Cerebellar Tissue Strain in Chiari Malformation with Headache.

OBJECTIVE: The pathogenesis of Chiari malformation type 1 (CM-1)-associated Valsalva headache is unknown, but it may be caused by abnormal cerebellar tonsil tissue strain. Advances in cardiac-gated magnetic resonance imaging (MRI) techniques such as balanced fast-field echo (bFFE) allow quantification of the motion of anatomic structures and can be used to measure tissue strain. The current study investigated the relationship between Valsalva heachache and tonsillar motion in patients with CM-1. METHODS: A retrospective review of patients with CM-1 who had undergone cardiac-gated bFFE MRI was performed. Headache symptoms were retrieved from the medical records. Anatomic landmarks were manually selected on the cine bFFE, and a validated motion-tracking software was used to assess motion over the cardiac cycle in patients at rest. For each patient, displacement, strain, and strain rate were calculated for 3 anatomic segments. Patients undergoing surgery were examined before and after surgery. RESULTS: From 88 patients, a total of 108 bFFE sequences were analyzed. Valsalva headache was present in 50% of patients. Cerebellar tonsil displacement (P = 0.003), strain (P = 0.012), and maximum strain rate (P = 0.04) were reduced after surgery (n = 20). There was no statistically significant association between tissue motion and headache symptoms. CONCLUSION: The results of this study do not support a relationship between cardiac cycle cerebellar strain and Valsalva headache in patients with CM-1. It is possible that cerebellar strain related to respiratory maneuvers is associated with headache in Chiari patients. Further investigation of tissue strain is warranted because it represents a potential biomarker for outcomes after surgery.