome have autoantibodies, which bind to the body’s organ tissue and cells. Some examples of autoantibodies in Sjögren’s syndrome include anti-Ro (or SS-A antibodies) and  anti-La (or SS-B antibodies).

However, more than 50% of patients with neurological manifestations of Sjögren’s may not have autoantibodies. In patients who have neuropathy and compelling glandular symptoms of dry eyes and dry mouth, negative blood tests for SS-A and SS-B antibodies do not exclude the diagnosis of Sjögren’s syndrome. In the context of sicca symptoms, further diagnostic studies are warranted, including a Schirmer’s test, and a minor salivary gland biopsy.

Continue reading this comprehensive article here.