What are the implications and management of a tuft of hair over a sacral dimple in a child or undiagnosed adult, potentially indicating spina bifida occulta or other spinal dysraphism?

Tuft of Hair Over Sacral Dimple

A sacral tuft of hair is a high-risk cutaneous marker that mandates spinal MRI and immediate neurosurgical referral, as approximately 70% of children with congenital spinal cord malformations display this finding. 1, 2

Risk Stratification

Hypertrichosis (focal tuft of hair) is classified as a HIGH-RISK cutaneous marker by the American Academy of Pediatrics, distinguishing it from the diffuse "light hair" commonly seen in normal infants. 1

• High-risk cutaneous markers are present in only 3% of normal neonates, but nearly 70% of children with congenital spinal cord malformations display at least one such marker. 1, 2
• Hair tufts are most strongly associated with split cord malformations, appearing in two-thirds of type I and one-third of type II cases. 1, 2
• Multiple high-risk markers commonly coexist, increasing the likelihood of underlying dysraphism. 1

Associated Findings to Assess

Examine for additional cutaneous and physical findings that frequently accompany sacral hair tufts:

• Capillary hemangiomas are often present alongside hair tufts. 1, 2
• Subcutaneous masses (lipomas) may be palpable. 1, 2
• Dermal sinus tracts located cranial to the gluteal cleft on the flat part of the sacrum. 2, 3
• Deviated or forked gluteal cleft can indicate underlying pathology. 1, 2
• Bone malformations or teratomas may be associated. 1, 2

Imaging Algorithm

MRI is the imaging modality of choice for all patients with sacral hypertrichosis, as recommended by the American Academy of Pediatrics. 2

Age-Based Approach:

• For infants <4-6 months: Spinal ultrasound may be used as initial screening, but MRI will ultimately be required if abnormalities are detected or if high suspicion remains despite normal ultrasound. 1, 3, 4
• For older infants and children: Proceed directly to MRI of the lumbar spine. 3
• If uncertainty exists about associated structural anomalies (e.g., markers of dysraphism like the hair tuft itself), imaging should be performed even with normal neurologic examination. 1, 2

Critical Imaging Details:

• MRI must evaluate the conus medullaris position, filum terminale thickness, and assess for open or closed spinal dysraphism. 3
• MRI has high sensitivity and specificity for detecting spinal dysraphism. 3

Neurosurgical Referral

Immediate referral to pediatric neurosurgery is mandatory for all infants with sacral hair tufts, regardless of neurologic examination findings. 2

• The presence of a hair tuft alone justifies imaging and referral, as recommended by the American Academy of Pediatrics. 2
• Do not wait for neurologic symptoms to develop before referring, as this approach risks irreversible deficits. 2, 5

Clinical Consequences of Delayed Diagnosis

Understanding the potential complications emphasizes the urgency of evaluation:

• Urologic dysfunction: Incontinence, frequency, recurrent UTIs, hydronephrosis, and bladder trabeculation occur in many patients with tethered cord. 1
• Orthopedic deformities: Up to 75% of patients with spinal dysraphism present with lower extremity neurologic and orthopedic abnormalities, including progressive scoliosis. 1
• Neurologic deterioration: Progressive symptoms from spinal cord tethering can cause permanent sensorimotor dysfunction. 1, 5
• CNS infection: Dermal sinus tracts can serve as portals for bacterial meningitis, and infection generates intradural scarring that complicates surgical excision. 3, 5

Timing and Prognosis

Early surgical detethering prevents permanent neurologic, orthopedic, and urologic deficits. 2, 6

• Tethered cord release is effective in arresting or improving neurologic symptoms and urologic deterioration when performed early. 1
• Long-standing or severe orthopedic deformities are unlikely to improve even after surgery, making early intervention critical. 1
• Delayed intervention risks permanent deficits that cannot be reversed. 6, 5

Common Pitfalls to Avoid

• Do not observe without imaging: Unlike simple coccygeal dimples (which are low-risk), hair tufts require definitive evaluation. 2, 4
• Do not rely on normal neurologic examination: Cutaneous markers may be the only indication of underlying spinal cord malformation before progressive symptoms develop. 1
• Do not mistake focal hypertrichosis for normal "light hair": The focality and midline location distinguish pathologic hair tufts from benign diffuse hair. 1