Today's post from painhq.org (see link below) is another article highlighting the commonest diagnosis/testing tools with regard to neuropathy. This is especially useful for people who have been told they probably have neuropathy but must undergo certain tests to establish that. Hopefully, your doctor will listen carefully to your story and conclude that there's enough evidence to diagnose nerve damage but many doctors (and insurance companies) require more than that - scientific proof. Unfortunately, even these tests can't prove neuropathy 100% but they are an accepted part of the process you go through. By the way, you're entitled to ask your doctor why you're having certain tests and not others. That may be perfectly reasonable but you deserve an explanation as to why.
How is neuropathic pain diagnosed?
Last updated August 5, 2014
Diagnosing neuropathy is often difficult because the symptoms are highly variable. A thorough neurological examination is usually required and involves taking an extensive patient history (including the patient’s symptoms, work environment, social habits, exposure to any toxins, history of alcoholism, risk of HIV or other infectious disease, and family history of neurological disease), performing tests that may identify the cause of the neuropathic disorder, and conducting tests to determine the extent and type of nerve damage.
A general physical examination and related tests may reveal the presence of a systemic disease causing nerve damage. Blood tests can detect diabetes, vitamin deficiencies, liver or kidney dysfunction, other metabolic disorders, and signs of abnormal immune system activity. An examination of cerebrospinal fluid that surrounds the brain and spinal cord can reveal abnormal antibodies associated with neuropathy. More specialized tests may reveal other blood or cardiovascular diseases, connective tissue disorders, or malignancies. Tests of muscle strength, as well as evidence of cramps or fasciculations, indicate motor fiber involvement. Evaluation of a patient’s ability to register vibration, light touch, body position, temperature, and pain reveals sensory nerve damage and may indicate whether small or large sensory nerve fibers are affected.
Based on the results of the neurological exam, physical exam, patient history, and any previous screening or testing, additional testing may be ordered to help determine the nature and extent of the neuropathy.
Computed tomography, or CT scan, is a noninvasive, painless process used to produce rapid, clear two-dimensional images of organs, bones, and tissues. X-rays are passed through the body at various angles and are detected by a computerized scanner. The data is processed and displayed as cross-sectional images, or "slices," of the internal structure of the body or organ. Neurological CT scans can detect bone and vascular irregularities, certain brain tumors and cysts, herniated disks, encephalitis, spinal stenosis (narrowing of the spinal canal), and other disorders.
Magnetic resonance imaging (MRI) can examine muscle quality and size, detect any fatty replacement of muscle tissue, and determine whether a nerve fiber has sustained compression damage. The MRI equipment creates a strong magnetic field around the body. Radio waves are then passed through the body to trigger a resonance signal that can be detected at different angles within the body. A computer processes this resonance into either a three-dimensional picture or a two-dimensional "slice" of the scanned area.
Electromyography (EMG) involves inserting a fine needle into a muscle to compare the amount of electrical activity present when muscles are at rest and when they contract. EMG tests can help differentiate between muscle and nerve disorders.
Nerve conduction velocity (NCV) tests can precisely measure the degree of damage in larger nerve fibers, revealing whether symptoms are being caused by degeneration of the myelin sheath or the axon. During this test, a probe electrically stimulates a nerve fiber, which responds by generating its own electrical impulse. An electrode placed further along the nerve’s pathway measures the speed of impulse transmission along the axon. Slow transmission rates and impulse blockage tend to indicate damage to the myelin sheath, while a reduction in the strength of impulses is a sign of axonal degeneration.
Nerve biopsy involves removing and examining a sample of nerve tissue, most often from the lower leg. Although this test can provide valuable information about the degree of nerve damage, it is an invasive procedure that is difficult to perform and may itself cause neuropathic side effects. Many experts do not believe that a biopsy is always needed for diagnosis.
Skin biopsy is a test in which doctors remove a thin skin sample and examine nerve fiber endings. This test offers some unique advantages over NCV tests and nerve biopsy. Unlike NCV, it can reveal damage present in smaller fibers; in contrast to conventional nerve biopsy, skin biopsy is less invasive, has fewer side effects, and is easier to perform.
https://www.painhq.org/learning/knowledge-base/category/clinical-assessment/neuropathic-pain-overview/how-is-neuropathic-pain-diagnosed
Today's post from neuropathyjournal.org (see link below) highlights the necessity for doctors to test properly for neuropathy (if they are going to test at all). Many patients go home with clear neuropathic symptoms but a negative diagnosis, purely because the neurologist hasn't tested for small fibre neuropathy and has instead concentrated on large fibre nerve damage by using EMGs and nerve conduct studies. Strictly speaking, the only way to confirm small fibre neuropathy is by conducting a skin biopsy but most neurologists and doctors won't do this because of cost and other difficulties. For this reason, many patients are simply misdiagnosed as not having neuropathy when in fact they do. This useful article provides the facts about small fibre neuropathy and if you recognise yourself in these descriptions, it may be worth having another discussion with your doctor about your original diagnosis.
By LtCol Eugene B Richardson, USA (Retired) BA, MDiv, EdM, MS1
So many neuropathy patients have heard these words from very qualified neurologists and health professionals. “Your EMG and Nerve Conduct Studies are normal and you do not have neuropathy!” Right? Wrong!
Dr. Norman Latov of Cornell University states clearly along with many other professionals that the EMG and Nerve Conduct Studies only measure damage to the large fibers. In fact it is well known that a patient can have symptoms of Peripheral Neuropathy long before damage is done to either the large or small fiber nerves! Plus small fiber damage can only be measured by a simple Skin Biopsy to determine if the patient has damage to the small fibers.
David Saperstein M.D. and Todd Levine M.D. write for the GBS/CIDP Foundation International in Summer 2012 in The Communicator: “Immune-Mediated Small Fiber Neuropathy: A Treatable Condition That Can Mimic GBS and CIDP” . The authors note that “some patients may have elevated spinal fluid protein levels as in (GBS and CIDP), while other patients will have evidence of a monoclonal protein in their blood (which can be associated with some kinds of CIDP) and note that acute onset SFN can be immune-mediated and may respond to the same therapies used for GBS, such as intravenous immunoglobulin (IVIg). In contrast to GBS, however patients with acute onset SFN may respond to corticosteroid medications such as prednisone.” The doctors continue with a recommendation that the skin biopsy is a very useful tool in the diagnosis of SFN.
Testing-Skin Biopsy
Therapath Pathology does epidermal nerve fiber density testing. Skin Biopsy
Small Fiber Neuropathy
Small fiber neuropathies affect the small, unmyelinated nerve fibers in the sensory nerves. These fibers convey pain and temperature sensations from the skin, as well as maintain autonomic functions (Stewart el al, 1992; Novak et al 2001). The diagnosis can easily be missed, as the neurological examination may reveal only minor sensory abnormalities and EMG and nerve conduction studies, that measure the large fibers, are frequently normal. Consequently, some patients with small fiber neuropathy are misdiagnosed as having a psychosomatic disorder, RSD, fibromyalgia, or restless leg syndrome instead. (Lacomia, 2002; Hermann et al, 2004; Polydefkis et al, 2005).
Symptoms of Small Fiber Neuropathy
Symptoms of small fiber neuropathy include numbness and annoying or painful spontaneous sensations, called paresthesias, that are variably described as tingling, stinging, burning, freezing, itching, aching, pulling, squeezing, or electric shock-like in character. Innocuous stimuli can provoke unpleasant sensations, called dysesthesias, as when clothes feel like sandpaper against the skin, the hands are hypersensitive to touch, and pressure from shoes or socks causes severe pain. These symptoms can occur anywhere in the body, including the arms, legs, torso, face, or even the mouth. (Walk et al, 2003; Lauria et al. 2005)
Causes of Small Fiber Neuropathy
Small fiber neuropathy can result from a number of causes and the neuropathy is often the first manifestation of an underlying systemic disease. It can be caused by diabetes mellitus or glucose intolerance (Polydefkis and McArthur, 2005) and by such autoimmune conditions as Sjogren’s syndrome (Chat et al, 2005) Lupus (Omdal et al, 2002), sarcoid (Hoitsman et al, 2005) vasculitis (Lacomis et al, 1997; Zafrir et al, 2004) Lee et al, 2005), inflammatory bowel disease (Gondim et al. 2005) or variants of Guillain-Barre syndrome (Seneviraine and Gunasekera, 2002). Other causes include nutritional deficiencies, celiac disease (Brannagan et al, 2005), Lyme disease, HIV-1 infection (Polydefkis et al. 2002) hereditary disease (Dyck et al, 1985) Dutsch et al, 2003), amyloid, alcohol abuse (Zambelis et al, 2005) or toxins (Kuo et al, 2005). Some sensory neuropathies that affect both the small and large nerve fibers can cause a reduction in epidermal nerve fiber density, before electrodiagnostic abnormalities.
How is SFN diagnosed
The diagnosis of small fiber neuropathy can be made with certainty, by demonstrating a reduction in the density of small nerve fibers in the skin. EMG and nerve conduction studies are usually normal in this condition, as they mostly measure the large nerve fibers in the motor or sensory nerves. The epidermal nerve fiber is normal in patients with central nervous system disease. (Latov; Brannagan)
About the Author
Col Richardson has suffered with severe neuropathy for over 45 years. A 27 year military veteran and veteran of the Vietnam War, he was diagnosed with a progressive chronic peripheral neuropathy resulting in severe disability. This diagnosis has been confirmed as due to exposure to Agent Orange. It was not until 2010, 42 years after his exposure to Agent Orange, that his diagnosis was recognized by Veterans Affairs as service connected.
https://neuropathyjournal.org/small-fiber-neuropathy/
