Radiation myelopathy in children

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.

Role of resection and adjuvant therapy in long-term disease outcomes for low-grade pediatric intramedullary spinal cord tumors

OBJECTIVE Surgical excision is the mainstay treatment for resectable low-grade intramedullary spinal cord tumors (IMSCTs) in the pediatric age group. Chemotherapy and radiation treatments are generally reserved for progressive or recurrent disease. Given the indolent nature of low-grade tumors and the potential side effects of these approaches, their long-term treatment benefits are unclear. The aim of the study was to determine long-term disease outcomes and the therapeutic roles of surgery and adjuvant therapies in pediatric patients with low-grade IMSCTs over an extended follow-up period. METHODS Case records for all pediatric patients (< 21 years of age) with a histopathological diagnosis of low-grade IMSCT were selected over a period from January 1975 to January 2010. Outcome variables including McCormick functional grade, overall survival (OS), and progression-free survival (PFS) were analyzed with respect to demographic and treatment variables. RESULTS Case records of 37 patients with low-grade IMSCTs were identified, with a mean follow-up duration of 12.3 ± 1.4 years (range 0.5-37.2 years). Low-grade astrocytomas were the most prevalent histological subtype (n = 22, 59%). Gross-total resection (GTR) was achieved in 38% of patients (n = 14). Fusion surgery was required in 62% of patients with pre- or postoperative deformity (10 of 16). On presentation, functional improvement was observed in 87% and 46% of patients in McCormick Grades I and II, respectively, and in 100%, 100%, and 75% in Grades III, IV, and V, respectively. Kaplan-Meier PFS rates were 63% at 5 years, 57% at 10 years, and 44% at 20 years. OS rates were 92% at 5 years, 80% at 10 years, and 65% at 20 years. On multivariate analysis, shunt placement (hazard ratio [HR] 0.33, p = 0.01) correlated with disease progression. There was a trend toward improved 5-year PFS in patients who received adjuvant chemotherapy and radiation therapy (RT; 55%) compared with those who did not (36%). Patients who underwent subtotal resection (STR) were most likely to undergo adjuvant therapy (HR 7.86, p = 0.02). CONCLUSIONS This extended follow-up duration in patients with low-grade IMSCTs beyond the first decade indicates favorable long-term OS up to 65% at 20 years. GTR improved PFS and was well tolerated with sustained functional improvement in the majority of patients. Adjuvant chemotherapy and RT improved PFS in patients who underwent STR. These results emphasize the role of resection as the primary treatment approach, with adjuvant therapy reserved for patients at risk for disease progression and those with residual tumor burden.

Low-dose cranial boost in high-risk adult acute lymphoblastic leukemia patients undergoing bone marrow transplant

PURPOSE

Acute lymphoblastic leukemia (ALL) has a predilection for CNS involvement. Patients with high-risk ALL are often managed with transplant using a radiation-based conditioning regimen. Historically, a high-dose prophylactic cranial boost (CB) of ≥12 Gy was given to reduce risk of central nervous system (CNS) recurrence. However, the use of CB has fallen out of favor because of toxicity concerns. In high-risk adults undergoing transplant at our institution, we have used a low-dose 6 Gy CB to reduce toxicity while conditioning adults with fully developed brains. The safety, efficacy, and utility of a low-dose CB in adults are poorly studied; herein, we report their outcomes and toxicity.

METHODS AND MATERIALS

We identified all high-risk ALL patients undergoing total body irradiation as part of their conditioning regimen. Those who received 6 Gy CB or no CB were included (55 total). Their charts were reviewed and statistical analyses were completed with R, version 2.15.2.

RESULTS

In patients undergoing CB, 3-year CNS disease-free survival and overall survival were 94.7% and 62.7%. In those not undergoing CBs, survivals were 81.8% and 51.5%. Notably, within the CB cohort, patients without prior CNS involvement had no CNS failures. In contrast, in the non-CB cohort, there were 2 CNS failures in patients with no history of CNS involvement. In the CB cohort, the only notable acute toxicity was parotitis (2.8%). Late toxicity in the CB cohort included 1 instance of cataracts (2.8%) without any evidence of cognitive impairment or potential radiation induced secondary malignancy.

CONCLUSIONS

A dose of 6 Gy CB is well-tolerated in the adult ALL population as part of a radiation-based conditioning regimen. Low-dose CB may be considered in adult patients with high-risk ALL without prior CNS involvement to reduce the likelihood of recurrence.

Pediatric intramedullary spinal cord lesions: Pathological spectrum and outcome of surgery

Background:

Pediatric intramedullary spinal cord lesions are not only rare but also different from adults in a number of aspects. We aimed to study the incidence and the frequencies of various pediatric intramedullary mass lesions, their outcome to treatment and the factors determining their outcome of treatment.

Materials and Methods:

Thirty-one consecutive children (aged 1–18 years, mean 11.1 years, male: female = 1.8:1) with pathologically proven intramedullary spinal cord lesions treated at our center were studied. Clinico-radiological, histopathological, operative, and outcome data were reviewed retrospectively. The functional status was assessed using the modified McCormick grading system.

Results:

Gross total tumor excision was performed in 19 patients (61.3%), subtotal in 9 patients (29%), partial excision was performed in 2 (6.5%) patient, and only biopsy was performed in 1 patient (6.5%). There was one peroperative death, 2 patients died at follow-up. Complications included wound related complications (n = 4), transient deterioration in the motor power, and respiratory complication requiring a tracheostomy. Six patients showed recurrence at a mean follow-up of 16.4 months. Developmental tumors, high-grade ependymomas, and incompletely excised grade 2 ependymomas showed a tendency to recur.

Conclusions:

Children constituted nearly 1/5^th (17.4%) of intramedullary spinal cord tumors. Astrocytomas and ependymomas taken together constituted the most common intramedullary spinal lesions in children; however, developmental tumors predominated in the first decade. Children usually presented in good functional grades preoperatively and maintained good grades after surgery. Functional outcome was dependent on the preoperative neurological status and histopathology of the lesions.

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.

Neurosurgical management of intramedullary spinal cord tumors in children

The majority of intramedullary spinal cord tumors in children are low-grade glial tumors. They become symptomatic with pain, neurologic deficits or spinal deformity. The diagnosis is most readily obtained using magnetic resonance imaging. The natural history is significant for slow progression of symptoms. Surgery is the best treatment and is also indicated to confirm the histological diagnosis. In case of a low-grade tumor or a vascular lesion such as hemangioblastoma or cavernoma, a total or near-total resection is attempted. For astrocytomas the resection almost always remains biologically incomplete, but a near-total resection is still associated with a long progression-free survival. Neurologic morbidity is relatively low during long-term follow-up but can be up to 30% for transient motor deficits. The risk for neurologic deterioration is higher for patients with pronounced dysfunction preoperatively. This is an important argument for early surgical resection. Surgery is performed using the spectrum of microsurgical techniques as well as advanced technology, e.g. lasers and intraoperative neurophysiological monitoring with motor evoked potentials. High-grade tumors are resected conservatively and treated with radiation and chemotherapy. The prognosis of high-grade glial tumors remains poor.

Basic principles of radiobiology, radiotherapy, and radiosurgery

This article reviews the basic principles of radiobiology and the application thereof to the treatment of metastatic spine tumors. The most important concepts of dose fractionation and the concept of biologically effective dose as well as spinal cord tolerance to single and multiple doses of radiotherapy are emphasized. Basic principles of treatment planning for radiotherapy and radiosurgery are outlined.

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 therapy and the management of intramedullary spinal cord tumors

The use of radiation therapy in the management of intramedullary spinal cord tumors remains controversial. Several studies indicate that the use of postoperative radiation therapy modestly improves both local control and survival in spinal cord ependymomas and astrocytomas. Modern treatment planning and imaging allow more accurate target definition and respect for related normal tissue tolerances.

Treatment of spinal cord tumors in children

BACKGROUND

A retrospective review was carried out of nine children under 17 years of age with a diagnosis of intramedullary tumor seen during the period 1989-1995. Six had astrocytomas; one each had an ependymoma, a PNET, and a choroid plexus papilloma. Five patients had back pain, 3 others had mild pareses and the ninth had incapacitating defects. Seven of the 9 were treated by subtotal extirpation of the lesion, and biopsy alone was performed in the other two. All tumors were low grade (grade I or II) and therefore radiation therapy (RT) was performed as the only postoperative treatment in 8 of the 9 children.

RESULTS

In February 1996, seven (77.8%) children were alive and two (22.2%) died of recurrent tumor (7 months and 5 years after diagnosis, respectively). Median follow-up was 3 years 4 months (range: 1 year 6 months to 7 years 3 months).

CONCLUSION

Surgical removal of intraspinal tumors provides the best hope of control, but spinal column deformity after laminectomy and irradiation is a serious long-term problem in children. Orthopedic supervision for the prevention of these deformities; e.g., by external immobilization, is mandatory.

Management of intramedullary tumours in children

Clinical presentation, diagnosis, surgical technique and results of 25 cases of intramedullary tumours in patients under 16 years of age are analyzed. Pre-operative spinal deformity was present in 9 patients. Surgery was performed in all. After multilaminectomy with preservation of the intervertebral joints, total removal of the lesion was achieved in 11 patients and subtotal removal in 14 others. After surgery, external immobilization lasting an average period of 5 years was instituted in all patients. Postoperative radiation therapy was performed in 11 cases (5 "high grade" astrocytomas, 5 ependymomas, 1 glioblastoma). There were 11 recurrences: 4 of which (2 ependymomas and 2 "low grade" astrocytomas) were treated surgically, 7 (5 "high grade" astrocytomas, 1 glioblastoma, 1 oligodendroglioma) with palliative radiation treatment. Six patients eventually developed postlaminectomy spinal deformities as diagnosed roentgenographically 6 to 50 months postoperatively. Of the 16 patients still alive, 7 did not present relevant neurological deficit, 1 presented a monoparesis, while the other 8 presented invalidating deficits. Surgical treatment did not differ from that employed in the intramedullary tumours in the adult: radical resection is indeed the optimal therapeutic origin. The risk of radiation therapy are greater in children: it is crucial to limit radiation therapy to only some histotypes. The incidence of spinal column deformity after multilevel laminectomy is greater in young patients. It is advisable to implement prevention of spinal deformities by postoperative external immobilization and constant follow-up so as to detect early changes of spinal stability.

Congenital spinal cord astrocytomas

Congenital spinal cord astrocytomas have only rarely been reported. We report two additional cases and a review of the literature on these infrequent tumors. The congenital cord astrocytomas can have obscure initial presentations, including fever and irritability, leading to delays in diagnosis. Magnetic resonance imaging is the diagnostic procedure of choice, allowing noninvasive delineation of the lesion. The congenital tumors are similar in location and pathology to astrocytomas of the cord in older children. As in older patients, initial treatment should include attempted surgical extirpation, delaying or avoiding radiation therapy with its attendant risks. Reported follow-ups of the congenital astrocytomas suggest they will behave in a fashion similar to spinal cord astrocytomas in older children.

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.

Somatosensory evoked potentials: Part II. A review of the clinical applications in pediatric neurology

Fundamental to the clinical application of somatosensory evoked potentials is an understanding of the neural generators, the changes in disease states, and the effects of growth and maturation; aspects relevant to pediatric somatosensory evoked potentials were discussed previously (Part I). The importance of establishing normative data across age- and size-matched controls in the pediatric population, however, cannot be overstated. The following review of the clinical applications of somatosensory evoked potentials in pediatric neurology is based on a review of the literature and on the experience gained from over 900 studies performed in our laboratory during the last 4 years.

Radiation myelopathy: a review

Radiation myelopathy is a serious potential complication associated with radiation therapy to the spinal cord. Its exact cause is unknown. It represents a spectrum of syndromes, the most common of which are acute transient radiation myelopathy and chronic progressive radiation myelitis. A review of the literature indicates that cord damage is related to a number of controllable factors including dose fraction size, treatment time, total dose, length of cord irradiated, technical and clerical errors. Other less well understood factors that appear to contribute to the risk such as combined chemoradiotherapy effects and hyperthermia should also be recognized. A better awareness and understanding of these factors should ultimately lead to safer and more effective treatments.

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.

Myelopathy with severe structural derangement associated with combined modality therapy

Myelopathy is a known complication of radiation therapy, but its association with chemotherapy has been less well documented. The authors report the case of a 12-year-old boy with medulloblastoma who had been followed for an 8 1/2-year period. In the context of accepted doses of intrathecal methotrexate and spinal irradiation, he developed an extensive myelopathy. At postmortem he was found to have profound fibrosis of the leptomeninges and necrosis with structural derangement of the spinal cord. It is speculated that these findings are secondary to a combination of radiation acting in synergism with methotrexate. The pertinent literature relating to myelopathy associated with radiation and chemotherapy is reviewed.

Electrophysiologic evidence of subclinical injury to the posterior columns of the human spinal cord after therapeutic radiation

Spinal somatosensory conduction velocity (SSCV) was indirectly estimated from cerebral evoked potentials in 15 adults who had received therapeutic radiation (RT) (2000-4380 rad) to the thoracic spinal cord during treatment for lung cancer, and in 15 age-matched normal controls. Thirteen of the patients had also received 4400-5500 rad to the supraclavicular fossae. One-way impulse conduction time in the arm, estimated from F-wave latency, was prolonged in the patients as compared to controls (12.0 +/- 1.2 versus 10.4 +/- 1.0 msec; P less than 0.001) but conduction time in the leg was similar in the two groups (22.4 +/- 2.4 versus 22.0 +/- 2.5 msec; P less than 0.1). SSCV was significantly slower in the patient group (37.9 +/- 13.9 versus 54.5 +/- 12.9 m/sec; P less than 0.001) whereas supraspinal latency (cervical cord to cortex) was identical (5.5 +/- 0.9 versus 5.5 +/- 0.8 msec; P less than 0.1). SSCV in the patient group was not related to total RT dose (r = 0.15; P = 0.2), but was correlated with both treatment time and number of fractions (r = 0.49 and 0.43; P = 0.003 and 0.007, respectively). These findings suggest that RT may produce subclinical spinal cord dysfunction even at conventional dosage schedules, and that it may be possible physiologically to monitor the myelopathic effects of RT in individual patients.

A very delayed case of post-irradiation myelopathy with unusual features

A 48 year old man, irradiated 30 years before for a left laterocervical, lymphadenopathy, developed a progressive weakness of the left arm of two years duration. Myelography and other examinations excluded a compressive spinal process. The clinical and neurophysiological data point to a lesion in the spinal gray matter, probably due to the previous radiation treatment.

Progression of methotrexate-induced leukoencephalopathy in children with leukemia

From 1972-1974, 228 children began treatment for acute lymphocytic leukemia and were prospectively assessed for neurologic complications. After CNS irradiation (2,400 rad) and intrathecal methotrexate (MTX), they received weekly intravenous maintenance therapy with MTX alone (40-60 mg/m2; 20 patients) or MTX (10-30 mg/m2) with other drugs (208 patients). Signs of leukoencephalopathy appeared in 11 children (nine without CNS leukemia) after 4-15 months of IV MTX alone, and included lethargy, seizures, spasticity, paresis, drooling, and dementia. Before or during the clinical onset, EEG frequencies slowed (all ten patients tested). Radionuclide scans showed periventricular accumulation of 99mTc (9/11 patients) and remained abnormal for greater than or equal to six months in eight patients. Cranial computed tomograms or neuropathology findings (five patients each) demonstrated leukoencephalopathy (nine patients) and radiation-related microangiopathy (ten patients). Severe neurologic and neuropsychologic dysfunctions were present in four long-term survivors.