Spinal epidural lipomatosis - an easily ignored secondary intraspinal disorder in spinal kyphotic deformities

Role of epidural fat in the local milieu: what we know and what we don't

PURPOSE

Traditionally, the epidural fat (EF) is known as a physical buffer for the dural sac against the force and a lubricant facilitating the relative motion of the latter on the osseous spine. Along with the development of the studies on EF, controversies still exist on vital questions, such as the underlying mechanism of the spinal epidural lipomatosis. Meanwhile, the scattered and fragmented researches hinder the global insight into the seemingly dispensable tissue.

METHODS

Herein, we reviewed literature on the EF and its derivatives to elucidate the dynamic change and complex function of EF in the local milieu, especially at the pathophysiological conditions. We start with an introduction to EF and the current pathogenic landscape, emphasizing the interlink between the EF and adjacent structures. We generally categorize the major pathological changes of the EF into hypertrophy, atrophy, and inflammation.

RESULTS AND CONCLUSIONS

It is acknowledged that not only the EF (or its cellular components) may be influenced by various endogenic/exogenic and focal/systematic stimuli, but the adjacent structures can also in turn be affected by the EF, which may be a hidden pathogenic clue for specific spinal disease. Meanwhile, the unrevealed sections, which are also the directions the future research, are proposed according to the objective result and rational inference. Further effort should be taken to reveal the underlying mechanism and develop novel therapeutic pathways for the relevant diseases.

Spinal epidural lipomatosis in a pediatric patient with a malignant brain tumor: illustrative case

BACKGROUND

Spinal epidural lipomatosis (SEL) in pediatric patients with concomitant malignant brain neoplasms is rare and can present with rapid deterioration in neurological function.

OBSERVATIONS

A 4-year-old boy with SEL became paraplegic 4 months after completion of chemoradiation for his previously resected, intracranial atypical teratoid rhabdoid tumor. The patient presented with rapid deterioration in lower extremity sensory and motor function, which, given his oncological history, was concerning for disease progression. Of note, 8 months prior, the patient was started on corticosteroid therapy for respiratory dysfunction. Magnetic resonance imaging revealed significant progression of lumbosacral SEL requiring surgical decompression with subsequent neurological improvement.

LESSONS

When evaluating pediatric patients with primary or metastatic brain tumors with new or worsening myelopathy and motor or sensory deficits, it is important to consider SEL.

The Mysterious Role of Epidural Fat Tissue in Spine Surgery: A Comprehensive Descriptive Literature Review

BACKGROUND

Though both neurosurgeons and orthopedic spinal surgeons are keenly aware of the clinical importance of epidural fat (EF), surgical practice varies amongst individual surgeons and across both fields. Thus, an in-depth understanding of the anatomical structure and composition of EF is vital, as it will play a significant role in the therapeutic management and the surgical choice of treatment.

OBJECTIVE

We aim to extensively review the anatomical and biological properties of EF and further outline the surgical importance of EF management.

STUDY METHODOLOGY

(i) MEDLINE search 1966-July 2019. Keywords: Review of the Literature. Authorship, Meta-analysis, Descriptive/Narrative overview; (ii) CINAHL search from 1982 to May 2019. Keywords: Review of the Literature spinal epidural fat; Authorship; Meta-analysis; Descriptive/Narrative overview; (iii) Hand searches of the references of retrieved literature; (iv) Personal and college libraries were searched for texts on research methods and literature reviews; and (v) 200 articles were downloaded, 50 were excluded because of similarity of topics and also because of new update on the same topics. (vi) Discussions with experts in the field of reviews of the literature.

DISCUSSION

Though excessive or reductive amounts of EF usually exacerbates neurological symptoms and lead to various pathologic conditions such as spinal epidural lipomatosis, but there is no basic science, experimental, or clinical research that proves the role of EF in the aforementioned pathologic situations.

CONCLUSION

Anatomical illustration, biological function and properties of EF knowledge may lead to changes in the stages of the surgical approach to avoid postoperative complications. However, the role of EF is exclusively bound to a scientific hypothesis as one cannot be sure if an excessive or reductive amount in EF is entirely responsible for the pathologic findings, or just only an incidental finding.

Could Spinal Epidural Lipomatosis Be the Hallmark of Metabolic Syndrome on the Spine? A Literature Review with Emphasis on Etiology

Spinal epidural lipomatosis is defined by an excessive amount of epidural fat in the spinal canal, usually in the lumbosacral tract: a well-known cause of lumbar pain and spinal stenosis with a possible wide range of neurological symptoms. Recent research data reveal that, nowadays, obesity has become the main cause of spinal epidural lipomatosis. Moreover, this condition was recently recognized as a previously unknown manifestation of metabolic syndrome. Radiological studies (CT and MRI) are the only tools that are able to diagnose the disease non-invasively. Indeed, radiologists play a key role in disease recognition, with subsequent possible implications on patients' systemic health assessments. Despite its clinical importance, the condition is still underreported and neglected. The current literature review summarizes all the main etiologies of spinal epidural lipomatosis, particularly regarding its linkage with metabolic syndrome. An overview of disease characteristics from diagnosis to treatment strategies is also provided.

Surgical management of thoracic myelopathy from long-segment epidural lipomatosis with skip hemilaminotomies: illustrative case

BACKGROUND

Thoracic spinal epidural lipomatosis (SEL) involves the pathological overgrowth of histologically normal, unencapsulated adipose tissue that can compress the spinal cord and cause myelopathy. SEL has been associated with multiple medical conditions, including Scheuermann kyphosis (SK). Optimal treatment strategies for SEL, especially in the setting of a sagittal spinal deformity, remain unclear.

OBSERVATIONS

In this report, the authors discussed surgical management of a patient with thoracic SEL and SK using skip hemilaminotomies for resection of the epidural adipose tissue. To the authors’ knowledge, only one other report described a similar surgical technique in a patient who did not have a spinal deformity.

LESSONS

When conservative efforts fail, thoracic SEL may require surgical treatment. Surgical planning must account for co-medical conditions such as SK. The described approach involving skip laminotomies, which minimizes spine destabilization, is a viable option to treat SEL spanning multiple spinal segments. Prognosis after surgical treatment varies and is impacted by multiple factors, including severity of preoperative neurological deficits.

MRI Features and Clinical Significance of Spinal Epidural Lipomatosis: All You Should Know

Spinal epidural lipomatosis (SEL) is defined as the abnormal accumulation of unencapsulated adipose tissue in the spinal epidural space. SEL can be asymptomatic or can cause a wide range of symptoms, the most common of which is neurogenic claudication. Several other neurological manifestations may also occur, above all myelopathy and radicular symptoms. The spinal level most frequently involved in patients with SEL is the lumbar one, followed by the thoracic one. Imaging plays a key role in disease assessment. MRI is considered the most effective and sensitive modality for diagnosing and staging SEL. Anyway, also CT scan can diagnose SEL. The diagnosis may be incidental (in mild-moderate disease) or may be taken into account in cases with neurological symptoms (in moderate-severe disease). There are some recognized risk factors for SEL, the most common of which are exogenous steroid use and obesity. Recent studies have found an association between SEL and obesity, hyperlipidemia and liver fat deposition. As a matter of fact, SEL can be considered the spinal hallmark of metabolic syndrome. Risk factors control represents the initial treatment strategy in patients with SEL (e.g. weight loss, steroid therapy suspension). Surgical decompression may be required when conservative treatment fails or when the patient develops acute/severe neurological symptoms.

Occurrence of substance P and neurokinin receptors during the early phase of spinal fusion

Spinal fusion is widely used for patients with spinal disorders; however, patients often suffer from back pain following fusion surgery. Substance P (SP) acts as a pain neurotransmitter via the sensory nerve afferent fibres up to the spinal cord, and is involved in the conduction and modulation of pain. The use of specific SP neurokinin receptor (NKR) antagonists may decrease postoperative pain. In the present study, the effects of alterations in the quantity of SP and NKRs in the early spinal fusion process were investigated. The results of the present study revealed that SP and NKRs began to appear 1 week post‑surgery in fibrous tissues. The abundance of SP and NKRs peaked at 3 weeks post‑surgery; the majority of SP and NKRs were distributed around the allograft and the new microvessels. In conclusion, SP and NKRs are involved in early spinal fusion, a finding that may facilitate the development of novel strategies to promote spinal fusion from a neurogenesis perspective.