Postpolio Syndrome Workup

Updated: Jun 24, 2019
  • Author: Divakara Kedlaya, MBBS; Chief Editor: Stephen Kishner, MD, MHA  more...
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Workup

Laboratory Studies

Obtain a complete blood count (CBC) and cerebrospinal fluid analysis to exclude conditions other than postpolio syndrome. Also obtain swallowing studies.

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Imaging Studies

Computed tomography (CT) scanning and magnetic resonance imaging (MRI) can be ordered to rule out other possible diagnoses or structural neurologic processes (eg, stroke, multiple sclerosis, tumor).

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Other Tests

Electrodiagnostic studies [6] are used to rule out other neurologic or neuromuscular disorders in the differential diagnosis. The following 5 phases of electrodiagnostic study findings of anterior horn cell disease have been recognized:

  • Acute myelitis (first month)

  • Early recovery (2-12 mo)

  • Late recovery

  • Functional stability

  • Late changes during functional stability (eg, fasciculations, positive waves, fibrillations, increased amplitude and duration of motor unit potentials)

In postpolio syndrome (PPS), sensory conductions should be normal; motor conductions usually are normal but may be slow. In late stages, amplitude decreases significantly.

Single-fiber electromyography reveals increased jitter and blocking. This observation is related to the fact that in PPS, variable degrees and different types of neuromuscular transmission failure have been found in affected patients who had associated histologic signs of reinnervation in their muscle biopsies.

Functional and structural abnormalities of neuromuscular junctions are common, but not necessary, conditions for the diagnosis of PPS. These neuromuscular junction transmission defects typically are observed in the early stage of the neuronal degeneration that produces PPS. Whether neuromuscular junction transmission defects increase with the passage of time is unclear.

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Histologic Findings

In the chronically denervated muscles of patients with postpolio syndrome, there are secondary myopathic features, including endomysial inflammation and rare vacuolated fibers.

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