Universlty of Manitoba, ln Partîal Fulfiìlment - MSpace at the ...

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1.5.1 SÞlri¿i B_!ll i dê Occúl rå ând Cysr¡ca
ln spina blfîda occulta there ls no open neural lesion,but ro_
en tgenog rans revda I a defect of or¡e or more spinous processes or raminae.
The site of this bony defect may occasionar ry be marked by abrrormar ities
of overlying skin, such as pigmented or. hairy patches. Though often
undetected, spína bifida occulta is sometimes accompanied by symptoms
suggesting ínvolvement of the spinal cord or cauda equina. This could be
caused by ê tight filum terminale, fibrous bands, ¡ntrathecal I ipomas,
or frank myelodysplasia (¡ames and Lassman, ,|967). The symptomless and
symptomatic forms of spina bífida occulta may represent two distinct
leslons, the former being prima,r.iry a skeretar defect and the ratter
secondary to cord or cauda equ¡na defects,
By contrast, ân external ly visible defect is called a spina bifida
manífesta, or apertâ, or cystica (if cystíc). Several types may be distínguished.
I.5.2 Men!!rgoce I e
A meningocele invorves defects of severar neurar arches wrth herníation
of meninges but not of neural tissue, though the underlying cord may be
dysplastíc. For this reason a meningocete cannot always be diagnosed
w¡th certa¡nty, and may prove on exploration to be myelocele (Laurence,
1964',).
1,5.3. Myelomeningocele
An open lesion consisting of neural tissue, accumulated fluld,
abnormal vasular tíssue, and a variable amount of epithel íumrwith the
loss of several neural arches is tradítionar ry calred a myeromeningocere
(fig.3 ¡. However, it is now bel ieved that the tesion originates as a