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 at shelves or back up the car.

Balance and coordination drift. Quick turns make the legs wobble, handwriting becomes sloppy, and carrying a full coffee cup without spills feels like a circus act.

Numbness or tingling can travel into the hands or feet, often in a “stocking-glove” pattern. Some people burn themselves on hot pans because the warning temperature is gone.

Swallowing may catch. Liquids go down the wrong pipe, or the throat feels hollow and hard to clear.

Vision blurs or doubles. The outer edges dim first, and bright grocery-store lights can trigger a surge of pain behind the eyes.

In larger slips, heartbeat or breathing patterns can change, especially during deep sleep—partners may notice long pauses or sudden gasps.