Cutaneous back lesions
When performing a physical exam on a newborn, the midline back should be examined carefully for a cutaneous back lesion. Because these lesions are associated with neural tube defects (NTDs)/spinal dysraphism, and are sometimes the only indication that one exists, it is important to look for them, as serious deficits can be prevented with early intervention. These lesions include:
In addition to observation, the spine should be palpated to feel for incomplete fusion of the bony spine, and legs should be examined for equal length and sensory abnormalities. If the patient is slightly older, a history should be taken regarding bladder abnormalities (e.g. failure to urinate or empty bladder completely) and unexplained complication.
All of the above can indicate an underlying neural tube defect, NTD. (Notably, mongolion spots, which can also be mistaken for bruises, are benign.) With hypertrichosis, dimples, skin tags, lipomas, hemangiomas, aplasia cutis, or sinus tracts, there is a higher index of suspicion than with telangiectasias, hyperpigmentation, nevi, or teratomas.
If any cutaneous back lesion or abnormality is noted, an ultrasound of the lower back is the next screening tool, followed by an MRI (or CT if visualization of the bones are needed) and a neurosurgery consult.
What exactly is a neural tube defect? There are several kinds and can be either open or closed. Closed NTDs include spina bifida occulta, meningocele, and myelominingocele. In spina bifida, the vertebral arch is incompletely fused but no herniation of contents occurs – classically, this presents with a tuft of hair. In myelomeningocele, the meninges and neural tissue protrudes, and in meningocele, only the meninges protrudes. Open NTDs will not be discussed here, but includes anencephaly, which, together with spina bifida, is one of the most common NTDs.
Why do they occur? NTDs occur due to failure of closure of the neural tube, which happens by week 4 of gestation, before most women know they are pregnant. They can be prevented by supplementation of 0.4 mg of folic acid in the diet from conception to the end of the first trimester.
How common are they? In the United States, 1-2 of every 1000 newborns has a neural tube defect. It is the second most common congenital anomaly, and there are multiple factors that determine risk of an NTD, such as geographical location (Ireland and Wales high-risk), SES (poor high risk), maternal age (teenagers and older moms increased risk), and prenatal exposure to valproic acid (and other drugs) and maternal diabetes. If a first degree relative is affected that means another is more likely to have another affected.
Why screen? If a neural tube defect goes undetected, there can be serious consequences that can be prevented with early diagnosis and neurosurgical intervention. In meningocele and myelomeningocele, bowel and bladder sphincter dysfunction and sensorimotor loss below the lesion can result. The infant can be neurologically intact, but as the caudal end of cord is tethered to distal spine, when the spine grows, traction injury leads to issues with gait, sphincters, feet, and motor. Patients with spina bifida can get infectious complications, cortical malformations, and Chairi II malformations. In tethered cord, patients can be easily detected, as more than half of patients have a cutaneous lower back lesion while being otherwise asymptomatic until the child is walking or has neurological defects. This happens because as the spine grows, the cord cannot ascend as it normally does, leading to traction injuries and damage of the lower cord and conus. Symptoms that result are pain in legs, limp, atrophy, sensory deficits, incontinence, and bowel difficulties. They can have UTIs and enuresis. However, by the time symptoms arise, many are irreversible. Early surgery can prevent motor and sphincter deterioration in function and can partially reverse already-acquired defects. Fetal surgery may be possible in the future.
Thus, it is important to examine and palpate a newborn’s back carefully for cutaneous back lesions, as this is sometimes the only manifestation of a neural tube defect. Serious consequences can be prevented with early identification.
Quick case about a pseudotail: Benton TJ, Cheema R, Nirgiotis JG. A newborn with a skin lesion on the back. J Fam Pract Jan 2007; 56(1):E1-E3.\
Especially brief, helpful article: Drolet, Cutaneous signs of neural tube dysraphism
All references
Ackerman L. Spinal congenital Dermal Sinuses: A 30 Year Experience. Pediatrics Sept 2003
Albright AL, Gartner JC, and Wiener ES. Lumbar cutaneous hemangiomas as indicators of tethered spinal cords. Pediatrics. Vol 83 No. 6 pp977-980 June 1989
Benton TJ, Cheema R, Nirgiotis JG. A newborn with a skin lesion on the back. J Fam Pract Jan 2007; 56(1):E1-E3.
Douvoyiannis M, Goldman DL, Abbott IR 3rd, Litman N. Posterior fossa dermoid cyst with sinus tract and meningitis in a toddler. Pediatr Neurol 2008; 39:63.Drolet BA. Cutaneous signs of neural tube dysraphism. Pediatr Clin North Am 2000; 47:813.
Kriss Botoo l, and Moore C. et al. Neural Tube Defects NEJM Nov. 11, 1999. Vol 341 No 20. pp 1509-1519 Vesna, Kriss Timothy, Desai Nirmala, Warf Benjamin. Occult Dysraphism in the Infant. Clinical Pediatrics Dec. 1995
Weprin and Oakes Cocygeal Pits Pediatics Electronic pages e69 May 2000
Zywicke,H and Roxxelle C. Sacral Dimples. Pediatrics in Review March 2011
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