Piriformis Syndrome

What is a Piriformis Syndrome?

• Piriformis syndrome (PS) is a painful musculoskeletal condition, characterized by a combination of symptoms including buttock or hip pain.

• In several articles, piriformis syndrome is defined as peripheral neuritis of the branches of the sciatic nerve caused by an abnormal condition of the piriformis muscle (PM), such as an injured or irritated muscle.

• There are two types of piriformis syndrome. The first type is called Primary piriformis syndrome. It is caused by an anatomical variation, like a split piriformis muscle, a split sciatic nerve or an anomalous sciatic nerve path.
• The second type is called Secondary piriformis syndrome. It is the result of a precipitating cause, such as microtrauma, ischemic mass effect, or local ischemia.

Anatomy of Piriformis Muscle

• 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 sacro-iliac 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.
• The relationships between the PM and sciatic nerve have been classified by Beaton and Anson using a six category classification system.
• An anomalous relationship would be labelled between type ‘‘B’’ through type ‘‘F’’ since type ‘‘A’’ is considered to have a normal relationship between the PM and the sciatic nerve.

• Variations in the relationship of the sciatic nerve to the piriformis muscle shown on the diagram above: (A) the sciatic nerve exiting the greater sciatic foramen along the inferior surface of the piriformis muscle; the sciatic nerve splitting as it passes through the piriformis muscle with the tibial branch passing (B) inferiorly or (C) superiorly; (D) the entire sciatic nerve passing through the muscle belly; (E) the sciatic nerve exiting the greater sciatic foramen along the superior surface of the piriformis muscle. The nerve may also divide proximally, where the nerve or a division of the nerve may pass through the belly of the muscle, through its tendons or between the part of a congenitally bifid muscle.
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Causes of Piriformis Syndrome

• There are two types of piriformis syndrome- primary and secondary.
• Primary piriformis syndrome: Primary piriformis syndrome has an anatomical cause, with variations such as a split piriformis muscle, split sciatic nerve, or an anomalous sciatic nerve path. Among patients with piriformis syndrome, fewer than 15% of cases have primary causes.
• Secondary piriformis syndrome: Secondary piriformis syndrome occurs as a result of a precipitating cause, including macrotrauma, microtrauma, ischemic mass effect, and local ischemia.
• Piriformis syndrome is most often (50% of the cases) caused by macrotrauma to the buttocks, leading to inflammation of soft tissue, muscle spasms, or both, with resulting nerve compression.
• Muscle spasms of the PM are most often caused by direct trauma, post-surgical injury, lumbar and sacroiliac joint pathologies or overuse.
• PS may also be caused by shortening of the muscles due to altered biomechanics of the lower limb, low back and pelvic region. This can result in compression or irritation of the sciatic nerve.
• When there is a dysfunction of the piriformis muscle, it can cause various signs and symptoms such as pain in the sciatic nerve distribution, including the gluteal area, posterior thigh, posterior leg and lateral aspect of the foot.
• Microtrauma may result from overuse of the piriformis muscle, such as in long-distance walking or running or by direct compression. An example of this kind of direct compression is known as “wallet neuritis”, which is a repetitive trauma caused by sitting on hard surfaces.
• Etiology of the piriformis syndrome:
• Gluteal trauma in the sacroiliac or gluteal areas:-Predisposing anatomic variants
• Myofascial trigger points:-Hypertrophy and spasm of the piriformis muscle
• Secondary to laminectomy:- Abscess, hematoma, myositis
• Bursitis of the piriformis muscle:- Neoplasms in the area of the infrapiriform foramen
• Colorectal carcinoma:- Neurinoma of the sciatic nerve
• Episacroiliac lipoma:- Intragluteal injection
• Femoral nailing:- Myositis ossificans of the piriformis muscle
• Klippel-Trénaunay syndrome.
• Other causative factors are anatomic variations of the divisions of the sciatic nerve, anatomic variations or hypertrophy of piriformis muscle, repetitive trauma, sacro-iliac arthritis and total hip replacement.
• A Morton’s Toe can also predispose the patient to developing piriformis syndrome. A fraction of the population is at high risk, particularly skiers, truck drivers, tennis players and long-distance bikers.
• The piriformis muscle may be functioning in an elongated position or subjected to high eccentric loads during functional activities secondary to weak agonist muscles.
• For example, if the hip excessively adducts and internally rotates during weight-bearing tasks, due to weakness of the gluteal maximus and / or the gluteus medius, a greater eccentric load may be shifted to the piriformis muscle. Perpetual loading of the piriformis muscle through over lengthening and eccentric demand may result in sciatic nerve compression or irritation.

Symptoms of Piriformis Syndrome

• Patients with piriformis syndrome have many symptoms that typically consist of persistent and radiating low back pain, (chronic) buttock pain, numbness, paraesthesia, difficulty with walking and other functional activities such as pain with sitting, squatting, standing, with bowel movements and dyspareunia in women.
• They can also have pressure pain on the buttock on the same side as the piriformis lesion and point tenderness over the sciatic notch in almost all instances.
• Swelling in the legs and disturbances of sexual functions have also been observed in patients with PS.
• The buttock pain can radiate into the hip, the posterior aspect of the thigh and the proximal portion of the lower leg.
• There may be an aggravation of pain with activity, prolonged sitting or walking, squatting, hip adduction and internal rotation and maneuvers that increase the tension of the piriformis muscle.
• Depending on the patient, the pain can lessens when lying down, bending the knee or when walking. However, some patients cannot tolerate the pain in any position and can only find relief when they’re walking.
• Piriformis syndrome is not characterized by neurological deficits typical for a radicular syndrome, such as declined deep tendon reflexes and myotomal weakness. The patient may present with a limp when walking or with their leg in a shortened and externally rotated position while supine. This external rotation while supine can be a positive piriformis sign, also called a splayfoot. It can be the result of a contracted piriformis muscle.
• Three specific conditions may contribute to PS:
• (1) Myofascial referred pain from trigger points in the PM.
• (2) Adjacent muscles, nerve and vascular entrapment by the PM at the greater sciatic foramen.
• (3) Dysfunction of the sacroiliac joint.

Differential Diagnosis

• Dysfunction, lesion and inflammation of sacroiliac joint
• Pseudoaneurysm in the inferior gluteal artery following gynaecologic surgery
• Thrombosis of the iliac vein
• Painful vascular compression syndrome of the sciatic nerve, caused by gluteal varicosities
• Herniated intervertebral disc
• Post-laminectomy syndrome or coccygodinia
• Posterior facet syndrome at L4-5 or L5-S1
• Unrecognized pelvic fracture
• Lumbar osteochondrosis
• Undiagnosed renal stones
• Lumbosacral radiculopathies
• Osteoarthritis (lumbosacral spine)
• Sacroiliac joint syndrome
• Degenerative disc disease
• Compression fractures
• Intra-articular pathology in the hip joint: labral tears, femuro-acetabular impingement (FAI)
• Lumbar spinal stenosis
• Tumors, cysts
• Gynaecological conditions
• Diseases such as appendicitis, pyelitis, hypernephroma, uterine disorders, prostate disorders and malignancies in pelvic viscera.
• Psychgenic disorders: physical fatigue, depression, frustration
• Sacroiliitis

PATHOLOGY:

• There are two types of piriformis syndrome: primary and secondary.
• Primary piriformis syndrome has an anatomic cause, such as a split piriformis muscle, split sciatic nerve, or an anomalous sciatic nerve path.
• Secondary piriformis syndrome occurs as a result of a precipitating cause, including macrotrauma, microtrauma, ischemic mass effect, and local ischemia.
• Among patients with piriformis syndrome, fewer than 15% of cases have primary causes. Piriformis syndrome is most often caused by macrotrauma to the buttocks, leading to inflammation of soft tissue, muscle spasm, or both, with resulting nerve compression. Microtrauma may result from overuse of the piriformis muscle, such as in long-distance walking or running or by direct compression. An example of this kind of direct compression is “wallet neuritis” (ie, repetitive trauma from sitting on hard surfaces).

Diagnosis

INVESTIGATIONS:

• Radiographic studies have limited application to the diagnosis of piriformis syndrome.
• Although standard antero-posterior radiographs of the pelvis and hips, lateral views of the hips and either CT or MRI of the lumbar spine are recommended to rule out the possibility that the symptoms experienced by the patients originate from the spine or the hip joint.
• Electromyography (EMG) may be also beneficial in differentiating piriformis syndrome from other possible disorders, such as intervertebral disc herniation. Interspinal nerve impingement will cause EMG abnormalities of muscles proximal to the piriformis muscle. In patients with piriformis syndrome however, EMG results will be normal for muscles proximal to the piriformis muscle and abnormal for muscles distal to it.
• Electromyography examinations that incorporate active maneuvers, such as the FAIR test, may have a greater specificity and sensitivity than other available tests for the diagnosis of piriformis syndrome

EXAMINATION:

• A complete neurological history and physical assessment of the patient is essential for an accurate diagnosis. The physical assessment should include the following points:
• An osteopathic structural examination with special attention to the lumbar spine, pelvis and sacrum, as well as any leg length discrepancies.
• Diagnostic tests.
• Deep-tendon reflex testing, strength and sensory testing.

DIAGNOSTIC TESTS:

Palpation:

• The patient reports sensitivity during palpation at the greater sciatic notch, in the region of sacroiliac joint or over the piriformis muscle belly. It is possible to detect the spasm of the PM by careful, deep palpation.
• With deep digital palpation in the gluteal and retro-trochanteric area, there may be tenderness and pain with an exacerbation of tightness and leg numbness.

Pace sign:

• Pace’s sign consists of pain and weakness by resisted abduction and external rotation of the hip in a sitting position. A positive test is occurs in 46.5% of the patients with piriformis syndrome.

Lasèque sign / Straight Leg Raise Test:

• The patient reports buttock and leg pain during passive a straight leg raise performed by the examiner.

Freiberg sign:

• Involves pain and weakness on passive forced internal rotation of the hip in the supine position. The pain is thought to be a result of passive stretching of the piriformis muscle and pressure placed on the sciatic nerve at the sacrospinous ligament. Positive in 56,2% of the patients.

FAIR:

• Painful flexion-adduction-internal rotation

Beatty’s maneuver:

• An active test that involves elevation of the flexed leg on the painful side, while the patient is lying on the asymptomatic side. The abduction causes deep buttock pain in patients with PS, but back and leg pain in patients with lumbar disc disease.

The Hughes test:

• External isometric rotation of the affected lower extremity following maximal internal rotation may also be positive in PS patients.

Hip Adbuction Test:

• The patient lies on the side with lower leg flexed to provide support and the upper leg straight, in line with the trunk. The practitioner stands in front of the patient at the level of the feet and observes (no hands on) as the patient is asked to abduct the leg slowly.
• Normal – Hip abduction to 45°.
• Abnormal – if hip flexion occurs (indicating TFL shortness) and/or leg externally rotates (indicating piriformis shortening) and/or ‘hiking’ of the hip occurs at the outset of the movement (indicating quadratus overactivity and therefore, by implication, shortness).
• Patients with piriformis syndrome may also present with gluteal atrophy, as well as shortening of the limb on the affected side.
• In chronic cases muscle hypotrophy is present in the affected extremity.
• Trendelenburg test may also be positive.

Treatment of Piriformis Syndrome

Medical management:

• Conservative treatment for piriformis syndrome includes pharmacological agents (non-steroidal anti-inflammatory agents (NSAIDs), muscle relaxants and neuropathic pain medication), physical therapy, lifestyle modifications and psychotherapy.
• Injections of local anaesthetics, steroids, and botulinum toxin into the PM muscle can serve both diagnostic and therapeutic purposes. The practitioner should be familiar with variations in the anatomy and the limitations of landmark-based techniques. An ultrasound guided injection technique has recently been utilized. This technique has been shown to have both diagnostic and therapeutic value in the treatment of PS.
• Piriformis syndrome often becomes chronic and pharmacological treatment is recommended for a short time period.

Surgical management:

• Surgical interventions should be considered only when nonsurgical treatment has failed and the symptoms are becoming intractable and disabling. Classic indications for surgical treatment include abscess, neoplasms, hematoma, and painful vascular compression of the sciatic nerve caused by gluteal varicosities.
• Surgical release with tenotomy of the piriformis tendon to relieve the nerve from the pressure of the tense muscle has resulted in immediate pain relief, as reported by several authors.
• Sometimes, the obturator internus muscle should be considered as a possible cause of sciatic pain. However, the diagnosis of the obturator internus syndrome can only be made by ruling out other possible causes of sciatic pain, which is similar to the manner in which piriformis syndrome is diagnosed. Surgical release of the internal obturator muscle can result in both a short- and long-term reduction in pain in patients with retro-trochanteric pain syndrome and should be considered if conservative treatment fails.
• The postoperative management consists of partial weight-bearing using crutches for 2 weeks and unrestricted range of motion exercises. The above surgical approach has shown promising short-term results
• The treatment algorithm for retro-trochanteric pain syndrome:

Physiotherapy Treatment

• Physiotherapy interventions include ultrasound, soft tissue mobilization, piriformis stretching, hot packs or cold spray and various lumbar spine treatments.
• The intervention focused on functional exercises therapy exercises for the hip aimed at strengthening the hip extensors, abductors and external rotators, as well as correction of faulty movement patterns .
• To achieve a 60 – 70% improvement, the patient usually follows 2-3 treatments weekly for 2-3 months.
• First of all, the patient must be placed in contralateral decubitus and FAIR position (Flexed Adducted Internally Rotated).
• Start with an ultrasound treatment: 2.0-2.5 W/cm2, for 10-14 minutes. Apply the ultrasound gel in broad strokes longitudinally along the piriformis muscle from the conjoint tendon to the lateral edge of the greater sciatic foramen.
• Before stretching the piriformis muscle, treat the same location with hot packs or cold spray for 10 minutes.
• The use of hot and cold before stretching is very useful to decrease pain.After that, begin with stretching of the piriformis which can be executed in a variety of ways.
• Stretch the piriformis muscle by applying manual pressure to the muscle’s inferior border.
• It is important not to press downward, rather directing pressure tangentially, toward the ipsilateral shoulder.
• When pressing downward, the sciatic nerve will compress against the tendinous edge of the gemellus superior.
• However, when applying tangential pressure, the muscle’s grip will weaken on the nerve and relieve the pain of the syndrome.
• Another way to stretch this muscle is in the FAIR position. The patient lies in a supine position with the hip flexed, adducted and internally rotated. Then the patient brings his foot of the involved side across and over the knee of the uninvolved leg. We can enhance the stretch, by letting the physical therapist perform a muscle–energy technique. This technique involves the patient abducting his limb against light resistance, which is provided by the therapist for 5-7 seconds, with 5-7 repetitions.
• After stretching, continue with myofascial release at the lumbosacral paraspinal muscles and McKenzie exercises. When the patient lies in the FAIR position, the lumbosacral corset can be used.
• The therapist can also give several tips to avoid an aggravation of the symptoms. This includes:
• Avoid sitting for a long period.
• Stand and walk every 20 minutes.
• Make frequent stops when driving to stand and stretch.
• Prevent trauma to the gluteal region.
• Avoid further offending activities.
• Daily stretching is recommended to avoid the recurrence of the piriformis syndrome.
• The patient can also perform several exercises and treatments at home including:
• Rolling side to side with flexion and extension of the knees while lying on each side
• Rotate side to side while standing with the arms relaxed for 1 minute every few hours
• Take a warm bath
• Lie flat on the back and raise the hips with your hands and pedal with the legs like you are riding a bicycle
• Knee bends, with as many as 6 repetitions every few hours.

Piriformis syndrome rehabilitation exercises:

• Gluteal stretch:Lying on your back with both knees bent, rest the ankle of one leg over the knee of your other leg. Grasp the thigh of the bottom leg and pull that knee toward your chest. You will feel a stretch along the buttocks and possibly along the outside of your hip on the top leg. Hold this for 15 to 30 seconds. Repeat 3 times

• Standing hamstring stretch: Place the heel of your injured leg on a stool about 15 inches high. Keep your knee straight. Lean forward, bending at the hips until you feel a mild stretch in the back of your thigh. Make sure you do not roll your shoulders and bend at the waist when doing this or you will stretch your lower back instead of your leg. Hold the stretch for 15 to 30 seconds. Repeat 3 times.

• Resisted hip abduction: Stand sideways near a doorway. Tie elastic tubing around the ankle on your leg which is away from the door. Knot the other end of the tubing and close the knot in the door. Extend your leg out to the side, keeping your knee straight. Return to the starting position.

• Prone hip extension (bent leg): Lie on your stomach with a pillow underneath your hips. Bend one knee, tighten up your buttocks muscles, and lift your leg off the floor about 6 inches. Keep the leg on the floor straight. Hold for 5 seconds. Then lower your leg and relax.

• Quadruped arm/leg raise: Get down on your hands and knees. Tighten your abdominal muscles to stiffen your spine. While keeping your abdominals tight, raise one arm and the opposite leg away from you. Hold this position for 5 seconds. Lower your arm and leg slowly and alternate sides.

• Partial curl: Lie on your back with your knees bent and your feet flat on the floor. Tighten your stomach muscles. Tuck your chin to your chest. With your hands stretched out in front of you, curl your upper body forward until your shoulders clear the floor. Hold this position for 3 seconds. Don’t hold your breath. It helps to breathe out as you lift your shoulders up. Relax. Repeat 10 times. Build to 3 sets of 10. To challenge yourself, clasp your hands behind your head and keep your elbows out to the side.

• Stretch Piriformis Long sit: Sit with right knee bent, right ankle to outside of left leg. Grasp knee and pull thigh across chest toward left shoulder. Relax, repeat with left leg. Perform 1 set of 10 repetitions, twice a day. Hold exercise for 10 seconds.

• Stretch IT band supine hip rotation:Stretch only to within your limits. Do not try to push knee all the way to the floor. Keep back and hips level with floor.
• Lie on back, knees bent. Lift right leg over left knee. Use right leg to pull left leg down. Repeat with other leg. Perform 1 set of 10 repetitions, twice a day. Hold exercise for 10 seconds.

• Stretch hip/knee: Lie on back, knees bent. Move left ankle over right knee. Gently left right knee up to chest until stretch is felt. Repeat with other leg. Perform 1 set of 10 repetitions, twice a day. Hold exercise for 10 seconds.
  

• Stretch piriformis supine crossed leg: Lie on back, right knee bent, right ankle across left leg. Place right hand on hip to keep pelvic area at on floor. Grasp knee and pull thigh inward while actively trying to move right knee inward until a stretch is felt in the right buttocks area. Relax and repeat with left leg. Perform 1 set of 10 repetitions, twice a day. Hold exercise for 10 seconds.
  

• Resist hip external rotation(ER) stand with elastic: Attach elastic to secure object at waist level. Grasp elastic with both hands in front of waist, involved side toward the elastic. Stand on involved leg, toe touching for balance with uninvolved leg. Twist trunk away from elastic as shown. Perform 3 sets of 20 repetitions, once every other day. Rest 1 minute between sets. Perform 1 repetition every 4 seconds.
• Resist hip with elastic: Attach elastic to secure object at ankle level. Loop elastic around ankle,  Pull ankle inward. Return to starting position and repeat. Perform 3 sets of 210 repetitions, once every other day. Rest 1 minute between sets. Perform 1 repetition every 4 seconds.
• Resist hip extension stand with elastic: Attach elastic to secure the object at ankle level. Loop around the ankle. Stand, facing toward the pull. Extend the leg backward, keeping the knee straight. Return to the start position. Perform 3 sets of 20 repetitions, once every other day. Rest 1 minute between sets. Perform 1 repetition every 4 seconds.
• Resist hip abduction sit with elastic: Sit on a chair. Loop elastic around the thighs near the knees. Keep ankles together and spread knees apart. Return to the start position and repeat. perform 5 sets of 1 minute, once a day. Rest 1 minute between sets. Perform 1 repetition every 4 seconds.

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