Most infants also develop hydrocephaly, an accumulation of excess fluid in the four cavities of the brain.
Paralysis below the level of the abnormality and fluid on the brain (hydrocephaly) may contribute to the diagnosis.
In cases in which there are no external findings, the diagnosis is more difficult and may not become evident until neurological abnormalities or hydrocephaly develop weeks, months, or years following birth.
This deficit may result, in part, from hydrocephaly and/or infections of the nervous system.
Although complications from paralysis, hydrocephaly, Chiari II malformation, and urinary tract deterioration threaten the well-being of the survivors, the outlook for normal intellectual function is good.