Spinal lipomas are a type of benign, fatty growth that develops along the spinal cord. These masses are composed of normal fat cells that have formed into a lump or mass within or near the spinal canal. Spinal lipomas are congenital, meaning they are present at birth, resulting from an error during fetal development.
Understanding Spinal Lipomas
They are non-cancerous collections of fat cells abnormally attached to the spinal cord or its protective coverings. They arise due to an error in fetal development where normal fatty tissue becomes stuck to developing spinal cord tissue. This developmental anomaly occurs during the early weeks of pregnancy.
Lipomas are classified by their location. Intradural lipomas are within the dura mater, the outermost membrane covering the spinal cord, and can be subpial (under the pia mater) or intramedullary (within the spinal cord). Conus medullaris lipomas are found at the end of the spinal cord. Filum terminale lipomas occur in the filum terminale, a thin fibrous tissue extending from the bottom of the spinal cord.
Recognizing Symptoms and Diagnosis
Symptoms vary widely based on the lipoma’s size, location, and whether it causes pressure on the spinal cord. Many individuals are asymptomatic, with discovery often incidental during imaging for other conditions. When symptoms occur, they include neurological issues like weakness or numbness in the legs, pain radiating to the legs or arms, and changes in bladder and bowel function, including incontinence.
Orthopedic problems, especially in children, can include foot deformities like club foot and gait abnormalities leading to walking difficulties. Visible skin manifestations on the back, such as dimples, hairy patches, skin tags, or discolored skin, can also indicate an underlying spinal lipoma.
Diagnosis primarily relies on imaging. Magnetic Resonance Imaging (MRI) is the preferred diagnostic tool, clearly visualizing soft tissues and delineating the lipoma’s relationship to the spinal cord. MRI’s high signal intensity on T1-weighted images, due to fat content, helps distinguish lipomas. Computed Tomography (CT) scans can also identify lipomas by showing low-density fat and may reveal associated vertebral abnormalities. Early diagnosis aids management and can prevent neurological progression.
Treatment Approaches and Management
Surgical intervention is the primary treatment for spinal lipomas, especially when symptoms are present or progressing, to prevent further neurological damage. Surgery aims to detach the lipoma from the spinal cord to relieve tension and decompress it. This procedure, known as untethering, restores the spinal cord’s mobility.
Complete removal of the lipoma is often not feasible or advisable due to its delicate and often intertwined attachment to the spinal cord and nerve roots. Surgeons typically aim for a subtotal resection, where a significant portion of the fatty tissue is removed to reduce pressure, but some fat may remain closely adhered to the neural tissue. This approach helps to minimize the risk of damaging the spinal cord.
Potential risks and complications associated with spinal surgery for lipomas include infection at the incision site, bleeding, and the formation of scar tissue, which could potentially lead to re-tethering of the spinal cord. There is also a minor risk of nerve injury, which could result in decreased muscle strength or changes in bladder or bowel function. Despite these risks, the benefits of surgery, such as symptom relief and improved mobility, often outweigh the potential complications for symptomatic individuals.
For individuals who are asymptomatic, particularly adults, an observation approach may be considered. Regular monitoring with MRI scans can track the lipoma’s growth and any changes in its relationship to the spinal cord. However, even in asymptomatic cases, some medical professionals may suggest surgical removal as lipomas can progress and cause symptoms over time, with a risk of developing symptoms in about 40% of cases within 10 years of follow-up.
Related Conditions and Long-Term Outlook
Spinal lipomas are often associated with abnormal spinal development conditions, such as spina bifida, a neural tube defect. A common related condition is tethered cord syndrome, where the spinal cord becomes abnormally anchored or stretched by the lipoma, causing tension and progressive neurological symptoms.
The long-term outlook for individuals with spinal lipomas varies depending on the specific type of lipoma, the presence and severity of symptoms, and the timing and effectiveness of treatment. With appropriate management, including surgical intervention when indicated, many individuals can experience a halt in symptom progression and lead fulfilling lives. However, some may require ongoing monitoring or management for residual symptoms, and regular follow-up appointments are generally recommended to assess for any recurrence of tethering or new symptom development. While surgical intervention can prevent further decline, the recovery of lost function, particularly bladder control, can be limited if symptoms were present for a long duration before treatment.