Complex neurological and multisystem presentations in mitochondrial disease.

Mitochondrial diseases typically involve organs highly dependent on aerobic metabolism and are often progressive with high morbidity and mortality. In the previous chapters of this book, classical mitochondrial phenotypes and syndromes are extensively described. However, these well-known clinical pictures are more the exception rather than the rule in mitochondrial medicine. In fact, more complex, unspecified, incomplete, and/or overlap clinical entities may be even more frequent, with multisystem appearance or progression. In this chapter, we describe some complex neurological presentations, as well as the multisystem manifestations of mitochondrial diseases, ranging from the brain to the other organs.