Management of Sacral Dimple with Normal Spinal Anatomy
Based on the imaging findings showing a small, shallow sacral dimple with normal conus position (L1-L2), normal filum terminale thickness (1.3 mm), and no dermal tract, this patient requires no further intervention or imaging—reassurance and routine follow-up are appropriate. 1
Key Imaging Findings Analysis
The MRI demonstrates reassuring anatomical features:
- Conus medullaris at L1-L2: This is within normal limits, as the conus should terminate at or above the L2-L3 disc space 2, 3
- Filum terminale 1.3 mm: Well below the 2 mm threshold for normal, indicating no thickening or fatty infiltration 4, 5
- Mildly dilated central canal (1 mm): This minor finding is not clinically significant in isolation without other abnormalities 2
- Thecal sac at S2: Normal termination level 4
- No dermal tract visualized: Critical finding that excludes the most concerning pathology 1
Clinical Significance of Dimple Location
The location and characteristics of the sacral dimple are the most important determinants of pathological significance, not whether you can visualize the base. 4, 1
- A dimple at or below an imaginary line between the tops of the gluteal cleft is considered a normal coccygeal dimple requiring no workup 1
- The description of this dimple as "small and shallow" without an identifiable dermal tract indicates a benign finding 4, 1
- Simple sacral dimples alone carry an exceedingly low risk (0.13%) of significant spinal malformations 6
Risk Stratification Based on Evidence
The absence of a dermal sinus tract is the critical distinguishing feature. 4
- Dermal sinus tracts correlate with the highest risk of spinal cord lesions and require surgical intervention due to risks of CNS infection, aseptic meningitis, spinal cord compression, and neurologic deterioration from tethering 4, 2
- In contrast, isolated simple sacral dimples without dermal tracts represent negligible risk for occult neural pathology 2, 6
- Among 3,884 healthy infants with simple sacral dimples, only 0.13% required surgical intervention 6
Management Recommendations
No further imaging or intervention is indicated. 1, 6
- The completed MRI has definitively excluded spinal dysraphism, tethered cord syndrome, and dermal sinus tract 4
- Routine clinical follow-up is appropriate to monitor for any new neurological symptoms, though development of problems is extremely unlikely 7, 6
- Parents should be counseled about the benign nature of this finding and reassured that no restrictions on activity are necessary 1
Red Flags That Would Change Management
Watch for these features that would require neurosurgical consultation (none present in this case): 4, 1
- Dermal sinus tract above the gluteal cleft line 4, 1
- Associated cutaneous markers: hairy patches, vascular malformations, subcutaneous masses, or skin tags 4, 2
- Neurological symptoms: lower extremity weakness, bowel/bladder dysfunction, or foot deformities 3
- Conus medullaris below L2-L3 disc space 2, 3
- Filum terminale thickness >2 mm or containing fat 5
Common Pitfalls to Avoid
Do not rely on outdated teaching about dimple depth or visibility of the base. 4, 1
- The American Academy of Pediatrics explicitly states that whether you can see the "bottom" of a dimple has little to do with its pathologic nature 4
- Location along the craniocaudal axis is the most important feature, not depth 4, 1
- The presence of multiple skin markers or a single dermal sinus tract (not present here) would indicate higher risk requiring evaluation 2