"Motion-specific Headache": A Predictor for Diagnosis and Favorable Prognosis after Surgery in Young Patients with Chiari Malformation Type 1.

As headache is known as one of the most common symptoms in the patients with Chiari malformation type 1 (CM1), it is difficult to find out CM1-related headache among the symptoms because headache itself is commonly seen. Herein, we retrospectively review the cases of six CM1 patients complaining only of headache by which they complained of deterioration in daily life activities. The symptom of headache worsened during anteflexion (n = 2; 33%), retroflexion (n = 1; 17%), jumping (n = 3; 50%), going up the stairs (n = 1; 17%), and running (n = 1; 17%). Mean age at the onset was 15.7 years old (ranging 11-18) and four out of six were female. These inductive factors were clearly different from "Valsalva-like maneuvers," although the mechanism might originate from dynamic tonsil changes. We named these headaches as "motion-specific." These headaches radiated to the posterior side. MRI revealed that the extent of tonsillar ectopia was 11.3 mm, while syringomyelia was observed in three out of six patients (50%). All patients underwent surgical treatment, with the "motion-specific headache" completely disappearing 12.5 days thereafter. Although headaches are common, "motion-specific headache" may be a good candidate symptom to distinguish CM1 patients, especially among teenagers with headaches, and a good predictor for favorable outcomes after surgical treatment.