AAN.com Talks with John England About New Distal Symmetric Polyneuropathy Guidelines

December 2, 2008


AAN.com met with John D. England MD, FAAN, Louisiana State University Health Sciences Center School of Medicine, to find out more about the new guidelines on distal symmetric polyneuropathy. He spoke with AAN.com Practice Editor Neil A. Busis, MD, FAAN.

AAN.com: What is the purpose of these AAN clinical practice guidelines?

England: To help clinicians select the most appropriate tests for the evaluation of patients with distal symmetric polyneuropathy (DSP).

AAN.com: Who is the target audience?

England: Physicians and other health care providers who evaluate patients with polyneuropathy. Neurologists and physiatrists will especially find the guidelines useful.

AAN.com: What are the main conclusions of these new guidelines?

England: The guidelines start with the premise that the combination of neuropathic symptoms, signs, and electrodiagnostic findings (NCS/EMG) are useful for the accurate diagnosis of distal symmetric polyneuropathy (see Neurology 2005;64:199-207).

The two new guidelines provide the current best evidence regarding the appropriate choice of tests to refine the diagnosis and get at the cause of DSP. The guidelines conclude the following:

  1. Screening blood tests may be useful, and blood glucose, serum B12 with metabolites (methylmalonic acid with or without homocysteine), and serum protein immunofixation electrophoresis provide the highest yield.
  2. Tailored genetic testing is recommended for the accurate diagnosis of hereditary neuropathies. Initial genetic testing should be guided by the clinical phenotype, inheritance pattern, and electrodiagnostic features, and should focus on the most common abnormalities, which are CMT1A duplication/HNPP deletion, Cx32 (GJB1) and MFN2 mutation screening.
  3. Autonomic testing to document autonomic nervous system dysfunction should be considered in patients with polyneuropathy. Autonomic testing should be considered in the evaluation of patients suspected of having autonomic neuropathies and may be considered in patients with suspected distal small fiber sensory polyneuropathy (SFSN). For the highest diagnostic accuracy, the combination of autonomic screening tests in the composite autonomic scoring scale (CASS) should be considered.
  4. Skin biopsy is a validated technique for determining intraepidermal nerve fiber density and may be considered for diagnosing symptomatic patients with suspected polyneuropathy, especially SFSN.
  5. Nerve biopsy is generally accepted as useful in the evaluation of certain inflammatory nerve diseases, and is especially useful in diagnosing mononeuropathy multiplex and vasculitic neuropathy—conditions which can often present as DSP. However, there is insufficient evidence to recommend whether a nerve biopsy may be useful in the evaluation of DSP.

AAN.com: How should these guidelines be used in clinical practice?

England: These practice parameters should be utilized as a reference to help clinicians select the most appropriate tests to consider in the evaluation of patients with DSP. They are intended as an evidence-based supplement for experienced clinicians; they are not intended to replace the judgment of experienced physicians. They should not be viewed as a "cookbook" to evaluate patients with polyneuropathy. Since the diagnosis of polyneuropathy is complex, many patients will not require all of these tests, and many patients will require tests that are not included in these guidelines.

AAN.com: The guidelines say, "Report of the American Academy of Neurology, the American Association of Neuromuscular & Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation." Please explain.

England: These guidelines represent the fulfillment of a collaborative effort from the three organizations. All three organizations agreed that there was a need for evidence-based and clinically relevant practice parameters on the evaluation of polyneuropathy. As a prelude to these two new guidelines, the three organizations worked together to develop a case definition of DSP (see Neurology 2005;64:199-207). All of these projects were completed by representatives from all three organizations. All have been extensively reviewed by the three organizations. All are being published simultaneously in the journals of the three organizations (i.e., Neurology®, Muscle & Nerve, and the Archives of Physical Medicine and Rehabilitation).

AAN.com: How were the potential conflicts of interest of the authors handled?

England: Conflict of interest forms were obtained from all authors and reviewed by an oversight committee prior to the projects. The Academy limits the participation of authors with substantial conflicts of interest. This information is disclosed in the articles. Additionally, the fact that these reports utilize formal methods for rating evidence reduces the potential for bias of any single author. The large number of authors (19) on these papers also reduces the potential bias of any single author.

AAN.com: What hurdles had to be overcome before the guidelines could be finalized?

England: The major hurdles involved coordination of the efforts with three different and influential organizations. Coordinating the simultaneous publication of these articles in three different journals is very difficult. The fact that this is being accomplished is a tribute to the cooperativeness of the organizations and the incredible efforts of the staffs of the AAN, the American Association of Neuromuscular & Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation.

AAN.com: Can we expect additional collaborative reports on peripheral neuropathy from these groups in the future? If so, what topics will be covered?

England: We are currently writing an evidence-based guideline on the treatment of painful diabetic polyneuropathy.

Author Disclosure

Within the past 24 months, Dr. England received personal compensation from TEVA as an honorarium for speaking. In addition, he has served as the Associate Editor for Current Treatment Options in Neurology. Dr. England has also prepared a deposition in a toxic tort case involving carbon disulfide in the same period. In the past five years, he has received research support from Pfizer.