Spina Bifida Occulta¶
Definition¶
Spina bifida occulta is the mildest form of spinal dysraphism, consisting of incomplete fusion of the posterior vertebral arch (laminae) without herniation of meninges or neural tissue. It is an extremely common incidental finding, present in approximately 10–20% of the general population, most often at L5 or S1.
Imaging Findings¶
Radiography/CT¶
- Midline bony defect in the posterior arch — the laminae fail to fuse at the midline
- Most common at L5 and S1
- No associated soft tissue mass
- The spinal cord and nerve roots are normal
MRI¶
- Usually not indicated for isolated spina bifida occulta
- If obtained, the cord position and morphology are normal
- MRI is indicated only if cutaneous markers or neurological symptoms suggest an associated closed dysraphism (tethered cord, lipoma, diastematomyelia)
Clinical Pearl
Isolated spina bifida occulta is an incidental finding that requires no treatment, follow-up, or further imaging. It should not be confused with more significant dysraphisms. However, if spina bifida occulta is seen in a child with cutaneous stigmata (hairy patch, dimple, lipoma) or neurological symptoms (bladder dysfunction, foot deformity), MRI should be obtained to evaluate for associated occult dysraphism.
Key Points¶
- Present in 10–20% of the population — usually an incidental finding
- Incomplete fusion of posterior arch at L5 or S1
- No herniation of meninges or neural tissue
- No treatment or follow-up needed for isolated findings
- MRI only if cutaneous markers or neurological symptoms are present
References¶
- Trapp B, Freddi TAL, Hans MOM, et al. A practical approach to diagnosis of spinal dysraphism. RadioGraphics. 2021;41(2):559–575. doi:10.1148/rg.2021200103. Available from: https://pubmed.ncbi.nlm.nih.gov/33449837/
- Kumar J, Afsal M, Garg A. Imaging spectrum of spinal dysraphism on magnetic resonance: a pictorial review. World J Radiol. 2017;9(4):178–190. doi:10.4329/wjr.v9.i4.178. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC5415887/
- Sarin YK. Cutaneous stigmata of occult spinal dysraphism. J Neonatal Surg. 2013;2(1):15. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC4420352/
- Li W, Xiong Z, Dong C, et al. Distribution and imaging characteristics of spina bifida occulta in young people with low back pain: a retrospective cross-sectional study. J Orthop Surg Res. 2021;16:151. doi:10.1186/s13018-021-02285-w. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC7898417/
- Karsonovich T, Munakomi S. Spina bifida. In: StatPearls. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559265/
- Gaillard F, et al. Spina bifida occulta. Radiopaedia.org. Available from: https://radiopaedia.org/articles/spina-bifida-occulta