Weakness and sensory loss are also present in multiple sclerosis, which helps explain why multiple sclerosis is often considered in the differential diagnosis of CIDP. Both conditions are characterized by recurrent episodes of nervous system demyelination, with improvement of the symptoms and clinical examination between episodes. Patients who have CIDP often have diminished or completely absent distal reflexes because the demyelination affects the peripheral nerves. In multiple sclerosis, patients have preserved or hyperactive reflexes upon clinical examination because the demyelination affects the brain and spinal cord. A lack of visual and cognitive deficits on clinical examination also differentiates CIDP from multiple sclerosis. In both conditions, episodes of relapse can be treated with steroid treatment, but multiple sclerosis is often also treated with maintenance medications, such as interferons or immunomodulatory treatments, in between episodes.
Amyotrophic lateral sclerosis and CIDP can both present with weakness and do not affect cognition, although amyotrophic lateral sclerosis is more rapidly progressive, whereas CIDP is often associated with sensory symptoms. Amyotrophic lateral sclerosis is a degenerative motor neuron disease, whereas CIDP is a demyelinating neuropathy that affects the sensory and motor nerve roots. They both commonly present in patients aged approximately 40 to 60 years, with some variation. Both conditions are more common in men than in women. Patients with amyotrophic lateral sclerosis also often have muscle fasciculations, a sign that is not seen in patients with CIDP. Another important distinction is that CIDP can be treated with medication whereas amyotrophic lateral sclerosis cannot.
Rheumatoid arthritis is an inflammatory condition that may manifest with symptoms of weakness and sensory loss due to neurologic involvement; however, it is not a demyelinating disease. Demyelination of the nerves occurs in CIDP. A demyelinating pattern seen on electromyography (EMG) and nerve conduction studies supports the diagnosis of CIDP (Figure 1).
Typical electrophysiologic findings in CIDP include reduced motor conduction velocity, which reflects reduced speed of motor nerve conduction, and prolonged distal motor latency, which reflects demyelination. Multiple motor conduction blocks also result when the demyelination prevents areas of transmission along nerve fibers.
Other diagnostic tests used for CIDP include blood tests, lumbar puncture, MRI of the spinal cord, and nerve biopsy. A blood test may reveal an increase in inflammatory cells, although this may not be the case; this increase in inflammatory cells may be seen in numerous other inflammatory or infectious disorders. Lumbar puncture may reveal elevated protein in the cerebrospinal fluid, which is also considered a nonspecific finding. MRI of the spine, particularly the lumbar spinal, may show thickening of the nerve roots, although this may not be present and may not be visualized in all patients with CIDP. Nerve biopsy shows an appearance of inflammation, axonal degeneration, and onion-bulb formation (Figure 2).
The onion-bulb formation describes a pattern of concentric layers of myelination around a nerve axon. This develops as the result of recurrent demyelination and remyelination. However, some of these biopsy findings might not be present in all patients with CIDP and are not definitively diagnostic of CIDP.
Medscape © 2023 WebMD, LLC
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Heidi Moawad. Neurology Case Challenge: After Respiratory Infection, 57-Year-Old Has Trouble Walking - Medscape - Feb 20, 2023.