Idiopathic epidural lipomatosis
The patient is on neurology follow-up and has been put on weight reduction therapy.
Plain CT of the dorsolumbar spine revealed an extradural fat-density mass at multiple levels compressing the spinal cord. The vertebral bodies and posterior arches were normal. No paravertebral mass or collection was seen (Figure 1).
MRI was then performed. T1- and T2- weighted images of the dorsolumbar spine revealed a multisegmental extra dural hyperintensemass, with compression of posterior dorsolumbar thecal sac. The spinal cord showed normal signal intensity and morphology (Figures 2 and 3). There was no evidence of any vertebral or intervertebral hyperintensity or paravertebral collection.
Epidural lipomatosis is an uncommon disorder defined as a pathologic overgrowth of normal epidural fat.1-4 It is more often associated with the administration of exogenous steroid with variable duration and doses1,2,4-7 and can also be seen in patients with endogenous steroid overproduction, obesity, or idiopathic disease.3,6,7 Furthermore, it may occur in some patients in the absence of exposure to steroids but is generally associated with obesity. Whatever the predisposing factor, the majority of these patients are men. It can lead to the development of spinal cord or radicular compression and can be the cause of back pain.1,8 It is a rare cause of paraparesis.7 The number of involved vertebral levels and obesity are strongly correlated, whereas severity of dural compression is not always significantly associated with neurological complications. This indicates that epidural fat of the lumbar spine contributes to neurological deficits.9 Most cases of epidural lipomatosis associated with corticosteroid use occur in the thoracic region, while most idiopathic cases occur in the lumbar region.1
The diagnosis of epidural lipomatosis can be established by myelography, CT, and MRI. MRI is considered to be the imaging procedure of choice,1,8,9 allowing an assessment of the extent of lipomatosis and allowing (as CT does also) an identification of the lipomatous tissue.1 MRI-based grading is helpful for the diagnosis and evaluation of this condition.9
The most common treatment for epidural lipomatosis associated with corticosteroid use consists of surgical decompression.1,8,2,10 Medicaltreatment includes corticosteroid withdrawal and weight reduction.1,3,9 Treatment for idiopathic epidural lipomatosis is more often medical.1
The pathogenesis of epidural lipomatosis remains unknown, but some hypotheses suggest a metabolic disorder as the underlying cause.1 With increased awareness of this condition and with improved imaging techniques, further studies of this disease should be undertaken.7
Idiopathic epidural lipomatosis is a rare cause of spinal cord compression. Since most patients respond to conservative management, an exact diagnosis is very important. MRI is the modality of choice for the diagnosis and follow-up of these patients.
Online Radiological Case: Idiopathic epidural lipomatosis. Appl Radiol.