The present study was undertaken to clarify how vile should assess the
necessity of close follow-up in each case, when we first examine an i
nfant with ankle clonus within the first year of life. The neurologic
prognoses of 169 infants who had exhibited ankle clonus at least once
during the first year of life were reviewed in relation to the age at
examination for positive response, degree of response, and coexisting
neurologic signs other than ankle clonus. Ninety-seven of them (57.4%)
were normal, while the rest had diverse pathologic outcomes: cerebral
palsy in 49, mental retardation in 12, borderline intelligence in 9,
and motor delay in 2. The neurologic prognoses in infants whose ankle
clonus was more than ten beats at any age within the first year of lif
e, and ten or less beats over 8 months of age were always abnormal. In
the subjects whose neurologic signs other than ankle clonus appeared
within 4 months of age and persisted after 5 months of age, prognoses
were generally pear. In infants with such findings, their clinical cou
rses should be closely observed for the possible development of neurol
ogic abnormalities. (C) 1997 Elsevier Science B.V.