Neurologic complications after irradiation of the cervical spinal cord for malignant tumour of the head and neck

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.

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.

Normal-tissue toxicities of thoracic radiation therapy: esophagus, lung, and spinal cord as organs at risk

The evolution of therapeutic approaches for lung cancer illustrates the trend for treatment intensification, with hopes that dose-intense chemotherapy regimens, higher radiation therapy (RT) doses, or novel fractionation schemes will result in prolongation of survival. Current chemotherapy- and RT-intense regimens may not be intensified further without addressing dose-limiting toxicities such as esophagitis. It is important to understand factors pre-disposing to esophagitis so that strategies to minimize its severity can be investigated. Pulmonary complications such as pneumonitis and fibrosis from RT (with or without chemotherapy) are dose and volume dependent. Methods to better identify the target tissues and improved RT-delivery systems may facilitate increasing target doses or reducing doses to adjacent normal tissues. Biologic predictors may allow clinicians in the future to individualize RT treatment based on a patient's toxicity risk profile. Radiation myelopathy is still the most feared radiation complication of lung cancer treatment. The authors address the known parameters that influence the incidence of thoracic radiation myelopathy and the putative factors that could be considered when a clinician may be required to push the spinal cord dose in favor of tumor control.

Radiation myelopathy

Radiation myelitis has long been recognised as a sinister consequence of spinal irradiation and has limited the acceptable dose of therapeutic radiation to the cord. Over the past 10 years, the pathogenesis has been increasingly understood through the use of animal models. The importance of 'dose per fraction' and 'inter-fraction interval' have been incorporated into new mathematical models which suggest that, for small fractions, the cord may tolerate higher doses of radiation than was previously thought. Clinical recognition of the condition has improved through the description of characteristic magnetic resonance imaging changes. However little advance has been made in its treatment.

Incidence of radiation myelitis of the cervical spinal cord at doses of 5500 cGy or greater

The incidence of permanent damage to the spinal cord as a complication of radiation therapy generally correlates positively with total radiation dose. However, several reports have indicated that fraction size is also an important factor in the development of late damage in normal tissue. To determine the effect of fraction size on the incidence of radiation-induced spinal cord damage, the authors reviewed 176 cases of head and neck cancer treated at their department between 1980 and 1990 with radiation doses of 5500 cGy or greater to a portion of the cervical spinal cord. Majority of these patients received 6000 cGy or greater with fraction size ranging from 150 to 200 cGy. Seventy-two of 176 patients have been observed for 2 years or more. More than one third (26 patients) of these received greater than 6000 cGy with fraction sizes of 157 to 170 cGy. Four of 72 (5.6%) patients had experienced permanent cervical spinal cord damage. The results of this study suggest that radiation damage to the cervical spinal cord correlates not only with total radiation dose, but also with fraction size. Low fraction sizes appear to decrease the incidence of such damage.

The incidence of myelitis after irradiation of the cervical spinal cord

To further define the tolerance of the cervical spinal cord, the dose of radiation to the cervical spinal cord was calculated for all 2901 patients with malignancies of the upper respiratory tract treated at the University of Florida between October 1964 and December 1987. To further define the population evaluated, certain criteria were used: (a) a minimum of 3000 cGy to at least 2 cm of cervical spinal cord and (b) a minimum of 1 year of follow-up, unless a neurological complication occurred before 1 year. A total of 1112 patients were evaluable, of which 2 (0.18%) developed radiation myelitis. One received 4658 cGy to the cervical cord at 172.5 cGy per day, and the other patient received 4907 cGy to the cord at 169.2 cGy per day. The risk of myelitis at each dose level was 0/124 at 3000-3999 cGy, 0/442 at 4000-4499 cGy, 2/471 at 4500-4999 cGy, and 0/75 at a cord dose of 5000 cGy or greater.

Radiation tolerance of the cervical spinal cord

The incidence of permanent injury to the spinal cord as a complication of radiation therapy generally correlates positively with total radiation dosage. However, several reports in the literature have indicated that fraction size is also an important factor in the development or nondevelopment of late injuries in normal tissue. To determine the effect of fraction size on the incidence of radiation-induced spinal cord injuries, we reviewed 144 cases of head and neck cancer treated at our institution between 1971 and 1980 with radiation greater than 5600 cGy to a portion of the cervical spinal cord. Most of these patients received greater than or equal to 6000 cGy, with fraction sizes ranging from 133 cGy to 200 cGy. Fifty-three of the 144 patients have been followed up for 2 years or more. Nearly half of these (26 patients) received greater than 6000 cGy with fraction sizes of 133 cGy to 180 cGy. Only 1 of the 53 (1.9%) has sustained permanent spinal cord injury; 20 months after completion of radiation treatments he developed Brown-Séquard syndrome. Our experience suggests that radiation injuries to the spinal cord correlate not only with total radiation dosage, but also with fraction size; low fraction sizes appear to decrease the incidence of such injuries.

Myelopathy following radiotherapy of bronchial carcinoma with large single fractions: a retrospective study

A series of 387 patients with bronchial carcinoma treated with a concentrated split course regimen was surveyed for radiation myelitis. The total dose was 38 Gy. Three fractions of 6 Gy were given the first week. After a three-week interval the patients had a second course of radiotherapy with fractions of 4 Gy on 5 consecutive days. A spinal shield was used in 230 patients for the last two fractions of radiotherapy. The median survival for all patients was 9.4 months. Seventeen cases of radiation myelopathy were found. The life table method was used to calculate the risk of myelopathy in surviving patients, showing risk levels of 30 +/- 15% in patients surviving three years or more. The average age of the patients with myelopathy was 57.6 years, compared to 62.9% years in the total population. Statistical analysis showed a borderline significant increased risk for myelopathy in females, and a significant increased risk in younger patients (P = 0.03). No difference in the incidence of myelopathy was found in patients treated with or without a spinal shield.

Central nervous system changes complicating the use of radiotherapy for the treatment of a nasopharyngeal neoplasm in a diabetic patient

A case is reported of a diabetic patient with a nasopharyngeal neoplasm who developed radiation induced brainstem damage even though irradiated at a conventional time-dose-volume relationship. The clinical course was correlated with autopsy findings which revealed radiation changes in the brainstem consisting primarily of vascular hyalinization with foci of infarction, edema, and demyelination. Atherosclerotic changes were conspicuously absent and therefore not the case of the alterations. The changes occurred three months after completion of therapy, which was more rapid than expected for radiation injury. It is hypothesized that diabetes may have predisposed the patient to this severe complication of standard therapy. More needs to be learned concerning the relationship between diabetes mellitus and radiation complications. Perhaps a modified time-dose relationship should be considered.

Neurologic complications after irradiation of malignant tumors of the testis

Of 156 consecutive patients with malignant tumor of the testis 99 were alive two years after treatment. Of these, 12 had radiation-induced neurologic complications which, in 5 instances, consisted of persisting, wholly or partially disabling paresis in the lower limbs. Five had mild, transient symptoms and had persisting symptoms which were not incapacitating. In all those with disabling symptoms the irradiation dose had been higher than 1 600 reu, corresponding to 54.5 Gy over 6 weeks with daily fractions 5 days a week.

Parathyroid hormone and calcitonin in serum of patients with mammary carcinoma

Immunoreactive parathyroid hormone and calcitonin in serum were measured in 34 normocalcemic patients with mammary carcinoma. The mean value of parathyroid hormone was significantly higher in 26 patients with bone metastases than in 8 patients without (p less than 0.025). One patient with bone metastases had slightly raised calcitonin in serum. No difference as to parathyroid hormone values between the groups of previously irradiated and non-irradiated patients was found. A possible explanation of the normocalcemic hyperparathyroidism is presented.

En-bloc irradiation of tumours of the head and neck and their lymphatics. I. Technique and dosimetry

A technique for en-bloc irradiation of tumours of the head and neck and their lymphatics, as well as its dosimetry and control measures, are reported.