About back mice… backmice.info web page

(Studying back mice… page under construction)

This web was born in March 2018, as a result of the study that we began in the summer of 2017.

*We have published a review about back mice (September 2021): you can access a free on line pdf in the following link of the Pain and Therapy Journal→ Historical Review of Studies on Sacroiliac Fatty Nodules (Recently Termed “Back Mice”) as a Potential Cause of Low Back Pain. Cañis Parera et al. Pain ther (2021).

In backmice.info we aim to provide as much information as possible on the pathology known as back miceWe want to share all the knowledge we have about this OVERLOOKED medical condition and everything related to it, hoping that it will help to move forward its research.

Even though back mice (Chapter 1) will be the main topic, you will also find information about other related issues, such as cluneal nerve entrapment (Chapter 2),  knowledge about fatty tissue and fascia  (Chapter 3), pain mechanisms (Chapter 4), and some historical errors to think about…

What are back mice?

Simply put, back mice could be described as palpable deep fatty nodules, easily felt by the skilled examinar. The nodules lay within the fascial layers in the so-called sacroiliac area, a defined triangulated area formed by the sacrum, the iliac crest and the midline .

These nodules have received many names, but Peter Curtis coined the name back mice in the 90’s. We will use the name back mice through out the webpage (partly because it’s king of amusing).

Back mice are easily felt as deep nodules by a lubricated skilled hand.

These nodules are often painless upon palpation, so most people are not awere of their existence.

Here you can see an ultrasound image of non-painful back mice (it is fibro-fatty tissue)


Nevertheless, in some people they can be slightly tender or even excruciatingly painful upon examination, reproducing patient’s low back pain.

Some researchers suggested back mice could be caused by ‘fatty overgrowth’ that herniates through the deep fascial layer.

To better understand what  these  nodules exactly are  it is necessary to understand how the fibro-fatty tissue, hence the  fascial layers, are structured in the body.

Why so overlooked…

Unfortunately, there has been a coexistence of several factors that may explain why this entity has been NEGLECTED AND UNDERDIAGNOSED by mainstream medicine.

These are related to the fact that…

  • many physicians do not palpate during physical examination and they lack proper palpation skills. Even if they do so, the lumps are easily missed without proper lubrication of the fingers.
  • even though they palpate the painful nodules, somehow they confuse them with ‘conventional lipomas’ -which they are not- and it is widely believed that ‘conventional lipomas do not hurt’.
  • nodules may be mistaken with ‘myofascial trigger points’.
  • these nodules are neither visible in the Radiography nor in the Magnetic Resonance Imaging.
  • fibro-fatty tissue and the fascia, has been neglected as being a causative pain agent in musculoskeletical disorders.
  • many physicians are not familiar with the existence of the cluneal nerves entrapment.

Intrigued by chance…

Even though most physicians are completely unaware of the existence of back mice nowadays, they have indeed been studied throughout history by many physicians from around the world.

By chance, some of these researchers stumbled across this clinical condition and were intrigued by it like us…

  • ->LINK to the story how we were intrigued by back mice, ‘my personal story’.
  • ->LINK to the story about how Dr. H. Austin (one of our collaborators) operated on his first patient.

Similar stories to ours have been reported by many physicians in published articles. We recommend you the case of Dr Ries, Dr MacDermont, Dr Clavero-Núñez (in Spanish), and Dr Monnerot-Dumaine, among others.

Medical articles…

You can read a summary of all the articles we have found that studied and treated back mice throughout history in the following links:

LINKS to ALL the published medical articles about back mice

*We have published a review about back mice (September 2021): you can access a free on line pdf in the following link of the Pain and Therapy Journal→ Historical Review of Studies on Sacroiliac Fatty Nodules (Recently Termed “Back Mice”) as a Potential Cause of Low Back Pain. Cañis Parera et al. Pain ther (2021).

Back mice may be related to cluneal neuropathy. In the link below you can access the list of all the articles that have studied this peripheral neuropathy.

LINK to ALL the published medical articles about cluneal neuropathy

To better understand back mice, we need to study the fibro-fatty tissue and the fascial layers, which has been traditionally neglected. The reason why remains a puzzle to us. Sir William Copeman once said in 1954: ‘Since fibrositis lacks glamour it has been overlooked’ -back mice were named fibrositic nodules in the 50’s.

This is an altruistic project. We believe sharing is always a rewarding experience. So if you wish to contribute or correct something, make a remark or simply contact us,

don’t hesitate to write us to 


By visiting the backmice.info website, users agree to all of the following terms and conditions:

Our website provides only information about or related to a pathology that we are CURRENTLY STUDYING as a part of a PhD program. 


Always consult with professional physician or other qualified health care provider for specific personal recommendations. Never disregard professional medical advice or delay seeking such advice because of something you read this website.

There are still many questions to answer about the intriguing back mice:

what are back mice

What are back mice, the fibro-fatty lumbar nodules? How are they related to low back pain and other pain syndromes? Why are they sometimes tender other times asymptomatic? Why have the studies of W.S.C. Copeman and others  been overlooked? Sometimes they are identified by nodules, others by trigger points, why? Why are the tender nodules sometimes  just lobules under tension whereas other times they herniate? Why are them mainly BILATERAL? Why a bubble of fat?  Do they become painful by oedema or hemorrhage, congestion or torsion?  Does the edema respond to an hormonal response or sympathetic stimulus?  Why can the painful edema be recurrent? Are they made from brown adipose tissue? Why can they sometimes be just cured by anaesthetic injection? Why is it sometimes necessary to remove them surgically? During surgical incision the tender nodules protrude, because of edema and tension, why? Subfascial fat herniation… why? What are the subfascial basic fat pads? Can the nodules cause cluneal nerve entrapment?  Why are they related to fever or humid coldness? Why is fatty tissue so unknown? Why do NOT many physicians have the skills to palpated them? Why do they have so many names? …

LINK to the youtube video: are back mice real?

back mice

How to find back mice? (1 minut video)

How to infiltrate back mice? (1 minut video)

In the following video, you can see how to palpate and how to infiltrate simple lumbar “back mice” of a young patient who had right lumbar pain and referred pain to the posterior thigh since last 24 hours. The pain got worse with efforts or bending over.

She had past history of right lumbar pain some months ago, and some times she has lumbar pain randomly. When pressing the nodule the patient feels referred pain down the leg all the way to the knee. The pain disappears immediately after injecting 4ml 1% lidocaine. Pain relief lasted weeks.

Back mice is one of the many names of these intriguing nodules

Back mice is one of the many names that  the LUMBAR FIBRO-FATTY NODULES have received (Back mice was a name proposed by Peter Curtis on the 90’s).

Many doctors got intrigued to study the mysterious painful nodules and it seems everyone chose a different way to named…

List of names and studies about these nodules during history:

Other names for specific sacroiliac pain:

LINK to ALL the published medical articles about back mice

LINK to The history of the termfibrositis (an old name for back mice was lumbar fibrositis and an old name for fibromyalgia was generalized fibrositis)

LINK to the French studies about thecellulite (an old name for back mice by French doctors was lumbar cellulite)

LINK to the articles about the myofascial syndrome    (another view for back mice)

LINK to the articles about myogelosis [myogelose and muskelhärte(another view for back mice)

The palpation technique to search for back mice

examination for back mice-The best patient’s position is standing with back slightly bending (semiflexion) and hands resting on the examination table.

-Leave the zone uncovered and apply some substance to your hands so that the fingers can slide. For example, in these cases, we are using some sterilizer.

-Begin to palpate the midline by pressing firmly on the spinal apophyses. Ask the patient for any focalized pain.

-If the patient has a lumbar painful side, start with the painless side. Palpate with the fingertips, doing continuous circular movements to find nodular spots.

-When the patient says that the area of the nodule is painful, do a second palpation, asking the patient to recognize the spot of maximum pain.

-Press firmly on the spot of maximum pain, and ask the patient if the pain has any radiation (to abdomen, inguinal region, gluteal region or leg).

-Sometimes they are only present in one side, other times they are bilateral.

-Some nodules are tender or painful and some are painless. Remember that this can change over time, and a painless nodule can become painful.

-If we mark the nodules, they usually stay between 5-7 cm from the midline.

In the following videos we’ll show how to palpate to search nodules in the sacroiliac region

Video 1. To illustrate how to do a palpation of the lumbar region (bilateral backmice)

examination for back mice
Illustrative cases: three women, they DO NOT suffer low back pain at the moment of this examination. They explain past history of nonspecific recurrent moderate low back pain that they usually manage with oral or intramuscular analgesics. When the lumbar pain appears the nodules are the spot of maximum pain especially in one particular side. In case 1 the nodules are tender to palpation while examing.

(Page under construction)

By Marta Cañis Parera   ORCID iD icon

Chapter 2- Nerve entrapment

(under construction)

Back mice may cause cluneal neuropathy. Both entities seem to be quite UNDER-DIAGNOSED by the medical community. Cluneal neuropathy is a peripheral nerve neuropathy. 

Peripheral nerve neuropathies

Chapter 2.1 – Cluneal nerve entrapment

Chapter 2.2 – Ilioinguinal nerve entrapment


Chapter 3 -Fatty tissue

(under construction)

  1. 2020 Lee et al. (from Las Vegas, USA): Clinical Review Adipose Tissue as Pain Generator in the Lower Back and Lower Extremity : Application in Musculoskeletal Medicine. HCA Healthcare Journal of Medicine. 2020;1:257–68.

The backmice.info blog

Is plastic surgery an option to get relief from back mice?

Back mice is a colloquial term that has been popularized to named the painful palpable fibro-fatty nodules of the sacroiliac area (The term was coined by Peter Curtis in 1993, In the search of back mouse). An overlooked medical condition and the wrong dogma Since back mice is a condition that is still overlooked by …