PIRIFORMIS SYNDROME

Posted on by
0

PIRIFORMIS SYNDROME

Author: Ronnie Kaddu

Introduction

  • Piriformis syndrome is a neuro muscular disorder due to irritation of the sciatic nerve as it passes through or around the piriformis muscle. It is commonly an undiagnosed cause of buttock and leg pain.

Epidemiology

  • 5-6% cases of sciatica
  • 4 million per year
  • Middle aged patients (mean age 38 year)
  • F:M 6:1.4

Piriformis muscle

  • Origin: Antero-lateral surface of sacrum (S2-S4)
  • Insertion: Greater trochanter of femur
  • Blood supply: Inferior gluteal, lateral sacral, Superior gluteal artery
  • Nerve supply: nerve to piriformis (L5,S1,S2- posterior trunk of ventral rami)
  • Actions: Abduction & External rotator of thigh

Anatomical relationship between Sciatic nerve and the Piriformis musle

Beason and Anson’s Classification

Pathophysiology

  • Trauma/strain causes inflammation and piriformis spasm. This focal stimulate local inflammatory mediators to accumulate. These irritate the sciatic nerve and initiate a vicious cycle of pain, spasm, inflammation and irritation
  • The inflamed/spastic/stretched muscle compresses the sciatic nerve between the tendinous part of the muscle & bony pelvis

Etiology

  • Gluteal trauma
  • Predisposing anatomic variants
  • Myofascial trigger point
  • Hypertrophy and spasm of piriformis muscle
  • Abcess, haematoma, myoscitis, colorectal ca, bursitis
  • Femoral nailing
  • Intragluteal injection
  • Myositis ossificans of piriformis muscle
  • Post laminectomy

Differential Diagnosis

  • SI joint pathology
  • Myofascial Pain syndrome
  • Pseudoanurysm of inferior gluteal artery following gynec surgery
  • Trochanteric Bursitis
  • Thrombosis of iliac vein/Pelvic tumors
  • Endometriosis
  • Herniated intervertebral disc
  • Painful vascular compression syndrome of sciatic nerve
  • Post laminectomy syndrome; coccydynia
  • Posterior facet syndrome at L4-5 or L5-S1
  • Unrecogsined pelvic fracture, renal stone, benign tumour
  • Myositis ossificans

Symptoms

  • Gluteal pain (97.9%)
  • Pain and paraesthesia in the back, groin, perineum, buttocks, hip, back of thigh (81.9%)
  • Calf pain (59%)
  • Low back pain (18.1%)
  • Pain in rectum during defication and area of coccyx
  • Intense pain when sitting/squatting

Cardinal Features

  • H/o trauma to SI & gluteal region
  • Pain in region of SIJ, greater sciatic notch & piriformis muscle, extending down the leg – difficulty walking.
  • Acute exacerbation of pain on stooping/lifting; moderately relieved on traction.
  • Palpable sausage mass over piriformis, tender to touch
  • Positive Lasegue (straight leg test)
  • Possible gluteal atrophy

Signs

  • Tenderness in region of SI jt, Greater sciatic notch & piriformis muscle
  • Palpable mass in ipsilateral buttock
  • Traction of affected limb provides moderate relief
  • Asymmetric weakness of affected limb
  • Limited medial rotation of ipsilateral leg
  • Ipsilateral short leg
  • Gluteal atrophy (chronic cases only)
  • Persistent sacral rotation towards contralateral side with compensatory lumbar rotation

Physical Exam

  • Trigger point tenderness
  • Positive Piriformis sign
  • Positive Lasegue’s sign
  • Freiberg’s sign
  • Pace’s sign
  • Hughes test

Beatty’s manuever

Investigations

  • Clinical diagnosis mostly
  • No role of X-ray
  • NCV study shows delayed F&H wave reflex
  • MRI – diagnostic

Management

  • Physical therapy
  • Lifestyle modifications
  • Pharmacological agents (NSAIDS, muscle relaxants, neuropathic pain medications)
  • Piriformis muscle injection
    • C-arm guided
    • USG guided

A cadeveric study showed Only 30% of fluoroscopically placed priformis muscle injections were accurate, compared with 95% of ultrasound-guided injections (1) . More studies however need to be conducted to support a transition in clinical practise.

  • Botox injection
  • Surgery

References:

1.Finoff JT, Hurdle MF, Smith J. Accuracy of ultrasound-guided versus fluoroscopically guided contrast controlled piriformis injections. A cadaveric study. J Ultrasound Med 2008; 27: 1157-63.

Author's Name: Ronnie Kaddu

Email: rkaddu@hotmail.com
About me: