ri
is
Underdiagnosed Caus 2% Durrani, MD and Alon P. Winnie, MD mt OSAncstltwi~logy,Rush Medictal &liege, Rush-Presbyterian-St. Luke’s Medical Center (ZD); Department of Anesthesidogy and Pain Control Center, Wniversityof Illinois at Ckicago (APW), C&ago, Illinois
studyem#hmizes that the diagnosis of pirtformis muscle is clinical; without the aj$~opiate cMcat examina:izt2, it ccz !z c&!y aisdia~ased. J Pain Symptom Manage 1991;6:374-379. Key Words Failed back syndrome, low back pain, pirtformti muscle syndrome, sciatica
Piriformis muscle syndrome was first described over 80 years ago by Yeoman.’ It has subsequently been emphasized by othersgd as one of the many causes of sciatica. This easily treated syndrome is frequently overlooked when a patient presents with acute sciatica. As a result, many patients presenting with acute pain that occurs in a radicular distribution extelrding from the lower back and buttock down the lower extremity undergo extensive (and expensive) diagnostic studies, all of which turn out to be negative. Frequently. these patients undergo
WSLFto: Zia Durrani. MD, Elmhurst al. 200 Berteau Avenue, Elmhurst. pUbiicati0~1:December 5, 1990. US. Cancer Pain Relief Committee, 1991 Published by E&tier. New York, New York
unnecessary and ineffective therapeutic interventions (e.g., surgery or epidural blocks), despite the negative evaluation. The following case report exemplifies just such a situation.
Case Regort A 4 1-year-old male physician was referred to the University of Illinois Pain Control Center to receive an epidural injection of steroid for complaints of low back pain with radiation down the left leg to the lateral aspect of the foot. The pain had begun several weeks earlier while the patient was carrying a very heavy weight. Although he had a previous history of mild low back pain, he had never had such an acute episode as the one for which he was currently seeking treatment. He consulted an orthopedic surgeon with the emphasis to avoid surgery at all
olwi-3924/91/$3.50
that inclurles ~va~~~tio~
tie&s insistence upon conservative management, further diagnostic studies were not carried out. With the presumed diagnosis of herniated disc (L5-!&), he was given traction for a long period without any beneficial effects. With the exception of mild weakness of the planter flexors of the left foot and diminished left ankle reflex, the neurological examination was otherwise normal. Straight leg raising was limited to 60”, and the pain was increased with dorsal flexion of the foot. Methylprednisolone acetate (Depo-Medrot) 80 mg was injected epidurally at the L,_s interspace, and the patient was discharged with instructions ro report his response, if any, by telephone. The patient returned to the Pain Control Center 11 days after his first visit and reported no improvement. Further examination during this visit revealed a left piriformis trigger point, and deep digital palpation of the piriformis muscle reproduced the pain identical to that experienced by the patient. I-Iowever, because of tile presumptive diagnosis of the herniated disc, methylprednisolone acetate (Depo-Medrol) 80 mg was again injected into the epidural space at the L,-L, interspace. In addition, the piriformis muscle was also injected with 15 mL of 2% of chloroprocaine (Nesacaine). After this injection, straight leg raising could be carried out to 90” without any pain. The patient returned to the Pain Control Center 3 days later markedly improved, although deep digital palpation of the piriformis muscle still produced some pain. The piriformis muscle was again injected, this time with 15 cc of 0.25% bupivacaine, after which deep digital palpation no longer produced any pain. Following this visit the patient remained asymptomatic and returned to work.
of the pirifor e. The following clinical tests are ep digital pa~pati~~~~of the pirif~~~~~is for reproduction trf sciatica; 2) rectal examination to rule out lateral pelvic wa derness and reproduction of sciatica Freiberg’s sign, which inclerd.es pain a ness on internal rotation of a straight hip; 4) Pace’s sign, which consists of pain and weakness on resisted abduction and external rotation of the thigh in a sitting position: and, 5) sign, which presents as tonic external rotation of the affected lower extremity. A total of 26 patients were diagnosed as having the piriformis muscle syndrome. All were treated at the IJniversity of lllinois Pain Control Center after January 1980. A retrospective review of their medical records was undertaken to assess the following variables: I) common demographic variables (i.e., age, sex. etc,); 2) history of trauma, pain, and associated features (Table 1) ; 3) history of laminectomies, discectomies, chemonucleolysis, epidural methylprednisone acetate injection, or any other “pain treatments”; 4) response to deep digital palpation, pelvic/rectal examinations, Freiberg’s sign, Pace’s sign, piriformis’ sign, and Lasegue’s sign; and 5) results of spinal radiographs, computerized tomography. magnetic resonance imaging, myelography, or electromyography. All of the patients received infiltration of piriformis muscle with 5-15 mL of a local anesthetic. The agents utilized included I .5% mepivacaine, 0.5% bupivacaine. 1% etidocaine, and 2%-3% All patients were followed chloroprocaine. from 1 to 5 years after treatment in the Pain Control Center.
Tablr 1
Clinical Features
Suhsequent to the case presented above, evaluation of the piriformis muscle has been an integral part of our workup for sciatica. All patients referred to the University of Illinois Pain Control Center with the clinical presentation of low back pain, sciatica, an negative radiological findings undergo a routine clinical examination
Parameters
Symptoms Direct trauma
a
Reviewed
Indirect
trauma
Back and gluteal area Abnormal stretching and strain during jogging and other athletic activities
Sciatica and buttock area pain Difficulty sitting Low back pain Dyspareunia
Duration, frequency, and distribution that included gIuteaI, sacroiliac, trochanteric area Duration Duration Duration
and
and frequency and frequency and frequency
Taco 3 Incidence of Trauma Complaint
atients, 11 were female and 15 were male. Ages varied from 25 to 62, with a of 85.5. It did not appear that the piriformis syndrome was si~i~~antly more frequent in any particular age group, and it did not appear to be gender related.
Falling down +-$ng and other athletic activity
tients.
b!e 4) All patients complained primarily of sciatica and butt~k area pain which varied from patient ient with respect to intensity, distribution, haracter. The incidence of other symp tams, such as limp~n$, pain on sittiu~, low back pain, and dys~~~~nia, is shown in Table 2, Trauma appeared to be the most common preg factor (Table 6). Reported trauma from blls to accidental abnormal g postures during various athletic activities. Hi&My Of the 26 patients, 8 (31%) bad previously undergone one or more surgical procedures on the lumbar spine: most of these patients had been labelled as suffering from “failed back syndrome.” Of the 26, 11 (42%) patients had received one or more epidural injections of methylprednisolone acetate. Four patients had received trigger point infiltmtion with local anesthetics for presumed diagnosis of myofascial pain syndrome of various areas.
All 26 patients had moderate to severe tenderness of the lateral pelvic wall along with reproduction of their sciatica during pelvic or rettat examination. Deep digital palpation of the pi~fo~is muscle reproduced the pain in 24 pa-
Incidence
.
10 (38.5%) 24 (92.3%)
Other signs were positive less often (Ta-
Of the 26 patients, 38 (69%) had undergone a computerized tomogram of the lumbosacral spine, Of these patients, only 2 had positive endings: a recurrent disc herniation in one, and a bulging disc in the other. Of the 26 patients, I8 (69%) underwent electromyography. Of these, 8 were indicative of radiculopathies of various lumbar and sacral nerve roots, whereas the remaining 16 patienw had normal studies. Of the 18 patients who had not undergone previous surgery, 6 had myeiograms, ail of which were negative.
Pain relief was achieved in all patients within 5 min of infiltration of the piriformis muscle. After the initial injection, the pain relief lasted anywhere from 2 wk to 2.5 yr. Pain relief that lasted longer than 1 year was considered to be “long-term” pain relief. One to 6 treatments were required to obtain such long-term relief (see Table 5). There was a relationship between the duration of the patient’s pain and the numher of treatments required to produce longterm relief. All 26 patients were followed for a 1 yr period. Of those patients, 14 (54%) were available for a 3-yr fobtlow-up. None of the paTable4
Frequency of Positive Physical Signs TaMc2 Presenting Complex Total Patients Buttack area pain
Sciatica Difhculty sitting and walking Low back Pain D~S~~Un~
26
26 2ti 15 13 6
Physical Sign
Incidence
Rectal/pelvic exam Deep digital palpation of piriformis muscle Sacroiliac tenderness Pace’s Sign
26(100%)
Freiberg’s Sign Lasegue’s sign ~~formis sign
9 (34.6%) 12 (46.2%) 10 (38.5%)
24 (92.3%) 10 (38.5%) 8 (30.8%)
PIRIFORMIS
Total Number of Injections Versus NM~~~~of Patients With Variation5 of ?ain Relief Total Number of Injections
2 wk
lntermediate
Long-Term
1 2 3 4 5 6
14 -
10 20 16 8 6 -
2 4 4 N 2 6
MUSCLE
Duration of Pain Relief
tients who were available for follow-up after 3 yr had any recurrence of their pain syndrome. Six patients developed a partial but transient sciatic nerve block, and there were no other short or long-term sequelae. All of the patients, after the appropriate diagnosis and beneficial treatment, were referred for further evaluation and corrective physical therapy for any residual dysfunctions (e.g., short leg or muscle weakness). Once free of pain, each patient tolerated and benefitted from the prescribed physical therapy.
cussion The piriformis muscle (Figure IA) is a flat, pyramidal-shaped muscle that originates from the anterior surface of the sacrum and sacrotuberous ligament, passes through the upper part of the greater sciatic notch, and inserts on the superior surface of the greater trochanter.5 In addition to being a hip stabilizer, this muscle is also a lateral rotator and abducter of the hip during extension and flexion of the hip, respectively. The sciatic nerve emerges from the greater sciatic notch, very close to the inferior border of the piriformis muscle.” There is a ‘7%-21% incidence of passage of at least part of the nerve through the muscle? rarely (0.8%8%) does the entire nerve pass through the muscle6 (Figure I ). The compact physical proximity of the sciatic nerve to the piriformis muscle makes the former vulnerable to irritation, and entrapment secondary to the pathology involving the muscle. The two most commonly proposed theories explaining the cause of the piriformis muscle syndrome are 1) compression of the nerve between the inflamed muscle and the bony pelvis; this
7-214
Fig.
I. The
0.7-28
plriliwnlis
0.5%
muscle.
compression could be caused by generalized or focal hypertrophy of the muscle secondary to spasm and inflammation; and 2) Compression of the nerve between the two inflamed fascicles of the piriformis muscle. Robinson9 pointed out that because the piriformis muscle is stretched whenever the leg is raised more than a few degrees, any inflammation or spasm of the muscle will compress the sciatic nerve whenever the leg is raised, and thus produce sciatica. It is because of this observation that Robinson,g Solheim,” and Mizugichi”’ have ail advocated surgical sectioning of the piriformis muscle to alleviate the piriformis muscle syndrome, Etiologically. trauma is probably the most common cause of the piriformis muscle syndrome. Trauma may be direct to the low back or buttocks,“.’ ’ or indirect due to unusual stretching of the lumbosacral and/or hip muscles through athletic or other strenuous activities. Of our patients, 92% reported either direct or indirect trauma. Most likely, in all of’ these cases, the trauma or stretching can lead to inflammation, spasm, hypertrophy, and probably eventual contraction of the muscle. Because of the deep location of the piriformis muscle, this pathology could easily go undetected unless a deep digital palpation of the gluteal
area or a ~lv~/~tal examination is performed, Our data affirm the diagnostic value of these clinical tests. The other clinical tests (&toe’s sign, Frei~rg’s sign, piriformis sign, and Iasegue’s sign) are dependent upon the degree of dysfunction of the piriformis muscle and are therefore less sensitive indicators of the piriformis muscle syndmme. It is interesting that eight of our patients had a history of previous surgical procedures (often multi~~) on the lumbar spine. Whether these xiscing pirifarmia muscle this syndrome after sur-
ive, ~sutnab~y~ postamineecomysearrmg or arachnoiditis could Rsulc in cet~rin$ of the lumbar and sacral rants and fimit the normal tnovement of the ir~t~~i~ vie portion of the seiatie nerve during physical activity, Such limitation of movement could put the nerve uuder tension and ~tentia~~y enhance the impingement upon the nerve by the piriformis muscle during walking or jogging.‘a A history of failed lamin~tomy, discectomy, and chemonucleolysis, or a series of epidural methylprednisone acetate injections carried out with no change in the patient’s sciatica should certainly increase suspicion that piriformis muscle syndrome could be the problem. The fact that many of our patients had eiectromyographic evidence of radi~uIo~thy indicates that this finding does not rule out the possibility of a Coexistent piriformis muscle syndrome.‘” ce of low back pain, which ocThe pre
curred in 5 of our patients, may also mislead the physician.‘**t’ Low back pain, however, was nut the main complaint in other studies,‘*“*‘” and sciatica and pain in the buttock area (buttoek, sacroiliac,and trochancericareas) were the shief ~m~ai~ts for all of our 26 patients. DiHieulty in walking, limping, and exacerbatian of pain on sitting are frequent accompaniments of ~fo~is-India sciatica.‘” Irritation of the pudendal nerve frequently produces dyspareunia in female patients and rectal pain in male patients~.l”*“‘.‘” The dramatic and almost immediate relief of pain produced by infiltration of the piriformis mu&e with Ioealanesthetic is also considered to sign.” In order to infiltrate the piriformis muscle, Pace’s techniques has been aQmmanly advocated. This technique involves the insertion of a finger into the rectum to guide the tip of the percutaneous needle into the belly
of the pirifortnis muscle. We have observed that the rectal finger can cause extreme discomfort during this procedure. Therefore, we have modified the technique by a~ndoning the use of the rectal finger. Most of the time, in spite of its deep location, the piriformis muscle can be palpated as “sausage shaped,“a and the index finger can be steadied during the infiltration. If the muscle cannot be steadied between the 6ngers. then the needle can be inserted to make contact with the greater sciatic notch and then walked off that notch to enter the muscle. This technique was useful in ail cases and was also more acceptabie to the patients. In addition, the chance of any inadvertent contamination of
the needle with fecal material was eliminated. The local anesthetic apparently reverses the hyperirritability of the piriformis muscle, and produces relief that long outlasts the duration of the drug. ‘r In our patients. the duration of pain relief varied from a few weeks to 2.5 years. Ail local anesthetics can be utilized effectively. Ai~ough it might seem advantageous to use long-acting agents, our experience indicates that they are no more effective than the shortacting agents. If a long-acting drug is used and “spills over” onto the sciatic nerve, then the patient may be unable to ambulate for many hours.‘” Several inve st‘tgators have recommended the use of steroids aiong with the local anesthetics. but in view of our success with local anesthetics alone, the addition of steroids seems unnecessary. Similarly, others have advocated surgical sectioning of the piriformis muscle. And, we repeat, in view of our success with local anesthetic injections, such surgery seems unnecessary. In conclusion, we have presented a review of 26 patients who were diagnosed as having piriformis muscle syndrome. The diagnosis was made during a routine examination for low back pain and sciatica, which included a systematic evaluation of the piriformis muscle. Because of the similarity of symptoms to those of discogenic pain syndrome, patients with the pi~fo~is muscle syndrome can be easily misdiagnosed without such an examination. We feel that deep digital ~lpation of the piriformis muscle during rectal or pelvic examination should be a part of the routine examination for low back pain and sciatica. Reproduction of the sciatica upon rectal examination or deep digital palpation of the piriformis muscle appears to be diagnostic, as is
Vol. 6 No. 6
relief of pain upon infiltrative of t muscle with a local anesthetic. 0
tion of the ~~irif~)r~nis syndrome. 1!)74;105:181-187.
nosis is established, the treatment is easy and Long-term pain relief of sciatica can rewarding. be obtained with local anesthetic injection of the piriformis muscle and possibly with subsequent corrective physical therapy.
9. Robinsott sciatic pairt.
1. Yeoman W. The relation iliac joint to sciatica. Lancet 2. Kirkaldy-Willis lower back pain.
NW. Spine
of arthritis of the sacro1928: 11: I 177-l 180.
A more precise diaguosis 1979;4: 102-109.
3. Pace JB. Jagle D. Piriformis Med 1976; 124:435-439.
syndrome.
fog
5. Clemente Philadelphia:
CD. Gray’s anatomy. Lea and Febiger. 1985.
30th
ed.
DK. Piriti)rmis svndromc in relation Am J Surg 1947;73:355-358.
to
Il. Brown JA. Braun MA. Namcy TC. Piriformis syndrome in a lo-year-old boy as a complication of operation with patient iu sitting position. Neurosurgery I !Hi;23: I I7- I 19. 12. Hallen RP. Sciatic pain and the piriformis cle. Postgrad Mcd l!)W3;74:69-72.
mus-
%. “Sciatic radicular pain” or piriformis Aualg 19H!t;ti9:260.
m~~srlr sy~~dume.Anestb 14. Wyant
4. Solheim L. The piriformis muscle syndrome: Sciatic nerve entrapment treated with section of piriformis muscle. Acta Orthop Stand 198 I;5 1:73-75.
(
10. MiLuguchi ‘1‘. Division of the piriformis muscle for the treatment of sciatica: postlaminectomy syndrome and osteoarthritis of spine. Arch Surg 1976;ll l:71Y-722.
13. Durrani
West J
Acta Anat
tlPatl1wllt
Auaesth
(if). Chronic pain syndromes 111. ‘lhc piriformis syndrome. Sor J 107!j;2(i:305-308.
and their Canada
15. Adams JA. ‘l‘he piriformis sy~dr~mw: reportot four cases and review of the literature. S Afr J Surg I980;18: 13-18.
6. Beaton LE, Anson BJ. The relation of the sciatic nerve and of its subdivisions to piriformis muscle. Anat Ret 1937;7O(Supp. 1): l-5.
16. Thicle CH. ‘lbnic spasm of Icvater ani, cocrygeus and piriformis muscle. Tram Am Pratt Sot 1936;37: 145-155.
7. Beaton LE. Anson BJ. The sciatic nerve and the piriformis muscle: Their interrelationship. a possible cause of coccygodenia. J Bone Joint Surg [AM] 1938;20:686-688.
17. Bonica JJ. The management of chronic Philadelphia: Lea aud Febiger. 1953.
8. Pecina M. Contribution
to the etiological
explana-
pain.
18. Winnie AP. Masters RW. Durrani Z. et al. Motor block outlasts the Jcnsory block: A unique characteristic of ediocairc. Keg Anesthesia 1984;Y: 146153.
is
Underdiagnosed Caus 2% Durrani, MD and Alon P. Winnie, MD mt OSAncstltwi~logy,Rush Medictal &liege, Rush-Presbyterian-St. Luke’s Medical Center (ZD); Department of Anesthesidogy and Pain Control Center, Wniversityof Illinois at Ckicago (APW), C&ago, Illinois
studyem#hmizes that the diagnosis of pirtformis muscle is clinical; without the aj$~opiate cMcat examina:izt2, it ccz !z c&!y aisdia~ased. J Pain Symptom Manage 1991;6:374-379. Key Words Failed back syndrome, low back pain, pirtformti muscle syndrome, sciatica
Piriformis muscle syndrome was first described over 80 years ago by Yeoman.’ It has subsequently been emphasized by othersgd as one of the many causes of sciatica. This easily treated syndrome is frequently overlooked when a patient presents with acute sciatica. As a result, many patients presenting with acute pain that occurs in a radicular distribution extelrding from the lower back and buttock down the lower extremity undergo extensive (and expensive) diagnostic studies, all of which turn out to be negative. Frequently. these patients undergo
WSLFto: Zia Durrani. MD, Elmhurst al. 200 Berteau Avenue, Elmhurst. pUbiicati0~1:December 5, 1990. US. Cancer Pain Relief Committee, 1991 Published by E&tier. New York, New York
unnecessary and ineffective therapeutic interventions (e.g., surgery or epidural blocks), despite the negative evaluation. The following case report exemplifies just such a situation.
Case Regort A 4 1-year-old male physician was referred to the University of Illinois Pain Control Center to receive an epidural injection of steroid for complaints of low back pain with radiation down the left leg to the lateral aspect of the foot. The pain had begun several weeks earlier while the patient was carrying a very heavy weight. Although he had a previous history of mild low back pain, he had never had such an acute episode as the one for which he was currently seeking treatment. He consulted an orthopedic surgeon with the emphasis to avoid surgery at all
olwi-3924/91/$3.50
that inclurles ~va~~~tio~
tie&s insistence upon conservative management, further diagnostic studies were not carried out. With the presumed diagnosis of herniated disc (L5-!&), he was given traction for a long period without any beneficial effects. With the exception of mild weakness of the planter flexors of the left foot and diminished left ankle reflex, the neurological examination was otherwise normal. Straight leg raising was limited to 60”, and the pain was increased with dorsal flexion of the foot. Methylprednisolone acetate (Depo-Medrot) 80 mg was injected epidurally at the L,_s interspace, and the patient was discharged with instructions ro report his response, if any, by telephone. The patient returned to the Pain Control Center 11 days after his first visit and reported no improvement. Further examination during this visit revealed a left piriformis trigger point, and deep digital palpation of the piriformis muscle reproduced the pain identical to that experienced by the patient. I-Iowever, because of tile presumptive diagnosis of the herniated disc, methylprednisolone acetate (Depo-Medrol) 80 mg was again injected into the epidural space at the L,-L, interspace. In addition, the piriformis muscle was also injected with 15 mL of 2% of chloroprocaine (Nesacaine). After this injection, straight leg raising could be carried out to 90” without any pain. The patient returned to the Pain Control Center 3 days later markedly improved, although deep digital palpation of the piriformis muscle still produced some pain. The piriformis muscle was again injected, this time with 15 cc of 0.25% bupivacaine, after which deep digital palpation no longer produced any pain. Following this visit the patient remained asymptomatic and returned to work.
of the pirifor e. The following clinical tests are ep digital pa~pati~~~~of the pirif~~~~~is for reproduction trf sciatica; 2) rectal examination to rule out lateral pelvic wa derness and reproduction of sciatica Freiberg’s sign, which inclerd.es pain a ness on internal rotation of a straight hip; 4) Pace’s sign, which consists of pain and weakness on resisted abduction and external rotation of the thigh in a sitting position: and, 5) sign, which presents as tonic external rotation of the affected lower extremity. A total of 26 patients were diagnosed as having the piriformis muscle syndrome. All were treated at the IJniversity of lllinois Pain Control Center after January 1980. A retrospective review of their medical records was undertaken to assess the following variables: I) common demographic variables (i.e., age, sex. etc,); 2) history of trauma, pain, and associated features (Table 1) ; 3) history of laminectomies, discectomies, chemonucleolysis, epidural methylprednisone acetate injection, or any other “pain treatments”; 4) response to deep digital palpation, pelvic/rectal examinations, Freiberg’s sign, Pace’s sign, piriformis’ sign, and Lasegue’s sign; and 5) results of spinal radiographs, computerized tomography. magnetic resonance imaging, myelography, or electromyography. All of the patients received infiltration of piriformis muscle with 5-15 mL of a local anesthetic. The agents utilized included I .5% mepivacaine, 0.5% bupivacaine. 1% etidocaine, and 2%-3% All patients were followed chloroprocaine. from 1 to 5 years after treatment in the Pain Control Center.
Tablr 1
Clinical Features
Suhsequent to the case presented above, evaluation of the piriformis muscle has been an integral part of our workup for sciatica. All patients referred to the University of Illinois Pain Control Center with the clinical presentation of low back pain, sciatica, an negative radiological findings undergo a routine clinical examination
Parameters
Symptoms Direct trauma
a
Reviewed
Indirect
trauma
Back and gluteal area Abnormal stretching and strain during jogging and other athletic activities
Sciatica and buttock area pain Difficulty sitting Low back pain Dyspareunia
Duration, frequency, and distribution that included gIuteaI, sacroiliac, trochanteric area Duration Duration Duration
and
and frequency and frequency and frequency
Taco 3 Incidence of Trauma Complaint
atients, 11 were female and 15 were male. Ages varied from 25 to 62, with a of 85.5. It did not appear that the piriformis syndrome was si~i~~antly more frequent in any particular age group, and it did not appear to be gender related.
Falling down +-$ng and other athletic activity
tients.
b!e 4) All patients complained primarily of sciatica and butt~k area pain which varied from patient ient with respect to intensity, distribution, haracter. The incidence of other symp tams, such as limp~n$, pain on sittiu~, low back pain, and dys~~~~nia, is shown in Table 2, Trauma appeared to be the most common preg factor (Table 6). Reported trauma from blls to accidental abnormal g postures during various athletic activities. Hi&My Of the 26 patients, 8 (31%) bad previously undergone one or more surgical procedures on the lumbar spine: most of these patients had been labelled as suffering from “failed back syndrome.” Of the 26, 11 (42%) patients had received one or more epidural injections of methylprednisolone acetate. Four patients had received trigger point infiltmtion with local anesthetics for presumed diagnosis of myofascial pain syndrome of various areas.
All 26 patients had moderate to severe tenderness of the lateral pelvic wall along with reproduction of their sciatica during pelvic or rettat examination. Deep digital palpation of the pi~fo~is muscle reproduced the pain in 24 pa-
Incidence
.
10 (38.5%) 24 (92.3%)
Other signs were positive less often (Ta-
Of the 26 patients, 38 (69%) had undergone a computerized tomogram of the lumbosacral spine, Of these patients, only 2 had positive endings: a recurrent disc herniation in one, and a bulging disc in the other. Of the 26 patients, I8 (69%) underwent electromyography. Of these, 8 were indicative of radiculopathies of various lumbar and sacral nerve roots, whereas the remaining 16 patienw had normal studies. Of the 18 patients who had not undergone previous surgery, 6 had myeiograms, ail of which were negative.
Pain relief was achieved in all patients within 5 min of infiltration of the piriformis muscle. After the initial injection, the pain relief lasted anywhere from 2 wk to 2.5 yr. Pain relief that lasted longer than 1 year was considered to be “long-term” pain relief. One to 6 treatments were required to obtain such long-term relief (see Table 5). There was a relationship between the duration of the patient’s pain and the numher of treatments required to produce longterm relief. All 26 patients were followed for a 1 yr period. Of those patients, 14 (54%) were available for a 3-yr fobtlow-up. None of the paTable4
Frequency of Positive Physical Signs TaMc2 Presenting Complex Total Patients Buttack area pain
Sciatica Difhculty sitting and walking Low back Pain D~S~~Un~
26
26 2ti 15 13 6
Physical Sign
Incidence
Rectal/pelvic exam Deep digital palpation of piriformis muscle Sacroiliac tenderness Pace’s Sign
26(100%)
Freiberg’s Sign Lasegue’s sign ~~formis sign
9 (34.6%) 12 (46.2%) 10 (38.5%)
24 (92.3%) 10 (38.5%) 8 (30.8%)
PIRIFORMIS
Total Number of Injections Versus NM~~~~of Patients With Variation5 of ?ain Relief Total Number of Injections
2 wk
lntermediate
Long-Term
1 2 3 4 5 6
14 -
10 20 16 8 6 -
2 4 4 N 2 6
MUSCLE
Duration of Pain Relief
tients who were available for follow-up after 3 yr had any recurrence of their pain syndrome. Six patients developed a partial but transient sciatic nerve block, and there were no other short or long-term sequelae. All of the patients, after the appropriate diagnosis and beneficial treatment, were referred for further evaluation and corrective physical therapy for any residual dysfunctions (e.g., short leg or muscle weakness). Once free of pain, each patient tolerated and benefitted from the prescribed physical therapy.
cussion The piriformis muscle (Figure IA) is a flat, pyramidal-shaped muscle that originates from the anterior surface of the sacrum and sacrotuberous ligament, passes through the upper part of the greater sciatic notch, and inserts on the superior surface of the greater trochanter.5 In addition to being a hip stabilizer, this muscle is also a lateral rotator and abducter of the hip during extension and flexion of the hip, respectively. The sciatic nerve emerges from the greater sciatic notch, very close to the inferior border of the piriformis muscle.” There is a ‘7%-21% incidence of passage of at least part of the nerve through the muscle? rarely (0.8%8%) does the entire nerve pass through the muscle6 (Figure I ). The compact physical proximity of the sciatic nerve to the piriformis muscle makes the former vulnerable to irritation, and entrapment secondary to the pathology involving the muscle. The two most commonly proposed theories explaining the cause of the piriformis muscle syndrome are 1) compression of the nerve between the inflamed muscle and the bony pelvis; this
7-214
Fig.
I. The
0.7-28
plriliwnlis
0.5%
muscle.
compression could be caused by generalized or focal hypertrophy of the muscle secondary to spasm and inflammation; and 2) Compression of the nerve between the two inflamed fascicles of the piriformis muscle. Robinson9 pointed out that because the piriformis muscle is stretched whenever the leg is raised more than a few degrees, any inflammation or spasm of the muscle will compress the sciatic nerve whenever the leg is raised, and thus produce sciatica. It is because of this observation that Robinson,g Solheim,” and Mizugichi”’ have ail advocated surgical sectioning of the piriformis muscle to alleviate the piriformis muscle syndrome, Etiologically. trauma is probably the most common cause of the piriformis muscle syndrome. Trauma may be direct to the low back or buttocks,“.’ ’ or indirect due to unusual stretching of the lumbosacral and/or hip muscles through athletic or other strenuous activities. Of our patients, 92% reported either direct or indirect trauma. Most likely, in all of’ these cases, the trauma or stretching can lead to inflammation, spasm, hypertrophy, and probably eventual contraction of the muscle. Because of the deep location of the piriformis muscle, this pathology could easily go undetected unless a deep digital palpation of the gluteal
area or a ~lv~/~tal examination is performed, Our data affirm the diagnostic value of these clinical tests. The other clinical tests (&toe’s sign, Frei~rg’s sign, piriformis sign, and Iasegue’s sign) are dependent upon the degree of dysfunction of the piriformis muscle and are therefore less sensitive indicators of the piriformis muscle syndmme. It is interesting that eight of our patients had a history of previous surgical procedures (often multi~~) on the lumbar spine. Whether these xiscing pirifarmia muscle this syndrome after sur-
ive, ~sutnab~y~ postamineecomysearrmg or arachnoiditis could Rsulc in cet~rin$ of the lumbar and sacral rants and fimit the normal tnovement of the ir~t~~i~ vie portion of the seiatie nerve during physical activity, Such limitation of movement could put the nerve uuder tension and ~tentia~~y enhance the impingement upon the nerve by the piriformis muscle during walking or jogging.‘a A history of failed lamin~tomy, discectomy, and chemonucleolysis, or a series of epidural methylprednisone acetate injections carried out with no change in the patient’s sciatica should certainly increase suspicion that piriformis muscle syndrome could be the problem. The fact that many of our patients had eiectromyographic evidence of radi~uIo~thy indicates that this finding does not rule out the possibility of a Coexistent piriformis muscle syndrome.‘” ce of low back pain, which ocThe pre
curred in 5 of our patients, may also mislead the physician.‘**t’ Low back pain, however, was nut the main complaint in other studies,‘*“*‘” and sciatica and pain in the buttock area (buttoek, sacroiliac,and trochancericareas) were the shief ~m~ai~ts for all of our 26 patients. DiHieulty in walking, limping, and exacerbatian of pain on sitting are frequent accompaniments of ~fo~is-India sciatica.‘” Irritation of the pudendal nerve frequently produces dyspareunia in female patients and rectal pain in male patients~.l”*“‘.‘” The dramatic and almost immediate relief of pain produced by infiltration of the piriformis mu&e with Ioealanesthetic is also considered to sign.” In order to infiltrate the piriformis muscle, Pace’s techniques has been aQmmanly advocated. This technique involves the insertion of a finger into the rectum to guide the tip of the percutaneous needle into the belly
of the pirifortnis muscle. We have observed that the rectal finger can cause extreme discomfort during this procedure. Therefore, we have modified the technique by a~ndoning the use of the rectal finger. Most of the time, in spite of its deep location, the piriformis muscle can be palpated as “sausage shaped,“a and the index finger can be steadied during the infiltration. If the muscle cannot be steadied between the 6ngers. then the needle can be inserted to make contact with the greater sciatic notch and then walked off that notch to enter the muscle. This technique was useful in ail cases and was also more acceptabie to the patients. In addition, the chance of any inadvertent contamination of
the needle with fecal material was eliminated. The local anesthetic apparently reverses the hyperirritability of the piriformis muscle, and produces relief that long outlasts the duration of the drug. ‘r In our patients. the duration of pain relief varied from a few weeks to 2.5 years. Ail local anesthetics can be utilized effectively. Ai~ough it might seem advantageous to use long-acting agents, our experience indicates that they are no more effective than the shortacting agents. If a long-acting drug is used and “spills over” onto the sciatic nerve, then the patient may be unable to ambulate for many hours.‘” Several inve st‘tgators have recommended the use of steroids aiong with the local anesthetics. but in view of our success with local anesthetics alone, the addition of steroids seems unnecessary. Similarly, others have advocated surgical sectioning of the piriformis muscle. And, we repeat, in view of our success with local anesthetic injections, such surgery seems unnecessary. In conclusion, we have presented a review of 26 patients who were diagnosed as having piriformis muscle syndrome. The diagnosis was made during a routine examination for low back pain and sciatica, which included a systematic evaluation of the piriformis muscle. Because of the similarity of symptoms to those of discogenic pain syndrome, patients with the pi~fo~is muscle syndrome can be easily misdiagnosed without such an examination. We feel that deep digital ~lpation of the piriformis muscle during rectal or pelvic examination should be a part of the routine examination for low back pain and sciatica. Reproduction of the sciatica upon rectal examination or deep digital palpation of the piriformis muscle appears to be diagnostic, as is
Vol. 6 No. 6
relief of pain upon infiltrative of t muscle with a local anesthetic. 0
tion of the ~~irif~)r~nis syndrome. 1!)74;105:181-187.
nosis is established, the treatment is easy and Long-term pain relief of sciatica can rewarding. be obtained with local anesthetic injection of the piriformis muscle and possibly with subsequent corrective physical therapy.
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