CLINICAL-NEUROLOGICAL AND INTELLECTUAL CHARACTERISTICS OF MICROCEPHALY OF VARIOUS ETIOLOGIES

According to contemporary data, the prevalence of microcephaly is approximately 2 cases per 1,000 live births; however, this rate varies substantially depending on the applied diagnostic criteria, the demographic composition of the study population, and the degree of inbreeding [2,6]. In populations with high rates of consanguineous marriages—a characteristic feature of several regions in Central Asia—the incidence of hereditary forms significantly exceeds global averages and can reach up to 1:1,000 [1,4]. The diagnostic evaluation of microcephaly initiates with anthropometric assessment: systematic measurement of head circumference (HC) plotted on standard percentile growth curves. A reduction in head circumference below the 3rd percentile (−2 SD), or below the 0.4th percentile (−3 SD) in severe cases, is considered diagnostically significant. Measurements must be performed dynamically at least three times to accurately evaluate the trajectory of cranial growth [3,5]. A comprehensive neurological examination encompasses the assessment of muscle tone, motor milestone development, cranial nerve functions, reflex activity, coordination, and cognitive status. For standardized neurological evaluation in infants, the Hammersmith Infant Neurological Examination (HINE) scale is highly recommended. The HINE scale comprises 26 items evaluating posture, cranial nerve functions, reflexes, muscle tone, motor skills, and behavior. The sensitivity of the HINE scale for detecting neurological abnormalities in infants with microcephaly aged 3 to 24 months reaches up to 90% [2]. For older pediatric cohorts, the Pediatric Neurological Examination (PNE) scale is utilized to quantitatively grade psychomotor and intellectual development.