When Does Acute Guillain-Barré Presage Chronic Inflammatory Demyelinating Polyneuropathy?
Abstract & Commentary
By Michael Rubin, MD, Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Rubin reports he has no financial relationships relevant to this field of study.
Synopsis: Acute-onset CIDP is difficult to diagnose and distinguish from GBS. It should be suspected when there are prominent sensory signs at onset of the illness.
Source: Dionne A, et al. Clinical and electrophysiological parameters that distinguish acute-onset chronic inflammatory demyelinating polyneuropathy from acute inflammatory demyelinating polyneuropathy. Muscle Nerve 2009: (www.interscience.wiley.com). DOI 10.1002/mus.21480.
Can the acute presentation of chronic inflammatory demyelinating polyneuropathy (CIDP), which occurs in 16% of CIDP patients, be distinguished from Guillain-Barré syndrome (GBS), early in the course? Currently, two months of progression is mandated to consider a diagnosis of CIDP. Early differentiation would have obvious therapeutic and prognostic implications. To answer this question, a retrospective chart review of the clinical and electrodiagnostic record was undertaken of all patients with GBS and acute-onset CIDP (A-CIDP) seen between 1993 and 2007 at the London Health Sciences Center, London, Ontario, Canada, and examined by the senior author. GBS was diagnosed using the Asbury criteria and required muscle weakness with areflexia or hyporeflexia, reached a plateau in less than four weeks, and was confirmed at follow up with no relapse, no progression beyond eight weeks, and no need for ongoing treatment. GBS variants, including Miller-Fisher syndrome, regional variants, and axonal GBS were excluded, as were those with other possible etiologies, including hereditary neuropathy, diabetes, paraproteinemia, and neoplasm. A-CIDP diagnosis required an acute presentation over four weeks initially diagnosed as GBS, but which progressed beyond eight weeks, relapsed, or required continued therapy, including intravenous immunoglobulin, plasmapheresis, or immunosuppressive therapy. Motor and sensory nerve conduction studies were performed using standard technique and only the initial studies obtained within four weeks were analyzed. Criteria for diagnosing conduction block, temporal dispersion, slowed conduction velocity, and prolonged distal and F-wave latencies were those established by the Inflammatory Neuropathy Cause and Treatment Group (Ann Neurol 2001;50;195-201). Statistical analysis comprised Fisher's exact test and the unpaired t-test, with P<0.05 considered statistically significant.
Among 20 CIDP and 50 GBS patients screened over the study period, 15 CIDP and 30 GBS patients, respectively, satisfied inclusion criteria. Mean age at onset was 43 and 48 years, respectively, with no significant difference between groups for age or gender. Prominent sensory signs were more likely, and autonomic dysfunction, facial weakness, antecedent infectious illness, and assisted mechanical ventilation were less likely, in A-CIDP compared to GBS. Sensory signs included sensory ataxia, and stocking-glove distribution impairment of vibration and pinprick sensation. Sensory symptoms, back or radicular pain, and electrodiagnostic findings were not significantly different between the two groups. Consideration of the aforementioned early clinical features is worthwhile, as they may presage development of CIDP in a patient who otherwise resembles GBS.
Which treatments are available for chronic inflammatory demyelinating polyneuropathy? Up to 65% –95% respond to steroids. Some predominantly motor CIDP patients may worsen but this resolves after steroid withdrawal. Intravenous immunoglobulin (IVIG) provides both short- and long-term benefit, with 54% immediately responding and 34% maintaining stability with continued infusions. Plasma exchange (PE) is beneficial, but relapse rate after PE withdrawal, and the effects of continued maintenance therapy, remains unreported. No significant difference in efficacy has been demonstrated between steroids, IVIG, or PE, but cost and side-effect profiles differ significantly. In a recent report, methotrexate demonstrated no reduction in the need for ongoing steroid or IVIG. Uncontrolled studies suggest azathioprine may be beneficial, as well as interferon-beta, but in the single reported randomized controlled trial, the latter was of no benefit. Cyclosporin and cyclophosphamide are probably beneficial but the latter carries substantial toxicity. Mycophenolate mofetil, less toxic and reportedly beneficial in uncontrolled studies; and tacrolimus, etanercept, and stem-cell transplants are other potential therapies that await testing in randomized controlled trials.