Spinal epidural lipomatosis (SEL) is a condition characterized by an abnormal overgrowth of fat tissue in the epidural space — the area between the spinal canal wall and the protective covering of the spinal cord (dura mater). As this fat accumulates, it can compress the spinal cord and nerve roots, causing significant neurological symptoms.
Epidural lipomatosis is an underrecognized cause of spinal canal narrowing that produces symptoms nearly identical to those of Spinal Stenosis and Foraminal Stenosis. In severe cases it can precipitate Cauda Equina Syndrome. Notably, the corticosteroids used to treat conditions such as Ankylosing Spondylitis are themselves one of the most common causes of epidural lipomatosis, creating an important treatment-related complication to recognize.
Causes
Corticosteroid use and obesity.
The most common causes of spinal epidural lipomatosis are prolonged systemic corticosteroid therapy (such as prednisone used for inflammatory conditions) and obesity. Both conditions promote abnormal fat deposition throughout the body, including the epidural space. Cushing's syndrome — whether from exogenous steroids or endogenous overproduction — is also strongly associated.
Other causes
In a subset of cases, no clear precipitating factor is identified (idiopathic SEL). This form tends to occur in obese middle-aged men. Hypothyroidism and other endocrine disorders have also been implicated in some cases.
Symptoms
The most common symptoms are lower back pain, bilateral leg pain, and neurogenic claudication — pain, heaviness, or weakness in the legs that worsens with walking or prolonged standing and is relieved by sitting or bending forward. Severe cases can cause progressive leg weakness, sensory loss, and bowel or bladder dysfunction. Thoracic epidural lipomatosis may cause upper motor neuron signs including spasticity and gait difficulties.
Diagnosis
MRI is the definitive diagnostic tool for epidural lipomatosis. A lumbar spine MRI or cervical spine MRI will be obtained depending on the location of symptoms. Fat within the epidural space appears bright on T1-weighted sequences and can be confirmed with fat-saturation techniques. MRI demonstrates the extent of fat accumulation, the degree of thecal sac compression, and any associated nerve root or spinal cord compromise. The "Y sign" — a characteristic shape of the compressed thecal sac on axial MRI — is a classic imaging feature. CT scan can also identify epidural fat accumulation, though MRI provides superior soft tissue detail.
Classification
Epidural lipomatosis is classified based on the underlying cause and the severity of neural compression on MRI.
- Steroid-induced: Most common form, associated with exogenous corticosteroid therapy or Cushing's syndrome.
- Obesity-related: Occurring in the context of significant obesity without steroid use.
- Idiopathic: No identifiable underlying cause.
Treatments
Treatment is directed at addressing the underlying cause of fat accumulation. In many cases, correcting the precipitating factor leads to gradual improvement in symptoms and reduction in epidural fat.
For steroid-induced SEL, gradual tapering of corticosteroid dosage — under careful medical supervision to avoid adrenal insufficiency — is the primary intervention. For obesity-related SEL, significant weight loss can lead to meaningful reduction in epidural fat and symptom improvement.
Conservative treatment: Physical therapy, analgesics, and epidural steroid injections may help manage symptoms during the period of dietary and medication adjustment. Activity modification is important to avoid exacerbating neural compression.
Surgical treatment
When conservative measures fail and neurological compromise is significant or progressive, surgical decompression — typically a laminectomy to remove excess epidural fat and decompress the spinal canal — is highly effective. Surgery is considered when non-operative management has not adequately relieved symptoms or when there is urgent neurological compromise.
Related Spine Conditions
- Spinal Stenosis
- Foraminal Stenosis
- Cauda Equina Syndrome
- Ankylosing Spondylitis
- DISH
- Back to all Spine Conditions
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