Myelopathy due to intrathecal chemotherapy: magnetic resonance imaging findings

Neurologic pathologies of the vertebral spine

At some institutions, musculoskeletal and general radiologists rather than neuroradiologists are responsible for reading magnetic resonance imaging (MRI) of the spine. However, neurological findings, especially intrathecal ones, can be challenging. Intrathecal neurological findings in the spine can be classified by location (epidural, intradural extramedullary, and intramedullary) or etiology (tumor, infection, inflammatory, congenital). In this paper, we provide a succinct review of the intrathecal neurological findings that can be seen on MRI of the spine, primarily by location and secondarily by etiology, in order that this may serve as a helpful guide for musculoskeletal and general radiologists when encountering intrathecal neurological pathologies.

Imaging Aspects of Toxic and Metabolic Myelopathies

Metabolic and toxic myelopathies usually occurs due to several different causes. Metabolic myelopathy usually occurs due to deficiency of a nutrient, such as vitamin B12. Toxic myelopathy occurs secondary to the exposure to an external toxic agent. Although they may have a difficult diagnosis, determination of the specific cause of myelopathy is of utmost importance, because many causes are amenable to treatment. Although they have many clinical, electrophysiologic, and neuropathologic similarities, imaging may aid in the suspicion of toxic or metabolic myelopathy. The aim of this article, is to review the imaging features of the main toxic and metabolic myelopathies.

Myelopathy associated with intrathecal methotrexate

A 21-year-old man developed progressive and bilateral lower limb numbness, gait impairment and urinary incontinence over 10 days. He had received intrathecal methotrexate 20 days previously for acute lymphoblastic B-cell leukaemia, following 7 months of systemic chemotherapy. MR scan of the spinal cord showed bilateral symmetric and extensive T2/fluid attenuated inversion recovery (FLAIR) increased signal involving the dorsal columns in the thoracic cord. His serum folate concentration was at the lower end of the normal range. We stopped the intrathecal chemotherapy and gave folate; after a few days, he progressively improved. Myelopathy is an important adverse effect of intrathecal methotrexate, which may cause clinical and imaging features resembling subacute combined degeneration of the spinal cord. CNS infiltration must be excluded, intrathecal chemotherapy stopped and deficiency of folate or vitamin B12 treated as appropriate.

Dorsal column myelopathy after intrathecal chemotherapy for leukemia

Intrathecal chemotherapy with methotrexate, a folate antagonist, is widely used to treat central nervous system malignancies. The mechanisms underlying methotrexate-induced neurotoxicity are unclear but may be related to increased homocysteine levels. Intrathecal methotrexate-induced myelopathy mimicking subacute combined degeneration, with normal B12 levels, has been documented. We examined treatment and magnetic resonance imaging (MRI) characteristics of 13 patients with leukemia who received intrathecal methotrexate and developed urinary and bowel incontinence, ascending motor weakness, and sensory loss with dorsal column hyperintensity on MRI between 2000 and 2016. Cerebrospinal fluid evaluation was negative for leukemia in all patients and positive for elevated protein in 12 patients. Seven of eight patients with available data had reduced serum folate, increased serum homocysteine, or both, implicating methotrexate as the cause of neurotoxicity. Autopsy of one patient revealed loss of myelinated axons in the posterior columns. These findings suggest that methotrexate neurotoxicity may be mediated by folate antagonism. Awareness and a high index of suspicion of these characteristic clinical and radiographic features in patients who develop myelopathy after intrathecal methotrexate may help to avoid additional neurotoxic therapy in such patients.

Central Nervous System Complications in Children Receiving Chemotherapy or Hematopoietic Stem Cell Transplantation

Therapy-related neurotoxicity greatly affects possibility of survival and quality of life of pediatric patients treated for cancer. Central nervous system (CNS) involvement is heterogeneous, varying from very mild and transient symptoms to extremely severe and debilitating, or even lethal syndromes. In this review, we will discuss the broad scenario of CNS complications and toxicities occurring during the treatment of pediatric patients receiving both chemotherapies and hematopoietic stem cell transplantation. Different types of complications are reviewed ranging from therapy related to cerebrovascular with a specific focus on neuroradiologic and clinical features.

Toxic and Metabolic Myelopathies

Myelopathy describes any neurologic deficit related to the spinal cord. It is most commonly caused by its compression by neoplasms, degenerative disc disease, trauma, or infection. Less common causes of myelopathy include spinal cord tumors, infection, inflammatory, neurodegenerative, vascular, toxic, and metabolic disorders. Conditions affecting the spinal cord must be recognized as early as possible to prevent progression that may lead to permanent disability. Biopsy is rarely performed, thus the diagnosis and management rely on patient׳s history, physical examination, laboratory results, and imaging findings. Here we review the clinical presentations, pathophysiological mechanisms, and magnetic resonance imaging findings of myelopathies related to metabolic or toxic etiologies.

Methotrexate myelopathy after intrathecal chemotherapy: a case report

INTRODUCTION

Methotrexate is often administered intrathecally or into the cerebral ventricles, particularly in patients with central nervous system tumors. However, in addition to chemical arachnoiditis, methotrexate can induce severe myelopathy.

CASE PRESENTATION

A 59-year-old Japanese man with diffuse B-cell lymphoma who underwent systemic chemotherapy including methotrexate and 20 Gy of radiotherapy received intrathecal methotrexate for recurrence. Flaccid paresis of his lower limbs and fecal and urinary incontinence appeared 1 month later. All sensations were impaired below the Th10 dermatome level. Although the clinical symptoms were compatible with transverse myelitis, T2-weighted imaging of his thoracic spinal cord demonstrated signal hyperintensity localized to the posterior and lateral funiculi, which resembled subacute combined degeneration. His serum vitamin B12, folic acid, and total homocysteine levels were within normal limits, but total homocysteine levels in his cerebrospinal fluid were elevated, suggesting spinal cord demyelination.

CONCLUSIONS

Little is known of the pathogenesis of methotrexate myelopathy. A possible mechanism of methotrexate myelopathy with demyelination was suggested by the increased homocysteine levels in the cerebrospinal fluid.

Dorsal column myelopathy following intrathecal chemotherapy for acute lymphoblastic leukemia

OBJECTIVE/CONTEXT: To describe a distinctive clinical and radiographic pattern of myelopathy following intrathecal chemotherapy. Myelopathy is a rare complication of intrathecal chemotherapy used in the treatment of acute lymphoblastic leukemia (ALL). We present a 42-year-old female with T-cell ALL who developed a myelopathy primarily involving the dorsal columns.

METHOD

Case report and literature review.

FINDINGS

Within 24 hours of an injection of intrathecal methotrexate, cytarabine, and hydrocortisone, the patient developed ascending lower limb numbness and balance difficulties progressing to the inability to ambulate. Clinical examination showed profound loss of lower limb proprioception and light touch sensation below T5, mild proximal limb weakness, but preserved pinprick and temperature sensation with intact bowel and bladder function. Initial thoracic and lumbar spine magnetic resonance imaging (MRI) at 1 week revealed no abnormalities. However, repeat imaging at 6 weeks showed abnormal signal in the posterior cord with sparing of the anterior and lateral columns, diffusely involving the lower cervical cord through the conus medullaris. Dermatomal somatosensory-evoked potential (DSEP) conduction abnormalities were consistent with thoracic myelopathy. An empiric trial of high-dose intravenous corticosteroids during inpatient rehabilitation more than 6 weeks later produced no significant clinical improvement.

CONCLUSION/CLINICAL RELEVANCE

Preferential and persistent dorsal column myelopathy is a distinctive clinical and radiographic presentation of a rare complication of intrathecal chemotherapy. The MRI abnormalities were initially absent, but evolved to consist of multi-level spinal cord T2 and STIR hyperintensity with regional gadolinium enhancement. DSEPs more accurately reflected the clinical level of spinal cord dysfunction.

Lateral and dorsal column hyperintensity on magnetic resonance imaging in a patient with myelopathy associated with intrathecal chemotherapy

Chemotherapy-related myelopathy mimicking subacute combined degeneration (SCD) has rarely been reported. We encountered a 35-year-old female with sensory ataxia after intrathecal chemotherapy. Spinal magnetic resonance imaging showed localized abnormal signal areas in the lateral and dorsal white matter, mimicking SCD. Diffusion imaging showed restricted water diffusion and increased microstructural complexity, and cerebrospinal fluid analysis showed increased levels of myelin basic proteins, indicating demyelinating myelopathy. Advanced diffusion imaging can provide more information on the microstructure of chemotherapy-related myelopathy.

[Pharmacologically-induced neurocatastrophes]

Drug-induced adverse reactions represent a significant health problem in developed countries. These events cause 5% of hospital admissions and are one of the main causes of mortality. Neurological manifestations are among the most frequent. This article reviews catastrophic cerebrovascular situations and confusional syndromes, as well as epilepsy, structural encephalopathy, neuromuscular disorders, catastrophic movement disorders and infections, all of which can be drug-induced.

Intrathecal chemotherapy for hematologic malignancies: drugs and toxicities

Intrathecal (IT) chemotherapy is an important component of the prophylaxis or treatment of hematologic malignancies in the central nervous system (CNS), especially in patients with acute lymphoblastic leukemia and aggressive lymphomas. Different regimens of IT chemotherapies have been formulated, often in conjunction with systemic high-dose chemotherapy leading to penetration of the drugs into the cerebrospinal fluid (CSF). The three commonest IT drugs are methotrexate, cytosine arabinoside (Ara-C), and corticosteroids. The CSF half-lives of methotrexate and Ara-C are much prolonged, a factor to be considered if these drugs are also administered systemically in high doses. Neurotoxicities attributed to IT chemotherapy have been reported, including spinal cord lesions, seizures, and encephalopathy. Spinal cord lesions, manifesting as tetraplegia, paraplegia, and cauda equina syndrome, are the commonest neurotoxicity. It is mostly related to combined IT methotrexate and Ara-C, or Ara-C as the sole IT agent when given at high doses or as a slow-release preparation. Cord lesions rarely recover and patients are left with motor deficits, bowel and urinary disabilities. Seizures and encephalopathy are reported in relatively fewer patients, with variable manifestations and prognosis. Knowledge of the pharmacokinetics, dosing schedules and potential toxicities of IT chemotherapeutic drugs is important in the design of CNS prophylaxis and treatment in hematologic malignancies.