Sacral Tuft of Hair: Clinical Significance and Management
A sacral tuft of hair (hypertrichosis) is a high-risk cutaneous marker that requires spinal imaging with MRI and neurosurgical referral, as approximately 70% of children with congenital spinal cord malformations display this finding, and it is most commonly associated with split cord malformations. 1
Risk Stratification
Hypertrichosis—a focal tuft of hair located in the posterior spinal midline, often called a "fawn's tail"—is classified as a high-risk cutaneous anomaly for underlying spinal dysraphism. 1 This distinguishes it from diffuse or "light hair" commonly seen in normal infants. 1
Key epidemiologic data:
- High-risk cutaneous markers (including hair tufts) are present in only 3% of normal neonates 1
- Nearly 70% of children with congenital spinal cord malformations display at least one high-risk cutaneous marker 1
- Hair tufts are associated with two-thirds of type I split cord malformations and one-third of type II split cord malformations 1
Associated Findings to Assess
When evaluating a sacral hair tuft, examine for coexisting high-risk features that frequently accompany hypertrichosis:
- Capillary hemangiomas (often present alongside hair tufts) 1
- Subcutaneous masses such as lipomas 1
- Dimples or dermal sinus tracts located cranial to the gluteal cleft on the flat part of the sacrum 1
- Bone malformations or teratomas 1
- Deviated or forked gluteal cleft 1, 2
The presence of multiple cutaneous markers together is common and increases suspicion for underlying dysraphism. 1
Imaging Approach
All patients with sacral hypertrichosis require spinal imaging. 2, 3
- MRI is the imaging modality of choice for visualizing spinal cord malformations, tethered cord, split cord malformations, lipomyelomeningocele, and dermal sinus tracts 3, 4
- Spinal ultrasound may be used in neonates under 3-4 months when the posterior elements are not yet ossified, but MRI provides superior visualization 4
- Imaging should not be delayed based on absence of neurologic symptoms, as cutaneous markers may be the only indication of underlying malformation before progressive deficits develop 1
Neurosurgical Referral
Immediate referral to pediatric neurosurgery is mandatory for all infants with sacral hair tufts. 2, 3
The rationale for urgent referral includes:
- Prevention of irreversible neurologic deterioration from progressive tethering 4
- Early surgical intervention improves outcomes for neurological, orthopedic, and bladder function 4
- Risk of serious complications including CNS infections, spinal cord compression, and permanent deficits if undiagnosed 1, 2
Common Pitfalls to Avoid
Do not observe or delay evaluation based on absence of neurologic symptoms—cutaneous markers often precede clinical manifestations. 1
Do not confuse a sacral hair tuft with normal infant hair—hypertrichosis is focal, thick, and resembles a horse's tail, distinct from diffuse light hair. 1
Do not rely solely on physical examination—underlying spinal dysraphism cannot be excluded without imaging, even in neurologically intact infants. 3, 4
Do not mistake location—ensure the hair tuft is truly sacral/lumbosacral (above the gluteal cleft line) rather than coccygeal, though any midline posterior spinal hair tuft warrants evaluation. 2
Specific Malformations Associated with Hair Tufts
The most common underlying pathology is split cord malformation (diastematomyelia), where the spinal cord is divided by a bony or fibrous septum. 1, 5 Other associated conditions include:
- Tethered cord syndrome 4
- Lipomyelomeningocele 4
- Dermal sinus tracts (when hair tuft accompanies a dimple) 1
- Various forms of occult spinal dysraphism 3
Prognosis and Timing
Early surgical detethering, when indicated, prevents permanent neurologic, orthopedic, and urologic deficits. 4 Delayed intervention after symptom onset risks irreversible damage. 2, 4 The presence of a hair tuft alone justifies imaging and referral regardless of neurologic examination findings. 1, 2