Uncover the expertise

Key opinion leaders discuss how to recognize, confirm, and treat CIDP

hub_kol_B104_confirm_electrodiagnostic_techniques

Electrodiagnostic Techniques

Mark B. Bromberg, MD, PhD, Neurology, discusses the role of nerve conduction studies in documenting primary axonal and demyelinating neuropathies.

Transcript

Electrodiagnostic Techniques

Mark B. Bromberg, MD, PhD, Neurology, discusses the role of nerve conduction studies in documenting primary axonal and demyelinating neuropathies.

My name is Mark Bromberg. I'm a professor of neurology at the University of Utah. I began my career with a doctoral degree in neurophysiology. And when I decided to go into clinical medicine, I chose neurology with a subspecialization in nerve and muscle disorders and clinical neurophysiology.

So I'd like to talk to you about the electrodiagnosis of immune neuropathies. And the primary neuropathy we're going to focus on is chronic inflammatory demyelinating polyradiculoneuropathy, or abbreviated, CIDP.

Clinical neurophysiology or electrodiagnosis consists of nerve conduction studies and the needle EMG. What we're trying to do, primarily with the nerve conduction studies, is to estimate the underlying pathology. We're trying to determine the difference between a primary demyelinating neuropathy and a primary axonal neuropathy.

Some of the challenges are that the pattern might be mixed, both primary and secondary, and we have to try to decide which is the primary one because CIDP is felt to be a primary demyelinating neuropathy. Now to be open, our pathology data are relatively sparse. In other words, this is not a fatal disorder, so there are relatively few autopsies. And so most of the information comes from sensory nerve biopsies.

Occasionally when you look under the microscope, although a patient has such a condition like CIDP, you don't find underlying pathology. And then that brings in the concept of very localized pathology to the node of Ranvier and hence the term nodopathy. The role for the actual needle EMG study is much less prominent in trying to diagnose CIDP. You can use it to document axonal loss, but the problem is you can have primary or secondary axonal loss, and the needle EMG can't distinguish between the two.

It would be nice at times to know how much axonal loss you have, but the needle EMG cannot document that. Therefore, most of the information we get from electrodiagnostic studies or clinical neurophysiology comes from nerve conduction studies.

So this cartoon is a little complex, but in the very middle, we have a cartoon of a normal nerve. And you can see that there's a peripheral nerve segment. And on the left of that middle part, there is a motor nerve, and the right, there is a sensory nerve. And the sensory nerve also has a central projection. On the left side, you can see the changes that occur in a primary axonal neuropathy. So working from the middle out to the left, you can see that primary axonal neuropathy is length dependent. And that means the longest nerves are affected first. And as shorter and shorter nerves are affected, then you get a stocking distribution that moves up the leg. And when you get a nerve length to about the knee, then that's the same length as the nerve going to the hand. So then you get a glove distribution, or stocking glove distribution, with progression. If you can halt some of the pathologic changes, then you can get regeneration, which is shown on the extreme left.

In contrast, on the right we have primary demyelination. And so you can see here that the loss of myelin occurs at different points along the nerve. So we call that multifocal demyelination. And you can also see in the middle of that that some of the demyelination is at the nerve root level. And so that causes a breakdown in the nerve root blood brain barrier, and that can cause an increase in protein in the cerebral spinal fluid. Again, if you can stop the pathologic process, then there's a chance for remyelination.

Thank you, and I hope that my talk with you today has helped you understand how to use nerve conduction studies to confirm the diagnosis of CIDP.

Transcript

Electrodiagnostic Techniques

Mark B. Bromberg, MD, PhD, Neurology, discusses the role of nerve conduction studies in documenting primary axonal and demyelinating neuropathies.

My name is Mark Bromberg. I'm a professor of neurology at the University of Utah. I began my career with a doctoral degree in neurophysiology. And when I decided to go into clinical medicine, I chose neurology with a subspecialization in nerve and muscle disorders and clinical neurophysiology.

So I'd like to talk to you about the electrodiagnosis of immune neuropathies. And the primary neuropathy we're going to focus on is chronic inflammatory demyelinating polyradiculoneuropathy, or abbreviated, CIDP.

Clinical neurophysiology or electrodiagnosis consists of nerve conduction studies and the needle EMG. What we're trying to do, primarily with the nerve conduction studies, is to estimate the underlying pathology. We're trying to determine the difference between a primary demyelinating neuropathy and a primary axonal neuropathy.

Some of the challenges are that the pattern might be mixed, both primary and secondary, and we have to try to decide which is the primary one because CIDP is felt to be a primary demyelinating neuropathy. Now to be open, our pathology data are relatively sparse. In other words, this is not a fatal disorder, so there are relatively few autopsies. And so most of the information comes from sensory nerve biopsies.

Occasionally when you look under the microscope, although a patient has such a condition like CIDP, you don't find underlying pathology. And then that brings in the concept of very localized pathology to the node of Ranvier and hence the term nodopathy. The role for the actual needle EMG study is much less prominent in trying to diagnose CIDP. You can use it to document axonal loss, but the problem is you can have primary or secondary axonal loss, and the needle EMG can't distinguish between the two.

It would be nice at times to know how much axonal loss you have, but the needle EMG cannot document that. Therefore, most of the information we get from electrodiagnostic studies or clinical neurophysiology comes from nerve conduction studies.

So this cartoon is a little complex, but in the very middle, we have a cartoon of a normal nerve. And you can see that there's a peripheral nerve segment. And on the left of that middle part, there is a motor nerve, and the right, there is a sensory nerve. And the sensory nerve also has a central projection. On the left side, you can see the changes that occur in a primary axonal neuropathy. So working from the middle out to the left, you can see that primary axonal neuropathy is length dependent. And that means the longest nerves are affected first. And as shorter and shorter nerves are affected, then you get a stocking distribution that moves up the leg. And when you get a nerve length to about the knee, then that's the same length as the nerve going to the hand. So then you get a glove distribution, or stocking glove distribution, with progression. If you can halt some of the pathologic changes, then you can get regeneration, which is shown on the extreme left.

In contrast, on the right we have primary demyelination. And so you can see here that the loss of myelin occurs at different points along the nerve. So we call that multifocal demyelination. And you can also see in the middle of that that some of the demyelination is at the nerve root level. And so that causes a breakdown in the nerve root blood brain barrier, and that can cause an increase in protein in the cerebral spinal fluid. Again, if you can stop the pathologic process, then there's a chance for remyelination.

Thank you, and I hope that my talk with you today has helped you understand how to use nerve conduction studies to confirm the diagnosis of CIDP.


Gamunex Connexions Support 1-888-MYGAMUNEX (1-888-694-2686)

GAMUNEX®-C (immune globulin injection [human], 10% caprylate/chromatography purified) is indicated for the treatment of primary humoral immunodeficiency disease (PIDD) in patients 2 years of age and older, idiopathic thrombocytopenic purpura (ITP) in adults and children, and chronic inflammatory demyelinating polyneuropathy (CIDP) in adults.

Thrombosis may occur with immune globulin products, including GAMUNEX-C. Risk factors may include: advanced age, prolonged immobilization, hypercoagulable conditions, history of venous or arterial thrombosis, use of estrogens, indwelling central vascular catheters, hyperviscosity, and cardiovascular risk factors. Thrombosis may occur in the absence of known risk factors. For patients at risk of thrombosis, administer GAMUNEX-C at the minimum dose and infusion rate practicable. Ensure adequate hydration in patients before administration. Monitor for signs and symptoms of thrombosis and assess blood viscosity in patients at risk for hyperviscosity.

Renal dysfunction, acute renal failure, osmotic nephrosis, and death may occur with immune globulin intravenous (IVIG) products in predisposed patients. Patients predisposed to renal dysfunction include those with any degree of preexisting renal insufficiency, diabetes mellitus, age greater than 65, volume depletion, sepsis, paraproteinemia, or patients receiving known nephrotoxic drugs. Renal dysfunction and acute renal failure occur more commonly in patients receiving IVIG products containing sucrose. GAMUNEX-C does not contain sucrose. For patients at risk of renal dysfunction or failure, administer GAMUNEX-C at the minimum concentration available and the minimum infusion rate practicable.

GAMUNEX-C is contraindicated in patients who have had an anaphylactic or severe systemic reaction to the administration of human immune globulin. It is contraindicated in IgA-deficient patients with antibodies against IgA and history of hypersensitivity.

Severe hypersensitivity reactions may occur with IVIG products, including GAMUNEX-C. In case of hypersensitivity, discontinue GAMUNEX-C infusion immediately and institute appropriate treatment.

Monitor renal function, including blood urea nitrogen (BUN), serum creatinine, and urine output in patients at risk of developing acute renal failure.

Hyperproteinemia, increased serum viscosity, and hyponatremia may occur in patients receiving IVIG treatment, including GAMUNEX-C.

There have been reports of aseptic meningitis, hemolytic anemia, and noncardiogenic pulmonary edema (transfusion-related acute lung injury [TRALI]) in patients administered with IVIG, including GAMUNEX-C.

The high-dose regimen (1g/kg x 1-2 days) is not recommended for individuals with expanded fluid volumes or where fluid volume may be a concern.

Because GAMUNEX-C is made from human blood, it may carry a risk of transmitting infectious agents, eg, viruses, the variant Creutzfeldt-Jakob disease (vCJD) agent, and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent.

Do not administer GAMUNEX-C subcutaneously in patients with ITP because of the risk of hematoma formation.

Periodic monitoring of renal function and urine output is particularly important in patients judged to be at increased risk of developing acute renal failure. Assess renal function, including measurement of BUN and serum creatinine, before the initial infusion of GAMUNEX-C and at appropriate intervals thereafter.

Consider baseline assessment of blood viscosity in patients at risk for hyperviscosity, including those with cryoglobulins, fasting chylomicronemia/markedly high triacylglycerols (triglycerides), or monoclonal gammopathies, because of the potentially increased risk of thrombosis.

If signs and/or symptoms of hemolysis are present after an infusion of GAMUNEX-C, perform appropriate laboratory testing for confirmation.

If TRALI is suspected, perform appropriate tests for the presence of antineutrophil antibodies and anti-HLA antibodies in both the product and patient's serum.

After infusion of IgG, the transitory rise of the various passively transferred antibodies in the patient's blood may yield positive serological testing results, with the potential for misleading interpretation.

In clinical studies, the most common adverse reactions with GAMUNEX-C were headache, pyrexia, hypertension, chills, rash, nausea, arthralgia, and asthenia (in CIDP); cough, rhinitis, pharyngitis, headache, asthma, nausea, fever, diarrhea, and sinusitis with intravenous use (in PIDD) and local infusion-site reactions, fatigue, headache, upper respiratory tract infection, arthralgia, diarrhea, nausea, sinusitis, bronchitis, depression, allergic dermatitis, migraine, myalgia, viral infection, and pyrexia with subcutaneous use (in PIDD); and headache, ecchymosis, vomiting, fever, nausea, rash, abdominal pain, back pain, and dyspepsia (in ITP).

The most serious adverse reactions in clinical studies were pulmonary embolism (PE) in 1 subject with a history of PE (in CIDP), an exacerbation of autoimmune pure red cell aplasia in 1 subject (in PIDD), and myocarditis in 1 subject that occurred 50 days post-study drug infusion and was not considered drug related (in ITP).

Please see accompanying full Prescribing Information for GAMUNEX-C.

Terms to know

IG=immune globulin, CIDP=chronic inflammatory demyelinating polyneuropathy, PIDD=primary immunodeficiency disease, ITP=idiopathic thrombocytopenic purpura, Sub Q=subcutaneous, IV=intravenous, ICE=10% caprylate-chromatography purified immune globulin intravenous (IGIV-C) CIDP efficacy.

Are you sure you want to leave our site?

Please be advised that Grifols has no control over the content or presentation of the site you are about to view.

Please select "Continue" if you wish to be taken to this third-party website.