Hernias through the posterior abdominal wall are called lumbar hernias.
These hernias can occur spontaneously, after surgery, or after an injury, and
they can cause acute or chronic low-back pain. Their prevalence is not known.
In the orthopaedic literature, lumbar hernia has been reported after the
harvesting of a bone graft from the posterior iliac
crest1-5,
but we found no reports of spontaneous lumbar hernia. In addition, we found
only a single article in the Japanese-language literature, and none in the
English-language literature, on the appearance of a lumbar hernia on a
magnetic resonance
image6.
Lumbar hernias can occur anywhere within the boundaries of the posterior
abdominal wall; however, two areas within this region consist of only fascia,
and it is in these two areas that most lumbar hernias occur. The superior
lumbar space is triangular and is bounded by the twelfth rib superiorly, the
erector spinae muscle medially, and the internal oblique muscle laterally. The
latissimus dorsi muscle may cover the superior lumbar space but does not
provide support for it. The inferior lumbar space is also triangular and is
bounded by the latissimus dorsi muscle medially, the external oblique muscle
laterally, and the iliac crest inferiorly.
Thorek reviewed the prior medical observations and descriptions of lumbar
hernia7. He stated
that in 1733, Petit reported on a patient who had a lumbar hernia, for which
he described the anatomic boundaries. This hernia was in the inferior lumbar
space. Since then, a hernia through this space as well as the space itself
bears his name. Grynfeltt is credited with describing the superior lumbar
space in 1866, and Thorek reported that Lesshaft described the same area in
1870. This space and any hernias through it are named
Grynfeltt-Lesshaft.
We report the case of a patient who had spontaneous lumbar herniation of
retroperitoneal fat that presented as back pain and a lumbar mass. Our patient
was informed that data concerning the case would be submitted for
publication.
An eighty-two-year-old woman presented with back pain and a lumbar mass.
The pain was most severe when she rolled over in bed onto the affected area.
She had fallen six months earlier onto her right side and had been treated by
a physical therapist, who noticed the lumbar mass. She was referred to a
physician, and magnetic resonance imaging of the lumbosacral spine was
acquired; however, the magnetic resonance image did not include the site of
the mass. The radiologist reported degenerative change in the lumbosacral
spine. The patient was then referred to our office for evaluation of the
lumbar mass.
Physical examination revealed a hypertensive but otherwise healthy patient.
She had had no operations. A subtle mass was felt in the right flank when the
patient was sitting, and it became easily appreciated when she was standing.
The mass measured 4 × 5 cm in diameter and was smooth, moveable, and
slightly tender. The rest of the back and the chest wall were not tender.
Plain radiographs of the lumbosacral spine revealed degenerative scoliosis and
osteopenia. Magnetic resonance imaging of the abdomen and pelvis was acquired,
and the radiologist reported the findings as "normal"
(Fig. 1). We saw a mass in the
posterior abdominal wall. It had the signal characteristics of a lipoma, and
it appeared to extend into the retroperitoneum. The mass was diagnosed as a
lipoma within the lumbar muscle, and observation was recommended. The patient
returned six months later with persistent back pain. Another magnetic
resonance imaging scan was acquired, which revealed an ovoid, well-defined
mass in the right flank, involving the posterior truncal musculature with
possible penetration to the retroperitoneum. This mass was thought to be a
lipoma by the radiologist. An excision of the lipoma was planned.
The patient was placed in the left lateral decubitus position, and an
incision was made obliquely from medialproximal to lateral-distal across the
right flank. The dissection was carried down through the deep subcutaneous
tissue. When the deep fascia was opened, there was attenuated muscle with a
fatty mass within it. As this mass was being dissected free, the
retroperitoneum was identified, and it was apparent that the fatty mass was
adherent to the retroperitoneal tissue. The hernia was then seen and felt. A
portion of the mass (herniated retroperitoneal fat) was excised, and the
hernia was reduced. The defect was repaired with a dual Gore-Tex mesh (W.L.
Gore and Associates, Newark, Delaware). A second-layer closure was
accomplished by suturing the superficial fascia to the twelfth-rib fascia.
Magnetic resonance imaging was acquired two months after surgery and showed no
recurrence of the hernia. Eight months after surgery, the patient continued to
be relieved of pain.
Lumbar hernias are probably uncommon, but their exact prevalence is
unknown. They are likely to be more common than is reflected in the
literature. Since this hernia has been rarely discussed in the orthopaedic
literature, orthopaedists may be unaware that it can be a cause of low-back
pain. We did not recognize the hernia before surgery and neither did the
radiologist who interpreted the magnetic resonance imaging scan.
Only a few articles regarding lumbar hernia have been published in the
surgical literature, and these have dealt primarily with surgical treatment.
Most recently, intra-abdominal laparoscopic repair has become the treatment of
choice8. Had we
recognized that the patient had a lumbar hernia before surgery, a laparoscopic
reduction and repair would have been performed instead of the posterior,
extra-abdominal approach that was used.
A hernia can be diagnosed with the use of computed tomography without the
need for surgery9.
The subject of this case report underwent two magnetic resonance imaging scans
but did not undergo a computed tomographic scan. Although the diagnosis was
not made before surgery, in retrospect, the hernia can be seen clearly on both
magnetic resonance images of the abdomen. The retroperitoneal fat herniating
through the Grynfeltt-Lesshaft space is easily seen on the magnetic
resonance image (Fig. 2). This
hernia was not visible on the first magnetic resonance image of the
lumbosacral spine because the hernia was lateral to the anatomic region that
was included on that scan. It was only when magnetic resonance imaging of the
abdomen was acquired that the lumbar hernia was seen.
We suggest that a lumbar hernia be considered as a possible cause of acute
or chronic low-back pain. The percentage of lumbar hernias that can be
appreciated on physical examination is unknown, and they may not be visible on
routine magnetic resonance imaging that is localized to the lumbar spine.