Holothoracic spinal epidural lipomatosis: Report of a rare presentation and review of literature

Abstract

Spinal epidural lipomatosis refers to the abnormal accumulation of unencapsulated fat in the epidural space, possibly associated with spinal canal narrowing and compression of adjacent nerve structures. Risk factors for spinal epidural lipomatosis include older age, male sex, obesity, and systemic corticosteroid use. While spinal epidural lipomatosis typically involves the thoracic or lumbosacral regions of the spinal cord, there are no published cases involving the entire thoracic cord. This report presents the first case of spinal epidural lipomatosis affecting the whole thoracic cord, highlighting the complexity of its diagnosis and management.

Learning points

• Severe spinal epidural lipomatosis (SEL) is an uncommon disorder marked by excessive fat accumulation in the spinal canal.

• Extensive thoracic SEL is exceptionally rare.

• Steroid use, endogenous steroid hyperproduction, and obesity are key risk factors for the disease.

• Manjila classification of SEL shows both extent and severity of the disease using sagittal and axial magnetic resonance imaging sequences, respectively.

Introduction

Severe SEL is a rare condition caused by excessive fat accumulation in the lumbar spinal canal.^1,2 Symptoms often include lower back pain and neurogenic claudication, which may present as pain, weakness, or tingling in one or both legs. Magnetic resonance imaging (MRI) is the examination of choice for confirming the diagnosis. ³ SEL is typically localized to the posterior aspect of the spinal cord, specifically within the thoracic (T4–T8) and lumbar (L4–L5) vertebrae, with the deposition of adipose tissue varying according to the underlying cause of the condition. ⁴ SEL involving the entire thoracic cord is exceptionally rare, with no cases documented in the literature. ⁵ Here, we present a patient with SEL extending from the level of cervical vertebra 7 (C7) to lumbar vertebra 1 (L1), associated with long-segment lipogenic spinal canal stenosis, characterized by significant narrowing at the thoracic vertebrae 6–8 (T6–T8). To our knowledge, this is the first published case of severe SEL involving the full length of the thoracic cord.

Case presentation

An 81-year-old patient was admitted to our geriatric rehabilitation center with subacute, proximally predominant paraparesis. His medical history is notable for a cervical spine injury 3 years prior, managed with fracture repositioning and dorsal stabilization of C2–C7, following an incomplete tetraparesis below C3 (AIS D) due to a C4/5 fracture and associated C4-level myelopathy. Over the past several years, the patient developed progressive paraparesis, despite undergoing previous cervical decompression surgery. Additional comorbidities include axonal sensorimotor polyneuropathy, type II diabetes mellitus managed with metformin and dulaglutide, arterial hypertension treated with amlodipine, hydrochlorothiazide, and candesartan, as well as a history of WHO class II obesity. His actual body mass index (BMI) was 29.05 kg/m², classifying him as overweight. In addition, the patient had a history of SEL extending from the thoracic spine levels T2 to T9. Moreover, the patient was diagnosed with urothelial carcinoma of the bladder (pTa G2, cN0 cM0) in 2013 and treated with urethrotomy and transurethral resection of the bladder. Follow-ups, including cystoscopy and cytology, remained unremarkable, with tumor surveillance completed in March 2021. Additionally, a recurrent, castration-sensitive prostate carcinoma (initial pT3a pN0 cM0, Gleason 9) was managed with robot-assisted radical prostatectomy in 2013, followed by intensity-modulated radiotherapy for PSA recurrence in 2015. Since 2016, the patient has been on antihormonal therapy (currently Eligard) for bone metastasis, with PSA levels maintained at <0.006 ng/ml. He was also diagnosed with lymphogenically metastatic papillary thyroid carcinoma (right-sided, 2.2 cm, pT2, pN1, L1, R1) in December 2019 and underwent total thyroidectomy with right neck dissection (levels II–IV) in January 2020. Normal whole-body scintigraphy and single photon emission computed tomography-computed tomography (SPECT–CT) followed subsequent radiotherapy with 3.7 GBq iodine-131 in March 2020 and in September 2020. Additionally, a well-differentiated neuroendocrine tumor of the pancreas (pT2, pN0, cM0, V1, G1, R0) was resected in September 2014 with distal pancreatectomy, splenectomy, lymphadenectomy, and left adrenalectomy. The tumor follow-up revealed no abnormalities for any malignancy.

The patient reported that for ~5 weeks before admission, he had been experiencing slowly worsening heaviness in his legs. Since the accident and cervical fracture 3 years ago, there has been persistent weakness in the left leg, pain in the left upper arm, and numbness in the left thumb and index finger. He also reported limited neck rotation to the left following surgical fixation.

The clinical examination showed that he was unable to perform a leg positioning test or experienced a rapid lowering of the legs bilaterally. Iliopsoas muscle strength was M3–M4 bilaterally, with a slight emphasis on the left, and quadriceps muscle strength was M4 bilaterally, also slightly more pronounced on the left. Sensation for touch and pain in both legs was normal.

MRI of the spine revealed extensive epidural dorsal lipomatosis Manjila type II extending from C7 to L1 (Figures 1 and 2), resulting in a long-segment lipogenic spinal canal stenosis, with severe compression at its maximum point between T6 and T8 (Figure 2), showing compression of the spinal cord but without signs of myelopathy. No significant foraminal or recessal stenosis was found. No co-existing mediastinal or intraabdominal lipomatosis was observed. Laboratory parameters indicated a glycated haemoglobin (HbA1c) level at the upper limit of normal. Moreover, the lipid profile showed overall acceptable cholesterol levels. Cortisol levels suggest no significant adrenal dysfunction.

Figure 1.

MRI findings at the cervical and thoracic spine level. (a) T1 TSE dark fluid, sagittal cervical MRI: epidural lipomatosis (delimited area), with a double arrow indicating its location at the T5 level. (b) T2 TSE Dixon, sagittal cervical MRI: spinal cord (outlined and pointed area), with an arrow marking its location at T5.

Figure 2.

Thoracic epidural lipomatosis, dorsal (posterior; Manjila classification type II). (a) T1 TSE dark fluid, sagittal dorsal MRI: pointed area highlighting epidural lipomatosis from T4 to L1. The double arrow indicates epidural lipomatosis at its maximum at the T5 level. (b) T2 TSE Dixon, sagittal dorsal MRI: Visualization of the cerebrospinal fluid (pointed area) with severe stenosis at the T7-T8 level.

Surgical treatment with decompression and potential stabilization was recommended, but the patient declined. The patient was discharged home in an improved condition, with recommendations for weight loss and optimal management of cardiovascular risk factors.

Discussion

The abnormal accumulation of unencapsulated fat in the epidural space, which may be associated with the narrowing of the spinal canal and compression of adjacent nerve structures, is termed epidural lipomatosis.^4,6 Although SEL is considered a rare condition, recent studies indicate that mild and moderate forms are relatively common, whereas severe SEL remains rare,^1,2 highlighting a substantial underestimation of disease prevalence. Several risk factors have been associated with SEL, including older age, a higher modified Charlson comorbidity index, male sex, a BMI over 30 kg/m2, Black or African American race, systemic corticosteroid therapy, and a history of epidural corticosteroid injections. ⁷ Based on its underlying causes or pathogenesis, SEL can be classified into five main categories: cases associated with exogenous steroid use, those resulting from endogenous steroid hormone imbalances, obesity-related cases, surgery-induced cases, and idiopathic cases with no identifiable cause. ⁸ Fogel et al. examined 107 cases of spinal SEL and reported that the majority of cases related to exogenous steroid use were connected to prolonged steroid therapy. On the other hand, only a small number—three cases—were associated with repeated epidural steroid injections. Additionally, idiopathic SEL has been observed in obese individuals who do not exhibit hypercortisolemia. ⁹

The exact pathophysiological mechanisms responsible for the corticosteroid-mediated hypertrophy of adipose tissue in constricted body areas (e.g. epidural space, face, and trunk) are not fully understood. However, it appears that subsequent doses of steroids lead to a progressive deterioration of fat accumulation. ¹⁰ Elevated levels of 11beta-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) linked to obesity are thought to promote the local conversion of corticosteroids into biologically active cortisol.^11–14 Another potential explanation highlights the pathophysiological mechanisms of obesity-induced hyperglycemia. Evidence suggests that 17-hydroxyprogesterone (a steroid intermediate in the cholesterol-to-cortisol conversion pathway) interacts with the glucocorticoid receptor to enhance its transcriptional activity, thereby contributing to obesity-associated hyperglycemia. ¹⁵ Plasma glucose levels contribute to lipogenesis through multiple pathways. These include serving as a substrate that undergoes glycolytic conversion into acetyl-CoA, which supports fatty acid synthesis, and enhancing the expression of genes involved in lipogenic processes. ¹⁶ Additionally, surgical intervention has been linked to the development of SEL, possibly due to increased deposition of epidural adipose tissue. In one case, a patient developed SEL 5 months after undergoing lumbar fusion and laminectomy, having received two rounds of epidural steroid injections prior to surgery. ¹⁷ Another case reported SEL following vertebroplasty, where a single dose of steroid was administered into the epidural space, and SEL appeared 5 months later. While steroid use was a factor in both cases, the role of surgery in triggering SEL cannot be ruled out. ¹⁷ Our patient underwent surgery for fracture reposition and stabilization from cervical spine levels C2–C7, but it remains unclear whether steroids were administered.

The modality of choice for the diagnosis of SEL is MRI. Typical radiological findings include high signal intensity on T1-weighted sequences and intermediate signal intensity on T2-weighted sequences. ¹⁸ Despite the fact that it can occur along the length of the spinal cord, cervical locations are considered rare, with only isolated case reports published in the literature.^7,19 Typically, SEL is confined to the posterior aspect of the spinal cord in the thoracic (T4–T8) or lumbar (L4–L5) vertebrae, and the deposition of adipose tissue varies in location based on the underlying cause of the disease. ⁴ Indeed, 55.8% of cases associated with the administration of exogenous steroids are located in the thoracic spine and 32.7% in the lumbοsacral spine, while 11.5% involve both regions. In cases of impaired endogenous steroid production, the distribution of lesions is almost equal between the thoracic and lumbosacral spine. Moreover, a substantial proportion of obesity-related SEL (69.6%) and idiopathic cases (50%) also exhibit lumbosacral involvement.^6,9 To our knowledge, the literature contains only two documented cases of SEL occurring in the cervical spine,^7,19 while SEL is generally more severe at the lumbar and lumbosacral levels. One possible explanation is that the spinal cord primarily occupies the cervical and thoracic vertebrae, narrowing from the level of the L1–L2 vertebrae to form the conus medullaris, thus creating more space that could accommodate potential fat accumulation resulting in greater severity of SEL in the lumbar and lumbosacral regions compared to the cervical, thoracic, or thoracolumbar regions. ¹⁸ Notably, compared to the lumbar cord, the thoracic cord is particularly susceptible to compression from even a small mass due to its restricted blood supply, narrow width, and greater amount of epidural fat. ⁴ The Manjila classification of SEL assesses both the extent and severity of the disease using sagittal and axial MRI sequences, respectively. ²⁰

A slow and gradual progression characterizes SLE. The main symptoms in the initial stages are atypical back pain, which may develop into muscle weakness and sensory disturbances of the lower extremities. Neurological symptoms are determined by which level of the spinal canal and neuronal structures—such as the spinal cord, conus medullaris, or cauda equina—are involved. When the thoracic region is affected, it may lead to progressive myelopathy, and compression of the spinal cord can result in widespread deficits in both motor and sensory functions. ²¹ Indeed, unlike lumbar SEL, which is associated with radicular symptoms, thoracic epidural SEL leads to progressive myelopathic effects, including lower extremity weakness, pain, ataxia, abnormal reflexes, incontinence, and, in ~5% of patients, paraplegia.^22,23 Cauda equina syndrome (CES) is a less common manifestation of SEL, often characterized by gradually worsening lower back pain, as well as pain or sensory deficits in the perineal area. Patients may also experience sensorimotor signs in the lower limbs and autonomic nervous system dysfunction that affects bowel and bladder control. In cases where CES is associated with lipomatosis, symptoms can persist for several months to years and may eventually lead to either progressive or abrupt neurological deficits. ²⁴

In cases where exogenous steroid use is identified as the underlying cause of SEL, a gradual reduction in neurological symptoms may be achieved by tapering or discontinuing the offending medication. For patients with a high BMI who have no history of exogenous steroid use, it is crucial to conduct a thorough endocrinological assessment to rule out endogenous steroid hyperproduction before attributing obesity as a possible cause. ⁸ Manjila et al. recently proposed differentiating the management of obese and nonobese patients. Obese patients with mild stenosis may be managed with weight loss and conservative medical therapies, whereas in nonobese patients, weight loss programs, and imaging to assess stenosis severity can be considered. Furthermore, the study emphasizes the role of bariatric surgery, particularly when severe extraspinal lipomatosis is present. ²⁰ However, if conservative treatments prove ineffective, surgical decompression may still be necessary. Though limited laminotomy with suction or scraping can remove excess adipose tissue, the preferred treatment for SEL is often a standard wide decompressive laminectomy. For thoracic SEL, thoracic laminectomy is recommended over bariatric surgery in cases of acute myelopathy worsening or fixed focal neurological deficits. Concurrent skipped laminectomies may be employed for cases involving tandem thoracolumbar lesions, creating mass effects at two separate areas of the spinal neuraxis. ²⁰

Conclusion

Although rare, severe SEL is an important clinical entity. SEL may lead to compression of neural structures and significant neurological deficits through abnormal fat accumulation in the spinal canal. Manjila classification of SEL shows both extent and severity of the disease using sagittal and axial MRI sequences, respectively. A decompressive laminectomy is recommended over bariatric surgery in cases with acute worsening of myelopathy or fixed focal neurological deficits. The presented clinical report concerns the very rare case of a patient with extensive SEL involving the thoracic spine. In-depth control and treatment of etiological factors are crucial for the patient’s treatment and prognosis, given the disease’s multifactorial nature.