Chiari malformations: diagnosis, treatments and failures.

Chiari malformations refer to abnormalities of the hindbrain originally described by the Austrian pathologist Hans Chiari in the early 1890s. These malformations range from herniation of the cerebellar tonsils through the foramen magnum to complete agenesis of the cerebellum. In this review, we review the different classification schemes of Chiari malformations. We discuss the different signs and symptoms that the two most common malformations present with and diagnostic criteria. We next discuss current treatment paradigms, including the new measure of possible in utero surgery to help decrease the incidence of Chiari type II malformations. There is also a small discussion of treatment failures and salvage procedures in these difficult cases. Chiari malformations are a difficult clinical entity to treat. As more is learned about the genetic and environmental factors relating to their characteristics, it will be interesting if we are able to predict which treatments are better suited for different patients. Similarly, with the evolution of in utero techniques especially for Chiari II malformations, it will be interesting to see if the incidence and practice of treating these difficult patients will change.

Adenosine-induced transient asystole for management of a basilar artery aneurysm. Case report.

Advances in anesthetic and surgical management, such as induced deep hypothermic circulatory arrest and application of temporary clips, have improved outcome for patients with basilar artery aneurysms. Nonetheless, these techniques are associated with significant risks. The authors report a case in which three transient periods of cardiac asystole were induced during basilar artery aneurysm surgery. Adenosine-induced asystole facilitated the safe clipping of the aneurysm by producing consistent periods of profound hypotension and collapse of the aneurysm without the need for temporary clipping. This technique provided unencumbered identification of perforating arteries, precise definition of the local anatomy, and an ideal environment for the safe placement of the aneurysm clip.