From the Guidelines
Post radiation myelopathy is a rare but serious complication of radiation therapy, with a frequency of less than 2%, and its management primarily focuses on symptom control and prevention of further complications. The condition results from radiation-induced damage to the spinal cord tissue, leading to progressive neurological symptoms. According to the most recent study 1, the maximum point dose to the spinal cord should be carefully planned to maintain the risk of radiation-induced myelopathy under 5%. Treatment may include corticosteroids like dexamethasone to reduce inflammation and swelling, physical therapy to maintain function, and a multimodal approach to pain management, including gabapentin or pregabalin for neuropathic pain.
Key Considerations
- The risk of vertebral compression fracture (VCF) is a significant concern after spine SBRT, with rates ranging from 10 to 20% 1.
- Fractionated SBRT has not been associated with a higher risk of VCF compared to conventional RT, while single-fraction SBRT doses > 20 Gy appeared to be associated with a greater risk 1.
- Particular attention is needed when conventional RT or SBRT is performed in conjunction with systemic treatment, due to their potential radiosensitizing effect 1.
Management and Prevention
- Careful radiation treatment planning is crucial to minimize spinal cord exposure and prevent post radiation myelopathy, adhering to established dose constraints, and using modern radiation techniques that spare critical structures.
- Symptom management is essential, and may include antispasmodics such as baclofen or tizanidine to manage spasticity, and hyperbaric oxygen therapy in selected cases.
- The pathophysiology of post radiation myelopathy involves vascular damage, demyelination, and ultimately necrosis of the spinal cord tissue due to radiation-induced DNA damage and oxidative stress, with the thoracic spine being most vulnerable due to its relatively poor blood supply.
From the Research
Definition and Causes of Post Radiation Myelopathy
- Post radiation myelopathy is a serious potential complication associated with radiation therapy to the spinal cord 2.
- The exact cause of post radiation myelopathy is unknown, but it represents a spectrum of syndromes, including acute transient radiation myelopathy and chronic progressive radiation myelitis 2.
- Cord damage is related to controllable factors such as dose fraction size, treatment time, total dose, length of cord irradiated, technical and clerical errors 2.
Diagnosis and Imaging
- MR imaging is the primary modality for evaluating patients presenting with myelopathy, including post radiation myelopathy 3.
- The first step in diagnosis must be the exclusion of spinal cord compression 3.
- Careful attention to the time course of presentation, knowledge of common and uncommon causes of myelopathy, and identification of specific imaging patterns and features can help narrow the differential diagnosis or establish a definitive diagnosis 3.
Treatment and Management
- There is no known first-line and effective treatment available to alleviate the symptoms of delayed radiation myelopathy 4.
- Bevacizumab has been studied as a potential treatment for late-onset radiation-induced myelopathy, with some evidence suggesting it may improve radiologic outcomes, but have only a modest effect on clinical outcomes 5.
- Experimental biologic strategies targeting the injury response pathways hold promise in mitigating the effects of radiation myelopathy 6.
Prevention and Risk Reduction
- Awareness and understanding of the factors that contribute to the risk of post radiation myelopathy, such as dose fraction size and combined chemoradiotherapy effects, can help reduce the risk of incidence 2.
- Recognition of the factors associated with radiation doses and administration areas may also reduce the risk of delayed radiation myelopathy 4.