Spinal epidural lipomatosis after bariatric surgery

Spinal epidural lipomatosis (SEL) is a pathological overgrowth of normal
adipose tissue in the extradural space within the spinal canal causing
compression of the nerve roots and the spinal cord. This can occur
idiopathically or secondarily due to obesity, Cushing syndrome, endocrine
disorders and it is associated with a high visceral fat accumulation in
patients. These patients may present progressive and long standing complaints
of back pain, radiating leg pain, neurogenic claudication, decreased pinprick
sensation and, in some rare cases, lower extremity weakness. The first
description of SEL was given by Lee et al. (4) in 1975. The gold standard for
diagnosing SEL is a T1-weighted MRI. In the spine, the lumbar level is the
single most frequently affected region by SEL.

About one third of the world population is overweight and it is estimated that
by 2030 nearly 40% of the world*s adult population will be overweight (Body
Mass Index 25-30) and 20% will be considered obese. When the Body Mass Index
(BMI) is >=30, adults are classified as obese. Indications for bariatric surgery
vary across regions and practices, but a BMI >= 40 without comorbidities or a
BMI >= 35 with at least one obesity related comorbidity (e.g. hypertension,
diabetes, nonalcoholic fatty liver disease, osteoarthritis, or heart disease)
classifies a patient as morbidly obese. These levels of BMI are generally
accepted indications for bariatric surgery after conservative weight loss
measures have failed.
Of all the risk factors for SEL, obesity is a commonly observed comorbidity.
For SEL patients these symptoms can result in a severely reduced quality of
life comparable to a classical osteoligamentous spinal stenosis. Treatment of
SEL ranges from conservative management to surgical excision. Patients with
neurologic deficits caused by compression of SEL, frequently undergo a
decompressive procedure by means of laminectomies and fat debulking. For
patients without neurologic deficits, weight reduction as part of conservative
management is a serious and established option.

To the best of our knowledge, no studies have conducted direct volumetric
evaluations and comparisons of SEL in patients before and after bariatric
surgery and people with normal weight. One case report described complete
remission of SEL in the lumbar region and also remission in back pain symptoms
after sleeve gastroplasty. In this case report a 48-year-old man is described
with obesity and a history of chronic back pain who developed idiopathic spinal
epidural lipomatosis (as diagnosed by magnetic resonance imaging) and which
subsequently resolved completely after sleeve gastroplasty over a 6-month
follow-up period. This report suggests that spontaneous accumulation of fat in
the epidural space is a dynamic process and sometimes associated with an
increase in the peripheral fat mass. It would also be worthwhile to follow
bariatric surgery patients for longer postoperatively since it is known that
patients can gain weight again after post-sleeve gastroplasty. A study with a
larger sample, which evaluates the volume of SEL in bariatric patients, before
and after surgery, is needed to understand this process even better.

Lumbar spinal stenosis (LSS) is the most common indication for spinal surgery
in people older than 65 years. Different studies suggest an estimated
prevalence of lumbar spinal stenosis of 11% in the general population and in
the clinical population 25 to 39%. Diagnosing and treating lumbar spinal
stenosis has an increasing economic impact, the mean cost per patient is $1,010±
$1,13 (range: $716±$980 to $1,442±$1,170). Apart from the costs, the symptoms
in these patients have a substantial impact on mobility, functional autonomy
and performance in daily life. SEL is described in about 6% of the patients
with symptomatic spinal stenosis. Patients with SEL exhibited more severe pain
and less walking ability than those with LSS in the absence of SEL. The results
of spinal surgery in patients with SEL are less efficient in comparison to the
patients without SEL. Thus, the spinal surgeon may be reluctant to preform
spinal surgery in these patients.

This study may help to elucidate whether bariatric surgery can reduce not only
the total body weight, but also the volume of SEL in the lower spine and
positively influence the different pain symptoms in the patient*s back and
lower limbs.

Primary objective: To evaluate changes in the volume of spinal epidural
lipomatosis in the lumbar spine before and after bariatric surgery in patients
with obesity.

This is a pragmatic, explorative observational study during which a small
convenience sample of patients, that have already undergone a pre-operative MRI
(patients with obesity and patients with normal weight) and received bariatric
surgery (patients with obesity) in our hospital, will be included. The
bariatric surgery patient group will be invited to undergo one postoperative
MRI scan, and their changes in the volume of epidural lipomatosis before and
after bariatric surgery will be analyzed. The patients with normal weight will
be used as a proxy group to which the pre-operative volumes of epidural
lipomatosis will be compared to.

During this study participants will undergo one MRI scan. This procedure is
safe and poses no (radiation) risks to the participant.