Exogenous Toxins and CNS Injuries

Abstract

The interaction of numerous exogenous substances with the CNS may lead to toxic injuries. The CNS is more vulnerable to the effects of lipophilic compounds, and neurons are particularly susceptible due to their high lipid content and metabolic rates. Clinical neuroradiology plays an overall modest but, in some cases, very important role in the diagnosis of these disorders. Radiology techniques, primarily MRI and to some extent CT, can demonstrate toxic lesions at both early and delayed phases of disease, which may or may not match the severity of the neurological impairment, but in certain settings can predict the prognosis and clinical outcome. Toxic encephalopathies, along with hypoxic-ischemic brain injury, acquired metabolic disorders and inborn errors of metabolism, tend to produce a symmetric pattern of lesions often affecting cerebral deep grey matter. The white matter may also be involved with acute exposure to toxic agents, while neuroimaging in the chronic phase frequently reveals cortical and white matter abnormalities, including atrophy. Recognition of the specific imaging characteristics, presumably due to selective vulnerability, can often lead to the correct diagnosis, especially when combined with the clinical history and/or laboratory findings. However, some of the classic imaging presentations of certain poisonings are not necessarily very specific or sensitive, and neurological dysfunction may be caused by a combination of two or more toxic substances and/or other disorders. A few of the most common and important exogenous toxins will be covered in this chapter.

This publication is endorsed by: European Society of Neuroradiology (www.esnr.org).