Chiari type I malformation (CM-1) is encountered across the full spectrum of neurosurgical practice, affecting patients from infancy through adulthood. As with any neurosurgical disorder, understanding the pathophysiology, clinical presentation, and radiographic findings is paramount in determining the appropriate management approach for any given patient with CM-1. The objective of this issue of Neurosurgery Clinics of North America, titled “Chiari I Malformation,” is to provide this critical information in a single, concise volume with up-to-date reports from leading experts in the field of CM-1.
While there is general acknowledgment that CM-1 is characterized by cerebellar tonsillar ectopia, there remains no consensus definition of the disorder. Indeed, large institutional studies have shown that ∼3% of children and 1% of adults demonstrate radiographic evidence of CM-1, yet the conditions under which such radiographic findings translate to clinically significant CM-1 are unclear.1, 2 Furthermore, tonsillar ectopia also may be associated with any number of developmental and acquired disorders (eg, craniofacial syndromes, hydrocephalus, posterior fossa tumors). Thus, a clear understanding of the clinical presentation of CM-1 in both pediatric and adult patients has direct bearing on both patient selection and the approach for operative management.
This issue contains detailed descriptions of the surgical treatment of CM-1, with photos and videos showing posterior fossa decompression in stepwise fashion with expert technical details and operative nuances. These will undoubtedly be of interest to all neurosurgical audiences, from trainees to senior surgeons. There is also thorough consideration of operative risks and complications as well as treatment efficacy and need for additional, advanced neurosurgical procedures, for example, in cases of the “complex Chiari,” such as occipital-cervical fusion or ventral decompression.
Advances in the field of CM-1 have been closely linked to the implementation of novel imaging techniques, and it is expected that the development and application of new MRI protocols enabling detailed investigation of cerebrospinal fluid hydrodynamics, craniovertebral junction anatomy, and spinal cord and brainstem white matter tracts will facilitate our growing understanding of the pathophysiology and treatment of CM-1. Of particular importance in advancing CM-1 is the development of improved clinical outcomes instruments, those that are specific for CM-1 and place emphasis on patient-centered outcomes and quality of life. Using such instruments to track outcomes in large numbers of patients enrolled across multi-institutional clinical research networks will greatly facilitate our ability to optimize the care of patients with CM-1.