Radiation myelitis in carcinoma of the nasopharynx

Relationship between Curative Radiation Therapy of Paravertebral Tumors and the Incidence of Radiation Myelitis

The literature about radiation damage to the spinal cord is reviewed and 4 of own cases are presented. It is pointed out that in curative radiation therapy the risk of myelitis that accompanies higher spinal cord doses must be weighed against the therapeutic gains. However, in view of the lack of information about radiation damage to the spinal cord, this may be quite difficult.

[Repair and time-dose factor: The example of spinal cord irradiation]

The question whether a reirradiation is possible, with either curative of palliative intent, is a frequent issue and a true therapeutic challenge, in particular for a critical organ sensitive to cumulative dose, such as the spinal cord. Preclinical experimental data, based on debatable models that are hardly transferable to patients, suggest that there is a possibility of reirradiation, beyond the classical threshold for dose constraints, taking into account the "time-dose factor". Although the underlying biological mechanisms are however uncertain, scarce clinical data seem to confirm that the tolerance of spinal cord to reirradiation does exist, provided that a particular attention to total dose is given. In the context where modern stereotactic irradiation facilities expand therapeutic perspectives, we review the literature on possibilities of reirradiation, through the example of spinal cord reirradiation.

Overall survival after reirradiation of spinal metastases - independent validation of predictive models

BACKGROUND

It is unknown if survival prediction tools (SPTs) sufficiently predict survival in patients who undergo palliative reirradiation of spinal metastases. We therefore set out to clarify if SPTs can predict survival in this patient population.

METHODS

We retrospectively analyzed spinal reirradiations performed (n = 58, 52 patients, 44 included in analysis). SPTs for patients with spinal metastases were identified and compared to a general palliative score and to a dedicated SPT to estimate prognosis in palliative reirradiation independent of site (SPT-Nieder).

RESULTS

Consistently in all tests, SPT-Nieder showed best predictive performance as compared to other tools. Items associated with survival were general condition (KPS), liver metastases, and steroid use. Other factors like primary tumor site, pleural effusion, and bone metastases were not correlated with survival. We adapted an own score to the data which performed comparable to SPT-Nieder but avoids the pleural effusion item. Both scores showed good performance in identifying long-term survivors with late recurrences.

CONCLUSIONS

Survival prediction in case of spinal reirradiation is possible with sufficient predictive separation. Applying SPTs in case of reirradiation helps to identify patients with good life expectancy who might benefit from dose escalation or longer treatment courses.

Clinical trials and evidence-based medicine for metastatic spine disease

Treatment of metastatic epidural spinal disease has undergone significant changes over the last 20 years. No longer is indiscriminate decompressive laminectomy offered as the only surgical treatment. It carries all the risks associated with an invasive procedure and offers the patient little benefit unless it is used to remove disease isolated to the posterior elements. The existing literature suggests that surgery that frees the spinal cord at the site of compression in addition to reconstructing and stabilizing the spinal column is more effective at preserving and regaining neural function, notably ambulatory function and sphincter function, than conventional radiotherapy. It is also highly effective in relieving pain. The preliminary results ofa recent RCT provide the first class I evidence to support a reversal in the current philosophy of primary treatment for many patients with meta-static disease. Conventional radiotherapy has a clearly defined role as adjuvant therapy and as primary therapy in those who are unable to tolerate or benefit significantly from surgery. The role of nonconventional radiation therapy, such as IMRT and SRS, remains to be elucidated.

Surgical Management of Spinal Metastases

Metastatic spread to the spinal column is a growing problem in patients with cancer. It can cause a number of sequelae including pain, instability, and neurologic deficit. If left untreated, progressive myelopathy results in the loss of motor, sensory, and autonomic functions. Except in rare circumstances, treatment is palliative. Traditionally, conventional fractionated external beam radiotherapy has been the treatment of choice. "Surgery" for metastatic spinal disease was, and generally continues to be, equated with laminectomy by many physicians. However, there has been a remarkable evolution in surgical techniques over the last 20 years. Today, the goal of surgery is to achieve circumferential decompression of the neural elements while reconstructing and immediately stabilizing the spinal column. This has been made possible by the use of different surgical approaches and the exploitation of a burgeoning array of internal fixation devices. More recently, minimally invasive surgical techniques, such as endoscopy, kyphoplasty/vertebroplasty, and stereotactic radiosurgery, have been added to the surgeon's armamentarium. As the number of treatment options for metastatic spinal disease grows, it has become clear that effective implementation of treatment can only be achieved by a multidisciplinary approach. This will provide the surest means of maximizing the quality of the remainder of the patient's life.

Treatment of metastatic spinal epidural disease: a review of the literature

OBJECT

Spinal cord compression is one of the most dreaded complications of metastatic cancer. It can lead to a number of sequelae, including pain, spinal instability, neurological deficits, and a reduction in the patient's quality of life. Except in selected circumstances, treatment is palliative. Treatment options include surgery, radiation, and chemotherapy. The goal of this study was to summarize the existing data on the outcomes of various treatment methods for metastatic spinal epidural disease and to make appropriate recommendations for their use.

METHODS

The authors used a search strategy that included an electronic database search, a manual search of journals, analysis of bibliographies in relevant review papers, and consultation with the senior author. There is good evidence, including Class I data, that steroid drugs constitute a beneficial adjunctive therapy in patients with myelopathy from epidural compression. Historically, conventional radiation therapy has been viewed as the first-line treatment because it has been shown to be as effective as a decompressive laminectomy, with a lower incidence of complications (Class II data). Nevertheless, in the last 20 years there has been remarkable progress in surgical techniques and technology. Currently, the goals of surgery are to achieve a circumferential decompression of the spinal cord, and to reconstruct and immediately stabilize the spinal column. Results in a large body of literature support the belief that surgery is better at retaining or regaining neurological function than radiation and that surgery is highly effective in relieving pain. Most of the data on the treatment of metastatic spinal disease are Class II or III, but the preliminary results of a well-designed, randomized controlled trial in which surgery is compared with standard radiation therapy represents the first Class I data.

CONCLUSIONS

As the number of treatment options for metastatic spinal disease has grown, it has become clear that effective implementation of these treatments can only be achieved by a multidisciplinary approach.

Outcome after spinal reirradiation for malignant epidural spinal cord compression

Radiotherapy is effective for most cases of spinal cord compression. Although recurrent spinal cord compression is a common problem, little is known about whether reirradiation preserves neurologic function and what risk of radiation myelopathy it carries. To investigate this question, we reviewed patients at the Mayo Clinic between 1975 and 1992 undergoing two or more courses of radiotherapy to the same segment of the spinal column with radiographically documented epidural disease at the time of reirradiation to determine outcome as measured by the ability to walk and by survival. Fifty-four patients met the study criteria. Radiation doses for the first course ranged from 2,250 to 5,400 cGy (median, 3,000 cGy), and total dose for all courses to the reirradiated spinal segment ranged from 3,650 to 8,089 cGy (median, 5,425 cGy). All patients were ambulatory following the first course of radiation, 40 (74%) were ambulatory at the onset of reirradiation, and 42 (78%) were ambulatory at the end of reirradiation. Thirty-seven patients (69%) remained ambulatory at their last follow-up 6 days to 80 months following reirradiation (median, 4.7 months). Five patients eventually became nonambulatory 6.5 to 35 months following reirradiation. Median survival for all patients following reirradiation was 4.2 months. We conclude that for cancer patients with progressive epidural disease following radiotherapy, reirradiation frequently preserves ambulation and carries minimal risk of radiation myelopathy during the patients' lifetime.

Radiation myelopathy following single courses of radiotherapy and retreatment

PURPOSE

To assess the latent time, survival and dose-fractionation factors associated with permanent radiation myelopathy following single and multiple courses of radiotherapy to the spinal cord.

METHODS AND MATERIALS

A retrospective analysis was undertaken of all patients who were registered at the Princess Margaret Hospital between 1955 and 1985, and who developed permanent radiation myelopathy. There were 22 males and 13 females with ages ranging from 30 to 72 years. Twenty-four patients developed permanent myelopathy after one course of radiation therapy and 11 patients following retreatment. Seven patients had histological confirmation of radiation myelopathy at autopsy.

RESULTS

The actuarial survival was 14% at 5 years (median: 8.3 months) from the date of diagnosis of radiation myelopathy. Latent times for myelopathy following a single course of treatment (mean: 18.5 months, 7-57 months), were significantly longer than those after reirradiation (mean: 11.4 months, 4-25 months), p = 0.03. There was not a single incident of myelopathy in patients who received fractionated radiotherapy given once daily to an extrapolated response dose (ERD) of < or = 100 Gy2 (equivalent to 50 Gy in 25 daily fractions). Four patients who developed myelopathy after an ERD of < 100 Gy2 were all treated on accelerated fractionation protocols with multiple fractions given per day. Patients who were reirradiated received significantly higher doses (mean ERD of 148 Gy2) than those who had a single course of treatment (mean ERD of 121 Gy2), p = 0.001.

CONCLUSION

We conclude that the risk of radiation myelopathy following conventionally fractionated radiotherapy to the spinal cord is extremely small; giving multiple fractions per day reduces the spinal cord tolerance; latent time to myelopathy decreases following retreatment; and there is possible long-term recovery of radiation damage in the human spinal cord.

The latent period in clinical radiation myelopathy

Seventy-seven papers containing data on more than 300 cases of radiation myelopathy have been analyzed. The data suggest that the latent periods are similar in the cervical and thoracic levels of the spinal cord and are bimodally distributed. Myelopathy of lumbar cord apparently has a shorter latent period. As in controlled animal experiments, the latent period decreases with increasing dose. Furthermore, the variation in latent periods also decreases with dose. It is also seen that retreated patients and pediatric or adolescent patients have greatly reduced latent periods. The implications of these findings as they compare with the animal data are discussed.

Late sequelae of radiation therapy in cancer of the head and neck with particular reference to the nasopharynx

Sequlae of radiation therapy may be late in occurring and varied in their manifestations. Although some are untreatable and progressive, the risk of development of some other sequelae can be minimized by careful application of radiotherapy or by ancillary measures, such as dental decay prophylaxis. Some of the serious sequelae secondary to radiation therapy of the nasopharynx have been summarized. These include radiation myelitis, paralysis of the cranial nerves, stricture of the pharynx, radiation-induced cancer, and necrosis with fatal hemorrhage.

Radiation myelopathy of cervical spinal cord simulating intramedullary neoplasm

Radiation myelopathy is a well-known complication of irradiation therapy of neoplasms in the vicinity of the spinal cord. Most earlier authors have stressed the association of a normal myelogram and normal CSF protein level with this condition. One case of radiation myelopathy with a myelogram simulating intramedullary neoplasm and with extremely high CSF protein concentration is presented. Six months after myelography necropsy revealed severe atrophy of the previously thickened lower cervical spinal cord. The pathogenetic mechanisms are discussed.

Pathology of radiation myelopathy

After nothing the rarity of papers describing the pathology of delayed radiation necrosis of the spinal cord, the clinical and pathological findings from four cases are presented. The main pathological features are asymmetric demyelination of the lateral columns and to a lesser degree the posterior and anterior columns of white matter, with coagulative necrosis at the level of irradiation which affected the grey matter to a lesser degree. There is ascending and descending secondary tract degeneration, and poor glial response in the lesions themselves. Vascular changes, mainly hyalilne thickening of arteriolar walls, are present, but not in degree sufficient to explain the primary lesion. The discussion of the pathogenesis of the myelopathy weighs the merits of a primary vascular lesion against those of a primary effect of the radiation on neural tissue. The latter is favoured.