Presentation and evaluation of sacral dimples

Primary Steps for Primary Care | October 31, 2024 | Jane and John Justin Institute for Mind Health

Our team frequently gets calls and consults regarding children with sacral dimples, mostly newborns, but the occasional older child as well. This article's aim is to help you differentiate between benign dimples, and those that deserve additional workup.

Epidemiology

Depending on the cited source, these lesions occur in 2-8% of healthy newborns. Imaging evaluation and a specialist consult for every child with a sacral dimple can result in unnecessary stress and cost for the family and a burden on the health care system. A review article published by Gregory W. Albert, M.D. (1) showed that out of 5,166 children with sacral dimples evaluated with spinal ultrasounds, only 3.4% had abnormalities and an even smaller percentage of these had any clinical significance.

Sacral dimples are congenital, meaning the child is born with it and it is not something that occurs or appears later in life. To date, there are no definitive studies showing a hereditary risk or genetic association. True spinal dysraphism, open or closed, occurs with a frequency around 0.3-0.4 per 1,000 live births in the United States (2) and its etiology is multifactorial.

Physical exam

Benign sacral dimples are found in the midline within the gluteal crease, are less than 0.5cm in diameter, usually within 2.5cm of the anus, and have no associated cutaneous stigmata. Dimples that vary from these criteria may still be benign, but should raise a clinician's suspicion for signs suggesting the need for additional evaluation.

Often the most obvious sign is associated cutaneous stigmata. These include surrounding hair tufts, nearby capillary hemangiomas, palpable fatty masses over the spine, or gluteal clefts with curves, splits or duplications. While these findings should raise your suspicion for an underlying spinal dysraphism, it is important to remember that they do not make it a certainty and families should be counseled accordingly.

In addition to cutaneous findings, there are neurologic findings that should also prompt more careful consideration of a child with a sacral dimple. Asymmetric weakness between the upper and lower extremities, decreased sensation in the lower extremities or perineal region, delayed development of leg motor milestones, urologic difficulties or repeated UTIs are all signs that could point to pathology of the spinal cord and nerve roots.

Evaluation

For normally developing children, with benign dimples, no additional imaging or specialist referrals are needed. For those children with concerning dimples, or worrying associated findings, imaging will be the next appropriate step. Very young children, those under 9-12 months of age, can often start with an ultrasound of the spine. If the ultrasound is normal, this can be reassuring to both the physician and family. If the ultrasound is abnormal, or the child is older, an MRI of the lumbar spine will be the next test of choice.

As neurosurgeons, we appreciate the imaging being obtained prior to our seeing a patient. It allows us to have the most informed discussion with the family and minimizes their trips to our office. Frequently, a suspected abnormality on ultrasound, disappears with the clarity of an MRI and a specialist referral is not necessary after all. If the abnormality persists after appropriate imaging is obtained, a referral to your specialist team to review the findings with the family is likely in order.

Not all abnormalities need operative intervention and some will be simply followed over time, often with clinical exams and, sometimes, additional imaging. In another review by Coley et al. (3) of nearly 4,000 children with sacral dimples undergoing screening ultrasound, only 0.13% ultimately had a neurosurgical intervention.

Remember the odds are that a sacral dimple is benign and most children with them grow to be happy and healthy adults. But if you have concerns, your friendly neighborhood pediatric neurosurgeon, will be here for them.

“Spine ultrasounds should not be routinely performed for patients with simple sacral dimples.” Gregory W. Albert. Acta Paediatrica. 2016 April, 105(8).
“Updated estimates of neural tube defects prevented by mandatory folic Acid fortification - United States, 1995-2011.” Williams J, Mai CT, Mulinare J, Isenburg J, Flood TJ, Ethen M, Frohnert B, Kirby RS., Centers for Disease Control and Prevention. MMWR Morb Mortal Wkly Rep. 2015 Jan 16;64(1):1-5.
“The simple sacral dimple: diagnostic yield of ultrasound in neonates.” Kucera JN, Coley I, O'Hara S, Kosnik EJ, Coley BD. Pediatr Radiol. 2015 Feb;45(2):211-6
“Management of Sacral Dimples Detected on Routine Newborn Examination: A Case Series and Review.” ACW Lee, NS Kwong, YC Wong. HK J Paediatr. 2007;12:93-95.
“Sacral dimples.” Holly A Zywicke, Curtis J Rozzelle. Pediatr Rev. 2011 Mar;32(3):109-13.
“Correlation of cutaneous lesions with clinical radiological and urodynamic findings in the prognosis of underlying spinal dysraphism disorders.” Mehdi Sasani, Bahloul Asghari, Yalda Asghari, Ruya Afsharian, Ali Fahir Ozer. Pediatr Neurosurg. 2008;44(5):360-70.
“Coccygeal pits.” B E Weprin, W J Oakes. Pediatrics. 2000 May;105(5):E69

Consultations and Referrals
682-885-2500