Sacral Dimple – What is It, Types, 2 Best Procedures for Diagnosis

Sacral dimples are small indentations present in the lower back region of a baby near the buttocks. It is congenital and very less likely to be associated with a serious spinal problem.

What is a Sacral Dimple?

Sacral dimples are small pits or indentations that are present in a baby at the time of birth in the lower back near the crease just above or within the buttocks. It can be also defined as the formation of shallow or deep cleft-like formation or depressions which is present at the lower sacral region near or within the natal cleft.

Sacral dimples are found in 1.8%-7.2% of neonates. Clinically it has been described as a typical benign lesion if less than 0.5cm in size is harmless. But if they are more than 0.5cm, deep and far from the anus, presence of hair, or if they have changed color then it could be associated with some serious spinal problems.

The serious conditions of sacral dimple may include spina bifida or a tethered spinal cord.

Sacral Dimple
Fig1: Sacral Dimple

Types of Sacral Dimples

There are two types of sacral dimples:

  • Typical Dimples
  • Atypical Dimples

Typical Dimples

These are the harmless dimples that are found near or within the crease of the buttocks in the lower region of the back.

Atypical Dimples

Atypical dimples are a present little bit far or higher up on the back or inclined towards the side. Sometimes the end or bottom of the dimple may not be visible or it could be found along with a tuft of hair, lump, presence of skin tag, or different skin color.

Causes of Sacral Dimple

Since it is a congenital disorder the exact cause of the sacral dimples is not known. The reasons are unknown which causes sacral dimple during fetus development.

Symptoms of Sacral Dimple

A small pit or depression in the area of buttocks within or above the crease is a sacral dimple. It is very superficial and the bottom can be determined very easily.

But some factors can indicate defects, therefore, needs to be examined by ultrasound. The factors are:

  • swelling in the area
  • Presence of skin tags
  • Presence of a birthmark in the area
  • a tuft of hair
  • Presence of a fatty lump
  • discoloration
  • tenderness
  • Dimple size more than 5mm

It can normally form in adults or children also. The actual cause is still unknown but it is suspected that it appears due to the push of loose hairs in the skin.

However, there are some reasons which escalate the possibility of sacral dimple which include:

  • obesity
  • age 15 and 40 years
  • above-average amount of body hair
  • coarse or curly body hair
  • a previous injury to the area
  • family history
  • driving or sitting for long periods

Diagnosis of Sacral Dimple

For simple sacral dimples or typical sacral dimples with no spinal problems and no history, further diagnosis and treatment are unnecessary.

For diagnosis of atypical sacral dimple, clinicians look after some factors like

  • Size and position of the dimple with midline and anal margin
  • Any spinal defects like lumbosacral lipoma, skin tags, birthmark, patches of hairs, and vascular lesions.
  • Examination of the spinal cord whether it’s normal or not.
  • Position, power, tone, and reflex of lower extremities
  • Difficulty in passing urine or bowel movements.

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If all these signs are observed then certain tests are recommended then the clinician may ask for ultrasound and MRI

  • Ultrasound 

This is a technique that uses high-frequency sound waves helping in producing images of the structure of a body. This is a noninvasive procedure.

Ultrasound is generally done within 3 or 4 months after the birth of a child.

  • Magnetic Resonance Image (MRI)

If more detailed information is needed MRI is suggested which uses strong radio waves and magnetic field to produce a cross-sectional image.

In most cases, Complications like Tethered Cord Syndrome can be detected with the help of MRI or computed tomography (CT) scan. Some time electromyography can be also used to assess nerve function also.

Sacral Dimple
Fig2: Radiological images of sacral dimple

Complications

Simple sacral dimples are harmless. But the deeper depressions can affect directly the spinal cord and colon. This may lead to a chronic rash. Such cases should be treated by closing the dimples.

When the depression is deeper there is a high chance to get infected leading to the formation of a carbuncle or cyst. These abscesses are generally found in teens.

No known connection has been found between the presence of sacral dimple and incomplete development of the spinal cord.

One should get alarmed and contact a clinician if the following symptoms are observed:

  • Pus drain
  • Rubor(Redness)
  • a tumor(Swelling)
  • Tender

However, sometimes deep depressions can be signs of birth defects that involve the spinal cord and its bones. The most common complications are:

Spina Bifida 

This usually occurs in a very clement form called spina bifida occulta. In this case, the spine is not closed completely around the spinal cord instead it stays inside the spinal canal.

The gaps in the spinal cord are very less and the vertebrae are still covered or protected.

Even though Spina Bifida is mild some report having some problems like:

  • back pain
  • Weakness and numbness in the legs
  • Scoliosis; Spine curvature
  • Loose of control over bladder or bowel
  • legs and feet which seem abnormal shaped.
spina bifida
Fig3: Spina Bifida

Dermal Sinus Tract

This is characterized by an abnormal connection between the skin and spine that can lead to infection.

Dermal sinus tract
Fig4: Dermal Sinus Tract

Tethered Cord Syndrome

Tethered cord syndrome is also one of the complications in an atypical sacral dimple. In this condition, the spinal cord is fixed that causes limitations in spine movement.

This indicates an increase in spinal cord tension when a child grows resulting in several neurological issues. Further, it also causes bowel incontinence, resulting in the loss of control of bowel movements.

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But In maximum cases, the person will face problems in childhood which may later disappear until adulthood.

Some of the signs and symptoms of this disease are:

  • lower back pain
  • Numbness in the leg
  • Weakness in the leg
  • Difficulty in walking
  • foot or spinal deformities
  • high-arched feet and hammertoes
Tetheres cord syndrome
Fig5: Tethered Cord

Treatment and Management

In most cases no treatment is necessary.

If symptoms appear every case is individually treated depending upon the symptoms, severity, and complications which could be physiotherapy, surgery, antibiotic treatment, pain management medications.

In the case of tethered cord syndrome, a simple surgery could help.

Based on symptoms and recurring infections, surgery can be done out in three different ways.

  • cutting the dimple out and packing with dressing until it heals
  • With the help of flap or skin closing the dimples by stitching
  • scraping the dimples out and filling the space with a special type of glue
  • The dimple in the skin can sometimes collect dirt, sweat fecal matter, etc. which leads higher risk for infection. Therefore the area should be cleaned regularly to decrease the risk
  • A diaper rash cream could be helpful for this. If have any spinal problems like muscle weakness or numbness it’s better to contact a neurologist

Outlook

Most people live a normal life with sacral dimples. Rarely they could be problematic causing spinal defects. Even with these problems, they have only mild symptoms.

Sacral dimples are very common with very few complications in the vast majority of cases. The dimple does not cause any problem in movement.

Physiotherapeutic Measures for Control

  • Adductor stretch: It is just a simple exercise where the leg is kept on a table and stretching yourself to touch hand to the foot for about 20-30sec.
  • Glute Stretch: The ankle should be outstretched against a desk keeping it at 90 degrees. Then after trying to lean forward making your back as straight as possible for about 20-30 sec.

General FAQs

Are Sacral Dimples dangerous?

Ans- Most of the sacral dimples are harmless Except in very rare cases the pits may lead to infections or sometimes result in a tethered cord or spinal Bifida.

When should sacral dimples be taken seriously?

Ans- Normally sacral dimples do not cause any serious complications but if the pit is more than 5mm in size with the presence of a tuft of hair and discoloration or skin tags it is better to consult with a clinician.

What are the causes of sacral dimple?

Ans- The cause of sacral dimple is still unknown but studies have suggested that administration of folic acid before pregnancy could lower the risk.

 Is sacral dimple a birth defect?

Ans- A sacral dimple is a congenital disorder.

 Is spina bifida is a genetic disease?

Ans- Most of the cases of spina bifida are sporadic or we can also say that it occurs in people with no history of the disorder in their family. Therefore this disorder does not have a clear pattern of inheritance properties.

In which stage of pregnancy spina bifida develops?

Ans- Spina bifida is a congenital disease that develops within in first four weeks of pregnancy. An adequate supply of folic acid may prevent this neural tube defect.

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