What Is the Main Cause of Piriformis Syndrome?

Piriformis syndrome can be caused by a malformation of the piriformis muscle or spine, or it may be the result of nerve pain or muscle inflammation.

Piriformis syndrome is a neuromuscular condition in which the piriformis muscle compresses the sciatic nerve, causing hip and buttock pain. The piriformis muscle runs from the lower back, where the base of the spine meets the pelvis (sacrum), to the top of the thigh bone (femur).

Symptoms of piriformis syndrome include: 

• Hip, buttock, and lower back pain and/or numbness
  • Pain with sitting, standing, or lying down for more than 15 to 20 minutes
  • Pain and/or numbness radiating from the base of the spinal column (sacrum) through the buttocks and down the back of the thigh, down to just above the knee
  • Pain worsens when still and improves with movement
  • Pain occurs when standing up from a seated position 
  • Changing positions does not completely relieve pain 
• Difficulty walking
  • Abnormal gait
  • Foot drop
  • Numbness in foot
• Pain in lower extremity
• Headache
• Neck pain
• Abdominal, pelvic, and groin pain
• Pain with bowel movements
• Painful sexual intercourse in women

There are two types of piriformis syndrome: 

• Primary piriformis syndrome has an anatomic cause
  • Abnormal development or location of the piriformis muscle or sciatic nerve
  • Different leg lengths
  • Abnormal spine alignment, such as from scoliosis
  • Accounts for fewer than 15% of cases
• Secondary piriformis syndrome accounts for most cases of piriformis syndrome and is mainly caused by:
  • Injury/trauma 
  • Inflammation such as from overuse
  • Prolonged sitting
  • Scarring
  • Prior hip surgery
  • Foot problems, including Morton's neuroma

Piriformis syndrome is diagnosed with a patient history and physical examination. 

Certain physical tests may be used to help diagnose the condition, including: 

• Lasègue sign
  • Localized pain occurs when pressure is applied over the piriformis muscle and its tendon, especially when the hip is flexed at a 90-degree angle and the knee is extended
• Freiberg sign 
  • Pain experienced during passive internal rotation of the hip
• Pace sign
  • Uses the FAIR (flexion, adduction, and internal rotation) test to recreate sciatic symptoms
• Beatty test, also used to recreate sciatic symptoms

Other tests to diagnose piriformis syndrome include: 

• Electromyography (EMG) 
• Magnetic resonance imaging (MRI) and computed tomography (CT) scans to help rule out disc and vertebral conditions

Treatment for piriformis syndrome includes: 

• Ice
• Rest
• Medications
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Acetaminophen 
  • Muscle relaxants
  • Narcotic pain relievers for severe or debilitating pain (short-term use only)
  • Local steroid injections
• Osteopathic manipulative treatment (OMT)
• Prolotherapy (i.e., sclerotherapy, ligament reconstructive therapy)
  • Injection of an irritating solution at the origin or insertion of ligaments or tendons to strengthen the weakened or damaged connective tissue
• Physical therapy
  • Motion exercises
  • Stretching of the piriformis muscle
  • Strengthening of the abductor and adductor muscles 
• Surgical decompression — last resort