Toxic disorders and encephalopathy

The purpose of this chapter is to selectively review the literature on the neuroanatomical, neuropsychological, and emotional/behavioral effects of exposure to three different substances: organic solvents, lead, and carbon monoxide. Recent research regarding each of these substances has provided a window into the mechanisms for changes in behavior and cognition. There are far too many substances known to affect the central nervous system to review them all here. In addition, the volume of literature on each of the substances we discuss is too large for comprehensive review. Rather, our goal is to provide clinicians with a theoretical background of the changes in behavior/emotions and cognition commonly observed with exposure to these substances and to provide guidance for assessing exposed individuals. For each substance, we will review the particulars of exposure and symptom expression, the neurobehavioral symptoms, the neuroimaging changes, and the relationship between these. Based upon these findings, where possible, we will recommend areas to focus on and hypotheses to explore when evaluating patients with such exposures. We will finish up by addressing general themes for the assessment of patients with a history of toxic exposure, including measurement of exposure, determination of effort in medical-legal cases, and collaboration with occupational medicine specialists.