Long-term neurological implications of somnolence syndrome in children with acute lymphocytic leukemia

Comprehensive assessment of Somnolence Syndrome in patients undergoing radiation to the brain

AIM

The aim of this prospective study was to assess Somnolence Syndrome (SS) in patients undergoing radiation to the brain.

BACKGROUND

SS is one of the sequelae of radiation to the brain, which is observed within three months of radiation. This is a self-limiting condition and a failure to diagnose leads to unnecessary investigations. This study was undertaken to objectively and subjectively analyze the occurrence, clinical presentation and severity of SS.

MATERIALS AND METHODS

Thirty-three patients receiving radiation to the brain were included in the study. Visual Analog Scale (VAS) was used for subjective assessment and the Littman Somnolence Syndrome (LSS) scale was used for objective assessment of SS. Sleep Latency Test (SLT) was used to quantify SS.

RESULTS

VAS scores showed an initial fall until week 3, followed by a plateau and a sudden increase after week 10. LSS scale at week 11 and 12 showed that 13 patients (43.3%) had grade 2, 5 (16.7%) had grade 3; and 2 (6.7%) had grade 4 SS. SLT revealed a shift of predominant sleep pattern from NREM 1 to NREM 2 at 6 weeks after radiation with a p value of 0.0412.

CONCLUSIONS

An insight into SS, its features, frequency of occurrence and self limiting nature can prevent anxiety and unwarranted investigations in the immediate post radiation period.

Radiation therapy in neurologic disease

Radiotherapy is a primary mode of treatment of many of the disease entities seen by the neurologist. Therefore knowledge of how ionizing radiation works and when it is indicated is a crucial part of the field of Neurology. The neurologist may also be confronted with some of the side effects and complications or radiotherapy treatment. This chapter attempts to serve as a review of the current day process of radiotherapy, a brief review of biology and physics of radiation, and how it is used in the treatment diseases which are common to the Neurologist. In addition we review the more commonly seen side effects and complications of treatment which may be seen by the neurologist.

Whole brain radiotherapy for brain metastasis

Whole brain radiotherapy (WBRT) is a mainstay of treatment in patients with both identifiable brain metastases and prophylaxis for microscopic disease. The use of WBRT has decreased somewhat in recent years due to both advances in radiation technology, allowing for a more localized delivery of radiation, and growing concerns regarding the late toxicity profile associated with WBRT. This has prompted the development of several recent and ongoing prospective studies designed to provide Level I evidence to guide optimal treatment approaches for patients with intracranial metastases. In addition to defining the role of WBRT in patients with brain metastases, identifying methods to improve WBRT is an active area of investigation, and can be classified into two general categories: Those designed to decrease the morbidity of WBRT, primarily by reducing late toxicity, and those designed to improve the efficacy of WBRT. Both of these areas of research show diversity and promise, and it seems feasible that in the near future, the efficacy/toxicity ratio may be improved, allowing for a more diverse clinical application of WBRT.

Somnolence syndrome in patients receiving radical radiotherapy for primary brain tumours: a prospective study

BACKGROUND AND PURPOSE

To characterise the incidence, pattern and severity of post cranial radiotherapy somnolence and to identify factors predictive of frequency and severity.

MATERIALS AND METHODS

Seventy consecutive patients receiving radical cranial irradiation were prospectively assessed for somnolence at baseline, during and up to 10weeks following radiotherapy using five variables scored on a visual analogue scale (VAS) and the Littman scale. Fatigue was measured using the FACT-G score and quality of life using the EORTC QLQC30+3 with the brain tumour module questionnaire.

RESULTS

Ninety percent of patients experienced ⩾grade 1 somnolence (Littman score) and this correlated with VAS scores (r=0.456, p<0.001). The score increased from 3 to 12weeks (p<0.001) with a peak at the end of treatment and improvement 6weeks later. None of the patient, disease or treatment characteristics analysed were predictive for the development or the severity of somnolence.

CONCLUSIONS

The majority of patients experience some degree of somnolence following radical radiotherapy for primary brain tumour and this follows a clear pattern during and after treatment. While there are no clear predictors of severity, the pattern described allows for provision of information for patients and carers to minimise the distress the syndrome may cause.

Somnolence syndrome and fever in pediatric patients with cranial irradiation

BACKGROUND

During initial treatments, pediatric cancer patients are frequently hospitalized for fever, which may be due to neutropenia or a manifestation of the somnolence syndrome (SS) after cranial radiation therapy (CRT). This was a retrospective chart review of patients who received CRT for central nervous system prophylaxis or treatment in acute lymphoblastic leukemia or lymphoma.

OBSERVATIONS

Of 21 patients, 15 (71%) developed SS; 10 were hospitalized for fever. Comparing somnolent and nonsomnolent patients, there was no statistically significant difference in the admission absolute neutrophil count; radiation dose, fraction, or duration; and time between completion of CRT and first hospitalization.

CONCLUSIONS

In postradiation phase, patients with SS are more likely to get fever leading to hospital admission regardless of ANC.

Acute effects of irradiation on cognition: changes in attention on a computerized continuous performance test during radiotherapy in pediatric patients with localized primary brain tumors

PURPOSE

To assess sustained attention, impulsivity, and reaction time during radiotherapy (RT) for pediatric patients with localized primary brain tumors.

METHODS AND MATERIALS

Thirty-nine patients (median age 12.3 years, range 5.9-22.9) with primary brain tumors were evaluated prospectively using the computerized Conners' continuous performance test (CPT) before and during conformal RT (CRT). The data were modeled to assess the longitudinal changes in the CPT scores and the effects of clinical variables on these changes during the first 50 days after the initiation of CRT.

RESULTS

The CPT scores exhibited an increasing trend for errors of omission (inattentiveness), decreasing trend for errors of commission (impulsivity), and slower reaction times. However, none of the changes were statistically significant. The overall index, which is an algorithm-based weighted sum of the CPT scores, remained within the range of normal throughout treatment. Older patients (age >12 years) were more attentive (p < 0.0005), less impulsive (p < 0.07), and had faster reaction times (p < 0.001) at baseline than the younger patients. The reaction time was significantly reduced during treatment for the older patients and lengthened significantly for the younger patients (p < 0.04). Patients with a shunted hydrocephalus (p < 0.02), seizure history (p < 0.0006), and residual tumor (p < 0.02) were significantly more impulsive. Nonshunted patients (p < 0.0001), those with more extensive resection (p < 0.0001), and patients with ependymoma (p < 0.006) had slower initial reaction times.

CONCLUSION

Children with brain tumors have problems with sustained attention and reaction time resulting from the tumor and therapeutic interventions before RT. The reaction time slowed during treatment for patients <12 years old. RT, as administered in the trial from which these data were derived, has limited acute effects on changes in the CPT scores measuring attention, impulsiveness, and reaction time.

Radiation somnolence syndrome

Although initially described 7 decades ago, somnolence syndrome remains a poorly understood subacute effect of cranial irradiation. Despite the relatively transient and benign nature of somnolence syndrome, its symptoms can be distressing for children and caregivers. Anticipatory guidance related to radiation-induced somnolence remains a critical nursing intervention. This article reviews what is known about somnolence syndrome, including its causes, symptoms, and management.

Reduced incidence of the somnolence syndrome after prophylactic cranial irradiation in children with acute lymphoblastic leukemia

A prospective double blind randomized trial comparing two different dose schedules of continuous steroid coverage during prophylactic cranial radiotherapy (CRT) in leukemic children was conducted to find out the optimum dose to be prescribed to reduce the incidence of Somnolence Syndrome (SS). Between April 1994 and February 1996, 32 patients with acute lymphoblastic leukemia received CRT of 18 Gy in 10 fractions. Patients were randomized to receive oral dexamethasone of 2 or 4 mg/m2 during radiotherapy. The diagnosis of SS was made clinically based on symptoms of somnolence. All patients were followed for a minimum of 8 months. The overall incidence of SS was 40%. The development of SS was steroid dose dependent. In low dose steroid arm the incidence of SS was 64.3% (9/14), compared to 17.6% (3/17) in high dose arm with statistically significant difference (P = 0.008). The median time to development of SS was 4 weeks. The most common symptom of SS was drowsiness followed by anorexia, headache, nausea, vomiting, decreased activity, irritability, fever and ataxia, respectively. The duration of symptoms ranged from 2 to 14 days. The development of SS was not related to the presence of acute reactions, age at the time of CRT and sex. In all cases the symptoms subsided completely and spontaneously. Our results suggest that steroid coverage at a dose of 4 mg/m2 during CRT reduces the incidence of SS. However, a multicentric prospective randomized trial is needed to determine the role and the optimal dose of steroid.

Chemotherapy for acute lymphoblastic leukemia may cause subtle changes of the spinal cord detectable by somatosensory evoked potentials

Intrathecal chemotherapy has been determined to cause transient or permanent paraparesis due to myelopathy in patients with leukemia or other malignancies. To systematically evaluate the effect of methotrexate on spinal cord function, somatosensory evoked potentials (SEP) were measured in children with acute lymphoblastic leukemia (ALL). A prospective evaluation was performed in 38 consecutive children aged 1.4-15.3 years with newly diagnosed ALL during treatment. Intrathecal methotrexate therapy was included in the therapy schedule of all patients as central nervous system (CNS) therapy in addition to intravenous chemotherapy in 19 standard risk patients and intravenous chemotherapy with cranial irradiation in 19 intermediate or high-risk patients. The measured conduction times were compared with those of 38 control children matched for age, height, and sex. A significant increase in the conduction time of the tibial nerve SEP was found between the Th12 level and the cortex in children with ALL after receiving intrathecal methotrexate therapy during the induction and CNS therapy phases when compared with their controls. The difference of the mean latencies was 1.45 ms (95% CI 0.39-2.51; P < 0.01). There was no significant delay in the median nerve SEP from the brain stem to the cortex, indicating that the conduction delay was in the area of the spinal cord exposed to intrathecal methotrexate. Moreover, the cortical amplitudes of the median nerve SEPs were significantly reduced when measured immediately after intravenous and intrathecal methotrexate and compared to the amplitudes measured after induction therapy in standard risk patients (P = 0.001). Intrathecal methotrexate with systemic chemotherapy causes a deterioration in the somatosensory pathways within the CNS, suggesting also spinal cord dysfunction in children with ALL in addition to the cerebral dysfunction described earlier.

Central nervous system toxicity of cancer therapy in children

Cancer treatment of the central nervous system has contributed positively to long-term disease-free survival from childhood cancers such as acute leukemia and medulloblastoma. However, intrathecal chemotherapy and whole brain radiation are associated with acute, subacute, and delayed toxicities. The purpose of this review article is to summarize what is known about critical events in prenatal and postnatal brain development; the pathophysiology of radiation and chemotherapy neurotoxicity and clinical manifestations and risk factors for acute, subacute, and delayed toxicities. The importance of long-term follow-up and for multidisciplinary interventions that focus on prevention as well as management of identified problems are addressed.

Cytochrome c550 from Pseudomonas aeruginosa

In cells of Pseudomonas aeruginosa A.T.C.C. 17933 grown on ethanol the synthesis of a soluble c-type cytochrome, together with quinoprotein ethanol dehydrogenase, is induced. The cytochrome, with an alpha-absorption band at 550 nm, was purified to homogeneity. The molecular mass of the monomeric protein is 15 kDa, the pI is 4.8, and it contains one haem prosthetic group. The midpoint potential of the autoxidizable, but not autoreducible, cytochrome is 280 mV. Cytochrome c550 mediates electron transfer between quinoprotein ethanol dehydrogenase and ferricyanide. In a system composed of membrane particles with NN'NN'-tetramethyl-p-phenylenediamine oxidase activity and quinoprotein ethanol dehydrogenase, oxygen consumption is only observed in the presence of cytochrome c550. This indicates the participation of the cytochrome in the electron-transport chain linked to quinoprotein ethanol dehydrogenase in P. aeruginosa. The electron transport from ethanol dehydrogenase to oxygen is inhibited by myxothiazol and antimycin, indicating that a cytochrome bc1-like complex is involved.

Late effects of childhood acute leukemia and its treatment

Late effects of childhood acute leukemia and its treatment were studied in 776 patients (684 ALL, 73 ANLL, and 9 others) in Japan who had remained in remission for more than 1 year after their first complete remission. Delayed adverse sequelae involve a wide variety of organs and their functions. Short stature was present in 2.61%, obesity in 3.79%, abnormalities of growth hormone secretion in 1.5%, delayed secondary sex characteristics in 1.5% of males and 0.6% of females, motor disturbances in 1.17%, sensory disturbances in 0.91%, intellectual and learning disabilities in 2.48%, abnormal findings in routine neurologic examinations in 1.31%, EEG abnormalities in 4.30%, brain CT abnormalities in 5.09% and cardiac dysfunction in 1.07%. Various other disorders were seen in 20 patients. Many of these delayed adverse sequelae are caused by or related to central nervous system prophylaxis and systemic combination chemotherapy. The results suggest that it is needed to improve therapeutic methods through the stratification of patients by risk factors and detailed analysis of prognostic factors. Moreover it is important to render medical and psychosocial support to long-term survivors of childhood leukemia through interactions between the patient, parents and medical staff.

CNS prophylaxis of childhood leukemia: what are the long-term neurological, neuropsychological, and behavioral effects?

Current medical treatments for childhood acute lymphoblastic leukemia (ALL) have improved the outlook to where more than 50% can be expected to survive five years or more. The use of CNS prophylaxis has contributed in a significant way to these improved survival statistics by reducing the likelihood of CNS relapses. The literature relating to the potential adverse psychological consequences of CNS prophylaxis, which include cranial radiation therapy (CRT), is reviewed and analyzed. The majority of published papers of children in first remission report that CNS prophylaxis, which include both CRT and intrathecal methotrexate, results in a variety of learning problems in many children who were younger than age 5 when treated. The available literature on the social, emotional, and educational sequelae of childhood ALL is also reviewed.

Initial electroencephalographic findings in children with acute lymphoblastic leukaemia

Electroencephalography (EEG) was performed on 66 children with acute lymphoblastic leukaemia, 45 before treatment and 21 during the first 5 days of chemotherapy. The patients, aged 7 months to 16 years, 33 boys and 33 girls, had been admitted to the Department of Paediatrics, University of Oulu, between March 1976 and January 1987. The EEG findings were compared with those in 66 age and sex-matched control children chosen at random from the local population. The patients had significantly more frequent and more severe disturbances in background activity (p less than 0.001) than the controls and increased slow waves in the occipital (p less than 0.001) and temporal regions (p less than 0.01). The patients who had received chemotherapy before the EEG recording had EEG disturbances significantly more frequently than the other patients (p less than 0.01), but the latter still had EEG abnormalities significantly more frequently than their matched controls, although they did not have severe changes (grade 3). The results suggest that chemotherapy increases EEG changes during the early days of induction therapy and possibly induces long-term disturbances in brain function. The associations between EEG changes and clinical findings were also analysed and the results show that a long duration of leukaemic symptoms or an aggressive disease may lead to EEG abnormalities.

Abnormal cerebral glucose metabolism in long-term survivors of childhood acute lymphocytic leukemia

Chemotherapy and radiation treatment of the central nervous system may cause delayed neurotoxicity in children with acute lymphocytic leukemia. We evaluated 12 long-term survivors of childhood leukemia using [18F]fluorodeoxyglucose positron emission tomography, computed tomography scans, clinical neurological examinations, and neuropsychological tests. Regional cerebral metabolic rate for glucose (rCMRGlc) values for white matter were lower in the older long-term survivors (greater than 18 years old) treated with cranial radiation and intrathecal chemotherapy than in normal control subjects or survivors who had been treated with intrathecal chemotherapy alone. The ratio of white matter: cortex rCMRGlc values was lower than control values in the long-term survivors treated with cranial radiation and intrathecal chemotherapy, regardless of age, but not in those treated with intrathecal chemotherapy alone. By contrast, thalamic rCMRGlc values were lower than control values in older survivors regardless of treatment, and the ratio for thalamus:cortex rCMRGlc values was lower in all the treatment groups than in the control subjects. The highest rCMRGlc values were found in the youngest children, indicating an important effect of age on cerebral glucose metabolism. No neuropsychological deficits were identified in patients treated only with intrathecal chemotherapy; however, lower IQ scores were found in the long-term survivors who had been treated with cranial radiation and intrathecal chemotherapy. Treatment of the central nervous system with cranial radiation and intrathecal chemotherapy may cause prolonged alterations in white-matter and thalamic rCMRGlc, which may permit the identification and assessment of neurotoxicity in long-term survivors of acute lymphocytic leukemia by [18F]fluorodeoxyglucose positron emission tomography.

Reduced incidence of the somnolence syndrome in leukemic children with steroid coverage during prophylactic cranial radiation therapy. Results of a pilot study

Chemotherapeutic regimens for childhood acute lymphoblastic leukemia (ALL) include a remission induction period with high, daily doses of prednisone among other agents. A period of central nervous system (CNS) prophylaxis follows, during which steroids are often tapered entirely before cranial radiation (CRT) is completed or even initiated. The somnolence syndrome (SS) has been described 4 to 6 weeks after completion of CRT in up to 60% of the children with doses as low as 1800 cGy. A pilot study of continuous steroid coverage during CRT in childhood ALL was conducted. From July 1984 to July 1986, 38 children entered on Children's Cancer Study Group ALL protocols received CRT of 1800 cGy (180 cGy x 10). All patients received oral prednisone throughout the entire course of CRT at daily doses varying from 3.0 to 60.0 mg/m2. The overall incidence of the SS was 13% (five patients). The development of the syndrome was steroid dose-dependent: greater than or equal to 15 mg/m2/d (one of 32 patients), 3% incidence; less than 15 mg/m2 (four of six patients), 67% incidence. The presence of headache during CRT was also steroid dose-related: greater than or equal to 15 mg/m2, one of 32 patients; less than 15 mg/m2, six of six patients. Of the seven patients with headache during CRT, five developed the SS. The two patients (both of the less than 15 mg/m2 group) who did not develop the SS were the only cases treated with increased steroid doses at the onset of headache symptoms. Steroid coverage at a dose of greater than or equal to 15 mg/m2 during CRT appears to significantly reduce the incidence of acute radiation reactions and the SS. A prospective randomized study is planned to confirm these initial findings.

Central nervous system leukemia

With one exception, the risk and severity of neurotoxicity is directly proportional to the number of therapeutic modalities used. Three are worse than two, and two are worse than one. Combinations of therapeutic modalities which include CNS RT appear to be the most neurotoxic. The least neurotoxic combination of two modalities appears to be the IT MTX with high-dose intravenous MTX. Thus far, high-dose MTX appear to be the safest single modality, in terms of acute, subacute, and delayed neurotoxicity. The improved outcome in intellectual and academic performance in the NCI-191/CCG-134P conjoint trial of the CCSG and the Pediatric Branch described above (see section of Presymptomatic CNS Therapy) appears to confirm this observation. Whether triple IT chemotherapy will have the same result remains to be established. If CNS RT must be combined with MTX therapy, the least neurotoxic approach appears to be to administer these modalities in sequence, IT MTX, or high-dose intravenous MTX followed by CNS RT. MTX given during or after CNS RT appears from the clinical data to be more likely to produce severe neurologic sequelae. An ultimate goal would be to avoid both ionizing RT and IT chemotherapy. To this end, the NCI/CCSG study has demonstrated that this may be possible, except for those patients who are at the highest risk for CNS relapse despite conventional CNS prophylaxis. Meanwhile, for presymptomatic therapy, either cranial RT (18 Gy total dose at 120-180 cGy per day) in conjunction with IT MTX, or frequent IT chemotherapy with MTX, cytarabine, and hydrocortisone combined and administered throughout induction, consolidation, and maintenance is eminently justified in the majority of children with ALL. On a worldwide basis, chemoradiotherapy with cranial RT and IT MTX remains the established method of preventing overt CNS leukemia. The benefits of this intervention, in terms of prevention of symptomatic CNS leukemia, prolongation of complete remission, and increased cure rates, are clearly worth the risks.

Neurobehavioral effects of central nervous system prophylactic treatment of cancer in children

This article reviews 41 studies of the effects of prophylactic CNS treatment on the neurobehavioral development of children with cancer. This research is classified according to studies of (a) children in treatment; (b) long-term survivors; and (c) longitudinal follow-ups of children from the time of diagnosis. Studies vary considerably in design, sample, and outcome variables, so firm conclusions regarding the morbidity of CNS prophylaxis are not currently possible. However, the studies do suggest that CNS prophylaxis does impair cognitive development, particularly when cranial radiation therapy is part of the treatment. There is also evidence of greater impairment in younger children and some suggestion of more frequent impairment of non-language skills relative to language skills. The possible relationships among age, radiation, and non-language cognitive skills may be linked to disruption of white matter CNS structures apparent on autopsy and cerebral tomography following treatment.

Leptomeningeal cancer in leukemia and solid tumors

Although some patients with overt leptomeningeal cancer can now be cured, the proportion of patients who survive is very small, and the cost of cure, in terms of neuropsychological and educational morbidity, is substantial. Yet the incidence of central nervous system infiltration of systemic cancer is generally increasing, in most instances because control of systemic cancer has sufficiently prolonged survival to permit leptomeningeal metastases to develop and become symptomatic or detectable. The best chance for prolongation of life and possible cure is early detection and aggressive therapy in those forms of cancer that are amenable to therapy. We review the incidence of the various forms of leptomeningeal metastases, current concepts of pathogenesis and pathophysiology, clinical and laboratory features of leptomeningeal cancer, the available therapies, and the associated toxicities. The various methods that have been used to prevent and treat leptomeningeal cancer are described with an emphasis on childhood acute lymphoblastic leukemia (ALL) because it plays a predominant role in our understanding of meningeal neoplasms in general.

Cranial computerized tomography and cerebrospinal fluid procoagulant activity in childhood acute lymphoblastic leukemia

Thirty-three children with acute lymphoblastic leukemia (ALL) were studied using serial cranial computerized tomography (CCT) and cerebrospinal fluid procoagulant activity (PCA) for 5 years from the time of diagnosis. PCA was also studied in control children without neurological disease and in those with a variety of neurological disorders. Temporary elevation in the CSF PCA was observed during the phase of prophylactic central nervous system treatment in ALL and there was a late rise at 2-3 years off treatment. PCA also rose in the CSF following CNS disturbance in neurologically abnormal children, which suggests that the elevation observed in ALL is not specific to myelin disturbance.

Long-term psychological effects of childhood leukemia and its treatment

We report the results of a 5-year follow-up of the cognitive development of 19 survivors of acute lymphoblastic leukemia, all of whom received 24 Gy cranial irradiation and a course of intrathecal methotrexate. Assessment was made before radiotherapy and annually thereafter. Cognitive impairment was found to be transient in children who did not manifest somnolence who were under 5 years at the time of treatment. Despite having normal IQs and normal CT scans, 9 of 18 survivors in continuous complete remission were having learning problems at school 5 years after diagnosis. Assessment of their intellectual and memory functions revealed that as compared with matched healthy children, patients had lowered IQs but also had a specific auditory learning deficit independent of IQ. Long-term memory was found to be impaired for verbal auditory but not for verbal visual material. Results are discussed in terms of possible remediation of the learning disability.

Changes in the EEG background activity of children with acute lymphoblastic leukemia during cytotoxic therapy

Thirteen children with acute lymphoblastic leukemia (ALL) were investigated before and during cytotoxic therapy. EEG findings were correlated with the clinical course and the therapy protocol and compared with normal data obtained from 295 healthy children. Frequency analysis of the background activity of the EEG revealed an initial slowing of the background activity prior to therapy and further slowing each time a combination of vincristine (VCR), daunorubicin (DAU) or adriblastine (ADR), prednisone (PRED), and L-asparaginase (L-ASP) was administered. The slowing of the background activity correlated only with the administration of these drugs. DAU, ADR, and PRED are not known to influence the EEG; therefore, VCR and L-ASP remain the primary candidates responsible for the central nervous system alteration.

Long-term sequelae of cancer treatment on the central nervous system in childhood

Increasing numbers of children with cancer, including those with acute lymphocytic leukemia and medulloblastoma, are experiencing long-term disease control. As survival increases, so does the recognition that the treatment used to prolong survival may have significant detrimental effects on the central nervous system (CNS). Because of the slow replication rate of most constituents of the CNS, these effects tend to be delayed. Radiotherapy, and to a lesser extent, chemotherapy (primarily methotrexate) have been implicated in the causation of such sequelae. The pathogenesis of CNS damage is only partially understood and evidence suggests that direct effects on intracranial endothelial cells and brain white matter and immunologic mechanism play a role. A spectrum of clinical syndromes may occur, including radionecrosis, necrotizing leukoencephalopathy, mineralizing microangiopathy with dystrophic calcification, cerebellar sclerosis and spinal cord dysfunction. The two most common forms of sequelae are neuropsychological and neuroendocrinologic damage. The frequency, degree of and etiology of neurocognitive dysfunction is less than completely elucidated. Radiotherapy has been implicated as the major cause of damage, but the relationship between radiotherapy and the type of damage caused and the volume and dose of radiotherapy and degree of cognitive damage is unclear. Cognitive deficits are progressive in nature. Younger children are more likely to suffer the severest damage; but no patient of any age is free of risk of damage. Growth hormone impairment is the most common form of neuroendocrinologic dysfunction. There is increasing evidence that children with cancer who are long-term survivors are at increased risk for the development of secondary CNS tumors; possibly due, in part, to previous treatment. Much work needs to be done to characterize the sequelae which may occur, develop means of earlier detection, investigate ways to ameliorate sequelae and devise less toxic treatment.

A model of methotrexate encephalopathy: neurotransmitter and pathologic abnormalities

Methotrexate may cause seizures, dementia, and leukoencephalopathy when given in toxic doses to children with leukemia or solid tumors. Even in therapeutic doses, treatment with this drug is associated with an increased incidence of seizures in children with leukemia. To study mechanisms of injury, juvenile rats were given multiple intraventricular injections of methotrexate and the brains were analyzed for histopathology and biogenic amine metabolites of dopamine and serotonin. Disruption of monoamine metabolism has been proposed as a cause of brain dysfunction from this chemotherapy. Multiple injections (1 or 2 mg/kg) produced convulsions in an increasingly larger percentage of animals at higher cumulative doses, and five doses produced the neuropathological changes seen in human leukoencephalopathy. A single dose reduced the concentration of brain metabolites of dopamine, but not serotonin, six hours later. The effect was less pronounced after five doses. This rodent model should be useful for studying the metabolic basis of methotrexate encephalopathy.

Magnetic resonance imaging in the evaluation of treatment-related central nervous system damage

Neurologic and neuropsychologic treatment related sequelae are increasingly encountered in children with cancer, but conventional means of neurologic investigation are insensitive to the presence and extent of damage. Magnetic resonance imaging (MRI) has shown brain damage not demonstrable by other means of investigation. For this reason, 11 children with cancer and with nontumor-related neurologic dysfunction were studied on a 1.5 Tesla MRI unit. All had concurrent computed tomography (CT). MRI abnormalities were seen in all (100%) patients. In 10 of 11 patients, abnormalities were of greater extent on MRI than on CT. White matter changes were frequently seen on MRI without corresponding CT abnormality. Those patients with the most severe forms of neurologic compromise had the most extensive changes on MRI. Focal neurologic findings correlated well with regions of focal signal change. Milder forms of neurologic compromise occurred in patients with definite, but less extensive, periventricular and/or subcortical change on MRI. MRI is more sensitive than CT in demonstrating treatment-related neurologic damage in children with cancer, and the type of change seen on MRI seems to correlate well with the type and severity of neurologic dysfunction present.

Neurotoxicity in long-term survivors of small cell lung cancer

Chronic central nervous system neurotoxicity was studied in 38 long-term survivors (greater than or equal to 3 years) of small cell lung cancer who were treated at the University of Texas M. D. Anderson Hospital and Tumor Institute at Houston between 1971 and 1980. All but one patient received combination chemotherapy with or without chest irradiation. Twenty-four patients received whole brain irradiation (Group I), 22 for "elective" and two for therapeutic purposes, while 14 did not (Group II). Abnormalities in computed tomographic (CT) scans of the brain were more frequently observed in Group I than in Group II (70% vs. 0%, p less than 0.01). Clinical central nervous system neurotoxicity developed in three patients in Group I, while none developed in patients in Group II (p less than 0.05). Patients who received methotrexate and procarbazine after whole brain irradiation were at a higher risk for clinical central nervous system neurotoxicity (p less than 0.05), and for development of periventricular white matter changes in CT brain scans (p less than 0.05) than were patients in Group II. Impaired methylation of the myelin sheath is proposed as a possible underlying pathogenic mechanism.

Sequential quantitative EEG analysis in acute lymphocytic leukemia of children

Potential brain toxicity is a major concern in the treatment of acute lymphocytic leukemia with cranial irradiation or intrathecal methotrexate. We used quantitative EEG analysis based on the Fourier transform to study 13 children at the time of diagnosis, after induction, and following consolidation which included extended intrathecal chemotherapy. None had detectable CNS infiltration by leukemia. Nonetheless, initial EEG frequencies were markedly depressed compared to expected values for age (p less than .001), and improved dramatically after induction (p less than .001). Following consolidation, EEG frequencies remained significantly lower than predicted from a control population (p less than .05). Quantitative EEG is a sensitive procedure that appears useful in assessing subtle neurologic effects of acute leukemia and its treatment.

Isotachophoresis as a useful tool for monitoring neurological complications of acute leukaemia in children

Cerebrospinal fluid proteins from 42 children with acute lymphoblastic leukaemia were analysed by isotachophoresis. The isotachopherograms of cerebrospinal fluid taken from patients undergoing central nervous system prophylaxis with neurological complications showed an increase of several peaks (albumin, prealbumin, and an unidentified peak), and changes in the globulin zone, compared with those from patients who had completed central nervous system prophylaxis for at least six months. The most striking finding was that these alterations were not associated with any other biochemical changes in the cerebrospinal fluid, as assayed by routine analysis. Isotachophoresis may be useful in the monitoring of therapy in children affected with acute lymphoblastic leukaemia.

Medulloblastoma. Results of a sequential combined treatment

Actuarial progression-free survival rate at 5 years of a series of 34 patients with medulloblastoma treated by combined surgery, radiotherapy, and chemotherapy was 71%. No relapses were observed in 14 patients followed for more than 5 years. Treatment consisted of a short postoperative course of vincristine (VCR) and intrathecal (IT) methotrexate (MTX) followed by irradiation to the entire cranio spinal axis. Maintenance chemotherapy (CCNU, VCR, and IT MTX) was then continued to encompass 2 years from surgery. Failure occurred in nine patients: four had local recurrence, four dissemination within the central nervous system, and one widespread skeletal metastases. Poor prognostic factors such as presence of malignant cells in the cerebrospinal fluid, non-radical surgery, young age, and radiation doses less than 50 Gy to the tumor bed, did not adversely affect the outcome of patients in this series. Long-term sequelae from the treatment program could be observed in all patients, and in 58% they were severe enough to interfere with normal, active life.

The somnolence syndrome in leukemic children following reduced daily dose fractions of cranial radiation

A group of children with acute lymphocytic leukemia was studied to investigate if a reduction in daily dose fraction of cranial radiation would reduce the incidence of somnolence syndrome. Thirty-one evaluable patients received 100 rad X 18 cranial radiation therapy. Sixty-six similar evaluable patients were given 180 rad X 10. Both groups received the same chemotherapy including intrathecal methotrexate. Clinically detectable somnolence appeared in 58% of ech group without significant differences in the overall frequency or severity of somnolence (p greater than 0.5). This study failed to substantiate a radiation dose fraction size dependence for somnolence syndrome in children with acute lymphocytic leukemia.

Slight impairment of psychomotor skills in children after treatment of acute lymphoblastic leukemia

Several studies have reported a decline in intelligence and cognitive functions in survivors of childhood acute lymphoblastic leukemia (ALL). Other investigators, however, have found no intellectual impairment in these children. Fifty-one long-term survivors of ALL, having been treated according to the protocols of the BFM Study Group from 1970 to 1979, were assessed retrospectively using neurophysical methods. The results were compared with those obtained from 30 patients with other malignancies, who had received neither radiation therapy to the central nervous system (CRT) nor any methotrexate during chemotherapy. Additionally, neurological examinations and cranial computed tomography (CCT) were performed. neuropsychological examinations included verbal functions, intelligence (performance), psychomotor speed, motor skills and sensory integration. The results of verbal tests and the IQs, tested by nonspeed-related measures, were within normal limits in both groups. About one-third of all patients showed mild disturbances of psychomotor speed and motor skills. Children with leukemia had lower scores than those with solid tumors for nearly all tasks, but only tests for sensory integration revealed significant differences between former ALL patients and tumor patients. Furthermore, the following results were obtained related to different therapeutic modalities: The higher total radiation doses had been during CRT (maximum 24 GY), the more neuropsychological functions were impaired, particularly motor accuracy and sensory integration. These disturbances improved with the length of survival. Widening of subarachnoidal space was found in 33% of the CCT obtained. There was no correlation between the intellectual functions of the survivors and the CCT abnormalities. Neurological findings mainly consisted of slight fine motor disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of intermediate dose methotrexate in increased risk childhood acute lymphoblastic leukemia. A comparison of three versus six courses

Between January 1974 and November 1978, 41 consecutive increased risk (age less than 24 months or less than 120 months, or leukocyte count greater than 30,000/mm3) patients with acute lymphoblastic leukemia (ALL) were entered on two consecutive treatment protocols which employed intermediate dose methotrexate (IDM). IDM was employed for central nervous system prophylaxis and systemic intensification. It was anticipated that the avoidance of prophylactic cranial irradiation would result in a lower incidence of longterm central nervous system sequelae. Twenty-two children and adolescents were entered on the first study (IDM X 3) which employed three courses of IDM (500 mg/m2) and six doses of intrathecal (IT) methotrexate (MTX). Nineteen children and adolescents were entered on the second study (IDM X 6) which employed six courses of IDM (3-500 mg/m2 and 3-1500 mg/m2), six doses of IT MTX and three additional doses of triple IT chemotherapy (MTX, cytosine arabinoside, and hydrocortisone or dexamethasone). The cumulative percentage of patients who remained in continuous complete remission was 30% for IDM X 3 and 57% for IDM X 6. This difference was statistically significant (P = 0.046; and BM + CNS, I-using IDM X 6. The cumulative incidence of primary CNS relapse was 36.4% for IDM X 3 and 29.9% for IDM X 6. This difference was not statistically significant (P = 0.44). The use of more intensive therapy with IDM and triple IT chemotherapy did improve the duration of continuous, complete remission but did not decrease the incidence of primary CNS relapse in increased risk patients.

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.

The interrelation of the two c-type cytochromes in Rhodopseudomonas sphaeroides photosynthesis

Photosynthetic electron flow in the bacterium Rhodopseudomonas sphaeroides involves two c-type cytochromes, one membrane-bound and the other a soluble protein, cytochrome c2. Membranes deficient in cytochrome c2 were used for photo-oxidation studies, with and without the addition of purified cytochrome c2. The results favour a series interrelation, membrane cytochrome c-cytochrome c2-reaction centre.

Do photosynthetic bacteria contain cytochrome c1?

A method is described for characterizing, c-type cytochromes in bacterial membrane preparations according to molecular weight on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Applied to the photosynthetic bacterium Rhodopseudomonas sphaeroides this technique is used, together with spectroscopic measurements, to demonstrate that a membrane-bound cytochrome c of mol.wt. 30000 is active in photosynthetic electron transport in addition to the well-known soluble cytochrome, cytochrome c2. The membrane cytochrome has a midpoint potential (E'0) at pH 7 of +290 mV, as compared with +360 mV for purified cytochrome c2. Its alpha-band has a peak near 552 nm, as compared with 550 nm for cytochrome c2. Evidence is presented that chromatophores contain roughly equal amounts of the two cytochromes.