National Rehabilitation Hospital Postpolio Limb Classification

Class of Polio	Remote History	Recent History	Physical Examination	Neurological Examination
I No clinical	No weakness	No new weakness	Good-to-normal strength, normal sensation and reflexes, no atrophy.	Normal using standard screening examination.
II Subclinical	No weakness or, if effected, full clinical recovery.			Chronic denervation consistent with anterior horn cell disease, no evidence of acute denervation.
III Clinically stable	Weakness with variable recovery.		Poor-to-good strength, normal sensation, normal-to-decreased reflexes, may have atrophy.	Chronic denervation consistent with anterior horn cell disease, may have evidence of acute denervation.
IV Clinically unstable		New weakness
V Severely Atrophic	Weakness with little recovery.	May have new weakness	Trace-to-poor strength, normal sensation, areflexic, severe atrophy.	Decreased insertional activity, few to no motor unit action potentials, may have acute denervation.