Clincal analysis of spinal epidural lipomatosis according to MR imaging

Abstract

ABSTRACT

Clinical analysis of spinal epidural lipomatosis according to MR imaging

Hui Sun Wang Advisor : Prof. Ju Chang Il, M.D., Ph. D. Department of Neurosurgery, Graduate school of Chosun University

Objective: This study was designed to identify characteristics, diagnosis, clinical outcomes according to the magnetic resonance imaging(MRI) and treatment of epidural lipomatosis at chosun university in Gwang-ju.

Methods: A total of 2309 subjects who were check lumbar MRI in Chosun University hospital from March 2011 to April 2012 were enrolled in this study. All subjects are free from infection, spinal tumor, trauma and previous spinal surgery. Spinal epidural lipomatosis(SEL) is a rare condition of abnormal uncapsulated adipose tissue accumulation in the epidural space. Abnormal fat deposition usually is involved most of extremities, the trunk, but rarely is involved the epidural space of vertebral cannal. Most of SEL are associated with the exogenous steroid(iatrogenic), Cushing Syndrome(endocrinopathies), obesity, hypothyroidism and idiopathic which is medically normal. Clinical profiles were investigated including of age, gender, body mass index(BMI), diabetes mellitus(DM), history of prior steroidal admistration, degenerative spinal disease.

Results: The overall prevalence of severe smptomatic SEL was 1.5%. This condition was more common in men than in women (75% vs 25%). SEL has statistically significant correlation with BMI, exogenous steroid including oral and intravenous (IV) treatment or spinal steroid block(p<0.05). According MRI grading of SEL based on the spatial relation between spinal cannal and epidural fat(EF). (EF/Spic C Index, Spi C: dural sac+EF, EF : epidural fat located ventrally and dorsally to the dural sac). MRI grading showed the following EF/Spi C index : grade 0(<40 %), grade I(41-50%), grade II(51-74%) and grade III(>75 %. severe SEL (grade III) is an end stage that, in many cases, leads to neurogenic claudication and cauda equina syndrome. We carried out operation in pateients at SEL grade III with neurologic symptom. However in grade III, we found different morphologic “variants” of the dural sac compressed by the severe accumulation of epidural adipose tissue. The trifid shape resembling the letter “Y" was the most frequent form. The round shape (circular dural sac with a diameter <4 mm) was seen in other cases. The regional lateral recess patterns were mainly resembling to degenerative stenosis. But regardless of morphologic patterns, surgical procedure was carried out including laminectomy and debulking of the epidural fat. All patients recovered completely. After 6 months follow-up, all patients were symptom-improved and no other neurological sequelae were left.

Conclusion: Adipose tissue is usually found in the spinal epidural space. However, abnormal fat overgrowth contribute to a clear conflict between the dural sac and the adipose tissue within the noncompliant space of the osseous spinal canal. Nevertheless the direct mechanical compression of different morphologic “variants” of the dural sac contribute to diverse neurologic symptoms, surgical treatment according to decompressive laminectomy and fat debulking immedately improve neurologic symptoms