| | Surgery & Procedures | Brain Surgery

Microcephaly: Causes, Consequences, and Clinical Management

Microcephaly: Small Brain, Significant Implications

Microcephaly is a neurodevelopmental condition defined as an occipitofrontal circumference (OFC) >2 standard deviations below the mean for age and sex (some guidelines use ≤3 SD). It reflects reduced brain growth—either prenatal (congenital) or postnatal (acquired).

Etiology

Category	Examples
Genetic	Autosomal recessive (MCPH genes: ASPM, WDR62, etc.), chromosomal (Down, Cri-du-chat, 1p36 deletion), single-gene syndromes (Seckel, Rett)
Prenatal Infection	Zika (congenital Zika syndrome), CMV, rubella, toxoplasmosis, syphilis, HSV, VZV
Teratogens	Alcohol (FASD), radiation, valproate, warfarin, isotretinoin
Metabolic/Nutritional	Severe malnutrition, phenylketonuria (untreated), maternal diabetes
Perinatal/Postnatal	Hypoxic-ischemic encephalopathy, stroke, meningitis, craniosynostosis (premature suture fusion restricts growth)

Clinical Consequences

Intellectual disability: Varies from mild to profound; correlates with brain volume reduction.
Developmental delays: Motor, speech, social.
Seizures: 20–40% (especially with structural malformations).
Spasticity, hypertonia.
Facial features: Sloping forehead, prominent ears, micrognathia (in some syndromes).
Associated anomalies: Cardiac, renal, ocular, skeletal.

Diagnostic Evaluation

Serial OFC measurements (birth, 2, 4, 6, 9, 12, 18, 24 months).
Neuroimaging: MRI brain (preferred)—cortical architecture, myelination, posterior fossa.
Genetic testing: Chromosomal microarray → exome sequencing → targeted panels.
TORCH screen, metabolic labs if indicated.
Ophthalmology, audiology, developmental assessment.

Management

Early intervention (PT, OT, speech) maximizes potential.
Seizure control.
Surgical release if craniosynostosis.
Genetic counseling for family.
Multidisciplinary care: neurology, genetics, developmental pediatrics.

Prognosis

Highly variable. Isolated mild microcephaly may have near-normal cognition. Syndromic/severe forms require lifelong support. Early, comprehensive care improves functional outcomes.