Preprocedural Evaluation
Before the diagnosis of piriformis syndrome is made, other causes of gluteal, hip, and leg pain must be ruled out. Various physical testing maneuvers are helpful in making a diagnosis. One such maneuver consists of flexion, passive adduction, and internal rotation of the involved hip with the patient standing (see the first image below) or reclining (see the second and third images below).
Testing for piriformis pain. Involved hip is flexed, passively adducted, and internally rotated with patient standing.
Testing for piriformis pain. Involved hip is flexed, passively adducted, and internally rotated with patient reclining.
Testing for piriformis pain. Involved hip is flexed, passively adducted, and internally rotated with patient reclining.
The Freiberg test (see the first image below) and the Beatty maneuver (see the second image below) are also commonly performed to test for piriformis pain. [8]
Freiberg test. Forceful internal rotation of thigh on affected side elicits pain.
Beatty maneuver. Patient lies on uninvolved side and abducts involved thigh upward, which elicits pain.
Equipment
Equipment that may be employed in piriformis injection includes the following:
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Needle (25 gauge; 0.75 in.)
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Needle (22 gauge; 2, 4, or 6 in.)
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Needle (18 gauge; 1.5 in.)
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Syringe (3 mL)
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Two syringes (10 mL)
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Intravenous (IV) extension set
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Metal marker or clamp
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Bandage or appropriate dressing
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Electromyography (EMG) disposable injectable monopolar needle (if EMG localization is being used; see Technique)
Medications that may be required include the following:
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Iohexol
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Normal saline (preservative-free)
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Lidocaine 1%
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Ropivacaine or bupivacaine 0.5% (preservative-free)
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Corticosteroids (preservative-free and water-soluble), such as methylprednisolone or triamcinolone diacetate
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OnabotulinumtoxinA
Patient Preparation
Piriformis injection is done with local anesthesia. Typically, 5 mL of 1% lidocaine is infiltrated into a skin wheal. As the needle is advanced, the remaining lidocaine is infiltrated along the path of the needle, as needed. (See Local Anesthetic Agents, Infiltrative Administration.)
Naja et al investigated whether clonidine-bupivacaine nerve-stimulator–guided injections are effective in achieving long-lasting pain relief in piriformis syndrome as compared with bupivacaine-guided injection. [9] Significantly lower pain scores and analgesic consumption were observed with bupivacaine-clonidine than with bupivacaine-saline. Additionally, pain at 6 months was significantly greater in the bupivacaine-saline group (78%) than in the bupivacaine-clonidine group (8%).
The procedure is done with the patient in a prone position.
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Testing for piriformis pain. Involved hip is flexed, passively adducted, and internally rotated with patient standing.
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Testing for piriformis pain. Involved hip is flexed, passively adducted, and internally rotated with patient reclining.
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Testing for piriformis pain. Involved hip is flexed, passively adducted, and internally rotated with patient reclining.
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Freiberg test. Forceful internal rotation of thigh on affected side elicits pain.
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Beatty maneuver. Patient lies on uninvolved side and abducts involved thigh upward, which elicits pain.
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Fluoroscopy-guided piriformis injection. Anteroposterior fluoroscopic image of piriformis after contrast administration.
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Ultrasound-guided piriformis injection. Greater trochanter and lateral border of sacrum are identified. Ultrasound probe is directed parallel to piriformis. Needle is inserted in lateral third of piriformis.
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Ultrasonogram identifies sciatic nerve, gluteus, and piriformis.
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Fluoroscopy-guided piriformis injection. Greater trochanter and lateral border of sacrum are identified fluoroscopically and used as markers for needle insertion.
