What are the symptoms and diagnosis of piriformis syndrome?

The piriformis muscle is an important part of the buttocks, and piriformis syndrome refers to a disease in which damage to the piriformis muscle causes pain in the buttocks or legs. The symptoms of piriformis syndrome mainly include symptoms of sciatic nerve damage, which can be diagnosed through tender points, lower limb rotation test, straight leg raising test, tissue hydraulic pressure measurement, etc. Below, we will introduce you to the relevant knowledge of piriformis syndrome.

1. Symptoms of sciatic nerve damage

Sciatic pelvic outlet stenosis and piriformis syndrome are compression syndromes caused by local lesions that occur after the sciatic nerve separates from the sacral plexus and before it leaves the pelvis through the bone fibrous canal to reach the buttocks.

The main manifestations are the characteristics of trunk involvement, namely radiating pain along the sciatic nerve and the movement (posterior thigh, front and back of calf, and various muscles of the foot), sensory (lateral calf, sole and front of foot) and reflex (Achilles tendon reflex and plantar reflex) disorders in the areas it supplies. If the disease lasts for a long time, symptoms such as calf muscle atrophy and even foot drop may occur.

2. Tenderness point

The tenderness is most severe at the surface projection of the pelvic outlet of the sciatic nerve (at the ring jump), and radiates downward along the nerve trunk. In addition, about half of the cases may experience tenderness at the tibia or peroneal point. In piriformis syndrome, the tenderness point is slightly higher than the former by 1 to 2 cm.

3. Lower limb rotation test

Internal rotation of the limbs puts the piriformis muscle, superior gemelli, obturator internus muscle, and inferior gemelli muscle in a state of tension, which aggravates the stenosis of the exit and may induce sciatica symptoms. In addition to the radiating pain along the sciatic nerve, there is also numbness from the outer side of the calf to the sole of the foot. However, in patients with simple piriformis syndrome, symptoms are triggered by external rotation. This is mainly because when the contracted and scarred piriformis muscle contracts and the lower limb is externally rotated, the exit becomes narrow.

4. Straight Leg Raise Test

They are generally positive, and the degree of pain is between radicular pain and plexus pain. This test is not specific.

5. Tissue hydraulic pressure measurement

It is considered abnormal if it is more than 1 times the normal value (1, 33 kPa, 10 mmHg) or 50% higher than the normal value. This test is mainly used for certain cases where diagnosis is difficult.