ABSTRACT
Although bipolar disorder is a common psychiatric condition with significant morbidity and mortality, its neuropathophysiology remains essentially unknown [1-4]. Major advances during the past 2 decades in the in vivo imaging of the human brain have led to a proliferation of structural and, to a lesser degree, functional imaging studies in bipolar disorder [5-8]. These studies suggest abnormalities in a number of brain regions in bipolar patients, including the ventricular system, striatum, and amygdala. Findings among studies often disagree, however, and unfortunately it remains undetermined how these abnormalities translate into the symptoms and signs of bipolar disorder. An alternative and complementary approach to deciphering the neuropathophysiology of bipolar disorder is to study patients who have developed secondary mania (ie, mania after specific brain injury or medical illness). In these patients, it may be possible to identify which types of brain lesions produce manic symptoms, thereby clarifying the neuropathophysiology of bipolar disorder. Of course, the causal factors of secondary mania may have no relationship to the causal factors of primary mania. Nonetheless, identifying brain lesions that produce secondary mania provides neuroanatomic or neurophysiologic substrates to consider when studying patients with primary bipolar disorder using neuroimaging and other techniques.
