In cerebellar tonsillar herniation, the lowest part of the cerebellum slips down through the hole at the base of the skull. This crowding can squeeze nearby nerves and block spinal-fluid flow, producing a mix of head, neck, and nerve symptoms that often start mild and worsen with time. Headache is the most common complaint. It sits at the back of the head and upper neck, pounding or pressure-like, and grows worse with coughing, sneezing, or bending forward. Neck pain and stiffness follow the same track. Many patients feel a constant “pull” or cramp that makes it hard to look up... Learn more