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POLL: Do You Have a Sacral Dimple on Your Lower Back? (Can be Medically Significant, and May be Linked to ME/CFS)

Do you have a sacral dimple on your lower back, just above or within the crease of your buttocks?

  • Total voters


Senior Member
This poll asks whether you have a sacral dimple on your lower back, within (or just above) the crease between the buttocks.

If you have a sacral dimple, this may be medically significant, as it can be an indicator of possible spinal abnormalities. And a sacral dimple may also be linked to ME/CFS, as will explained shortly.

What Is a Sacral Dimple?

A sacral dimple is an indentation in the skin, within (or just above) the buttock crease (the butt crack, or bum crack) on the lower back.

A sacral dimple is a congenital condition, present at birth and persisting into adulthood. Here is an example of a sacral dimple in a baby (adult dimples look similar):

A Sacral Dimple in a Baby
Baby sacral dimple.png

The above sacral dimple example is just a few millimeters in size, but sacral dimples can be indented depressions that are 1 or 2 centimeters in size (see the sacral dimple pictures below).

A sacral dimple is typically not associated with any noticeable health issues, but sometimes a sacral dimple can suggest a spinal problem, such as tethered cord, spina bifida, or other neural tube defects. Ref: here.

Sacral Dimple Connection to ME/CFS

A recent poll on Jen Brea's craniocervical instability Facebook group showed that more than 50% of ME/CFS patients in that group have a sacral dimple. This is remarkable, as sacral dimples are normally quite uncommon: only about 4% of the population have one.

Now many patients in that Facebook group have occult tethered cord syndrome, and tethered cord is associated with a sacral dimple. So that might explain the high prevalence of sacral dimples in that group. But the question remains whether sacral dimples might be prevalent in the general ME/CFS patient community.

So the purpose of this poll is to see if sacral dimples are common in ME/CFS patients.

If an ME/CFS patient does have a sacral dimple, conceivably this might indicate the possibility of some sub-clinical neural tube abnormalities that they were born with.

And if this poll finds lots of ME/CFS patients have sacral dimples, we might then speculate that sacral dimples could indicate some sub-clinical neural tube abnormalities or neurological abnormalities that may not cause any overt health issues, but might conceivably predispose to developing ME/CFS.

Identifying Sacral Dimples

How do you know if you have a sacral dimple? They are easy enough to recognize: they are located within, or just above, the buttock crease, and may look similar to the baby's sacral dimple shown above, or may look like any of the three adult sacral dimple examples shown below.

As you can see from these pictures, sacral dimples can be small indented spot just a few millimeters across, or an indentation around 1 or 2 centimeters wide.

Three Examples of Adult Sacral Dimples
Sacral dimple 1.jpg
Sacral dimple 2.jpg
Large sacral dimple.jpg

As a point of comparison, below are a two butt/bum pictures which are free of any sacral dimples (96% of the population do not have a sacral dimple).

Two Backsides Free of Any Sacral Dimples
Bums Without a Sacral Dimple.png

Note that a sacral dimple is not to be confused with the dimples of Venus, which are shown below:

Dimples of Venus: NOT the Same as a Sacral Dimple
Dimples of Venus.gif

How to View Your Butt

It is difficult to examine the butt/bum area of your body, because it's pretty much impossible to directly view that zone, even with a mirror.

So the trick to observing your derrière is to prop up a smartphone on a tabletop, and start the video camera. Then expose your behind to the smartphone, and hopefully you will capture the right area in the video. You can also set the smartphone camera on a 10 second timer to take some still pictures of your butt.

If you have a willing partner to do the photography, that may be easier. You may have to pull your buttock cheeks apart with your hands in order to pull the butt/bum crack open, because the sacral dimple may be hidden in the crack.

Just don't accidentally share your video on social media!

To prop up a smartphone, you can fix it to a jar, or wedge it into a drawer, as show below:
Propping up a smartphone.png

So have a look at your derrière, and please answer this poll stating whether you have a sacral dimple or not.

Optionally, it would be very helpful if you could report in this thread whether your ME/CFS-free partner (or any other ME/CFS-free friend or relative you choose) has a sacral dimple or not. This can act as the healthy control group in this survey.

So please ask your partner to examine themselves (or you can examine them), or ask a willing relative or friend whether they have a sacral dimple. Report this by posting a message in this thread, saying either "My healthy control person HAS a sacral dimple" or "My healthy control person DOES NOT HAVE a sacral dimple".

I was surprised to find I have an easily-noticeable sacral dimple, something I was completely unaware of before.

What Is Tethered Cord Syndrome?

A tethered cord is where the spinal cord becomes stuck to the wall of the spinal canal, this attachment typically occurring at the base of the spine. As a result, the spinal cord cannot move freely within the spinal canal, and this may cause an abnormal stretching of the spinal cord, putting strain on the spinal nerve fibers.

The spinal cord gets stuck because it may attach to an area of scar tissue within the spine, or because it sticks to an area of fatty tissue (see image below).

Tethered Cord = the Spinal Cord Sticking to the Spinal Canal
Tethered Cord.png

A tethered cord can be seen on an MRI scan, but a tethered cord observed on MRI does not always create symptoms: it may cause symptoms, or may be entirely asymptomatic. When a tethered cord is observed on MRI and its symptoms are present, the condition is referred to as tethered cord syndrome.

The most common symptoms of tethered cord syndrome are the following:
Lower extremity pain (leg pain), lower extremity weakness (leg weakness), back pain, urinary incontinence, decreased sensation, hyperreflexia (over-responsive reflexes), cramps, paresthesias, general headaches, constipation, neck pain, clonus (involuntary muscle contractions), and many others.
Source: 2019 ASAP Conference: Tethered Cord Syndrome, Dr Petra Klinge.

Sometimes no tethered cord can be observed on the MRI, but a patient has the symptoms of tethered cord syndrome. In this case, the patient is said to have occult tethered cord syndrome. Most of the ME/CFS patients in @JenB's CCI Facebook group with this condition have the occult form of tethered cord, though some have a tethered cord observable on MRI.

Tethered cord may be congenital or it may be acquired (arise later in life).

A tethered cord is associated with sacral dimples.

More info on tethered cord syndrome in this MEpedia article.

Risk Factors For Neural Tube Defects

Risk factors for neural tube issues (such as tethered cord or spina bifida) developing during pregnancy include:
  • Maternal MTHFR C677T +/+ mutation
  • Maternal type 1 diabetes
  • Maternal use of medications during pregnancy which decrease folate levels (these include certain anticonvulsants, methotrexate, sulfasalazine, triamterene or trimethoprim). Ref: 1
  • Maternal exposure to the mycotoxin fumonisin during pregnancy (fumonisin is found on maize, and affects folate metabolism)

And Finally

Thanks go to Elke (@ehc918 on Phoenix Rising) for helping me organize this poll, for supplying some of the sacral dimple images, and moreover, for discovering the sacral dimple possible connection to ME/CFS in the first place!

After watching a video of spinal neurosurgeon Dr Petra Klinge talking about sacral dimples as a possible indicator of neural tube spinal defects, Elke had a brainwave one night, and decided to take some backside snapshots with her smartphone!

To her surprise, she noticed she had a sacral dimple! After posting this discovery in Jen's Facebook group, many other members of the group also reported they had a dimple.
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Senior Member
I have a weird large-ish depression of some sort just at the top of it in the sacral area, but not a distinct dimple.

If your area of depression looks a bit like the indentation in the third image in the row of three adult sacral dimple images above, that would count as a sacral dimple.

Sacral dimples can be just a tiny spot a few mm across (as in the baby picture image), but sacral dimples can also be depressions that are 1 or 2 cm across.


Senior Member
I have one, but was unaware of it being abnormal until earlier this year. I also have scoliosis and pectus excavatum, which are probably related. Spine MRI was reported as normal otherwise.


Senior Member
Northern California
I voted above.

I have a prominent sacral dimple, which I was not aware of until 2019. A physician took pictures for me during an office visit for severe tailbone pain, pain radiating to buttocks, and symptoms similar to sciatica, plus urinary urgency. The resulting L-spine MRI was read as normal.

The physician must not have known about the possible significance of the sacral dimple in relation to my symptoms, or maybe the MRI report eliminated any suspicion. Or perhaps she assumed I had been screened for spina bifida, tethered cord syndrome, etc. as an infant, but I had not.

I later learned that a sacral dimple could be indicitive of tethered spinal cord, but I have not had time to pursue this course of investigation due to multiple acute health issues.

I do appreciate this thread and will follow as able.

@dimitri, I, too have mild scoliosis to the right, but mild pectus carinatum (opposite of you) on the left. I also have a markedly winged right scapula, a sacral dimple, symptoms of tethered cord, Tarlov cysts, etc. When I am able to pursue this avenue of investigation, I will surely share with the group. I've got more emergent issues to contend with right now.


Senior Member
Brisbane, Australia
I, too have mild scoliosis to the right
A physician took pictures for me during an office visit for severe tailbone pain, pain radiating to buttocks, and symptoms similar to sciatica, plus urinary urgency.
Just something to be aware of. Scoliosis to the right can cause stretching of the left renal vein which can be enough to impair return blood flow (an atypical Nutcracker Syndrome) and be a cause of the symptoms you listed here .
FWIW I had full thoracic fusion in 1989 for crazy scoliosis- not once did any doctor consider it anything other than idiopathic. All of my musculoskeletal issues have been dismissed as “prob fusion related”. I do have a “flat neck”- no curve at all, and lumbar curve is pretty much absent. After I discovered the dimple- I pushed and got a both a supine AND prone MRI- supine showed mild degenerative changes, but the supine showed a probable tethered cord. Whether it’s truly causing issues or not is TBD- but the ortho I saw said that the degree of low back pain I have (along with other TC-ish Sx’s) can’t be explained by any disc issues. I’ve also been diagnosed with hEDS, thoracic outlet syndrome, vascular compression/stenosis, intracranial hypertension and am 1 mo post surgery to remove the compression in my right int. Jugular vein (was trapped between C1 and styloid and had additional soft tissue adhesions. D4C4E1E0-8191-497E-BF66-E5FA19F9CE0A.jpeg100C436B-96D0-42D2-8C21-C45997391DBC.jpeg


Senior Member
I have a sacral dimple. Strangely it is the first place to get a hive when my MCAS became severe and I had fully body hives for months. I always thought it was an odd connection.

I have really horrible low back pain, which I assumed was due to SI hypermobility, and nerve pain going into the groin and down the back of my legs. Recently I’ve been wondering if all my low back and groin pain is due to TC.


Senior Member
I brought my borescope from work and was able to do a view of the hiney regions, I have a sacral dimple like the middle picture.
I have a mild rightward rotatory scoliosis at the neck and spondylosis along the whole spine.
I watched Dr Klinge’s (OTC expert) 2019 ASAP presentation and complied this list of symptom data- pts at the top means patients.

Symptoms are much more global than i thought.


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Senior Member
Interestingly enough I have one as well. Anyone know where the tests and treatments start with this?

Is it normal to spontaneously have CFS symptoms after a medically healthy life for 25 years?


Senior Member
Anyone know where the tests and treatments start with this?

The sacral dimple may possibly link to skull/spinal issues such as: craniocervical instability (CCI), atlantoaxial instability (AAI), Chiari malformation, cervical spinal stenosis and tethered cord.

Back in around 2018, a couple of ME/CFS patients on this forum (Jen Brea was one of them) discovered they had CCI and tethered cord (a ligamentous laxity of the connection between skull and spine). After corrective neurosurgery, their ME/CFS went into remission. Since then, there has been speculation whether some cases of ME/CFS might be caused by CCI and related conditions.

About a dozen other ME/CFS patients with CCI or related condition have now also had surgery, with mixed results: most have had major improvements and there have been a couple more remissions; but a couple of patients have not seen any improvements after surgery. These CCI ME/CFS patients typically had their ME/CFS start by the usual viral infection trigger. One speculation is that the infection causes the ligament laxity which leads to CCI.

The CCI threads you can find on this PR forum.


I do not have a dimple but have a very distintive line, that runs up a bit. DOes that mean anything?