Overview
This lecture discusses the types of spina bifida, focusing on the differences between open and closed forms, their neurological impacts, and associated brain malformations.
Types of Spina Bifida
- Spina bifida can be classified as open or closed (occult) and presents in various forms along the spinal midline.
- Open spina bifida occurs when the spinal cord is exposed, while closed lesions do not expose the spinal cord.
Impact of Open vs. Closed Lesions
- Both lesion types affect lower limb function, bowel/bladder control, and sexual function.
- Open lesions expose the spinal cord and leak cerebrospinal fluid (CSF) during early pregnancy, disrupting nervous system development.
- Closed or occult lesions do not expose the spinal cord or leak CSF but can still impair function locally.
Neurological Consequences and Chiari II Malformation
- Open spina bifida leads to loss of CSF, causing defects in brain and spinal cord development.
- Chiari II malformation results when the posterior part of the brain (posterior fossa) is too small and the brainstem is displaced onto the cervical spinal cord.
- The collapse of CSF spaces and abnormal wiring in the brain contribute to hydrocephalus (excess fluid in the brain).
Key Terms & Definitions
- Open Spina Bifida — A neural tube defect where the spinal cord is exposed and CSF leaks out.
- Closed (Occult) Spina Bifida — A form where the spinal cord is not exposed and CSF does not leak.
- Cerebrospinal Fluid (CSF) — The fluid surrounding the brain and spinal cord.
- Chiari II Malformation — Brain abnormality where the posterior fossa is too small and the brainstem herniates.
- Hydrocephalus — A condition of excess CSF in the brain's cavities.
Action Items / Next Steps
- Review images comparing normal and spina bifida-affected brain anatomy.
- Study definitions and implications of open versus closed spina bifida.
- Prepare questions about Chiari II malformation and hydrocephalus for discussion.