Metabolic and Toxic Myelopathies

This article describes the clinical presentation, relevant diagnostic investigations, and treatment of metabolic and toxic myelopathies.

Metabolic myelopathies, including those due to deficiency of vitamin B12, folate, copper, or vitamin E, are preventable and typically respond to supplementation. In metabolic myelopathy, early recognition and treatment are important to reduce morbidity, particularly due to subacute combined degeneration of the spinal cord. Toxic myelopathies, including those due to medical interventions (eg, methotrexate, radiation), dietary toxins (eg, lathyrism, konzo), and drugs of abuse (eg, heroin), typically result in permanent neurologic deficits. Toxic myelopathy due to hepatic dysfunction may be reversible if patients receive early intervention, whereas nitrous oxide myelopathy responds to vitamin B12 replacement and cessation of exposure. In toxic myelopathy, it is best to avoid the provoking factor when possible or attempt to mitigate risk by identifying risk factors for developing myelopathy.

Metabolic and toxic myelopathies are important causes of morbidity that require a high index of suspicion for diagnosis.