Piriformis steroid injection is an injection of a long-lasting steroid into the piriformis muscle of your buttock. This muscle attaches to the side of the sacrum, which is the side, flat bone at the base of your spine just above your tailbone.
Piriformis muscle injections provide diagnostic information and therapeutic relief for those suffering from piriformis syndrome. Common conditions for which this procedure is used include piriformis muscle spasm and inflammation.
Arriving at the diagnosis of piriformis muscle injection requires a thorough history, physical exam, and the exclusion of more common diagnoses, including lumbar stenosis, lumbar radiculopathy, lumbar facet joint arthritis, sacroiliac (SI) joint dysfunction, trochanteric bursitis, and myofascial pain syndrome
Indications of Piriformis Steroid Injection
Piriformis syndrome may be responsible for 0.3% to 6% of all cases of low back pain and/or sciatica. With an estimated amount of new cases of low back pain and sciatica at 40 million annually, the incidence of piriformis syndrome would be roughly 2.4 million per year. In the majority of cases, piriformis syndrome occurs in middle-aged patients with a reported ratio of male to female patients being affected 1:6.
Contraindications of Piriformis Steroid Injection
Two components contribute to the clinical presentation of piriformis syndrome: somatic and neuropathic. The somatic component is a myofascial pain component of the syndrome secondary to any of the surrounding muscles/fascia (i.e. any of the short external rotators of the hip). The neuropathic component refers to the compression or irritation of the sciatic nerve as it courses through above, near, or through, the piriformis muscle itself.
Patients may present acutely in cases of post-traumatic piriformis syndrome or insidiously as in cases of overuse or myofascial pain. Patients will report having gluteal pain with possible associated paresthesias in the back, groin, perineum, buttocks, hip, back of the thigh, calf, foot, and rectum. There is also intense and worsened pain with sitting or squatting.
Preparation of Piriformis Steroid Injection
Initial evaluation should start with a lumbar spine examination. The examination should take into account the patient’s gait, posture, and alignment as well as any leg length discrepancies. Also, the practitioner should examine the patient’s hips, pelvis, and the sacroiliac joint, noting sensory, motor, and deep tendon reflexes.
In piriformis syndrome, sensory, motor, and deep tendon reflexes are normal. The piriformis should be palpated as well just posterior to the hip joint and in the area of the greater sciatic notch. Straight leg raise may also be positive although there is variable sensitivity and specificity for this provocative maneuver.
There are individual tests that stretch the piriformis and can be used to help aid in the diagnosis of exclusion. One of these is the Freiberg sign, which is performed by putting the hip in extension and internal rotation and having the patient externally rotate against resistance. The positive exam will reproduce pain around the piriformis. This test will have positive results in up to 63% of patients. Another individual test called the Pace sign is performed by resisting abduction and external rotation of the hip while the patient is in a seated position. Pace sign occurs in 30% to 74% in piriformis syndrome. FAIR test or also known as the piriformis stretch may elicit pain. Beatty sign has also been described and is accomplished by elevating the flexed leg on the irritated side while the patient lies on the asymptomatic side. Pain and reproduction of the symptoms are a positive test result.
No definitive diagnostic criteria has been validated and established for piriformis syndrome. It remains a diagnosis of exclusion, but many of the following exam findings can aid the clinician in honing in on this diagnosis:
Unilateral or bilateral buttock pain with fluctuating periods of pain throughout the day
No lower back pain,
No pain upon palpation of axial spine
Negative results for straight leg raise
Prolonged sitting triggering gluteal pain or sciatica
Fluctuating sciatica through the course of the day
Buttock pain near projection of the piriformis reproduced by FAIR or Freiberg sign or Beatty sign, or palpitations
The absence of perineal irradiation
Sciatica reproduced by FAIR, Freiberg sign, or Beatty sign.
Standard radiographs of the pelvis and hip should be done to rule out underlying hip pathology. MRI of the lumbar spine is also recommended to evaluate for a discogenic causes of lumbar radiculopathy and to rule out other sources of compression (e.g. soft tissue tumors or masses). MRI can also evaluate for spinal stenosis, herniated disks, facet arthrosis, SI joint pathology, occult pelvic fractures, and any surrounding tendinopathies or bursitides.
EMG is often normal in patients with acute piriformis syndrome presentations, however, chronically, EMG/NCS can be useful in identifying neuropathic changes and abnormal results in muscles innervated by the sciatic nerve [rx].
Corticosteroids: 40-mg of Depo-Medrol or Kenalog
Local anesthetics: 3-5-ml of local anesthetic such as lidocaine or bupivacaine
It is also done with botulinum toxin for longer relief than steroid and local anesthetic.
Patient Position: Prone
Fluoroscopy starting position:
An A-P view is adjusted so that the inferior part of the sacroiliac joint is in the middle of the screen.
Piriformis Muscle Injection with Fluoroscopic Guidance
18-gauge 1.5″ needle tip is placed on the cleaned skin over the inferior SI joint.
Create a skin wheal and then anesthetize the deeper subcutaneous skin with 1% lidocaine and a 27-gauge 1.25-inch needle.
A 22-gauge 3.5″ or 5″ Quincke needle is used to contact the very tip of the inferior sacroiliac joint. As the procedure is performed, note of the approximate needle depth.
After injection, the needle is withdrawn and redirected to a target site 1-cm inferior, 1-cm lateral, and 1-cm deeper than the SI joint.
Caution: Never inject if the patient feels a sharp pain shooting down their leg as the needle tip may be inside the sciatic nerve. The needle should be repositioned and then retry.
Prior to the Procedure
- All blood-thinning products – (except aspirin) must be stopped prior to your procedure. You will be advised by letter when to stop taking these medications at the time that your admission date is arranged.
- You are able to take your other regular medications with a sip of water on the morning of your procedure.
- If you are an insulin-dependent diabetic you will always be at the beginning of the list. Please bring your insulin with you and it will be given to you following your procedure.
- Hamilton Day Surgery Centre staff will advise you of your fasting and admission times.
- You must not have anything to eat, drink, smoke or chew prior to your procedure.
- You will need to organise someone to drive you home after the procedure as you will not be able to drive for 24 hours after your procedure.
What Will Happen?
- You will be admitted to the day surgery by a nurse and you will be asked to change into a gown.
- The anesthetist will speak with you and place a cannula (plastic needle) into a vein in your hand.
- In the procedure room, you will be assisted to position on the procedure table lying on your abdomen with a pillow under your hips and abdomen.
- The anesthetist will give you some sedation into your vein.
- An X-ray machine will be used to determine where the doctor will place the needle for your procedure.
- Local anesthetic and either Botox or steroid will be injected once correct needle placement has been established with the use of X-ray contrast (Omnipaque).
- The procedure will take approximately 10 minutes to complete.
- After the procedure, you will be placed on a trolley and taken to recovery, where you will remain for approximately 1 hour.
- After having something to eat and drink, you will be discharged with a carer.
- Gentle activity and rest is recommended in the first 24 hours following the procedure. You may then return to normal activity.
- The local anesthetic will wear off 12-18 hours following your procedure.
- Botox will take approximately 5 days to start working. During the first 5 days, you may experience some pain at the site of the injection and some flu-like symptoms. Other possible side effects include headache, temporarily increased pain, irritation of nerves at the site of the injection, and rarely paralysis of muscle outside the area of spasm.
- The steroid will take approximately 48 hours to start working. During this time there may be a window of increased discomfort or pain.
- Caution should be taken if any leg heaviness occurs. If this occurs, activity should be kept to a minimum until full leg sensation returns.
- A nurse from HPC will telephone you 24 to 48 hours following your procedure to check on your progress and organize a follow-up appointment.
Treatment for piriformis syndrome begins with nonoperative modalities including:
Oral analgesics (e.g. NSAIDs, muscle relaxants, and gabapentin)
Regimens include nerve stretches, isometric exercises, gluteal muscle strengthening
Diagnostic and therapeutic modalities
Agents used include cortisone, local anesthetic, or botulinum toxin
A recent study reported positive outcomes in patients managed with physical therapy and Botulinum toxin injection
Surgery is considered in refractory cases after exhausting nonoperative modalities
A 2005 study reported surgical outcomes in 64 patients managed with surgical intervention for refractory symptoms: [rx]
82% reported initial improvement
76% had long-term positive outcomes
92% of those managed with surgery returned to work or presurgical baseline activity levels within 2 weeks of the surgery
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