Epidural lipomatosis refers to an excessive accumulation of fat within the spinal epidural space, typically in the lumbar region, such that the thecal sac is compressed, and in some instances results in compressive symptoms.
Demographic of affected individuals reflects the underlying causes, the most common being excessive glucocorticoids. Other causes are also encountered, including 5:
- glucocorticoid excess
- long term steroid administration (e.g. for asthma): 55% - most common
- endogenous Cushing syndrome: 3%
- obesity: 25%
- idiopathic: 17%
Clinical presentation is non-specific, with pain, radicular symptoms and weakness and paresthesia encountered, similar to other degenerative conditions of the spine resulting in stenosis.
Characterized by the abnormal accumulation of unencapsulated adipose tissue in the extradural space.
Epidural lipomatosis typically involves the lower lumbar and/or lower thoracic levels, and can be visualized with both CT and MRI, although the later is better able to identify impingement upon the cauda equina.
There is an often generalized excess of fat seen in the extradural space. As a result, the dural sac can appear narrowed or even resemble a "Y" shaped configuration.
Signal characteristics follow fat on all sequences:
- T1: high signal
- T1 (FS): shows fat suppression
- T2: high signal
Treatment and prognosis
In most instances no specific treatment is required, although review of need for steroid and weight loss are sensible interventions.
The use of epidural steroid injection is controversial. Some authors argue against it, on the grounds of existing compression and implication of steroids in the pathogenesis of epidural lipomatosis 5. Others report successful pain management 6.
In some patients symptoms are severe and operative decompression is required, and is usually successful 7,8.