Neurological correlates of fetal cocaine exposure: transient hypertonia of infancy and early childhood

Abstract

Objective: To assess whether prenatal cocaine exposure has any long-term effects on neurodevelopment.

Design: A prospective cohort study with examiners blind to drug exposure and human immunodeficiency virus (HIV) status.

Subjects: Of 144 high-risk infants enrolled in a perinatal HIV neurodevelopmental study, 119 (83%) infants with both neurological and urine toxicology measures were followed up to age 24 months.

Methods: Neurological and developmental assessments were analyzed at 6-month intervals grouped according to the presence of cocaine in urine toxicology: 51 infants were cocaine-positive. Adjusted odds ratios (ORs) and 95% confidence interval (CI) were obtained by logistic regression equations that adjusted for perinatal variables, including measures of fetal growth, gestation, HIV status, and infant toxicology results.

Setting: Harlem Hospital Center from 1988 to 1992.

Results: At age 6 months, 21 of 51 (41%) cocaine-positive children exhibited hypertonia of any type (hypertonic tetraparesis, hypertonic diparesis, and hypertonic hemiparesis) compared with 17 of 68 (25%) cocaine-negative infants (OR = 2.1, CI = 1.0-4.6). Cocaine-positive infants were four times more likely to show hypertonic tetraparesis (HTP) than cocaine-negative infants (OR = 4.0; CI = 1.5-10.8). The association remained significant in multivariate analyses. Hypertonia, consistent with cerebral palsy, diminished over time in both groups. In 97% of affected infants hypertonia resolved by 24 months. Arm hypertonia abated first; leg hypertonia remained in some children up to age 18 months. No differences in development scores between cocaine-positive and cocaine-negative were noted at any age interval. However, among cocaine-positive infants those with early HTP showed significantly lower mean developmental scores at 6 and 12 month compared to infants without HTP.

Conclusion: Cocaine positivity urine toxicology at birth is associated with hypertonia during infancy. Such cocaine-induced effects are usually symmetrical, transient, and the majority of exposed children outgrow hypertonia by 24 months of life. Among cocaine-positive infants, HTP may be a marker for later developmental impairments.