What Is Sacral Dimple

Have you ever noticed a dimple over the lower back of some infants?

Do we really need to explore it or just ignore it?

Let’s step by step unfold the answer.

It looks like a dimple and the area is referred to as sacral area because of the sacrum bone hence its name sacral dimple.

If you have a baby who's not sick but has a simple sacral dimple, it's not usually a sign of spine dysraphism.²

Despite being one of the most prevalent skin lesions, the sacral dimple is typically an ordinary skin lesion that has little effect on neurologic impairment.¹

Sacral dimples are termed as simple if the diameter is less than 5 mm or deep and large is greater than 5 mm in diameter.⁶

The association of any spine anomaly with the sacral dimple is rare if there are no symptoms, and it constitutes only 0.13% of cases that require surgical intervention.²

Introduction 

Definition of a sacral dimple 

A simple sacral dimple is a single dimple that is not more than five millimetres in diameter that extends less than 2.5 cm from the anus, located midline, and without obvious drainage or further accompanying cutaneous stigmata such as a hairy tuft, hemangioma, skin tag, or tail.²

Prevalence and occurrence 

About 1.8%-7.2% of infants have sacral dimples, and it is a common skin occurrence among admitted neonates. A dimple size of less than 5 mm can mostly be considered harmless; additionally, it should be a single dimple lesion present in the midline.¹

Importance of understanding sacral dimples

Understanding sacral dimples is necessary as the size and associated skin findings provide us regarding the severity and guide us about the steps to be taken.

• Single sacral dimples 2.5 cm from the anus and less than 5 mm in size with no skin lesions or associated factors like hair tuft or hemangioma are termed as simple and generally don’t require routine imaging.
• Two or multiple sacral dimples having a diameter greater than 5 mm have a higher chance of being associated with spinal dysraphism and need investigation and routine checkups. Moreover, atypical dimples may also be associated with neurological, orthopaedic or congenital deficits and may require surgical procedures.³ 

Diagnosis 

Simple sacral dimples without any specific physical findings need not require further screening as they are hardly associated with spinal dysraphism and additionally, they lead to financial burden over families.⁴

Physical examination 

During the physical examination of an infant, dimples at the sacral area are a common finding, though maximum is not linked with other cutaneous anomalies. However, it can be a sign of underlying pathology, which does require medical consultation.⁶

Physical findings that require a spinal ultrasonography are –

• Single deep dimple having a diameter larger than 5 mm (34%)
• Deep dimple with skin lesions-gluteal cleft, hemangioma, etc (3%)
• Atypical dimples or multiple dimples
• Hypertrichosis- excessive hair tuft over the sacral area(13%)⁶

Imaging tests (ultrasound, MRI)

With a sensitivity of 96% and a specificity of 96%, US imaging is a useful screening technique for the tethered cord. It has also been found to be a reasonably priced diagnostic tool for patients with simple sacral dimples. Recent research, however, indicates that patients with isolated simple sacral dimples might not require US screening.²

As an imaging test, ultrasound is advised, and one of the main justifications for USG is the early identification of potential tethered cord syndrome cases. Tethered cord syndrome is brought on by a malfunction of the caudal spinal cord and conus brought on by stretching, which is frequently linked to spinal dysraphism.¹

Only abnormal or insufficient ultrasounds can be further clarified with magnetic resonance imaging (MRI). If neurological symptoms are evident, MRI should be used as the main diagnostic modality.⁴

Differential diagnosis

Tethered spinal cord syndrome and spinal dysraphism can occur in any infant with gastrointestinal or bladder malfunction, musculoskeletal deformities, or increasing brain dysfunction.

Generally speaking, there are three different kinds of spinal dysraphism:

1. No skin cover over back lesion in open dysraphism;
2. A skin-covered back mass in closed spinal dysraphism, and
3. Absence of a back mass and concealed spinal dysraphism.

The position of the conus medullaris below the ( lumbar)L3 level is known as tethered spinal cord syndrome, and it may be linked to all three forms of dysraphism. Well-established cutaneous indicators, including tuft of hair, subcutaneous lipoma, and hemangioma, have been linked to tethered spinal cord disease; in fact, 86.3% of children with concealed dysraphism present with these lesions. However, 5-7% of normal kids have these skin indicators recorded, and 74% of these individuals appear as a form of simple sacral pit.⁵

Conclusion 

Screening is indicated when a newborn has sacral pits and whether or not there are dermatological signs present. This allows for the exclusion of neural abnormalities and spinal dysraphism.

Despite the fact that magnetic resonance imaging (MRI) is still the gold standard for imaging, ultrasonography has advanced recently and is now regarded as a valid modality for medical decision-making and obtaining high-quality pictures.⁵

Summary

A sacral dimple is a tiny, usually not harmful indentation or pit located near the sacrum at the base of the spine. These dimples are normally present from infancy and are harmless. While most sacral dimples are harmless, they might be connected with underlying spinal or neurological disorders, thus medical assessment is advised if they are deep, large, or have any worrying aspects. Regular monitoring and adequate medical evaluation can ensure the early discovery and management of any potential sacral dimple disorders.

Frequently asked questions

1. What is a sacral dimple?

A sacral dimple is a little skin indentation or pit that is seen close to the lower part of the back or at the lowest point of the spine, usually directly above the buttocks. It is additionally referred to as a pilonidal dimple or coccygeal dimple. It is often benign and present from birth.

1. Are all sacral dimples a cause for concern?

No, not every sacral dimple should be taken seriously. A lot of sacral dimples are benign and don't need to be treated medically. Nonetheless, a medical practitioner should be consulted as some may be linked to underlying skin or spinal anomalies.

1. When should I be concerned about my child's sacral dimple?

If the sacral dimple is massive, extremely deep, or exhibits odd traits like inflammation, drainage, or signs of infection, you should be concerned. In addition, you should seek medical evaluation if your kid exhibits any neurological symptoms or has a family history of spinal problems.

1. How is a sacral dimple evaluated in paediatrics?

In addition to physically examining the sacral dimple, paediatricians usually ask about any related signs and family history. Additional testing, such as an MRI, X-ray, or ultrasound, may be advised if the patient experiences any worrisome symptoms in order to evaluate the underlying structures of the spine and check out any possible problems.

1. What are the potential complications associated with sacral dimples?

Sacral dimples can occasionally be linked to underlying abnormalities of the spine, such as spinal dysraphism or tethered cord syndrome, which, if ignored, can result in neurological issues. Sacral dimples can also occasionally develop an infection.

1. Can a sacral dimple cause back pain or neurological problems?

While the majority of sacral dimples are painless or neurologically normal, some diseases related to them, such as tethered cord syndrome, can result in neurological abnormalities, back pain, or trouble walking. To prevent such issues, early detection and control are crucial.

1. What is the treatment for a problematic sacral dimple?

The underlying condition will determine how to treat a bothersome sacral dimple. In certain cases, surgery may be required to treat an infected dimple or to rectify a spinal deformity. The best course of action will be decided by your child's medical professional.

1. Can a sacral dimple go away on its own?

Sacral dimples that are present from birth usually do not go away on their own. Even as adults, they might still exist, but they won't hurt you unless they get infected or connected to other issues.

1. Is there a way to prevent sacral dimples in children?

Sacral dimples are usually a congenital defect that cannot be avoided. Problematic sacral dimples can lead to issues that can be avoided with routine health screenings and early assessment of any warning signs.