Spinal Dysraphism Overview¶

Definition¶

Spinal dysraphism refers to a group of congenital anomalies resulting from incomplete closure of the neural tube during embryological development. These conditions range from clinically insignificant incidental findings (spina bifida occulta) to severe malformations with significant neurological disability (myelomeningocele).

Classification¶

Open Spinal Dysraphism (OSD)¶

The neural tissue is exposed to the environment — no skin covering. Diagnosed at birth or prenatally on ultrasound. Elevated maternal serum alpha-fetoprotein (AFP).

• Myelomeningocele — The most common and most severe form of OSD
• Myelocele — Neural placode flush with the skin surface

Closed Spinal Dysraphism (CSD)¶

The defect is covered by skin. May be occult and diagnosed later in life.

With subcutaneous mass: - Lipomyelomeningocele - Meningocele - Lipoma

Without subcutaneous mass: - Spina bifida occulta - Tethered cord (tight filum terminale) - Diastematomyelia (split cord malformation) - Dermal sinus tract - Caudal regression syndrome

Imaging Approach¶

Prenatal¶

• Ultrasound — Open neural tube defects detected on anatomic survey (splaying of posterior elements, "lemon sign" of the skull, "banana sign" of the cerebellum)
• Fetal MRI — Further characterization of the defect and associated Chiari II malformation

Postnatal¶

• MRI — Modality of choice for all suspected spinal dysraphisms. Evaluates the cord, conus position, filum terminale, and associated anomalies.
• Ultrasound — Useful in neonates (before ossification of the posterior elements) for screening tethered cord and simple anomalies
• CT — Evaluates bony anomalies (spina bifida, diastematomyelia septum, segmentation anomalies)

Cutaneous Markers¶

Skin findings that should prompt imaging for occult spinal dysraphism:

• Midline lumbar dimple (above the gluteal creft)
• Hairy patch (hypertrichosis)
• Subcutaneous lipoma
• Hemangioma or skin discoloration over the spine
• Skin appendage or tail

Key Points¶

• Spinal dysraphism results from incomplete neural tube closure
• Open dysraphisms (myelomeningocele) are diagnosed prenatally or at birth
• Closed dysraphisms may be occult — cutaneous markers prompt imaging
• MRI is the modality of choice for postnatal evaluation
• Conus position, filum terminale thickness, and associated anomalies are the key MRI findings

References¶

1. Tortori-Donati P, Rossi A, Cama A. Spinal dysraphism: a review of neuroradiological features with embryological correlations and proposal for a new classification. Neuroradiology. 2000;42(7):471-491. doi:10.1007/s002340000325. PubMed
2. Rufener SL, Ibrahim M, Raybaud CA, Parmar HA. Congenital spine and spinal cord malformations--pictorial review. AJR Am J Roentgenol. 2010;194(3 Suppl):S26-S37. doi:10.2214/AJR.07.7141. PubMed
3. Trapp B, de Andrade Lourenção Freddi T, de Oliveira Morais Hans M, et al. A Practical Approach to Diagnosis of Spinal Dysraphism. RadioGraphics. 2021;41(2):559-575. doi:10.1148/rg.2021200103. PubMed
4. Chellathurai A, Kathirvelu G, Mukkada PJ, Rajendran K, Ramani R. Spinal Dysraphisms: A New Anatomical-Clinicoradiological Classification. Indian J Radiol Imaging. 2022;31(4):809-829. doi:10.1055/s-0041-1741100. PMC
5. Karsonovich T, Munakomi S. Spina Bifida. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2025. NCBI Bookshelf
6. Spinal dysraphism. Radiopaedia.org. Radiopaedia

Related Articles¶

• Myelomeningocele
• Tethered Cord Syndrome
• Lipomyelomeningocele