This is a rather short and simple article about a study of the presence of lumbar subcutaneous nodules (also named back mice) in a group of patients attending the rheumatologist clinic and its relation to the pain syndromes done in 1991.
Swezey designed a survey to study the relation of presence of what he called LSNs or lumbar subcutaneous nodules (also known as back mice) and pain. He concludes that the prevalence of these nodules is a NORMAL COMMON ANATOMICAL VARIATION, he presumes, in 25% of population and he concludes that they ARE NOT the cause of the low back pain or the fibromialgia syndrome.
My opinion about Swezey’s conclusions is that, indeed, we agree that the nodules are a common finding in general population, 25% or more (it has been published that even 60% of population could have them). BUT I DISAGREE that they are not related to the cause of pain. The problem with this study is that he just studied the population at a CERTAIN POINT IN TIME. It isn’t a prospective study; the nodules seem to cause pain when they become edematous or TURGID (the nodules and the tissue around them). A correct study should be related to a long following up of the patients to make more accurate conclusions.
Robert L. Swezey died in 2016. He was a known investigator about rheumatological rehabilitation. He was a pioneer for the nonsurgical neck and back pain treatment; he published self-care books such as Good News for Bad Backs.
Non-Fibrositic lumbar subcutaneous nodules: prevalence and clinical significance
By R. L. Swezey
The Arthritis and Back Pain Center, Santa Monica, California, USA
British Journal of Rheumatology 1991:30:376-378
Swezey starts commenting that the fibrositis and myofascial syndromes remained obscure or ignored for many years because of the paucity of objective clinical findings.
He states that the only clinically objective finding is the presence of palpable tender nodules and trigger points manifested as tender indurations in muscles. BUT there has been inability to demonstrate any laboratory, electrodiagnostic or radiographic abnormalities.
Swezey states that lately there has been emphasis and interest into he soft tissue and musculoskeletal palpation and the called myofascial syndromes, also in the lumbosacral subcutaneous nodules with fibromialgia.
Because of these, he thinks it is important to differentiate benign non-specific subcutaneous nodules that are located adjacent to the lumbosacral and iliac crest area next to the tender points.
That’s why they made a survey to determinate the presence of the nodules in patients with low back pain and fibromialgia syndrome.
METHODS: the Swezey survey about lumbar subcutaneous nodules (LSN)
They studied 126 consecutive adult white patients.
53 males and 73 females.
They were examined by careful palpation of the lumbar subcutaneous nodules (LSN) in a private rheumatological facility.
RESULTS of the study about presence of lumbar subcutaneous nodules (LSN) from a group of patients
33 patients from 126 had LSNs (total number 47).
-the lumbar subcutaneous nodules varied in size from 3mm ‘corn kernel’ to pea size, to grape size nodule.
-22 nodules were single and the rest with uni or bilateral clusters.
-8 nodules/47 nodules were tender overlying the posterior superior iliac spines.
-14 patients/93 patients without LSNs also had tenderness on palpation of the PSIS, on careful palpation it seemed a painful nodule; it showed that the painful site was actually the psis.
-In one case one patient that presented a VERY TENDER LSN overlaying the sacrum was relieved after intranodular steroid injection of 1mg triamcinolone hexacetonide.
SWEZEY mentions PREVIOUS WORKS FROM COPEMAN about the lumbar nodules from an old edition of a rheumatology book
Copeman’s textbook of the rheumatic disease, 4th edition, 1969, in a discussion of fibrositis, describes FIBROFATTY SUBCUTANEOUS NODULES, which represent herniation of the fibrous tissue of the deep layer of the fascia. And that the strangulation of the stalk of these herniated lobules is a cause of pain (let’s specify that this is according to Swezey’s view, Copeman explained all his theories in a more sophisticated way, from my point of view).
This description is in sharp contrast with many anatomical and pathological studies and descriptions of the lumbar area in which LSNs are NOT MENTIONED (Swezey mentions some medical references).
SWEZEY ADMITS the lumbar subcutaneous NODULES EXIST, BUT HE THINKS THEY ARE NOT A CAUSE OF PAIN
Swezey says that despite many anatomical descriptions do not mention these NODULES; it has been his own experience that these NODULES ARE COMMONLY PRESENT over the lumbosacral area. Namely, the posterior iliac spines, posterior iliac crest and proximal lateral sacrum.
The author even comments that on INFORMAL SURVEYS by him (a show of hands during discussions following lectures on low back pain in several occasions) revealed that less than 10% of primary care physicians and rheumatologist are aware of these nodules.
Some patients had biopsy of the lumbar subcutaneous nodules (LSNs). Two patients with diagnosis of fibromyalgia and chronic pain had persistent pain at the biopsy site.
He calculates (despite the lack of general knowledge from the medical community) that the prevalence of the nodules is of 25% of the patients seen in rheumatological practice. This high prevalence makes him to conclude that the LSNs are a common ANATOMICAL VARIANT and he thinks that they are rarely a source of back pain.
He concluded that LUMBAR SUBCUTANEOUS NODULES are a common anatomical FINDING occurring in 25% of the study population and that they do not seem to be related to any specific clinical disorder.
He concludes that they are NOT RELATED TO PAIN disorders, and says that biopsy or removal should be rarely or ever indicated.