Radiation myelopathy: a review

Characterizing Proton-Induced Biological Effects in a Mouse Spinal Cord Model: A Comparison of Bragg Peak and Entrance Beam Response in Single and Fractionated Exposures

PURPOSE

Proton relative biological effectiveness (RBE) is a dynamic variable influenced by factors like linear energy transfer (LET), dose, tissue type, and biological endpoint. The standard fixed proton RBE of 1.1, currently used in clinical planning, may not accurately represent the true biological effects of proton therapy (PT) in all cases. This uncertainty can contribute to radiation-induced normal tissue toxicity in patients. In late-responding tissues such as the spinal cord, toxicity can cause devastating complications. This study investigated spinal cord tolerance in mice subjected to proton irradiation and characterized the influence of fractionation on proton- induced myelopathy at entrance (ENT) and Bragg peak (BP) positions.

METHODS AND MATERIALS

Cervical spinal cords of 8-week-old C57BL/6J female mice were irradiated with single- or multi-fractions (18x) using lateral opposed radiation fields at 1 of 2 positions along the Bragg curve: ENT (dose-mean LET = 1.2 keV/μm) and BP (LET = 6.9 keV/μm). Mice were monitored over 1 year for changes in weight, mobility, and general health, with radiation-induced myelopathy as the primary biological endpoint. Calculations of the RBE of the ENT and BP curve (RBEENT/BP) were performed.

RESULTS

Single-fraction RBEENT/BP for 50% effect probability (tolerance dose (TD50), grade II paresis, determined using log-logistic model fitting) was 1.10 ± 0.06 (95% CI) and for multifraction treatments it was 1.19 ± 0.05 (95% CI). Higher incidence and faster onset of paralysis were seen in mice treated at the BP compared with ENT.

CONCLUSIONS

The findings challenge the universally fixed RBE value in PT, indicating up to a 25% mouse spinal cord RBEENT/BP variation for multifraction treatments. These results highlight the importance of considering fractionation in determining RBE for PT. Robust characterization of proton-induced toxicity, aided by in vivo models, is paramount for refining clinical decision-making and mitigating potential patient side effects.

Predictive Factors Associated With Radiation Myelopathy in Pediatric Patients With Cancer: A PENTEC Comprehensive Review

PURPOSE

Radiation myelitis (RM) is a rare complication of radiation therapy (RT). The Pediatric Normal Tissue Effects in the Clinic spinal cord task force aimed to identify RT dose effects and assess risk factors for RM in children. Through systematic review, we analyzed RT dose, fraction size, latency between completion of RT and toxicity, chemotherapy use, age when irradiated, and sex.

METHODS AND MATERIALS

We conducted literature searches of peer-reviewed manuscripts published from 1964 to June 2017 evaluating RM among children. Normality of variables was assessed with Kolmogorov-Smirnov or Shapiro-Wilk tests. Spearman's rank correlation coefficients were used to test correlations between RT dose/fraction size and latency between RT and development of toxicity.

RESULTS

Of 1329 identified and screened reports, 144 reports were fully reviewed and determined to have adequate data for analysis; 16 of these reports had a total of 33 cases of RM with a median age of 13 years (range, 0.2-18) at the time of RT. The most common primary tumor histologies were rhabdomyosarcoma (n = 9), medulloblastoma (n = 5), and Hodgkin lymphoma (n = 2); the most common chemotherapy agents given were vincristine (n = 15), intrathecal methotrexate (n = 12), and intrathecal cytarabine (n = 10). The median RT dose and fraction size were 40 Gy (range, 24-57.4 Gy) and 1.8 Gy (range, 1.3-2.6 Gy), respectively. RT dose resulting in RM in patients who also received chemotherapy was lower than in those not receiving chemotherapy (mean 39.6 vs 49.7 Gy; P = .04). There was no association of age with RT dose. The median latency period was 7 months (range, 1-29). Higher RT dose was correlated with longer latency periods (P = .03) to RM whereas sex, age, fraction size, and chemotherapy use were not. Two of 17 patients with adequate follow-up recovered from RM; unfortunately, it was fatal in 6 of 15 evaluable patients. Complication probability modeling was not possible because of the rarity of events.

CONCLUSIONS

This report demonstrates a relatively short latency from RT (with or without chemotherapy) to RM and a wide range of doses (including fraction sizes) associated with RM. No apparent association with age at the time of RT could be discerned. Chemotherapy appears to reduce spinal cord tolerance. Recovery from RM is rare, and it is often fatal.

Spinal Cord Delineation Based on Computed Tomography Myelogram Versus T2 Magnetic Resonance Imaging in Spinal Stereotactic Body Radiation Therapy

Purpose

Spinal cord delineation is critical to the delivery of stereotactic body radiation therapy (SBRT). Although underestimating the spinal cord can lead to irreversible myelopathy, overestimating the spinal cord may compromise the planning target volume coverage. We compare spinal cord contours based on computed tomography (CT) simulation with a myelogram to spinal cord contours based on fused axial T2 magnetic resonance imaging (MRI).

Methods and Materials

Eight patients with 9 spinal metastases treated with spinal SBRT were contoured by 8 radiation oncologists, neurosurgeons, and physicists, with spinal cord definition based on (1) fused axial T2 MRI and (2) CT-myelogram simulation images, yielding 72 sets of spinal cord contours. The spinal cord volume was contoured at the target vertebral body volume based on both images. The mixed-effect model assessed comparisons of T2 MRI- to myelogram-defined spinal cord in centroid deviations (deviations in the center point of the cord) through the vertebral body target volume, spinal cord volumes, and maximum doses (0.035 cc point) to the spinal cord applying the patient's SBRT treatment plan, in addition to in-between and within-subject variabilities.

Results

The estimate for the fixed effect from the mixed model showed that the mean difference between 72 CT volumes and 72 MRI volumes was 0.06 cc and was not statistically significant (95% confidence interval, -0.034, 0.153; P = .1832). The mixed model showed that the mean dose at 0.035 cc for CT-defined spinal cord contours was 1.24 Gy lower than that of MRI-defined spinal cord contours and was statistically significant (95% confidence interval, -2.292, -0.180; P = .0271). Also, the mixed model indicated no statistical significance for deviations in any of the axes between MRI-defined spinal cord contours and CT-defined spinal cord contours.

Conclusions

CT myelogram may not be required when MRI imaging is feasible, although uncertainty at the cord-to-treatment volume interface may result in overcontouring and hence higher estimated cord dose-maximums with axial T2 MRI-based cord definition.

[Radiotherapy and spinal toxicity: News and perspectives]

Radiation-induced myelopathy is a devastating late effect of radiotherapy. Fortunately, this late effect is exceptional. The clinical presentation of radiation myelopathy is aspecific, typically occurring between 6 to 24 months after radiotherapy, and radiation-induced myelopathy remains a diagnosis of exclusion. Magnetic resonance imaging is the most commonly used imaging tool. Radiation oncologists must be extremely cautious to the spinal cord dose, particularly in stereotactic radiotherapy and reirradiation. Conventionally, a maximum dose of 50Gy is tolerated in normofractionated radiotherapy (1.8 to 2Gy per fraction). Repeat radiotherapies lead to consider cumulative doses above this recommendation to offer individualized reirradiation. Several factors increase the risk of radiation-induced myelopathy, such as concomitant or neurotoxic chemotherapy. The development of predictive algorithms to prevent the risk of radiation-induced myelopathy is promising. However, radiotherapy prescription should be cautious, regarding to ALARA principle (as low as reasonably achievable). As the advent of immunotherapy has improved patient survival data and the concept of oligometastatic cancer is increasing in daily practice, stereotactic treatments and reirradiations will be increasingly frequent indications. Predict the risk of radiation-induced myelopathy is therefore a major issue in the following years, and remains a daily challenge for radiation oncologists.

Prophylactic enlargement of the thecal sac volume by spinal expansion duroplasty in patients with unresectable malignant intramedullary tumors and metastases prior to radiotherapy

Unresectable malignant intramedullary tumors and metastases usually require radiotherapy which intensifies spinal cord edema and might result in neurological decline. Spinal expansion duroplasty before radiotherapy enlarges the intrathecal volume and might thus prevent neurological deficits. The study aims to evaluate the clinical course of patients undergoing expansion duroplasty. This retrospective analysis (2007-2016) included all patients with unresectable intramedullary tumors who underwent spinal expansion duroplasty. To assess the degree of preoperative cord enlargement, we calculated the "diameter ratio": diameter of the spinal cord below and above the tumor / diameter of the tumor × 2. The presence of perimedullary cerebrospinal fluid (CSF) at the affected levels was analyzed on the preoperative magnetic resonance imaging (MRI). We recorded the occurrence of neurological deficits, wound breakdown, and CSF fistula. We screened 985 patients, 11 of which were included. Eight patients had an intramedullary metastasis, three patients a spinal malignant glioma. A diameter ratio ≤ 0.8 representing a significant preoperative intramedullary enlargement was seen in 10 cases (90.9%). Postoperative imaging was available in 9 patients, demonstrating successful decompression in 8 of the 9 patients (88.9%). The postoperative course was uneventful in 9 patients (81.8%). Mean overall survival was 13.4 (SD 16.2) months. Spinal expansion duroplasty prior to radiotherapy is a previously undescribed concept. Despite neoadjuvant radiation, no wound breakdown or CSF fistula occurred. In unresectable intramedullary tumors and metastases, spinal expansion duroplasty seems to be a safe procedure with the potential to prevent neurological decline due to radiation-induced cord swelling.

Malignant Spinal Cord Compression: Adapting Conventional Rehabilitation Approaches

Spinal tumors are classically grouped into 3 categories: extradural, intradural extramedullary, and intradural intramedullary. Spinal tumors may cause spinal cord compression and vascular compromise resulting in pain or neurologic compromise. They may also alter the architecture of the spinal column, resulting in spinal instability. Oncologic management of spinal tumors varies according to the stability of the spine, neurologic status, and presence of pain. Treatment options include surgical intervention, radiation therapy, chemotherapy, and hormonal manipulation. When combined with this management, rehabilitation can serve to relieve symptoms, improve quality of life, enhance functional independence, and prevent further complications in patients.

The role of CT myelography in sparing the spinal cord during definitive radiotherapy in vertebral hemangioma

Introduction

The spinal cord is poorly visualized on CT images but is well visualized in MRI images. However, implants used for spinal stabilization can produce artifacts on the MRI images which can interfere with identification of the cord. CT myelography in conjunction with CT simulation helps to clearly delineate the cord.

Materials and methods

CT simulation was done in a patient with vertebral hemangioma. Pre‐ and post myelography images were obtained. Two plans were generated on pre and post myelography CT images using Eclipse™ treatment planning system (TPS) version 10.0, Varian Medical Systems, USA. The prescribed total dose to PTV was 40 Gy in 20 fractions.

Results

The cord was poorly visualized in the premyelogram CT images. The titanium implants used for spinal cord stabilization produced artifacts in the MRI images. Figure 1 Post myelogram, the contrast lit up the spinal cord.

There was an overlap of 0.75 cc volume of the spinal cord with the PTV in the premyelogram images. This volume was reduced to 0 cc in the post myelogram images. There was an overlap of 5.4 cc volume of the PRV of spinal cord with the PTV in the premyelogram images which was reduced to 1 cc in the post myelogram images. The overlap region between the PTV and spinal cord received around 71% of the prescribed dose in premyelogram CT could be reduced to 0% in the post myelogram CT. The mean dose received by the overlap PRV spinal cord and PTV could be increased from 70% in the premyelogram to 92% in the post myelogram plans.

Conclusion

CT myelogram in conjunction with CT simulation is particularly useful in cases where the tumor margin is very close to the cord and spinal implants are causing distortion of magnetic resonance images.

Transplantation of mesenchymal stem cells in a laryngeal carcinoma patient with radiation myelitis

Radiation myelitis is a rather rare but devastating complication following therapeutic irradiation to neoplasms when the spinal cord is included within the radiation field. Symptoms of radiation myelitis with the therapeutic doses of radiation commonly employed are usually delayed and most often appear about 6 to 24 months following irradiation. So far, no treatment has proved satisfactory.

Transplantation of allogeneic mesenchymal stem cells has been a promising therapy strategy for many disorders in the central nervous system, such as multiple sclerosis, neuromyelitis optica, and autoimmune encephalomyelitis. The cell-base therapy has shown to act to limit inflammation of central nervous system, stimulate neurogenesis, protect axons and promote remyelination. But it has not been established as a therapeutic option for radiation myelitis.

In this report, we describe the outcome of allogeneic umbilical cord-derived mesenchymal stem cell transplantation in a patient with laryngeal carcinoma who developed radiation-induced myelitis of his spinal cord with characteristic magnetic resonance imaging changes.

Effects of Radiation on Spinal Dura Mater and Surrounding Tissue in Mice

PURPOSE

Spinal surgery in a previously irradiated field carries increased risk of perioperative complications, such as delayed wound healing or wound infection. In addition, adhesion around the dura mater is often observed clinically. Therefore, similar to radiation-induced fibrosis--a major late-stage radiation injury in other tissue--epidural fibrosis is anticipated to occur after spinal radiation. In this study, we performed histopathologic assessment of postirradiation changes in the spinal dura mater and peridural tissue in mice.

MATERIALS AND METHODS

The thoracolumbar transition of ddY mice was irradiated with a single dose of 10 or 20 Gy. After resection of the irradiated spine, occurrence of epidural fibrosis and expression of transforming growth factor beta 1 in the spinal dura mater were evaluated. In addition, microstructures in the spinal dura mater and peridural tissue were assessed using an electron microscope.

RESULTS

In the 20-Gy irradiated mice, epidural fibrosis first occurred around 12 weeks postirradiation, and was observed in all cases from 16 weeks postirradiation. In contrast, epidural fibrosis was not observed in the nonirradiated mice. Compared with the nonirradiated mice, the 10- and 20-Gy irradiated mice had significantly more overexpression of transforming growth factor beta 1 at 1 week postirradiation and in the late stages after irradiation. In microstructural assessment, the arachnoid barrier cell layer was thinned at 12 and 24 weeks postirradiation compared with that in the nonirradiated mice.

CONCLUSION

In mice, spinal epidural fibrosis develops in the late stages after high-dose irradiation, and overexpression of transforming growth factor beta 1 occurs in a manner similar to that seen in radiation-induced fibrosis in other tissue. Additionally, thinning of the arachnoid barrier cell layer was observed in the late stages after irradiation. Thus, consideration should be given to the possibility that these phenomena can occur as radiation-induced injuries of the spine.

Diagnosis, investigation and management of hereditary spastic paraplegias in the era of next-generation sequencing

The hereditary spastic paraplegias (HSPs) are a group of genetic conditions in which spastic paralysis of the legs is the principal clinical feature. This is caused by a relatively selective distal axonal degeneration involving the longest axons of the corticospinal tracts. Consequently, these conditions provide an opportunity to identify genes, proteins and cellular pathways that are critical for axonal health. In this review, we will provide a brief overview of the classification, clinical features and genetics of HSP, highlighting selected HSP subtypes (i.e. those associated with thin corpus callosum or cerebellar ataxia) that are of particular clinical interest. We will then discuss appropriate investigation strategies for HSPs, suggesting how these might evolve with the introduction of next-generation sequencing technology. Finally, we will discuss the management of HSP, an area somewhat neglected by HSP research.

[Case of recurrent delayed radiation myelopathy with 5-year remission interval]

We report a 47-year-old woman with relapsed delayed radiation myelopathy (DRM), occurring 5 years and 10 years after radiation therapy for nasopharyngeal carcinoma at 37 years old. Sensations of pain and temperature had been disturbed in the right leg since 42 years old. MRI showed Gadolinium-enhanced lesion as a ring-like-enhancement of the spinal cord at C1-2 on T1-weighted image (T1WI), with high signal area and swelling of the spinal cord at the upper C1 to C6 areas on T2-weighted image. We diagnosed her as having DRM after considering the differential diagnosis, e.g., multiple sclerosis, spinal tumor and other neurological diseases. Her sensory symptoms quickly improved following therapy with prednisolone and warfarin. Although she remained healthy for a few years, dysesthesia of the neck on the right side appeared 5 years later after the first clinical occurrence. At this time, MRI demonstrated Gadolinium-enhanced lesion as a ring-like enhancement of the spinal cord at C2 on T1WI. but the area also differed from that of previous lesion; a high signal area and swelling of the spinal cord was also seen on FLAIR image of the medulla and upper C1 to C6. For recurrence of DRM, we administered prednisolone and warfarin. Thereafter, the patient recovered and the spinal cord lesion on MRI decreased markedly. The clinical course demonstrated that administration of prednisolone and warfarin might be effective for relapsed DRM.

Stereotactic radiosurgery for treatment of spinal metastases recurring in close proximity to previously irradiated spinal cord

PURPOSE

As the spinal cord tolerance often precludes reirradiation with conventional techniques, local recurrence within a previously irradiated field presents a treatment challenge.

METHODS AND MATERIALS

We retrospectively reviewed 51 lesions in 42 patients treated from 2002 to 2008 whose spinal metastases recurred in a previous radiation field (median previous spinal cord dose of 40 Gy) and were subsequently treated with stereotactic radiosurgery (SRS).

RESULTS

SRS was delivered to a median marginal dose of 20 Gy (range, 10-30 Gy) in 1-5 fractions (median, 2), targeting a median tumor volume of 10.3 cm(3) (range, 0.2-128.6 cm(3)). Converting the SRS regimens with the linear quadratic model (α/β = 3), the median spinal cord maximum single-session equivalent dose (SSED) was 12.1 Gy(3) (range, 4.7-19.3 Gy(3)). With a median follow-up of 7 months (range, 2-47 months), the Kaplan-Meier local control and overall survival rates at 6/12 months were 87%/73% and 81%/68%, respectively. A time to retreatment of ≤12 months and the combination of time to retreatment of ≤12 months with an SSED of <15 Gy(10) were significant predictors of local failure on univariate and multivariate analyses. In patients with a retreatment interval of <12 months, 6/12 month local control rates were 88%/58%, with a SSED of >15 Gy(10), compared to 45%/0% with <15 Gy(10), respectively. One patient (2%) experienced Grade 4 neurotoxicity.

CONCLUSION

SRS is safe and effective in the treatment of spinal metastases recurring in previously irradiated fields. Tumor recurrence within 12 months may correlate with biologic aggressiveness and require higher SRS doses (SSED >15 Gy(10)). Further research is needed to define the partial volume retreatment tolerance of the spinal cord and the optimal target dose.

Diagnostic and therapeutic strategy for confounding radiation myelitis

We report a case of confounding radiation myelitis to demonstrate the usefulness of surgical biopsy in ensuring the correct diagnosis and to avoid unnecessary treatment. The patient was a 40-year-old man with a history of epiglottis carcinoma and sarcoidosis. Six months after radiation therapy and chemotherapy for epiglottis carcinoma, he noticed paresthesia and dysesthesia in the left arm and leg. Two months after that, he complained of severe neck pain and rapidly progressing weakness in all extremities. MRI showed an enhanced intramedullary lesion with extensive edema in the cervical spinal cord. Radiation myelitis, intramedullary spinal tumor, and neurosarcoidosis were considered as differential diagnoses. Spinal cord biopsy with laminectomy was performed and radiation myelitis was diagnosed. After the surgery, the lesion was significantly decreased in size even though corticosteroid therapy was rapidly tapered. We emphasize that a spinal cord biopsy is indicated to obtain a pathological diagnosis and to make a clear treatment strategy for patients with associated diseases causing lesions of the spinal cord.

Increased vulnerability of the spinal cord to radiation or intrathecal chemotherapy during adolescence: A report from the Children's Oncology Group

PURPOSE

To assess the rate of spinal cord toxicity in adolescents resulting from chemoradiotherapy of parameningeal sarcoma.

METHODS AND MATERIALS

Of 152 patients with parameningeal sarcoma treated per the Intergroup Rhabdomyosarcoma Study Group protocol from 1977 through 1989, eight developed paralyzing ascending myelitis after intrathecal chemotherapy with cytosine arabinoside, methotrexate, and hydrocortisone administered during and after radiation therapy to volumes that included part of the spinal cord. The eight cases include three not previously published.

RESULTS

Of eight patients who developed CNS toxicity after intrathecal chemotherapy and radiotherapy for parameningeal rhabdomyosarcoma, all but one were between 13 and 18 years of age when treated. This severe toxicity occurred in one quarter of 28 adolescents treated with the regimen in comparison with one of 123 children 12 years of age or less (P < 0.0001), a rate that was as much as 30 times higher in the adolescents. Lengthening of the spinal cord during the pubertal growth spurt may account for the apparent increased vulnerability.

CONCLUSIONS

Chemoradiotoxicity-associated spinal cord injury appears to be more likely to occur in adolescents than in younger or older ages. This observation appears to reverse a conventional wisdom in which the central nervous system is thought to become more resistant to the neurotoxic effects of chemoradiotherapy as it matures.

Significant response of radiation induced CNS toxicity to high dose steroid administration

Treatment of radiation myelopathy remains a challenge. Supportive and rehabilitative therapy is the mainstay of treatment. This article describes a case of central nervous system (CNS) toxicity of radiation with a progressive improvement in the clinicoradiological picture following high dose steroid treatment. A female patient was admitted to the neurology department of our hospital 7 months after a course of radiotherapy in another centre for lingual epidermoid cancer. Neurological examination revealed a heavy spastic quadriplegia syndrome. On MRI examination, T2 weighted hyperintensities were observed in cerebral and cerebellar peduncles, periventricular regions and medulla spinalis at Th1-Th2 levels. The patient was treated with high dose methylprednisolone, 1 g day(-1) for 5 days (pulse therapy) followed by oral methylprednisolone 80 mg day(-1) for a week, tapered over 3 weeks. Within the first week of pulse therapy, she regained muscle strength of upper limbs against gravity. At the 2 year follow-up, MRI demonstrated obvious regression of the lesions in the medulla and cerebellum with disappearance of contrast enhancement. This case report is notable with the complete disappearance of MRI lesions at the 2 year follow-up after the treatment with high dose steroid.

Transverse myelitis after therapy for primitive neuroectodermal tumors

Traditional therapy for malignant primitive neuroectodermal tumors in children includes surgery, multi-agent chemotherapy, and radiation. Given the poor prognosis with conventional therapy alone, newer treatment approaches have incorporated high-dose chemotherapy followed by autologous stem cell rescue. Treatment with chemotherapy and radiation is not without unanticipated and unwanted side effects. Specifically, radiation-induced damage to the central nervous system can occur, though the frequency is thought to be acceptably low. This report describes two cases of treatment-related transverse myelitis in patients who received induction chemotherapy and craniospinal irradiation followed by high-dose chemotherapy with autologous stem cell rescue. Other patients treated with a similar strategy but different sequence and timing of treatment did not experience symptoms of myelitis, suggesting that the specific timing of radiation in relationship to the chemotherapy may be of critical importance.

Radiation myelopathy after radioactive iodine therapy for spine metastasis

A case of radiation myelopathy after radioactive iodine therapy is reported. This is the first report to describe radiation myelopathy after I-131 therapy. A 62-year-old female with spinal metastasis of T10 received I-131 therapy. She presented with radiation myelopathy 34 months after the irradiation. We need to recognize the possibility of this serious complication even in the case of I-131 therapy. There is a risk of radiation myelopathy even after I-131 therapy, especially in cases with spinal cord compression such as this.

Radiation-induced Spinal Cord Glioma Subsequent to Treatment of Hodgkin’s Disease: Case Report and Review

Radiation-induced neoplasms of the central nervous system generally present as meningioma or sarcoma. Spinal cord glioma after radiation therapy is rare and half of the cases documented occurred after treatment of Hodgkin's disease.A 39-year-old male presented with a 1-month history of gradually worsening neck ache and paraparesis. The patient had been treated for stage IB Hodgkin's disease 9 years previously with combined therapy: MOPP-ABV and a 40-Gray mediastinal radiotherapy from T1 to T10. Magnetic resonance imaging disclosed an intramedullary lesion from C6 to T2 and histopathological examination from biopsy demonstrated a malignant glioma. Despite chemotherapy and additional radiotherapy, the patient's neurological status worsened and he died 11 months after initial presentation. We suggest a strategy aimed solely at obtaining a tissue diagnosis to differentiate myelitis from tumor, and, in the event of tumor, confirming the strong likelihood of a high histopathological grade. The very limited survival associated with these tumors regardless of therapy advocates palliative therapies without attempting complete resection.

Lhermitte's sign among nasopharyngeal cancer patients after radiotherapy

BACKGROUND

Lhermitte's sign (LS) is a side effect of radiotherapy (RT) on the spinal cord and typically occurs shortly after the procedure has been conducted. When treating patients with cancer of the head and neck region with irradiation, it remains difficult to avoid exposing the cervical spinal cord to unintended radiation. In this study, we focused on nasopharyngeal cancer (NPC) alone and looked for various parameters that might influence the occurrence of LS associated with this disease after RT.

METHODS

From 1979 through 1990, 1171 patients with NPC completed RT either with or without chemotherapy at the Lin-Kou Medical Center, Chang Gung Memorial Hospital (CGMH), Tao-Yuan, Taiwan; the RT regimens for these treated patients were very similar. The nasopharyngeal tumor was treated to 75 Gy by photon teletherapy and after-loading brachytherapy. The neck lymphatics were irradiated with photon irradiation to 46.8 Gy and then boosted with electron beams to 10 to 30 Gy, in accordance with the patient's nodal status, either unilaterally or bilaterally. Every patient was followed monthly for the first 3 months after therapy and subsequently every 2 to 3 months for the next 2 years and, finally, every 6 months thereafter. At follow-up, a neurologic checkup of each patient was performed to determine whether any injury to the spinal cord or brain stem had arisen.

RESULTS

LS was observed for 121 patients (10.3%). The median development time for such signs was 3.0 months after the completion of RT (range, 0.2-72 months), and the appearance of such a sign lasted 1 to 82 weeks (median, 17 weeks). No statistically significant differences between the sexes were noted in the development of such a sign (p = .5263),or among various T classifications (p = .0757) and N classifications (p = .4412). The incidence of LS was significantly lower for those patients who had also received chemotherapy than it was for those who had not (p = .003), and it was also lower for patients older than 60 years than for those younger than 60 years (p = .0061). Of the subjects who did not undergo neck-lymphatic boosting or who had undergone only unilateral neck-lymphatic boosting, 7.2% had LS develop, whereas 11.5% of patients who had been boosted bilaterally had LS develop (p = .0285).

CONCLUSIONS

The incidence of LS associated with NPC and after RT was higher in patients who underwent bilateral neck-lymphatic boosting by electron beams than for those who underwent unilateral boosting or who did not undergo boosting. A correlation between increased incidence of LS and RT dose on the cervical spinal cord was noted when the cord dose exceeded 48.9 Gy. Therefore, wherever possible, a CT simulator and a three-dimensional treatment-planning system should necessarily be used to verify the dose distribution of electron-beam RT to diminish the chance of radiation overdose on the cervical cord.

Safety of a simple asymmetric jaw technique in the treatment of head and neck cancer

We reviewed our experience treating head and neck malignancies junctioning over the spinal cord using asymmetric collimation. The mean dose delivered to the cord was 43.28 Gy above to the junction, 40.36 Gy below it. With a median follow-up of 20 months, none of our 32 patients developed radiation myelitis.

Neurologic complications of radiation therapy

Injury to the central and peripheral nervous systems is an increasingly frequent consequence of standard radiation treatment protocols for tumors involving or adjacent to nervous system structures. Characteristic temporal, clinical, radiographic, and laboratory features distinguish a number of specific radiation injury syndromes, but meticulous and repeated evaluations over time are often required to establish a diagnosis. These syndromes vary with regard to prognosis and therapeutic options, and competing diagnoses with very different natural histories and therapies often mask or mimic the signs and symptoms of radiation-related nervous system injury. The ability to efficiently negotiate this complicated differential diagnostic landscape allows for early diagnosis of tumor recurrence or an alternative etiology, prompt institution of appropriate therapy, avoidance of unnecessary diagnostic studies, and confident prognostication for patients and families. Even after the diagnosis of a radiation-related complication is made, continued vigilance for additional sites or manifestations of radiation injury is mandatory. Meanwhile, further research into treatment, prevention, and the causes of individual susceptibility to radiation injury are essential.

Spinal cord compression

Back pain and suspected spinal cord compression remains one of the most frequent reasons for neurologic consultation in cancer patients. While treatment generally results in stabilization or improvement, early diagnosis remains the cornerstone of improving neurologic outcome. This article reviews the clinical features, differential diagnosis, and management of neoplastic epidural spinal cord compression.

Intensity-modulated radiation therapy for the spine at the University of California, Irvine

Radiation treatment of malignant diseases of the spine poses unique challenges to the radiation oncology treatment team. Intensity-modulated radiation therapy (IMRT) offers the capability of delivering high doses to targets near the spine while respecting spinal cord tolerance. At the University of California, Irvine, 8 patients received a total of 10 courses to the spine for a variety of primary and metastatic malignant conditions. This paper discusses anatomical considerations, spinal cord radiation myelopathy, and treatment planning issues as it relates to the treatment of spinal cord lesions. Between October 1997 and August 2001, a total of 8 patients received 10 courses of IMRT for primary or metastatic disease of the spine. Cancers treated included metastatic lung, renal, adrenocortical cancers, and primary sarcomas and giant cell tumor. Five cases had 6 courses given for re-irradiation of symptomatic disease and 3 cases had 4 courses of IMRT as primary management of their spinal lesions. Although 3 courses were given postoperatively, these were for grossly residual disease. For the re-irradiation patients, the mean follow-up interval was 4 months. The local control was estimated at 14%. Of the patients treated with primary intent, the mean follow-up was 9 months and the local control rate 75%. No patients developed spinal cord complications.

Radiation myelitis in a 5-year-old girl

Myelopathy is an uncommon complication of radiotherapy, particularly in the pediatric age group. A 5-year-old girl with acute lymphoblastic leukemia developed a severe but transient radiculopathy after intrathecal administration of methotrexate and cytarabine for an isolated central nervous system relapse. Chemotherapy was then given through an intraventricular catheter. Owing to a second central nervous system recurrence, she was treated with craniospinal radiation. The whole brain down to the level of C2 received a dose of 2400 cGy. Two months after completion of radiation, the child developed a progressive tetraparesis, and magnetic resonance imaging revealed an enhancing lesion involving the medulla and upper cervical cord. A biopsy was consistent with a treatment-related necrotizing leukoencephalopathy. This case suggests that patients who develop neurologic dysfunction when treated with methotrexate can also be particularly susceptible to radiation-related injury.

Radiation-induced myelopathy in long-term surviving metastatic spinal cord compression patients after hypofractionated radiotherapy: a clinical and magnetic resonance imaging analysis

BACKGROUND AND PURPOSE

Hypofractionated radiotherapy is often administered in metastatic spinal cord compression (MSCC), but no studies have been published on the incidence of radiation-induced myelopathy (RIM) in long-term surviving patients. Our report addresses this topic.

PATIENTS AND METHODS

Of 465 consecutive MSCC patients submitted to radiotherapy between 1988 and 1997, 13 live patients (seven females, six males, median age 69 years, median follow-up 69 months) surviving for 2 years or more were retrospectively reviewed to evaluate RIM. All patients underwent radiotherapy. Eight patients underwent a short-course regimen of 8 Gy, with 7 days rest, and then another 8 Gy. Five patients underwent a split-course regimen of 5 Gy x 3, 4 days rest, and then 3 Gy x 5. Only one patient also underwent laminectomy. Full neurological examination and magnetic resonance imaging (MRI) were performed.

RESULTS

Of 12 patients submitted to radiotherapy alone, 11 were ambulant (eight without support and three with support) with good bladder function. In nine of these 11 patients, MRI was negative; in one case MRI evidenced an in-field relapse 30 months after the end of radiotherapy, and in the other, two new MSCC foci outside the irradiated spine. In the remaining patient RIM was suspected at 18 months after radiotherapy when the patient became paraplegic and cystoplegic, and magnetic resonance images evidenced an ischemic injury in the irradiated area. The only patient treated with surgery plus postoperative radiotherapy worsened and remained paraparetic. Magnetic resonance images showed cord atrophy at the surgical level, explained as an ischemic necrosis due to surgery injury.

CONCLUSIONS

On the grounds of our data regarding RIM in long-term surviving MSCC patients, we believe that a hypofractionated radiotherapy regimen can be used for the majority of patients. For a minority of patients, more protracted radiation regimens could be considered.

Anticoagulation therapy for radiation-induced myelopathy

OBJECTIVE

To report the use of heparin and enoxaparin for radiation-induced myelopathy.

CASE SUMMARY

A 48-year-old White woman with presumed metastatic lung cancer presented with worsening numbness and weakness of both legs. The neuro-oncology service was consulted and determined that the symptoms were consistent with radiation-induced myelopathy. The patient briefly responded to steroid treatment. A trial of intravenous heparin therapy was initiated by the primary team and managed by the clinical pharmacy services. Her symptoms improved when heparin was begun. She was able to walk and was subsequently discharged home on enoxaparin.

DISCUSSION

Spinal cord injury is one of the known adverse effects of radiation. The onset of symptoms can be acute or delayed. The clinical signs and symptoms of delayed neurologic injury are related to the narrowing and occlusion of the vessel lumen, ischemia, edema, and cell death in the surrounding nervous tissue. Treatment often consists of corticosteroids and/or hyperbaric oxygen; however, the outcomes are often disappointing. In addition to the inhibition of serum protein-mediated coagulation, heparin inactivates or prevents the release of mediators of vascular injury inflammation, permeability, and edema. Therefore, patients with radiation-induced spinal cord injury may benefit from anticoagulant therapy.

CONCLUSIONS

Heparin and/or enoxaparin may be considered as potential treatments for patients with radiation-induced myelopathy.

Clinical radiation doses for spinal cord: the 1998 international questionnaire

BACKGROUND AND PURPOSE

Emmanuel van der Schueren gave a keynote lecture at the 1988 ASTRO annual conference pointing out that the spinal cord 'tolerance doses' then prescribed were probably unnecessarily cautious, resulting in probable underdosing of some tumours. This lecture was supported both by an international questionnaire which he and two of the present authors had conducted, and by animal experimental data. In 1997 he initiated a 10-year follow-up questionnaire, the results of which are summarised here.

MATERIALS AND METHODS

The present report analyses the change in prescriptions from 1988 to 1998 and the variation in prescriptions among various regions of the World.

RESULTS AND CONCLUSIONS

The main conclusion is that prescribed dose levels have increased significantly in this period. Large geographical variations still exist. Among responders who use a formula to correct for changed dose per fraction, 90% are now using the linear-quadratic model vs. 33% in 1988. The current status of clinically acceptable doses to spinal cord in 2-Gy fractions is discussed briefly. Further details from the responses to the 1998 questionnaire will be presented in another publication.

Post-radiotherapy myelitis observed in an AIDS patient with a meningioma: case report and review of the literature

Radiation myelitis is an uncommon but serious complication of radiation therapy. Although the definitive threshold to cause myelitis is unknown, it is believed that less than 50 Gy when given in 25 or more fractions is highly unlikely to cause myelopathy. This report describes a case of myelitis within the radiotherapy portal in an HIV infected patient who received radiation therapy for an atypical meningioma located in the cervical spine. A complete resolution of the meningioma was also noted in this case. The possible contributing roles of HIV infection and concomitant administration of antiviral drugs are discussed.

Non-neoplastic intramedullary pathology. Diagnostic dilemma: to Bx or not to Bx

There are several non-neoplastic lesions which may mimic intramedullary spinal cord neoplasm in their radiographic and clinical presentation. These can be classified as either infectious (TB, fungal, bacterial, parasitic, syphilis, CMV, HSV) and non-infectious (sarcoid, MS, myelitis, ADEM, SLE) inflammatory lesions, idiopathic necrotizing myelopathy, unusual vascular lesions (amyloid, infarct, isolated intramedullary vascular lesions) and radiation myelopathy. Although biopsy may be indicated in many cases, the mistaken diagnosis of intramedullary neoplasm can often be eliminated pre-operatively.

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-induced myelopathy and vertebral necrosis

Radiation-induced myelopathy is often a diagnosis of exclusion. In addition to the classic criteria needed to support the diagnosis, the presence of another radiation-induced lesion, such as aseptic vertebral necrosis, is useful to confirm the cause of the spinal cord lesion.

[Late post-irradiation cervical spinal cord disease. A case]

A case of delayed progressive radiation myelitis (DPRM) which begin 11 months after naso pharyngeal carcinoma radiation, in a young man, is reported. The initial manifestation is often a Brown-Sequard's syndrome progressing to complete and permanent myelopathy, with notable absence of localized or radicular pain. The parenchymal change of the spinal cord in radiation myelopathy can be easily visualized with magnetic resonance imaging (MRI) however there may be cases in which MRI appearance alone does not distinguish specially between tumor and radiation necrosis with absolute confidence: therefore, DPRM is by necessity a diagnosis of exclusion, based on clinical, paraclinical results and course of disease. Corticosteroid therapy is accompanied by a significant remission of symptoms. The evolution is characterized by a worse prognosis, prevention is absolutely necessary based on perfect radiation technic, knowledge on tolerance of spinal cord to irradiation (time-dose-volume factors) and other risks factors (chemotherapy, age and vascular disease).

Significance of gadolinium-enhanced magnetic resonance imaging in differentiating spinal cord radiation myelopathy from tumor. Case report

A young woman with a fourth ventricular ependymoma underwent radiotherapy following tumor excision. Twenty months later she developed a progressive neurological deficit at the C-2 vertebral level. Gadolinium-enhanced magnetic resonance imaging, showed an intramedullary lesion at the C-2 level. Although radiation myelopathy was suspected, tumor recurrence could not be excluded. Re-exploration and histopathology both confirmed a diagnosis of radiation myelopathy. A retrospective review of the case indicated findings favoring radiation myelopathy. The pertinent literature is reviewed and the findings discussed.

Recurrent transverse myelitis, myasthenia gravis, and autoantibodies

A 45-year-old man with a longstanding diagnosis of myasthenia gravis presented with four episodes of transverse myelitis in 5 years. Each episode improved after treatment with steroids. Laboratory studies revealed no evidence of multiple sclerosis or a structural spinal lesion. He had antinuclear and anti-DNA antibodies and the HLA-A1, B8, DR3 haplotype known to be associated with certain autoimmune diseases. We propose an autoimmune cause for the recurrent episodes of myelitis.

Ascending myelitis after intensive chemotherapy and radiation therapy in children with cranial parameningeal sarcoma

In 1977, a program of early, wide-field radiation therapy (RT) to the central nervous system and repeated lumbar intrathecal (IT) medications along with systemic chemotherapy was begun by the Intergroup Rhabdomyosarcoma Study (IRS) for patients younger than 21 years of age with cranial parameningeal sarcoma and a high risk of meningeal extension. From 1977 until 1987, 149 eligible patients with high-risk cranial parameningeal sarcoma were enrolled in IRS trials. None had evidence of lower extremity or sphincter impairment at diagnosis. Five of the 149 (3.4%) had ascending myelitis at 5.5 to 9 months after the initiation of therapy, with loss of sphincter control and inability to walk; this progressed to severe flaccid quadriparesis and necessitated long-term ventilatory support in 4. All five had received vincristine, dactinomycin, cyclophosphamide, and doxorubicin; four also had received cisplatin and three also had received etoposide. All patients received 4770 to 5500 cGy to the primary tumor, and four patients received 3000 cGy of cranial RT. Three patients received cervical RT and two received spinal RT. The patients also received four to seven courses of IT methotrexate, hydrocortisone, and cytosine arabinoside. Three patients died: one after local tumor recurrence with central nervous system extension and two without known recurrence. In one of the latter patients, the results of an autopsy showed necrosis of the cervical spinal cord and caudal medulla. Although the exact cause of this complication is unclear, no additional cases have been reported to the IRS since the protocol was revised in 1987 to reduce the doses of the IT drugs and to limit them to four courses each.

Radiation myelitis: a complication of concurrent cisplatin and 5-fluorouracil chemotherapy with extended field radiotherapy for carcinoma of the uterine cervix

Radiation myelitis is a rare but serious complication of radiation therapy. The total dose of radiation to the spinal cord required to cause myelopathy is greater than 50 Gy when the treatment is administered in 25 or more fractions; however, recent evidence has suggested that the concurrent use of chemotherapy may decrease the tolerance of the spinal cord to radiation. This report describes a case of radiation myelitis in a patient after concomitant fluorouracil/cisplatin chemotherapy and extended field radiotherapy for stage IIA adenosquamous cell carcinoma of the uterine cervix metastatic to the para-aortic lymph nodes.

On the significance of Lhermitte's sign in oncology

We present three cases of Lhermitte's sign out of twenty consecutive cases of epidural spinal cord compression due to metastatic cancer. The three patients were diagnosed with epidural thoracic compressions. The literature on Lhermitte's sign is reviewed with emphasis on the differential diagnosis of this symptom in oncological patients.

Long-term nervous system damage from radiation of the spinal cord: an electrophysiological study

A group of 13 patients suffering from Hodgkin's disease who had undergone chemotherapy and radiotherapy (above and below the diaphragm) approximately 10 years earlier was studied. The total chemotherapeutic dose was similar for all patients; the radiotherapy dose, however, was standard for 7 patients, while the other 6 received much higher dosages over limited regions of the spinal cord. Although most of these patients appeared normal both clinically and on magnetic resonance imaging, a neurophysiological study was performed to determine whether there was any involvement of the central or peripheral nervous system. Motor conduction velocity and sensory conduction velocity were measured in the lower limbs as well as spinal- and scalp-recorded somatosensory evoked potentials (SEPs) in response to stimulation of the posterior tibial and sural nerves at the ankle. In addition, motor evoked potentials were recorded from the upper and lower limbs during cortical stimulation. All neurophysiological data were normal in patients who had received a standard radiation dose, while most of those who had been exposed to higher doses showed altered cortical SEPs and a slowing of central conduction time (D10-P1). Thus even though they were asymptomatic, these patients appeared to have sustained CNS damage, mainly at the level of the spinal cord.

Radiation myelopathy: significance of gadolinium-DTPA enhancement in the diagnosis

We described two cases of chronic progressive radiation myelopathy (CPRM), in which magnetic resonance imaging (MRI) was of great value for the diagnosis. Gadolinium-DTPA (Gd-DTPA) enhancement delineated precise lesions responsible for Brown-Séquard syndrome caused by CPRM in both cases. This safe, sensitive procedure will be a requisite study in patients who are suspected of CPRM.

MRI of radiation induced spinal cord glioma

Radiation induced neoplasms of the spinal cord are rare lesions. This report details the MR evaluation of a patient with radiation induced astrocytoma of the cervical cord. The diagnosis of second primary neoplasm should be considered in patients with prior radiation therapy when MRI demonstrates an intramedullary lesion.

Neurological damage in patients irradiated twice on the spinal cord: a morphologic and electrophysiological study

We reviewed the files of 950 patients treated for Hodgkin's disease since 1966 and were able to find five patients treated with radiochemotherapy and irradiated twice on volumes including a cord segment, at various time intervals, and surviving until now. Seven patients with comparable clinical and therapeutic features, but not reirradiated on the cord, were chosen as a control group and were examined with the same diagnostic procedures. The cumulative cord dose in the reirradiated patients was recalculated and ranged from 50 to 70 Gy. All these patients and the control cases were followed up for more than 10 years and presented no or only minor neurological symptoms. We compare the results of both magnetic resonance imaging (MRI) and electrophysiological studies (spinal and scalp recorded somatosensory evoked potentials--SEPs) in an attempt to define the characteristics of the subclinical damage present in these patients. While no cord abnormality was demonstrated with MRI, electrophysiological studies evidenced a clear difference between cases and controls, as far as the D10-P1 conduction time and SEPs average amplitude are concerned. Advantages and drawbacks of a wider use of electrophysiological methods in research work on cord radiation damage are presented, along with the possible implications of the results obtained for the understanding of the pathogenesis and of the dose dependence of radiation myelitis (RM).