Piriformis Syndrome

Piriformis Syndrome

Introduction-
It is a condition which causes symptoms like true sciatica due to irritation of the sciatic nerve by the piriformis muscle. Some of the common synonyms are wallet neuritis, , deep gluteal syndrome. It has a preponderance for women with the ratio of prevalence of the same is 6:1.

 

  • Clinically relevant anatomy

    The piriformis muscle (PM) originates from the pelvic surface of the sacral segments S2-S4 in the regions between and lateral to the anterior sacral foramina, the sacroiliac joint (superior margin of the greater sciatic notch), the anterior sacroiliac ligament and occasionally the anterior surface of the sacro-tuberous ligament. It passes through the greater sciatic notch to insert onto the greater trochanter of the femur.
    The PM is functionally involved with external rotation, abduction and partial extension of the hip.
    The sciatic nerve generally exits the pelvis below the belly of the muscle, however many congenital variations may exist. For instance, it may pass through or above the piriformis to name a few.
    Due to these variations there is a chance of irritation to the sciatic nerve.

  • Causes

    Muscle spasm in the piriformis muscle causing irritation of the sciatic nerve.Muscle spasms of the PM are most often caused by direct trauma, post-surgical injury, lumbar and sacroiliac joint pathologies or overuse
    Hematoma in the piriformis muscle formed in the muscle after a fall on the buttock can irritate the sciatic nerve.
    Swelling and tightness in the piriformis as a response to injury or spasm.
    Even once the injured piriformis heals there is scar tissue which is not as flexible and can irritate the sciatic nerve
    Activities- prolonged sitting on a hard surface with wallet in the backpocket, exercise on hard and irregular surface, exercise after a long lay off.

  • Symptoms

    • Sciatica with radiating pain starting from the buttocks going along the back of the leg to the outer border of foot.
    • Buttock pain which is of a dull achy character
      Associated tingling and numbness. Weakness in lower limbs or reduced sensation is quite rare.
    • Sitting is particularly painful and difficult with patients preferring to her old the affected buttock a little up while sitting
    • Aggravated by adduction and internal rotation and Pain can lessen on the patient lying down, bending the knee or on walking.
  • Signs

    • FADIR test
    • PACE test
    • FREIBERG sign
    • Gluteal tenderness
    • P/R
  • Differential Diagnosis

    • Thrombosis of the iliac vein [2]
    • Trochanteric Bursitis[3]
    • Herniated intervertebral disc [3]
    • Post-laminectomy syndrome
    • Posterior facet syndrome at L4-5 or L5-S1 [6]
    • Unrecognized pelvic fractures [7]
    • Sacroiliac joint syndrome
    • Degenerative disc disease
    • Compression fractures
    • Intra-articular pathology in the hip joint: labral tears [10], femuro-acetabular
    • impingement (FAI)[14]
    • Lumbar spinal stenosis
    • Tumours, cysts
    • Gynaecological conditions
      Diseases such as appendicitis, pyelitis, hypernephroma, uterine disorders, prostate disorders and malignancies in pelvic viscera.
  • INVESTIGATIONS

    X rays are not helpful
    Nerve Conduction studies and MRI can help us towards the diagnosis on correlation with Clinical findings but even these are not helpful all the times.

    An injection of local anesthetic under USG or fluoroscopy is considered the most definitive means of diagnosis.

  • TREATMENT

    Rest, NSAIDS and muscle relaxants are used initially.
    Physical therapy has a very important role as many cases can resolve with focussed exercises.
    Modalities that are used are Ultrasound massage, Deep Tissue Release techniques with a structured program for piriformis and hamstring stretches.

    Patients not responding to these have an option of receiving USG or Fluoroscopy guided injections of LA+steroid.

    BOTOX can also be given as it causes functional denervation of muscle and relieve the spasm

    Surgical options include release of the tendon at the attachment on the greater trochanter, dissection through the piriformis muscle or neurolysis of the sciatic nerve

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