Acute flaccid paralysis (AFP) is a clinical syndrome characterized by rapid
onset of weakness, including (less frequently) weakness of the muscles of
respiration and swallowing, progressing to maximum severity within several days
to weeks. The term "flaccid" indicates the absence of spasticity or
other signs of disordered central nervous system motor tracts such as
hyperreflexia, clonus, or extensor plantar responses.
The
differential diagnosis of AFP varies considerably with age. No single operational
clinical case definition of AFP or paralytic poliomyelitis that combines
both high sensitivity and high specificity has emerged. The currently used case
definition increases sensitivity in detecting the existence of AFP but tends to
decrease specificity in detecting paralytic poliomyelitis.