Postural instability in chiari patients: an understudied biomechanical problem.

Chiari type I malformations (Chiari I) are congenital deformities characterized by migration of the cerebellar tonsils through the foramen magnum. The condition is associated with headaches, chronic fatigue syndrome, orthostatic intolerance, and other neurologic syndromes. Despite patients’ describing difficulties with gait and balance, to date there have been no biomechanical studies examining postural stability in this cohort of patients. CoP ranges and maximum velocities were examined in 15 Chiari patients during quiet upright stance, with feet together and eyes open. These data showed significant postural impairments (p< 0.01) when compared with control subjects, reinforcing qualitative reports of postural instability in Chiari patients. The findings also mesh with reports of “sudden drop attacks” (i.e., sudden unprovoked falls without loss of consciousness) in patients with tonsillar descent into the foramen magnum.