In clinical practice, we often encounter stroke patients who have undergone many tests and still cannot find the cause of the stroke, making the patient confused and the doctor embarrassed. How to understand this peculiar clinical phenomenon? It is well known that the treatment and prevention of stroke are closely related to the etiology and pathogenesis, and that different etiologies and pathogenesis have different acute treatment and secondary prevention measures. Therefore, the search for stroke etiology and the investigation of pathogenesis are crucial for stroke patients. One of the categories of stroke is stroke of unknown cause, which accounts for about one quarter of all strokes, and a stroke of unknown cause is one in which the exact cause cannot be found after standard screening procedures. Therefore, it is not that some strokes do not have a cause, but that the current medical methods are not up to date or that doctors do not investigate them in depth. With the advancement of medical science, strokes that were previously thought to have no cause have revealed their true nature, and studies have confirmed that most of these lesions are embolic lesions. Therefore the effort to find the cause of the disease, doctors and patients should not give up, and believe that in the near future, it will certainly unveil its mystery.