Treatment of massive intrathecal methotrexate overdose by ventriculolumbar perfusion

Cerebrospinal fluid flushing as a means of neuroprotection

Central nervous system (CNS) injury or disease states are often difficult to treat due to the closed system of the dura mater/blood-brain barrier and the bony skull and vertebrae. The closed system results in at least partial containment of any pro-inflammatory molecules, pathogens, or toxic byproducts in the case of brain or spinal cord lesions, which can result in a destructive feedback loop. Cervical-approach access techniques (lateral C1-C2, suboccipital and lateral atlanto-occipital space punctures) are less-common methods of cerebrospinal fluid (CSF) sampling due to the relative ease and safety of lumbar spinal taps. However, with improved image-guidance, these cervical-level CSF access points are still useful when there are certain contraindications and difficulties when attempting to sample the CSF via the typical lumbar spinal approach. With the advent of microcatheters and minimally invasive techniques, combined with body fluid filtration technology, the question arises: could dual microcatheters be introduced for inflow and outflow of purified or artificial CSF to break the destructive feedback loop and thus diminish CNS damage?. We hypothesize that intrathecal spinal catheters could be placed in 2 positions (e.g., via a cervical route and the typical lumbar spinal route) to allow for both an input and output to more effectively filter or "flush" the CSF. This could have broad implications in the treatment of strokes, traumatic brain or spinal cord injury, infections, autoimmune diseases, and even malignancies within the CNS-in short, any disease with abnormalities detectable in the CSF.

Drainage or lavage as a salvage manoeuvre after intrathecal drug errors: A systematic review with therapeutic recommendations

STUDY OBJECTIVE

Cerebrospinal fluid (CSF) drainage and lavage are reported to reduce drug exposure after inadvertant intrathecal drug administration errors. This reviews aims to provide recommendations for this salvage technique, with regard to methodology, effectiveness and adverse events.

DESIGN

Systematic review. A search in the databases of Embase, Medline, Web of Science, Cochrane Central Register of Randomized Trials and Google Scholar was performed in 2022.

STUDY ELIGIBILITY CRITERIA

All reports of individual patient data with CSF drainage or lavage with a percutaneous lumbar access for an intrathecal drug error were included.

MEASUREMENTS

The primary outcome is the description and count of CSF drainage or lavage, such as times and volume of drainage, volume of replacement and type of replacement fluid. Secondary outcomes are the effects, adverse events and overall outcome.

MAIN RESULTS

58 cases were found, of which 24 were paediatric cases. There was a large variance in methodology, with regard to volume t and type of replacement fluid. In 45% of the cases the intrathecal drug removal continued. The effects were specifically reported in 27 cases, all demonstrated drug removal based on drug concentrations in the CSF (n = 20) and clinical signs (n = 7). Adverse effects were sought for in 17 cases and found intracranial haemorrhage in 3 cases. No interventions were required for these adverse events and the only reported long-term sequelae in these three patients was short-term memory impairment up to 6 months after the event (n = 1). The overall outcome depended largely on the causative agent.

CONCLUSIONS

This review shows that CSF drainage or lavage leads to intrathecal drug removal, but it is unsure if this intervention leads to improved overall patient outcome. Based on aggregated data from case reports, we provide recommendations that may guide clinicians. The risk-benefit ratio should be weighed on a case-to-case basis.

A Case of Methotrexate Neurotoxicity Presented as Status Epilepticus, Encephalopathy, and High Fever

High-dose methotrexate is used to treat a range of adult and childhood cancers including osteosarcoma. Significant neurotoxicity is reported in 1% to 4.5% of patients treated with high-dose methotrexate and can present in a wide variety of symptoms. We present a case of a 14-year-old boy with a recent diagnosis of osteosarcoma who presented to the emergency department with status epilepticus, altered mental status, and very high fever secondary to methotrexate neurotoxicity. We review current literature and discuss some controversies related to this state. We also describe high fever as one of the possible symptoms associated with this condition and suggest using specific magnetic resonance imaging sequence to uncover abnormal findings related to this state. Since high-dose methotrexate is not a rare treatment in this era, we believe that in addition to oncologists, emergency department and intensive care providers should be aware of the potential role of methotrexate in causing significant neurotoxicity and include it in the differential diagnosis when treating a patient presenting with new neurological symptoms in the setting of recent high-dose methotrexate treatment.

Neurotoxicity after high-dose methotrexate (MTX) is adequately explained by insufficient folinic acid rescue

PURPOSE

To challenge the view that the dose of folinic acid rescue after high-dose methotrexate (MTX) has no significance in the prevention of neurotoxicity and to present the minority view that neurotoxicity can be prevented by an adequate dose of folinic acid, without compromising treatment results. Several fallacies that led to the misunderstanding of post MTX neurotoxicity are presented.

METHODS

Data mining using search engines was used to find relevant publications, and an e-mail survey of more than 60 authors of articles in this field was performed. All relevant articles identified were read in their entirety.

RESULTS

Examples of clinical studies with neurotoxicity following inadequate rescue are given. Some studies demonstrated no neurotoxicity when adequate doses of folinic acid rescue were started 24-36 h after the start of HDMTX rescue even after mega doses of MTX. Rescue started after 42 h was associated with neurotoxicity except in patients with low serum MTX levels after 24 and 36 h. ALL protocols with neurotoxicity, especially BFM-like protocols, are presented. Protocol is reported in which single protocol changes prevented neurotoxicity.

CONCLUSIONS

From the published data, when folinic acid rescue is given in a sufficiently high enough dose and is started 24-36 h after the beginning of the methotrexate exposure, and virtually all forms of post MTX neurotoxicity can be prevented without compromising therapeutic results.

Megaloblastic Anemias: Nutritional and Other Causes

Vitamin B₁₂ and folate deficiencies are major causes of megaloblastic anemia. Causes of B₁₂ deficiency include pernicious anemia, gastric surgery, intestinal disorders, dietary deficiency, and inherited disorders of B₁₂ transport or absorption. The prevalence of folate deficiency has decreased because of folate fortification, but deficiency still occurs from malabsorption and increased demand. Other causes include drugs and inborn metabolic errors. Clinical features of megaloblastic anemia include anemia, cytopenias, jaundice, and megaloblastic marrow morphology. Neurologic symptoms occur in B₁₂ deficiency, but not in folate deficiency. Management includes identifying any deficiency, establishing its cause, and replenishing B₁₂ or folate parenterally or orally.

Inadvertent intrathecal injections and best practice management

The intrathecal space has become an important anatomic site for medical intervention not only in anesthesia practice, but also in many other medical specialties. Undesired/inadvertent intrathecal injections (UII) are generally rare. There is tremendous variation in reported inadvertent administrations via an intrathecal route in the literature, mainly as individual cases and very small case-series reports. This review aims to identify potential sources of UII, its clinical presentations, and appropriate management. The inadvertent injectants are classified as anesthetic agents and pain medicines, chemotherapeutics, radiological contrast agents, antibiotics and corticosteroids, and miscellaneous chemical agents such as tranexamic acid. The clinical effects of UII are dependent upon inadvertent injectant(s) and dose being administered intrathecally, and can range from no adverse effect to profound neurological consequences and/or death. Prompt cerebrospinal fluid (CSF) lavage and cardiopulmonary support seem to be the mainstay of treatment. If serious consequences are anticipated, CSF lavage could be lifesaving. This review additionally provides some options for comprehensive management and preventing strategies.

Intrathecal chemotherapy: potential for medication error

BACKGROUND

The central nervous system is a unique sanctuary site for malignant disease. To ensure optimal disease control, intrathecal (IT) chemotherapy is commonly given in conjunction with standard chemotherapy protocols, thus providing the opportunity for medication errors.

OBJECTIVE

A systematic review of the current literature on medication errors associated with the administration of IT chemotherapy was conducted.

METHODS

English-language literature published from January 1960 through June 2013 was accessed. Case reports, clinical studies, and review articles pertaining to IT medication errors were included in the review. References of all relevant articles were searched for additional citations.

RESULTS

Twenty-two cases of accidental IT overdoses have been reported with methotrexate and 1 with cytarabine. There have been numerous cases of antineoplastic agents intended for administration by the parenteral route being inadvertently given intrathecally. Vincristine has been implicated 31 times (25 deaths), as well as vindesine, asparaginase, bortezomib, daunorubicin, and dactinomycin. This has led to profound toxicity and, commonly, death. Unfortunately, many cases go unrecognized or unreported.

CONCLUSIONS

The best method for eliminating the risk of IT medication errors is to develop effective methods of prevention and incorporate them into oncology and hematology practice internationally. Strategies include abolishing the syringe as a method of vinca alkaloid administration and substituting small-volume intravenous bags, and developing novel methods for intraspinal drug administration.

IMPLICATIONS FOR PRACTICE

The nursing profession is in a unique position to influence change and lead the way in establishing preventative strategies into current practice.

Errors involving patients receiving intrathecal chemotherapy

Errors involving patients receiving intrathecal chemotherapy are a significant problem in oncology. Despite the improvement in the management of antineoplastic agents, unintentional intrathecal administration of chemotherapic drugs that are indicated only for systemic administration or intrathecal overdose of drugs regularly used for intrathecal chemotherapy, continue to occur. These events can result in severe neurotoxicity, usually fatal in outcome. We review reported cases of medication errors in intrathecal administration of chemotherapy described in the literature. Diverse rescue therapies have been proposed but the most effective means of managing these errors remains prevention.

Delayed recognition of intrathecal methotrexate overdose

A 10-year-old girl who presented to our hospital was diagnosed as having B-precursor cell acute lymphoblastic leukemia. St Jude's Total XIII protocol was started. In the second block of the consolidation phase, 10 hours after triple intrathecal treatment, we realized that instead of 12 mg, 120 mg of methotrexate had accidentally been given. Although the patient had no symptoms 10 hours after intrathecal treatment, to prevent the possible neurotoxic effects of methotrexate, a cerebrospinal fluid exchange was performed. Simultaneously, systemic dexamethasone and calcium folinic acid were given. At the time of this writing (2 y), the patient has had no symptoms and has continued on the chemotherapy protocol as planned. Administration of high-dose intrathecal methotrexate may not lead to symptoms, as was the case in our patient. This may be related to individual variations in cerebrospinal fluid dynamics and drug metabolism.

Prevention of high-dose-methotrexate neurotoxicity by adequate folinic acid rescue is possible even after central nervous system irradiation

Neurotoxicity, especially associated with therapy for acute lymphatic leukemia, has been attributed by many to the use of methotrexate (MTX). After radiotherapy this has been reported even more frequently but no explanation has been suggested apart from "a complex interaction". The hypothesis presented here is as follows: (1) Inadequate folinic acid rescue alone accounts for MTX-induced neurotoxicity. (2) Adequate folinic acid after MTX can prevent neurotoxicity. (3) Higher doses of MTX require a disproportionately higher dose of folinic acid than MTX to prevent toxicity. Doubling the dose of MTX has required tripling and quadrupling the folinic acid dose to prevent neurotoxicity. Assuming that central nervous system radiotherapy increases the cerebrospinal fluid levels of MTX and folinic acid proportionally, the folinic acid level may now not be enough to prevent neurotoxicity. This neurotoxicity occurs when MTX is given after (but not before) radiotherapy, and can be prevented by appropriate doses of folinic acid. (4) There is no evidence that within the dose range currently being used, the administration of larger quantities of folinic acid to prevent neurotoxicity compromises prognosis. This hypothesis is supported by a large amount of published data. Critical reanalysis of studies that ostensibly contradict parts of the hypothesis showed that they, in fact, support it.

Intrathecal methotrexate neurotoxicity: clinical correlates and antidotal treatment

The neurotoxicity of methotrexate (MTX) is more severe when administered intrathecally (IT) than by the oral and intravenous (IV) routes, and has been reported even with a single administration of therapeutic doses of 12 or 15mg. Prompt recognition and treatment are essential to improve the outcome after massive IT-MTX overdose. Treatment options include CSF drainage or CSF exchange, ventriculolumbar perfusion, IT corticosteroids to reduce CSF inflammation and IV leucovorin to reduce systemic toxicity. Toxicity resulting from IT injection of leucovorin is controversial. CSF drainage and exchange are particularly effective if performed soon after the overdose. In this paper we describe a protocol of treatment for severe cases of IT-MTX overdose in excess of 100mg. The mainstay of treatment is dilution and removal from CSF of excessive methotrexate alongside with specific antidotal therapy.

Treatment of Accidental Intrathecal Methotrexate Overdose With Intrathecal Carboxypeptidase G2

The bacterial enzyme carboxypeptidase G2 (CPDG2) rapidly hydrolyzes methotrexate to inactive metabolites. We administered recombinant CPDG2 (2000 U) intrathecally to seven cancer patients 3 to 9 hours after they had received an accidental overdose of intrathecal methotrexate (median dose = 364 mg; range = 155-600 mg). Four of the seven patients had cerebrospinal fluid (CSF) exchange to remove methotrexate before CPDG2 administration. Immediate symptoms of the methotrexate overdoses included seizures (n = 5), coma (n = 2), and cardiopulmonary compromise (n = 2). Before CPDG2 administration, the median concentrations of methotrexate in CSF were 264 microM (range = 97-510 microM) among patients who had CSF exchange and 8050 microM (range = 2439-16 500 microM) among patients who did not. After intrathecal CPDG2 administration, methotrexate concentrations in CSF declined by more than 98%. All patients recovered completely from the intrathecal methotrexate overdose except for two patients who had memory impairments. Antibodies to CPDG2 were not detected in plasma after treatment with intrathecal CPDG2. Intrathecal CPDG2 is well tolerated, rapidly decreases CSF methotrexate concentrations, and appears to be efficacious for treating accidental intrathecal methotrexate overdoses.

Defining the appropriate dosage of folinic acid after high-dose methotrexate for childhood acute lymphatic leukemia that will prevent neurotoxicity without rescuing malignant cells in the central nervous system

Neurotoxicity after the administration of methotrexate continues to worry physicians. However, inadequate folinic acid rescue is often not considered as a cause of this complication. To clarify whether adequate folinic acid rescue prevents methotrexate-induced neurotoxicity without reducing the cure rate in childhood ALL, published evidence that supported or refuted this claim was investigated. A literature search was conducted and the authors of the relevant studies were contacted. The published data supported the contention that neurotoxicity can be prevented by adequate folinic acid rescue even after very high doses of methotrexate. The safe minimum dose of folinic acid can be defined in terms of the dose of methotrexate given; the time to start of rescue is probably less important. There was no evidence that higher doses of folinic acid, such as those used after methotrexate in the treatment of osteosarcoma, rescue leukemia cells. No change in cure rate was found in relation to changes in scheduling or clinically relevant doses of folinic acid rescue. The accumulation of folinic acid in the cerebrospinal fluid did not seem to be of clinical relevance. No studies indicate that doses of folinic acid after high-dose methotrexate administration interfere with the killing of leukemia cells, nor that delaying the start of rescue beyond a certain point increases the antileukemic effect; neurotoxicity will, however, be increased. Review of current protocols that use low-dose folinic acid rescue and are associated with neurotoxicity is highly recommended.

Neurologic complications of cancer therapy

Neurologic complications of chemotherapy are relatively common. The diagnosis of chemotherapy-associated neurotoxicity remains a clinical one, and is largely based on the exclusion of other possible causes. The goal of this review is to describe the neurotoxicity associated with established chemothrerapeutic agents and with some of the newer biologic agents, monoclonal antibodies and targeted molecular therapies used in the treatment of cancer.

Accidental iatrogenic intoxications by cytotoxic drugs: error analysis and practical preventive strategies

OBJECTIVES

Drug errors are quite common. Many of them become harmful only if they remain undetected, ultimately resulting in injury to the patient. Errors with cytotoxic drugs are especially dangerous because of the highly toxic potential of the drugs involved. For medico-legal reasons, only 1 case of accidental iatrogenic intoxication by cytotoxic drugs tends to be investigated at a time, because the focus is placed on individual responsibility rather than on system errors. The aim of our study was to investigate whether accidental iatrogenic intoxications by cytotoxic drugs are faults of either the individual or the system. The statistical analysis of distribution and quality of such errors, and the in-depth analysis of contributing factors delivered a rational basis for the development of practical preventive strategies.

METHODS

A total of 134 cases of accidental iatrogenic intoxication by a cytotoxic drug (from literature reports since 1966 identified by an electronic literature survey, as well as our own unpublished cases) underwent a systematic error analysis based on a 2-dimensional model of error generation. Incidents were classified by error characteristics and point in time of occurrence, and their distribution was statistically evaluated. The theories of error research, informatics, sensory physiology, cognitive psychology, occupational medicine and management have helped to classify and depict potential sources of error as well as reveal clues for error prevention.

RESULTS

Monocausal errors were the exception. In the majority of cases, a confluence of unfavourable circumstances either brought about the error, or prevented its timely interception. Most cases with a fatal outcome involved erroneous drug administration. Object-inherent factors were the predominant causes. A lack of expert as well as general knowledge was a contributing element. In error detection and prevention of error sequelae, supervision and back-checking are essential. Improvement of both the individual training and work environment, enhanced object identification by manufacturers and hospitals, increased redundancy, proper usage of technical aids, and restructuring of systems are the hallmarks for error prevention.

CONCLUSIONS

Errors follow general patterns even in oncology. Complex interdependencies of contributing factors are the rule. Thus, system changes of the working environment are most promising with regard to error prevention. Effective error control involves adapting a set of basic principles to the specific work environment. The work environment should allow for rectification of errors without penalty. Regular and ongoing intra-organisational error analysis needs to be an integral part of any error prevention strategy. However, it seems impossible to totally eliminate errors. Instead, if the environment guarantees timely error interception, most sequelae are avoided, and errors transform into a system-wide learning tool.

Intrathecal methotrexate overdose

We report two cases of intrathecal methotrexate overdose. A 3-y-old girl with acute lymphoblastic leukaemia and a 4-y-old boy with Burkitt's lymphoma were to receive an intrathecal injection of methotrexate after completion of intravenous methotrexate infusion. Instead of 12.5 mg, they both received a dose of 125 mg. Both children developed generalized convulsion 3 h after the overdose, but afterwards recovered completely. Intravenous folinic acid and dexamethasone rescue were employed, but no attempt was made to exchange the cerebrospinal fluid. In addition to the staff's failure to check the drug label carefully, the marked resemblance of the two dose preparations of methotrexate (50 mg/5 ml and 500 mg/5 ml) may have been contributory.

Intrathecal leucovorin after intrathecal methotrexate overdose

PURPOSE

Intrathecal methotrexate is a standard and important therapy in acute leukemia. Unfortunately, overdose is a well reported complication of this therapy. We report a fatal event secondary to intrathecal leucovorin.

PATIENTS, METHODS, AND RESULTS

An 11-year-old boy with a 6-month history of treatment of acute lymphocytic leukemia received an "overdose" of 20 mg of intrathecal methotrexate. He was treated with intrathecal leucovorin and subsequently experienced severe neurotoxicity and died. This was attributed to the use of intrathecal leucovorin, the first such case reported in the medical literature.

CONCLUSION

A review of the literature indicates that a careful definition of overdose needs to be applied in cases of intrathecal methotrexate: those <100 mg need less intervention, >500 mg will not respond to any intervention, and the middle group, 100-500 mg, can be treated with a variety of approaches, which are outlined. The standard treatment includes the use of ventriculolumbar washout, CSF exchange, or intravenous pharmacotherapy with leucovorin. Recently, the use of carboxypeptidase has been under investigation. All clinicians who administer intrathecal medications should be aware of these complications and the appropriate treatments of them (including rescue). Leucovorin should not be given intrathecally.

Errors involving pediatric patients receiving chemotherapy: a literature review

A review of mishaps involving pediatric patients receiving anticancer chemotherapy was undertaken in order to assist intervention. Although the case literature is too sparse to provide definite recommendations, suggestions for management are made in the event of an error with a high risk (based on the case literature) of life-threatening toxicities. It is recommended that all incidents be reported in the literature in order to provide a basis for devising standard treatment protocols. It is also suggested that studies using animal models continue to be done in order to provide more experimental data about toxicities and potentially beneficial rescue therapies.

Ventriculolumbar perfusion chemotherapy with methotrexate and cytosine arabinoside for meningeal carcinomatosis: a pilot study in 13 patients

Thirteen patients with meningeal carcinomatosis were treated by ventriculolumbar perfusion using methotrexate (MTX) and cytosine arabinoside (Ara-C). MTX (10-30 mg) and Ara-C (40 mg) were infused at 8- to 12-hour intervals on six or nine occasions via an Ommaya reservoir placed in the lateral ventricle. Nine of thirteen patients had evaluable response (69% response rate with a mean survival of 8.8 months among responders) and ventriculolumbar perfusion therapy was effective in improving cerebral, cranial nerve, and spinal root signs and symptoms, especially sensorimotor disturbance in the lower limbs. Three of the six bedridden patients became ambulatory without assistance and two of the four patients who were walking with assistance became ambulatory without assistance. Urinary incontinence also markedly improved, except in one nonresponder. Lumbar cerebrospinal fluid parameters (cytological findings and tumor markers) also improved in association with the clinical improvement. Our pilot results were encouraging, especially the improvement of sensorimotor function in the lower limbs. However, the toxicity was unacceptable when compared with that of standard intrathecal chemotherapy. Thus, this therapy needs to be investigated further to establish the most appropriate drug doses and perfusate volume to reduce toxicity as well as determine its true efficacy in the treatment of meningeal carcinomatosis.

Successful treatment of intrathecal methotrexate overdose by using ventriculolumbar perfusion and intrathecal instillation of carboxypeptidase G2

Prompt and appropriate management measures are critical in order to achieve a favorable outcome after a major overdose of intrathecally (IT) administered methotrexate (MTX). Published information available to guide clinicians in the immediate management of this medical emergency is scant. Herein we describe a 6-year-old boy with acute lymphoblastic leukemia who received an inadvertent overdose of 600 mg of IT administered MTX instead of the intended dose of 12 mg. Severe acute neurotoxicity developed rapidly. Lumbar puncture and drainage of 15 mL of cerebrospinal fluid 2 hours after administration resulted in removal of 32% of the administered drug. Ventriculolumbar perfusion with 240 mL of warmed isotonic saline through ventricular and lumbar catheters for 3 hours resulted in removal of a total of 90% of the drug within 8 1/2 hours after administration. IT administration of 2,000 U of carboxypeptidase G2 (CPDG2), an enzyme that inactivates MTX, resulted in a further 150-fold reduction in cerebrospinal fluid MTX concentration. The patient experienced complete recovery. To our knowledge, this is the first reported case of the use of IT instillation of CPDG2 for the treatment of an overdose of IT administered MTX in a human, and it is only the second reported favorable outcome after an IT overdose of more than 500 mg of MTX. Minor IT overdoses of MTX can be managed by immediate lumbar drainage alone. Major overdoses may also necessitate prompt ventriculolumbar perfusion, IT instillation of CPDG2, and further supportive measures for a successful outcome after this infrequent but potentially catastrophic event.

Myelopathy after intrathecal chemotherapy. A case report with unique magnetic resonance imaging changes

BACKGROUND

Paraplegia caused by intrathecal chemotherapy has no known pathognomonic features and is a diagnosis of exclusion.

METHODS

The authors reported the clinical and neuroimaging findings in one patient with this syndrome.

RESULTS

The patient had severe paraplegia with urinary retention and impaired pain and touch sensation below T-10 with sparing of proprioception and vibration sense. Magnetic resonance imaging (MRI) scan showed diminished intensity throughout the central cervical spinal cord. Post-gadopentetate dimeglumine enhancement was scattered throughout the cervical spinal cord and in two areas of the dorsal spinal cord. Axial views of the cervical spinal cord showed that this enhancement was limited to the lateral columns.

CONCLUSIONS

The MRI in myelopathy due to intrathecal chemotherapy may show a unique pattern of postgadopentetate dimeglumine enhancement limited to the lateral columns of the spinal cord. However, two recently encountered patients with the same syndrome did not show similar changes.

MK-801 and memantine protect cultured neurons from glutamate toxicity induced by glutamate carboxypeptidase-mediated cleavage of methotrexate

Cleavage of methotrexate into glutamate and diaminomethylpteroate by intrathecal glutamate carboxypeptidase is a new approach to the treatment of acute methotrexate neurotoxicity. The simulation of glutamate carboxypeptidase rescue from high-dose methotrexate in neuron astrocyte cocultures of rat cerebellum or cerebral cortex resulted in a selective, concentration-dependent neurotoxicity. The neurotoxicity was caused by the enzymatic release of glutamate from methotrexate at lower concentrations of methotrexate, and by both glutamate and diaminomethylpteroate at concentrations of methotrexate exceeding 200 microM. The good neuroprotection afforded by MK-801 and memantine suggested that glutamate toxicity was mediated by N-methyl-D-aspartate receptors. Methotrexate alone was not toxic to astrocytes, neurons, or the neurite networking. [3H]thymidine and [3H]deoxyuridine incorporation studies showed that astrocyte proliferation in the presence of methotrexate was maintained by the reutilization of pyrimidine bases for DNA synthesis. N-methyl-D-asparate receptor antagonists should be coadministered in future experimental and clinical trials examining intrathecal glutamate carboxypeptidase rescue of methotrexate toxicity.

Cerebrospinal fluid exchange after intrathecal methotrexate overdose. A report of two cases

Two patients aged 11 and four years, were accidentally given a 10-fold overdose of intrathecal methotrexate while being treated for malignant disease. Neither patient developed any signs of neurotoxicity and exchange of lumbar cerebro-spinal fluid was started 3 and 5 h later, respectively. In one of the patients, who received 120 mg of methotrexate intrathecally, 31% of the given dose was recovered during 2 h of cerebrospinal fluid exchange that was started 3 h after the accidental overdosage. No sequelae were observed in any of the patients. Cerebrospinal fluid exchange is safe and can be recommended in all cases of intrathecal methotrexate overdosage. Ventriculo-cisternal perfusion is not necessary in cases of a 10-fold overdose if the patient has no signs of acute neurotoxicity.

Vitamin neurotoxicity

Vitamins contain reactive functional groups necessary to their established roles as coenzymes and reducing agents. Their reactive potential may produce injury if vitamin concentration, distribution, or metabolism is altered. However, identification of vitamin toxicity has been difficult. The only well-established human vitamin neurotoxic effects are those due to hypervitaminosis A (pseudotumor cerebri) and pyridoxine (sensory neuropathy). In each case, the neurological effects of vitamin deficiency and vitamin excess are similar. Closely related to the neurological symptoms of hypervitaminosis A are symptoms including headache, pseudotumor cerebri, and embryotoxic effects reported in patients given vitamin A analogs or retinoids. Most tissues contain retinoic acid (RA) and vitamin D receptors, members of a steroid receptor superfamily known to regulate development and gene expression. Vitamin D3 effects on central nervous system (CNS) gene expression are predictable, in addition to the indirect effects owing to its influence on calcium and phosphorus homeostasis. Folates and thiamine cause seizures and excitation when administered in high dosage directly into the brain or cerebrospinal fluid (CSF) of experimental animals but have rarely been reported to cause human neurotoxicity, although fatal reactions to i.v. thiamine are well known. Ascorbic acid influences CNS function after peripheral administration and influences brain cell differentiation and 2-deoxyglucose accumulation by cultured glial cells. Biotin influences gene expression in animals that are not vitamin-deficient and alters astrocyte glucose utilization. The multiple enzymes and binding proteins involved in regeneration of retinal vitamin A illustrate the complexity of vitamin processing in the body. Vitamin A toxicity is also a good general model of vitamin neurotoxicity, because it shows the importance of the ratio of vitamin and vitamin-binding proteins in producing vitamin toxicity and of CNS permeability barriers. Because vitamin A and analogs enter the CNS better than most vitamins, and because retinoids have many effects on enzyme activity and gene expression, Vitamin A neurotoxicity is more likely than that of most, perhaps all other vitamins. Megadose vitamin therapy may cause injury that is confused with disease symptoms. High vitamin intake is more hazardous to peripheral organs than to the nervous system, because CNS vitamin entry is restricted. Vitamin administration into the brain or CSF, recommended in certain disease states, is hazardous and best avoided. The lack of controlled trials prevents us from defining the lowest human neurotoxic dose of any vitamin. Large differences in individual susceptibility to vitamin neurotoxicity probably exist, and ordinary vitamin doses may harm occasional patients with genetic disorders.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute reversible neurological deficit following intrathecal chemotherapy

We report on two patients with non-Hodgkin's lymphoma (NHL) who developed reversible, short-lived neurological deficit following intrathecal (i.t.) chemotherapy. One patient received i.t. methotrexate for treatment of meningeal disease, and the other received i.t. methotrexate with cytosine arabinoside (ara-C) and hydrocortisone as central nervous system (CNS) prophylaxis. Although transient paresis following i.t. chemotherapy has previously been reported, it has been attributed to the preservatives contained in the diluents. Our two patients, however, received preservative-free solutions.

High-dose leucovorin reverses acute high-dose methotrexate neurotoxicity in the rat

Intravenous high-dose methotrexate (HD-MTX) reduces cerebral glucose metabolism and produces behavioral abnormalities and electroencephalographic slowing in an animal model of acute HD-MTX neurotoxicity and in cancer patients undergoing HD-MTX chemotherapy. We used our model of HD-MTX neurotoxicity in the rat to determine if leucovorin (5-formyltetrahydrofolate) reduces this neurotoxicity, and extended our characterization of this model to identify regional as well as global HD-MTX treatment effects and to investigate HD-MTX-induced alterations in regional brain pH. Intravenous high-dose leucovorin reversed the HD-MTX-induced decrease in cerebral glucose metabolism and associated behavioral and electroencephalographic abnormalities in the rat, but low-dose leucovorin was ineffective. The major effect of HD-MTX on cerebral glucose metabolism was a global reduction; however, smaller region-specific treatment effects were identified in auditory, thalamic, and white matter structures. HD-MTX did not alter regional brain pH. These findings suggest a potential clinical role for high-dose leucovorin in severe or prolonged acute HD-MTX neurotoxicity and provide an important justification for the role of positron emission tomography in the early detection of clinical HD-MTX neurotoxicity.

Clinical management of cytotoxic drug overdose

In this article the pharmacological management of accidental drug overdose is discussed, with various treatments for overdose proposed, as supported by clinical facts and speculation. Current knowledge is outlined concerning dacarbazine, nitrosourea compounds, melphalan, procarbazine, cyclophosphamide, VP-16.213, l-asparaginase (colaspase), 6-mercaptopurine, mustine (nitrogen mustard), intravenous or intrathecal methotrexate (amethopterin), cytarabine (cytosine arabinoside), fluorouracil and bleomycin.

Exchange of cerebrospinal fluid in accidental intrathecal overdose of cytarabine

Intrathecal cytarabine (cytosine arabinoside) is included in many protocols for the treatment of acute lymphoblastic leukaemia of childhood. We report here the accidental administration of 200mg cytarabine intrathecally to a 4-year-old boy with CNS relapse. After the overdose the patient had dilated pupils during the first hour. One month later an unsteady gait and mild intention tremor in the hands were noted. By the exchange of cerebrospinal fluid with isotonic saline started 1 hour after overdose through a lumbar needle, about 27% of the administered dose was recovered. The estimated recovery in view of the time elapsed between overdose and start/end of the exchange procedure was 36%. This indicates that this procedure is of value in managing patients with heavy overdose of intrathecal cytarabine in hospitals without neurosurgical facilities.

Complications of chemotherapy

A 2-year-old previously healthy girl presented to hospital because of irritability, fatigue, pallor and lower extremity weakness. Acute lymphoblastic leukemia (non-T non-B type) was diagnosed by peripheral blood smear and bone marrow aspirate. Chemotherapy was given and included vincristine, prednisone, L-asparaginase and intrathecal methotrexate. In addition, blood and platelet transfusions were given as appropriate. A lumbar puncture showed no cells, glucose 2.7 mmol/L (normal 2.2 – 4.4 mmol/L), protein of 0.40 (normal 0.150 – 0.450 g/L).

A routine chest x-ray had shown probable spinal column anomalies subsequently confirmed on thoraco-lumbar views as splitting of the T10 and T11 vertebra with anterior fusion. Other examiners failed to demonstrate leg weakness and at discharge (5 weeks later) the child was walking normally.