Post-polio syndrome is a motor neuron disease that occurs in 15%-80% of patients with a history of polio.1 The diagnostic criteria for post-polio syndrome include a confirmed history of polio, partial or complete neurologic and functional recovery after acute polio, a period of more than 15 years with neurologic and functional stability, new symptoms that have been present for more than 1 year, such as weakness and abnormal muscle fatigability, and the exclusion of other medical conditions.1 To our knowledge no virus other than polio has been reported to cause such a disorder.
A 72-year-old woman noticed generalized fatigue and weakness in her upper and lower limbs 4 years earlier. She was referred to our hospital because her progressive weakness had not only stopped but had slightly improved, which was atypical for the progression of amyotrophic lateral sclerosis. She did not present with sensory impairment, respiratory disturbance, dysphasia, or dysautonomia. At the age of 33 years, she had been diagnosed with polio-like syndrome after acute hemorrhagic conjunctivitis due to enterovirus-70. At that time there was a 16-fold increase in her serum levels of neutralizing antibody to enterovirus-70. The weakness in her limbs had recovered to half its original degree, except in her right shoulder.
Manual muscle testing revealed that her deltoids were 1/5 (right/left), biceps brachii 4-/5, triceps brachii 3/4, wrist flexors 5/4-, wrist extensors 4/4-, iliopsoas 1/4, quadriceps femoris 1/2, hamstrings 4-/4-, tibial anterior 2/5, and triceps surae 4-/5. Fasciculations were not observed. The patient’s reflexes were reduced or absent in all limbs. She was able to walk with a back-knee gait using a handcart (Supplementary Video, available online). A blood test revealed a 4-fold increase in neutralizing antibody to enterovirus-70. Spirometry and cerebrospinal fluid tests showed no abnormalities. Segmental muscle atrophy and fatty change in the limbs were evident on computed tomography scans (Figure, panels A and B), but no causative abnormalities were observed on magnetic resonance imaging of the brain and spinal cord. Nerve conduction studies showed a reduction in compound muscle action potential amplitudes and normal sensory nerve action potential amplitudes in limbs. Chronic denervation with some fibrillations (acute denervation potentials) was seen in both tibial anterior muscles, whereas motor unit potentials were normal in the tongue. These findings were consistent with post-polio syndrome. On the basis of the criteria for post-polio syndrome and on her history of polio-like syndrome, she was diagnosed with “post-polio-like syndrome.”
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-Shingo Suzuki, MD, PhD Sonoko Misawa, MD, PhD, Takahiro Ota, MD, Yu Li, MD, Satoshi Kuwabara, MD, PhD, Masatomi Ikusaka, MD, PhD
This article originally appeared in the November 2017 issue of The American Journal of Medicine.
