Hydranencephaly is a rare condition. With this condition, the brain's cerebral hemispheres (the largest and main parts of the brain) are absent. They are replaced by sacs filled with cerebrospinal fluid.


Hydranencephaly may be caused by infections of the brain or its blood vessels or blockage of blood vessels to the brain after the 12th week of pregnancy.


An infant with hydranencephaly may appear normal at birth. The infant's head size and reflexes may all seem normal. These include:

  • Sucking.

  • Swallowing.

  • Crying.

  • Moving the arms and legs.

But after a few weeks the infant usually becomes irritable and has increased muscle tone. After a few months of life, certain symptoms may develop. They are:

  • Convulsions(seizures).

  • Large accumulation of cerebrospinal fluid in the brain (hydrocephalus).

Other symptoms may include:

  • Visual impairment.

  • Lack of growth.

  • Deafness.

  • Blindness.

  • Paralysis (spastic quadriparesis).

  • Intellectual deficits.


Diagnosis may be delayed for several months because some brain tissue is present and early behavior appears to be normal. Some infants may have additional abnormalities at birth. These include:

  • Seizures.

  • Spasm or twitching of a muscle or group of muscles (myoclonus).

  • Respiratory problems.


There is no treatment for this condition. Treatment is symptomatic and supportive.