Columbus, OH - January 2016
Chiari type 1 malformation (CM-1) is a complex structural defect in the cerebellum, characterized by tonsillar ectopia. CM-1 can be congenital or acquired through trauma and may be asymptomatic throughout childhood. Common early manifestations include headaches and cerebellar symptoms.
The incidence of Chiari type 1 malformations is relatively uncommon in the general population — studies have shown that up to 3 percent of children and 1 percent of adults demonstrate radiographic evidence of CM-1, but the conditions under which radiological findings translate to a meaningful clinical diagnosis are unclear. However, CM-1 is found across the spectrum of neurosurgical practice, from infant to adult, as outlined in Chiari I Malformations, a special issue of Neurosurgery Clinics of North America, published in October 2015.
“The biggest challenge we face is still deciding who to operate on and which symptoms will be positively affected,” says Jeffrey Leonard, MD, chief of Neurosurgery at Nationwide Children’s Hospital and co-editor of Chiari I Malformations. “The other challenge is deciding which of the complicated Chiari patients require occipital cervical fusion.”
The articles included in Chiari I Malformations address these challenges by covering the depth and breadth of current Chiari research. Topics include anatomic considerations for diagnosis, pathogenesis and formation of syrinx, associated conditions and surgical management.
One of the complications most associated with Chiari malformations is syringomyelia — the formation of a syrinx, a fluid-filled neuroglial cavity that obstructs cerebrospinal fluid flow in the spinal cord. Over time, the syrinx expands and elongates, damaging the center of the spinal cord and leading to a wide variety of symptoms. These symptoms may develop slowly or come on suddenly and include loss of sensitivity to temperature, numbness or tingling, pain, muscle weakness, spasticity and paralysis.
“The physiology and imaging changes for development of a syrinx is probably the greatest challenge in dealing with these children,” says Dr. Leonard. “Advances in our ability to identify the syrinx early are critical to improving outcomes.”
Advances in CM-1 practice and research are closely linked to advances in imaging techniques, and not just for cases involving syringomyelia.
“We expect 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,” says Dr. Leonard, who is also professor in the Department of Neurological Surgery at The Ohio State University College of Medicine.
Dr. Leonard also suggests that the formation of national registries is enabling researchers to better answer questions about CM-1 diagnosis and treatment. One such registry, a project sponsored by Conquer Chiari, collects health-related information supplied by volunteer patients and makes it available to researchers.
In addition to national registries, standardized outcomes measures such as the Chiari Outcome Scale and Chiari Symptom Profile, described in an article included in Chiari I Malformations, will enable more consistent data to be collected and compared across institutions.
“Using such instruments will greatly facilitate our ability to optimize care for patients with CM-1,” Dr. Leonard says.