Recently, I have encountered many parents on the Internet who have asked about extracerebral hydrocephalus (external hydrocephalus), especially in children just a few months old; some parents are very nervous about delaying the condition and developing cerebral palsy or intellectual disability in the future. In view of this, I have summarized and documented this common problem as follows, so please read it; however, please do not judge it mechanically by matching the numbers or relying too much on this content to avoid delaying the child’s condition.
Infantile hydrocephalus is a benign self-healing disease that occurs in infancy, also known as external hydrocephalus, or “benign subdural effusion in infants” in foreign literature. It can be divided into two types: idiopathic and secondary. Idiopathic hydrocephalus refers to extracerebral fluid without a clear cause, and is a benign self-healing disease that resolves spontaneously at the age of 2 to 3 years without sequelae.
Secondary hydrocephalus can be caused by genetic disorders, trauma, subdural hematoma, meningitis, systemic elevated venous pressure, premature birth, vitamin A deficiency, intraventricular hemorrhage and subarachnoid hemorrhage, etc. In milder cases, the disease will regress on its own as in idiopathic hydrocephalus. Neonatal ischemic-hypoxic encephalopathy is the main cause of external hydrocephalus, and some of them have a poor prognosis; those without obvious causes and those with external hydrocephalus in preterm infants mostly have a good prognosis.
The main reasons for consultation are: crying, excitement, irritability, shrieking and jumping; restless sleep, easy to wake up, difficulty in falling asleep, short duration of sleep; feeding difficulties, poor feeding, easy vomiting, etc. The clinical manifestations of hydrocephalus include larger head circumference than normal infants of the same age or rapid increase in head circumference, large anterior chimney or late closure; poor reaction, retardation, poor movement of hands and feet, and no response to sound and color. The main effects of external hydrocephalus on the growth and development of children include delayed motor development, transient convulsive seizures, delayed speech development, lack of weight gain, difficulty in feeding, excitement and irritability, etc.
CT findings (1) The subarachnoid space in the frontal and frontoparietal regions is widened by >5 mm, while the subarachnoid space in other regions is not widened or slightly widened.
(2) Widening of the anterior interhemispheric fissure.
(3) Enlargement of the basal pool, mainly the suprasellar pool.
(4) Deepening and widening of the frontoparietal sulcus.
(5) The ventricles are small or mildly dilated.
If the child has no symptoms of high cranial pressure, special treatment is not necessary and the child should be treated by itself. In the treatment of high cranial pressure, fontanelle puncture and continuous drainage of fontanelle are often used.
It is worth mentioning that in infants and young children aged 1 to 2 years, brain development and cranial growth are relatively slow, so the brain sulcus, fissure and pool are relatively wide. The subarachnoid space on the brain surface can widen up to 4mm, the longitudinal fissure pool 6mm, and the lateral fissure pool 10mm, which are all within the normal range; after 18 months to 2 years of age, brain development is accelerated, the brain sulcus becomes narrower, and extracerebral fluid will gradually decrease or disappear. In addition, in some children, due to premature birth or intrauterine cerebral dysplasia, a CT scan after birth may show a widening of the subarachnoid space, somewhat similar to extracerebral hydrocephalus. In this case, the child is observed if there are no signs of developmental or functional lag, and if there are, rehabilitation is provided, and surgical intervention is usually not required.