Sciatica refers to the pain caused by the sciatic nerve due to various reasons, such as compression from spinal diseases or simply sciatica itself, and it is inherently a symptom. What are the characteristics of this symptom? Sciatica can occur on one side or both sides simultaneously. When it occurs, the pain is usually continuous and can have episodic exacerbations. The pain is often dull, stabbing, burning, or like a knife-cutting sensation. It radiates from the buttocks along the back of the thigh and the outer back of the lower leg toward the foot. Clinically, sciatica is divided into secondary and primary types. Secondary pain is due to compression of the sciatic nerve root, commonly seen in conditions like lumbar disc herniation and other spinal disorders. It often accompanies percussion pain in the lumbar spine, and the pain may worsen with coughing, sneezing, or bending, and severe cases may experience numbness in the skin of the lower limbs. Primary sciatica refers to simple inflammation of the sciatic nerve. This type generally presents pain in the buttocks and back of the thigh and usually does not involve percussion pain in the lumbar spine.