Motor Outcomes in Premature Infants

Maureen Connors Lenke, BS, OTR/L

Disclosures

NAINR. 2003;3(3) 

In This Article

Transient Neurological Abnormalities of Preterm Infants

Another complicating factor in the early assessment of the premature infant is the fluctuation or transient nature of muscle tone. The incidence of transient neurologic abnormalities ranges from 40% to 80% in premature infants.[6] The clinical manifestations of "transient dystonia" increases in frequency as birth weight and gestational age decrease.[7] Components of transient dystonia include either hypotonia, or more typically, increased muscle tone with extensor hypertonus through the trunk and lower extremities and increased flexor tonus through the upper extremities.

Irritability and hypertonia with excessive neck hyperextension may also be present. Decreased alertness, poor state regulation, or hyperexcitability may also be a transient sign. Some degree of physiologic hypertonia is normally present during the first 3 months, making it difficult to differentiate from the early developing spasticity related to a diagnosis of CP.[6]

Continued transient signs in the third to ninth month are the persistence of primitive reflexes, high tone in the lower extremities with poor truncal tone, or a persistence of extensor tonus in the trunk and lower extremities. Even these later signs of motor dysfunction frequently resolve. In approximately 20% of the cases, the abnormalities in tone persist.[6] The persistence of abnormal motor findings during the newborn period indicates the highest probability of continued abnormality at 1 year of age.[6] Those infants without any transient abnormal motor signs have the lowest rate of subsequent abnormality. At early follow-up visits, it is more important to look for a combination of questionable motor findings than to be concerned about a single worrisome sign. As an example, mildly increased shoulder girdle tone with consistent weight bearing and the ability to reach forward may not be indicative of a future problem. At least two-thirds of very low birth weight infants exhibit a variety of transient neuromotor abnormalities, which will gradually resolve with continued development.[8] When motor impairment persists, a diagnosis of cerebral palsy may be considered.

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