Which form is the most common open protruding sac containing meninges and nonfunctional nerves?

Which form is the most common open protruding sac containing meninges and nonfunctional nerves?

• A. Meningocele
• B. Myelomeningocele
• C. Myeloschisis
• D. Occulta

Answer: (B)

In open spinal dysraphisms, the form that has a sac containing both meninges and neural tissue (with the nerves often nonfunctional) is myelomeningocele. This is the most common open form of spina bifida and typically presents with the spinal cord and nerve roots within the sac, leading to neurologic deficits below the level of the lesion. By comparison, meningocele involves only meninges (and CSF) protruding, with no neural tissue in the sac, so neurological function can be relatively preserved. Myeloschisis is a more severe defect where the neural tissue is exposed directly, without a protective sac. Occulta is a closed defect with no protruding sac and may show only subtle signs like a hair tuft or dimple.

In open spinal dysraphisms, the form that has a sac containing both meninges and neural tissue (with the nerves often nonfunctional) is myelomeningocele. This is the most common open form of spina bifida and typically presents with the spinal cord and nerve roots within the sac, leading to neurologic deficits below the level of the lesion.

By comparison, meningocele involves only meninges (and CSF) protruding, with no neural tissue in the sac, so neurological function can be relatively preserved. Myeloschisis is a more severe defect where the neural tissue is exposed directly, without a protective sac. Occulta is a closed defect with no protruding sac and may show only subtle signs like a hair tuft or dimple.