Microcephaly: A Rare Neurological Condition

What Is  Microcephaly?

rare birth defects

Microcephaly is a rare neurological condition in which the brain does not fully develop in the womb and the infant is born with a smaller than average head. It is usually already present at birth, but it can also develop in the first few months of life. Individuals born with microcephaly typically have severe mental deficits and have a poor long-term prognosis.


There are numerous factors or conditions that can lead to a baby being born with microcephaly or developing it shortly after being born. This includes, but is not limited to, the following:

  • Poland syndrome
  • Down syndrome
  • Edward syndrome
  • Patau syndrome
  • Unbalanced rearrangements
  • 4p deletion (Wolf–Hirschhorn syndrome)
  • 5p deletion (Cri-du-chat)
  • 7q11.23 deletion (Williams syndrome)
  • 22q11 deletion (DiGeorge syndrome)
  • Smith–Lemli–Opitz syndrome
  • Seckel syndrome
  • Cornelia de Lange syndrome
  • Holoprosencephaly
  • Primary microcephaly
  • Wiedemann-Steiner syndrome
  • Ischemic stroke
  • Hemorrhagic stroke
  • Death of a monozygotic twin
  • Vertically transmitted infections
  • Congenital cytomegalovirus infection
  • Toxoplasmosis
  • Congenital rubella syndrome
  • Zika virus
  • Drugs
  • Fetal hydantoin syndrome
  • Fetal alcohol syndrome
  • Radiation exposure to mother
  • Maternal malnutrition
  • Maternal phenylketonuria
  • Poorly controlled gestational diabetes
  • Hyperthermia
  • Maternal hypothyroidism
  • Placental insufficiency
  • Inborn errors of metabolism
  • Congenital disorder of glycosylation
  • Mitochondrial disorders
  • Peroxisomal disorder
  • Glucose transporter defect
  • Menkes disease
  • Congenital disorders of amino acid metabolism
  • Organic acidemia
  • Syndromes
  • Contiguous gene deletion
  • 17p13.3 deletion (Miller–Dieker syndrome)
  • Single gene defects
  • Rett syndrome (primarily girls)
  • Nijmegen breakage syndrome
  • X-linked lissencephaly with abnormal genitalia
  • Aicardi–Goutières syndrome
  • Ataxia telangiectasia
  • Cohen syndrome
  • Cockayne syndrome
  • Disruptive injuries
  • Traumatic brain injury
  • Hypoxic-ischemic encephalopathy
  • Ischemic stroke
  • Hemorrhagic stroke
  • Infections
  • Congenital HIV encephalopathy
  • Meningitis
  • Encephalitis
  • Toxins
  • Lead poisoning
  • Chronic renal failure
  • Deprivation
  • Hypothyroidism
  • Anemia
  • Congenital heart disease
  • Malnutrition

rare birth defects


Microcephaly is categorized in two different ways: Primary and Secondary.

Primary Microcephaly

Primary microcephaly refers to microcephaly that begins in utero, meaning the brain is not fully developing while the baby is still in the womb.

Secondary Microcephaly

Secondary microcephaly refers to microcephaly that begins after a baby is born, in which the brain stops developing early in infancy, usually due to an underlying condition or trauma.


  • Seizures
  • Convulsions
  • Severe neurological defects
  • Difficulty with motor functions
  • Low body weight
  • Dwarfism
  • Smaller than average head
  • Receding forehead
  • Wrinkled scalp
  • Spastic quadripalegia

neurological birth defects


In some cases, microcephaly can be diagnosed during a prenatal ultrasound. In other cases, microcephaly is often apparent at birth. For infants who develop microcephaly after birth, a pediatrician will often refer the child to a pediatric neurologist. Confirming microcephaly will involve an MRI (magnetic resonance imaging), which will produce a detailed image of the brain and show that the brain and skull are smaller than average size.


There is no cure for microcephaly. Medication can help with symptoms like seizures and convulsions, while physical therapy can improve motor function. The long-term prognosis for patients is often poor, with many not living past childhood.

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