myopathy. Cardiomyopathy in mini-
disease has not been documented by tissue examination; however, it was described in a single family based on the presence of electrocardiographic changes.14 Cardiac abnormalities in central core disease have been limited to conduction abnormalities (WolfParkinson-White or bundle-branch block15), mitral valve prolapse, or hy¬ pertrophie cardiomyopathy. In our case the pathological findings suggest that respiratory failure was secondary to the severe degree of somatic myop¬ athy and not cor pulmonale. Similarities in sarcomeric ultrastructural abnormalities led Bethlem et al16 to postulate a common origin of rods, cores, minicores, and focal loss of cross striations. Observation of rods, cores, and minicores occurring concur¬ rently in skeletal muscle was later de¬ scribed by Vallet et al17 and Seitz et al.18 The pathogenesis of these myofiber al¬ terations is currently unknown. Docu¬ mentation of cardiac involvement in rod body disease5 7 and generalized sar¬ comeric disruption as in our case indi¬ cates that sarcomeric structural ab¬ normalities may be a more generalized disease process in some patients. This case should enhance our awareness of this possibility. Cardiomyopathy should be considered in patients with core
congenital myopathies, particularly unexplained conduction abnor-
with
malities or contractile insufficiency. It should be underscored that light-mi¬ croscopic studies may underestimate the abnormalities, and ultrastructural evaluation of skeletal and cardiac muscle may be necessary to define dis¬ orders such as those in our case. We thank Richard H. Geissler, Jr, for the excellent ultrastructural photomicroscopy. References 1.
Landing BH, Shankle WR, Dixon LG. Myo¬
pathie skeletal muscle fiber abnormalities in car¬ diomyopathies. Pediatr Pathol. 1983;1:137-143. 2. Karpati G, Carpenter S, Wolfe LS, Sherwin A. A peculiar polysaccharide accumulation in muscle in a case of cardioskeletal myopathy. Neurology. 1979;19:553-564. 3. Normand J, Carrier H, Berthillier G, et al.
Myocardiopathie primitive de l'enfant avec surcharge lipidique des fibres myocardiques et mus-
culaires et mise en evidence d'un deficit en enzyme palmityl-carnitine-transferase: a propos de 4 observations. Arch Mal Coeur. 1979;72:529-535. 4. Garancis JC, Panares RR, Good TA, Kuzma JF. Type 3 glycogenosis: a biochemical and electron microscopic study. Lab Invest. 1970:22:468\x=req-\ 477. 5. Meier mann
C, Voellmy W, Gertsch M, ZimmerA, Geissbuhler J. Nemaline myopathy ap-
as cardiomyopathy. Arch Neurol. 1984;41:443-445. 6. Meier C, Gertsch M, Zimmermann A, Voellmy W, Geissbuhler J. Nemaline myopathy presenting as cardiomyopathy. N Engl J Med.
pearing in adults
1983;308:1536-1537. 7. Stoessl AJ, Hahn AF, Malott D, Jones DT,
Silver MD. Nemaline myopathy with associated cardiomyopathy. Arch Neurol. 1985;42:1084-1086. 8. Bertorini T, Engle WK, DiChiro G, Dalakas
Unusual Cause of 'Piriformis Muscle Stephen M. Papadopoulos, MD; John E. McGillicuddy, MD; James \s=b\ The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and symptoms of sciatic nerve compression at the region of the piriformis muscle as it passes through the greater sciatic notch. The syndrome is often referred to; however, cases are rarely reported, and it is generally an uncommon diagnosis. Of those cases reported, the incidence is six times more frequent in females than in males, and is typically temporally related to minor pelvic or buttock trauma. We describe a
Accepted for publication November 3, 1989. From the Section of Neurosurgery and Department of Neurology, University of Michigan, Ann Arbor.
Reprint requests to Section of Neurology, University of Michigan Medical Center, 1500 E Medical Center Dr, 2128 Taubman Health Care Center, Box 0338, Ann Arbor, MI 48109-0338 (Dr Papadopoulos).
W.
M. Leukoencephalopathy in oculocraniosomatic neuromuscular disease with ragged red fibers: mitochondrial abnormalities demonstrated by computerized tomography. Arch Neurol. 1978; 35:643-647. 9. Fisher ER, Danowski TS. Mitochondrial myopathy. Am J Clin Pathol. 1969;51:619-630. 10. Shy GM, Gonatas NK, Perez M. Two childhood myopathies with abnormal mitochondria, 1: megaconial myopathy, 2: pleconial myopathy. Brain. 1966;89:133-158. 11. Senger RCA, TerHaar BGA, Trijbels JMF, Willems JL, Daniels O, Stadthonders AM. Congenital cataract and mitochondrial myopathy of skeletal and heart muscle associated with lactic acidosis after exercise. J Pediatr. 1975;87:873-880. 12. Hotchi TI. Pathology of the heart in Duchenne type progressive muscular dystrophy: a study on 60 autopsy cases. Shikoku Acta Med.
1975;31:295-310. 13. Shulz DM, Giordano DA. Hearts of infants and children: weights and measurements. Arch Pathol. 1962;74:464-471.
14. Bender AN. Congenital myopathies. In: Vinken PJ, Bruyn GW, eds. Handbook of Clinical Neurology. Amsterdam, the Netherlands: NorthHolland; 1979:16-20. 15. Ashfaq S, Paasuke RT, Brownell KW. Central core disease, clinical features in 13 patients. Medicine. 1987;66:389-396. 16. Bethlem J, Arts WF, Dingemans KP. Common origin of rods, cores, miniature cores, and focal loss of cross striations. Arch Neurol. 1978; 35:555-566. 17. Vallet JM, Lumley L, Loubet A, Corvisier N, Umdenstock R. Coexistence of minicores, cores and rods in the same muscle biopsy: a new example of mixed congenital myopathy. Acta Neuro-
pathol. 1982;58:229-232. 18. Seitz RJ, Toyka KV, Wechsler W. Adultonset mixed myopathy with nemaline rods, minicores,
and central
cores: a
muscle disorder mim-
icking polymyositis. J Neurol. 1984;231:103-108.
Syndrome'
Albers, MD, PhD
of a 40-year-old woman presenting signs and symptoms suggestive of piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. Electromyographic findings were consistent with this clinical entity. Operative exploration, howcase
with
ever, revealed the source of neural compression to be a pseudoaneurysm of the
inferior gluteal artery adjacent to the piriformis muscle. The diagnostic features of this clinical syndrome are discussed. (Arch Neurol. 1990;47:1144-1146)
symptoms of sciatic nerve compres¬ sion at the region of the greater sciatic notch. It has been attributed, by some, to spasm and irritation of the adjacent
piriformis muscle, although surgical evidence of clear compression is sparse.29 There are no unique or con¬ firmatory radiologie findings. How¬ ever, a nuclear medicine bone scan may
show
a
is often referred to in the literature,
rarely reported, extremely uncommon di¬ agnosis even in tertiary referral jenters.5 Of those cases reported, the and it is
Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/18/2015
sup¬
porting the diagnosis.10 The syndrome although
Veornan,1 in 1928, was the first to describe the relationship between the piriformis muscle and sciatic nerve pain. The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and
characteristic scintigraphic
pattern of the piriformis muscle, cases are
an
incidence is six times more common in females than in males and typically follows a history of minor pelvic or buttock trauma.5"9 We recently cared
for
a 40-year-old woman with clinical signs and symptoms suggestive of the piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. The electromyographic findings were con¬ sistent with a left lumbosacral plexopathy localized to or proximal to the piriformis muscle. Computed tomog¬ raphy (CT) was interpreted as showing an intramuscular piriformis hemato¬ ma.
REPORT OF A CASE
A 40-year-old woman underwent a rou¬ tine transvaginal needle biopsy, performed in the dorsal lithotomy position under gen¬ eral anesthesia. Preoperative CT scan showed a small intrapelvic mass thought to be consistent with endometriosis. Shortly after awakening, she complained of left buttock pain extending down the posterior thigh in a typical sciatic distribution. The pain did not improve and a CT scan of the pelvis was obtained 1 week following the biopsy. This showed a mass interpreted as an intramuscular hematoma of the piri¬ formis muscle on the left side (Fig 1). Over the ensuing 2 weeks, she continued to have severe buttock and sciatic pain. She also developed rapidly progressive plantar flex¬ ion and dorsiflexion weakness and was re¬ ferred for neurosurgical evaluation. Physical examination revealed a tender, nonpulsatile mass palpable in the region of the piriformis muscle. Muscle strength was graded (MRC scale; 5 normal; right/left) as follows: hip abduction, 5/3; knee flexion, 5/3; foot dorsiflexion, 5/4; foot inversion, 5/4; and foot plantar flexion, 5/3. Other muscle groups were normal. She had pain on resisted abduction and external rotation of the thigh. There was diminished sensa¬ tion in the distribution of the sciatic nerve, pudendal nerve, and the posterior cutane¬ ous nerve of the thigh. The left external hamstring and Achilles reflexes were ab¬
Fig 1.—Pelvic computed tomographic scan shows interpreted as an intramuscular hematoma.
a
diffuse
enlargement of the piriformis muscle
=
sent.
Nerve conduction studies performed 3 weeks after biopsy showed reduced ampli¬ tude tibial and sural evoked responses on the left side compared with the right side (50% reduction). Needle electromyography showed abnormal spontaneous activity and fibrillation potentials in muscles of sciatic and inferior and superior gluteal innerva¬ tion on the left side. In all of these muscles, recruitment was decreased and no volun¬ tary motor units were present in the gluteus médius, gluteus maximus, external ham¬ string, and medial gastrocnemius muscles. All recorded motor unit action potentials were of normal configuration. Paraspinal muscles were spared, as was the adductor longus muscle. These findings were inter¬ preted as consistent with a lesion involving the left lumbosacral plexus, with combined sciatic, inferior gluteal, and superior glu¬ teal nerve involvement. Because of persistent pain and progres¬ sive neurologic deficit, the patient was taken to the operating room for neural decompression and evacuation of the pre¬ sumed piriformis hematoma. A large
Fig 2.—This diagram depicts the relationship of the sciatic nerve, inferior gluteal nerve, superior gluteal nerve, posterior cutaneous nerve of the thigh, and pudendal nerve to the piriformis muscle.
pseudoaneurysm of the inferior gluteal
ar¬
discovered. Proximal control of the distal branches of the internal iliac ar¬ tery was achieved and the aneurysm was decompressed and oversewn. The patient did well postoperatively and, on 1-year follow-up, is pain free with near complete resolution of her neurologic defi¬ cits.
tery
was
COMMENT
The
relationship between sciatic pain and the piriformis muscle was first described by Yoeman1 in 1928. The "piriformis muscle syndrome" was further elucidated by Freiberg nerve
and Vinkle in 19342 and 19373 and Thiele in 1937.8 Although this syn¬ drome is often included in the differ¬ ential diagnosis of nondiscogenic sci-
Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/18/2015
atic, few
cases have been reported in the literature.110 Pace and Nagle5 re¬
an atypically high incidence, 45 (6%) of 750 patients seen in a tertiary referral (refractory to conventional treatment) back pain clinic. The inci¬ dence was six times higher in females than in males, and often followed a history of hip or pelvic trauma.5 It is emphasized by many authors that the diagnosis of piriformis muscle syndrome is made strictly on clinical criteria, without the support of neuro¬ physiologic or radiologie studies.5"9 Characteristic presenting complaints are pain and paresthesias in the glu¬ teal region radiating to the hip and posterior thigh in a sciatic radicular distribution.1"9 Female patients may
port
complain of dyspareunia.5·6 Report¬ edly, there is often distinct tenderness and reproduction of the patient's pain by deep palpation over the belly of the piriformis muscle, particularly toward the sciatic notch and
on
the lateral
pelvic wall by rectal or pelvic examin¬ 8
ation.5 Pain and weakness on resisted abduction and external rotation of the thigh, "Pace's sign," have been inter¬ preted as an indication of piriformis muscle irritability.5,6 This is tested with the patient seated, abducting the legs against the resistance of the ex¬ aminer's hands. "Freiberg's sign," pain on internal rotation of the ex¬ tended thigh, may also be positive.3·6 This maneuver tightens the piriformis muscle and causes pressure on the sci¬ atic nerve at the sacrospinous liga¬ ment. Diagnostic "trigger point" injec¬
tions with a local anesthetic or steroids may confirm the diagnosis, and also be a means of therapeutic relief.5-9 The symptoms of the piriformis syn¬ drome are thought to be due to entrap¬ ment of the sciatic nerve in the region of the greater sciatic notch due to hy-
perirritability, spasm, hypertrophy, or contracture of the piriformis mus¬ cle.1"9 The piriformis muscle arises along the anterior border of the sacrum and capsule of the sacroiliac joint (Fig 2). It then runs laterally, passing through the greater sciatic fo¬ ramen, converging into a tendonous
insertion on the greater trochanter of the femur. Typically, the sciatic nerve exits the greater sciatic foramen, pass¬ ing below the belly of the piriformis muscle. However, in 15% of autopsy specimens the sciatic nerve actually passes through the belly of the mus¬ cle.11 Additionally, the inferior gluteal nerve and artery and the posterior cu¬ taneous nerve of the thigh also emerge below the inferior border of the piri¬ formis muscle after passing through the greater sciatic foramen. The pudendal nerve also exits the greater sci¬ atic foramen along the inferior border of the piriformis muscle, but quickly re-enters the pelvis through the lesser sciatic foramen. The superior gluteal nerve and artery exit the pelvis through the greater sciatic foramen, coursing above the superior border of the piriformis muscle. The superior gluteal nerve innervates the gluteus
médius, gluteus minimus, and the su¬ perior portion of the gluteus maximus. The inferior gluteal nerve courses along the undersurface of the gluteus maximus, widely innervating that muscle. The piriformis muscle itself is innervated by branches from L5, SI, and S2. Functionally, the piriformis muscle is primarily an external rota¬ tor of the hip joint when the thigh is extended and an abductor of the flexed thigh. The piriformis muscle syn¬
drome, although primarily involving
the sciatic nerve, may also include in¬ volvement of the superior gluteal nerve, inferior gluteal nerve, pudendal
nerve, and posterior cutaneous nerve of the thigh.112 Our patient had pain and associated neurologic deficit in¬ volving the sciatic, inferior gluteal, superior gluteal, pudendal, and poste¬ rior cutaneous nerves. Gluteal artery aneurysms are quite rare; approximately 100 cases have been reported.1318 The vast majority of the cases have been pseudoaneurysms
following major pelvic trauma.14"17 The superior gluteal artery is involved most commonly in penetrating trauma and the inferior gluteal artery in blunt trauma.1415 One case of a superior glu¬ teal aneurysm due to an iatrogenic in¬ jury has been reported.17 Neurologic signs and symptoms may involve not only the sciatic nerve, but also the superior gluteal, inferior gluteal, pu¬ dendal, and posterior cutaneous nerves.1318 The diagnosis of piriformis muscle syndrome and/or gluteal artery aneu¬ rysm should be considered in cases of atypical sciatica with normal radiologic studies for an intraspinal cause. This is particularly important if there is evidence of involvement of the supe¬ rior gluteal nerve (weakness of the gluteus médius and minimus muscles), inferior gluteal nerve (weakness of the gluteus maximus muscle), pudendal nerves (peroneal sensory loss, includ¬ ing the scrotum or labia majora), and/ or the posterior cutaneous nerve of the thigh. The differential diagnosis of a mass lesion in the region of the piri¬ formis muscle also includes pyogenic or tuberculous abscess, soft-tissue sar¬ coma, sciatic hernia, hygroma, chron¬ ic bursitis, lipoma, and echinoccal cyst.1416 Intramuscular injection of a
Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/18/2015
local anesthetic and/or steroids re¬ sulting in amelioration of sciatic pain is considered a confirmatory diagnos¬ tic test for piriformis muscle syn¬ drome.6·9 It should be emphasized that
aspiration prior to diagnostic injection should always be performed to rule out other possible causes and avoid direct intravascular injection. Pelvic CT scan and magnetic resonance imaging may be helpful in evaluation of the perti¬ nent gluteal musculature and also in detecting a vascular lesion such as a gluteal artery aneurysm. References 1. Yeoman W. The relation of arthritis of the sacroiliac joint to the sciatica. Lancet. 1928; 2:1119-1122. 2. Freiberg AH, Vinkle TH. Sciatica and the sacroiliac joint. J Bone Joint Surg. 1934;16:126139. 3. Freiberg AH. Sciatic pain and its relief by operations on the muscle and fascia. Arch Surg.
1937;34:337-350.
4. Mizuguchi T. Division of the piriformis muscle for treatment of sciatica. Can J Anaesth.
1976;3:719-722. 5. Pace JB, Nagle D. Piriformis syndrome. West J Med. 1976;124:435-439. 6. Sokheim LF, Siewers P, Paus B. The piriformis muscle syndrome. Acta Orthop Scand. 1981;52:73-75. 7. Stewart JD. Focal Peripheral Neuropathies. New York, NY: Elsevier; 1987;279-280. 8. Thiele GH. Coccydynia and pain in the superior gluteal region. JAMA. 1937;109:1271-1275. 9. Wyant GM. Chronic pain syndromes and their treatment; III: the piriformis syndrome. Can Anaesth Soc J 1979;26:305-308. 10. Karl RD, Yedinak MA, et al. Scintigraphic appearance of the piriformis muscle syndrome. Clin Nucl Med. 1985;10:361-363. 11. Beaton LE, Anson BJ. The relation of the sciatic nerve and of its subdivisions to the piriformis muscle. Anat Rec. 1937;70:1-5. 12. Rusk MR. Superior gluteal nerve entrapment syndrome. Muscle Nerve. 1980;3:304-307. 13. Battle WH. A case of traumatic gluteal aneursym. Br Med J. 1898;5:1415-1416. 14. Hultborn KA, Kjellman T. Gluteal aneurysm: report of three
cases
and review of litera-
ture. Acta Chir Scand.
1963;125:318-325. 15. Meek GN, Hill RL. Surgical treatment of gluteal artery aneurysms. Am J Surg. 1968;116: 731-734. 16. Proschek R, Fowles JV, Broneau L. A case of post traumatic false aneurysm of the superior gluteal artery with compression of the sciatic nerve. Can J Surg. 1983;26:554-555. 17. Rankin RN, Youngson GG, McKenzie FN. Management of superior gluteal artery aneurysm with percutaneous balloon catheter occlusion: a
report. Surgery. 1979;85:235-237. Smyth NPD, Rizzoli HV, Ordman CW, Khourny JW, Chiucca JC. Gluteal aneurysm: case report. Arch Surg. 1965;91:1014-1020. case
18.
disease has not been documented by tissue examination; however, it was described in a single family based on the presence of electrocardiographic changes.14 Cardiac abnormalities in central core disease have been limited to conduction abnormalities (WolfParkinson-White or bundle-branch block15), mitral valve prolapse, or hy¬ pertrophie cardiomyopathy. In our case the pathological findings suggest that respiratory failure was secondary to the severe degree of somatic myop¬ athy and not cor pulmonale. Similarities in sarcomeric ultrastructural abnormalities led Bethlem et al16 to postulate a common origin of rods, cores, minicores, and focal loss of cross striations. Observation of rods, cores, and minicores occurring concur¬ rently in skeletal muscle was later de¬ scribed by Vallet et al17 and Seitz et al.18 The pathogenesis of these myofiber al¬ terations is currently unknown. Docu¬ mentation of cardiac involvement in rod body disease5 7 and generalized sar¬ comeric disruption as in our case indi¬ cates that sarcomeric structural ab¬ normalities may be a more generalized disease process in some patients. This case should enhance our awareness of this possibility. Cardiomyopathy should be considered in patients with core
congenital myopathies, particularly unexplained conduction abnor-
with
malities or contractile insufficiency. It should be underscored that light-mi¬ croscopic studies may underestimate the abnormalities, and ultrastructural evaluation of skeletal and cardiac muscle may be necessary to define dis¬ orders such as those in our case. We thank Richard H. Geissler, Jr, for the excellent ultrastructural photomicroscopy. References 1.
Landing BH, Shankle WR, Dixon LG. Myo¬
pathie skeletal muscle fiber abnormalities in car¬ diomyopathies. Pediatr Pathol. 1983;1:137-143. 2. Karpati G, Carpenter S, Wolfe LS, Sherwin A. A peculiar polysaccharide accumulation in muscle in a case of cardioskeletal myopathy. Neurology. 1979;19:553-564. 3. Normand J, Carrier H, Berthillier G, et al.
Myocardiopathie primitive de l'enfant avec surcharge lipidique des fibres myocardiques et mus-
culaires et mise en evidence d'un deficit en enzyme palmityl-carnitine-transferase: a propos de 4 observations. Arch Mal Coeur. 1979;72:529-535. 4. Garancis JC, Panares RR, Good TA, Kuzma JF. Type 3 glycogenosis: a biochemical and electron microscopic study. Lab Invest. 1970:22:468\x=req-\ 477. 5. Meier mann
C, Voellmy W, Gertsch M, ZimmerA, Geissbuhler J. Nemaline myopathy ap-
as cardiomyopathy. Arch Neurol. 1984;41:443-445. 6. Meier C, Gertsch M, Zimmermann A, Voellmy W, Geissbuhler J. Nemaline myopathy presenting as cardiomyopathy. N Engl J Med.
pearing in adults
1983;308:1536-1537. 7. Stoessl AJ, Hahn AF, Malott D, Jones DT,
Silver MD. Nemaline myopathy with associated cardiomyopathy. Arch Neurol. 1985;42:1084-1086. 8. Bertorini T, Engle WK, DiChiro G, Dalakas
Unusual Cause of 'Piriformis Muscle Stephen M. Papadopoulos, MD; John E. McGillicuddy, MD; James \s=b\ The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and symptoms of sciatic nerve compression at the region of the piriformis muscle as it passes through the greater sciatic notch. The syndrome is often referred to; however, cases are rarely reported, and it is generally an uncommon diagnosis. Of those cases reported, the incidence is six times more frequent in females than in males, and is typically temporally related to minor pelvic or buttock trauma. We describe a
Accepted for publication November 3, 1989. From the Section of Neurosurgery and Department of Neurology, University of Michigan, Ann Arbor.
Reprint requests to Section of Neurology, University of Michigan Medical Center, 1500 E Medical Center Dr, 2128 Taubman Health Care Center, Box 0338, Ann Arbor, MI 48109-0338 (Dr Papadopoulos).
W.
M. Leukoencephalopathy in oculocraniosomatic neuromuscular disease with ragged red fibers: mitochondrial abnormalities demonstrated by computerized tomography. Arch Neurol. 1978; 35:643-647. 9. Fisher ER, Danowski TS. Mitochondrial myopathy. Am J Clin Pathol. 1969;51:619-630. 10. Shy GM, Gonatas NK, Perez M. Two childhood myopathies with abnormal mitochondria, 1: megaconial myopathy, 2: pleconial myopathy. Brain. 1966;89:133-158. 11. Senger RCA, TerHaar BGA, Trijbels JMF, Willems JL, Daniels O, Stadthonders AM. Congenital cataract and mitochondrial myopathy of skeletal and heart muscle associated with lactic acidosis after exercise. J Pediatr. 1975;87:873-880. 12. Hotchi TI. Pathology of the heart in Duchenne type progressive muscular dystrophy: a study on 60 autopsy cases. Shikoku Acta Med.
1975;31:295-310. 13. Shulz DM, Giordano DA. Hearts of infants and children: weights and measurements. Arch Pathol. 1962;74:464-471.
14. Bender AN. Congenital myopathies. In: Vinken PJ, Bruyn GW, eds. Handbook of Clinical Neurology. Amsterdam, the Netherlands: NorthHolland; 1979:16-20. 15. Ashfaq S, Paasuke RT, Brownell KW. Central core disease, clinical features in 13 patients. Medicine. 1987;66:389-396. 16. Bethlem J, Arts WF, Dingemans KP. Common origin of rods, cores, miniature cores, and focal loss of cross striations. Arch Neurol. 1978; 35:555-566. 17. Vallet JM, Lumley L, Loubet A, Corvisier N, Umdenstock R. Coexistence of minicores, cores and rods in the same muscle biopsy: a new example of mixed congenital myopathy. Acta Neuro-
pathol. 1982;58:229-232. 18. Seitz RJ, Toyka KV, Wechsler W. Adultonset mixed myopathy with nemaline rods, minicores,
and central
cores: a
muscle disorder mim-
icking polymyositis. J Neurol. 1984;231:103-108.
Syndrome'
Albers, MD, PhD
of a 40-year-old woman presenting signs and symptoms suggestive of piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. Electromyographic findings were consistent with this clinical entity. Operative exploration, howcase
with
ever, revealed the source of neural compression to be a pseudoaneurysm of the
inferior gluteal artery adjacent to the piriformis muscle. The diagnostic features of this clinical syndrome are discussed. (Arch Neurol. 1990;47:1144-1146)
symptoms of sciatic nerve compres¬ sion at the region of the greater sciatic notch. It has been attributed, by some, to spasm and irritation of the adjacent
piriformis muscle, although surgical evidence of clear compression is sparse.29 There are no unique or con¬ firmatory radiologie findings. How¬ ever, a nuclear medicine bone scan may
show
a
is often referred to in the literature,
rarely reported, extremely uncommon di¬ agnosis even in tertiary referral jenters.5 Of those cases reported, the and it is
Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/18/2015
sup¬
porting the diagnosis.10 The syndrome although
Veornan,1 in 1928, was the first to describe the relationship between the piriformis muscle and sciatic nerve pain. The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and
characteristic scintigraphic
pattern of the piriformis muscle, cases are
an
incidence is six times more common in females than in males and typically follows a history of minor pelvic or buttock trauma.5"9 We recently cared
for
a 40-year-old woman with clinical signs and symptoms suggestive of the piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. The electromyographic findings were con¬ sistent with a left lumbosacral plexopathy localized to or proximal to the piriformis muscle. Computed tomog¬ raphy (CT) was interpreted as showing an intramuscular piriformis hemato¬ ma.
REPORT OF A CASE
A 40-year-old woman underwent a rou¬ tine transvaginal needle biopsy, performed in the dorsal lithotomy position under gen¬ eral anesthesia. Preoperative CT scan showed a small intrapelvic mass thought to be consistent with endometriosis. Shortly after awakening, she complained of left buttock pain extending down the posterior thigh in a typical sciatic distribution. The pain did not improve and a CT scan of the pelvis was obtained 1 week following the biopsy. This showed a mass interpreted as an intramuscular hematoma of the piri¬ formis muscle on the left side (Fig 1). Over the ensuing 2 weeks, she continued to have severe buttock and sciatic pain. She also developed rapidly progressive plantar flex¬ ion and dorsiflexion weakness and was re¬ ferred for neurosurgical evaluation. Physical examination revealed a tender, nonpulsatile mass palpable in the region of the piriformis muscle. Muscle strength was graded (MRC scale; 5 normal; right/left) as follows: hip abduction, 5/3; knee flexion, 5/3; foot dorsiflexion, 5/4; foot inversion, 5/4; and foot plantar flexion, 5/3. Other muscle groups were normal. She had pain on resisted abduction and external rotation of the thigh. There was diminished sensa¬ tion in the distribution of the sciatic nerve, pudendal nerve, and the posterior cutane¬ ous nerve of the thigh. The left external hamstring and Achilles reflexes were ab¬
Fig 1.—Pelvic computed tomographic scan shows interpreted as an intramuscular hematoma.
a
diffuse
enlargement of the piriformis muscle
=
sent.
Nerve conduction studies performed 3 weeks after biopsy showed reduced ampli¬ tude tibial and sural evoked responses on the left side compared with the right side (50% reduction). Needle electromyography showed abnormal spontaneous activity and fibrillation potentials in muscles of sciatic and inferior and superior gluteal innerva¬ tion on the left side. In all of these muscles, recruitment was decreased and no volun¬ tary motor units were present in the gluteus médius, gluteus maximus, external ham¬ string, and medial gastrocnemius muscles. All recorded motor unit action potentials were of normal configuration. Paraspinal muscles were spared, as was the adductor longus muscle. These findings were inter¬ preted as consistent with a lesion involving the left lumbosacral plexus, with combined sciatic, inferior gluteal, and superior glu¬ teal nerve involvement. Because of persistent pain and progres¬ sive neurologic deficit, the patient was taken to the operating room for neural decompression and evacuation of the pre¬ sumed piriformis hematoma. A large
Fig 2.—This diagram depicts the relationship of the sciatic nerve, inferior gluteal nerve, superior gluteal nerve, posterior cutaneous nerve of the thigh, and pudendal nerve to the piriformis muscle.
pseudoaneurysm of the inferior gluteal
ar¬
discovered. Proximal control of the distal branches of the internal iliac ar¬ tery was achieved and the aneurysm was decompressed and oversewn. The patient did well postoperatively and, on 1-year follow-up, is pain free with near complete resolution of her neurologic defi¬ cits.
tery
was
COMMENT
The
relationship between sciatic pain and the piriformis muscle was first described by Yoeman1 in 1928. The "piriformis muscle syndrome" was further elucidated by Freiberg nerve
and Vinkle in 19342 and 19373 and Thiele in 1937.8 Although this syn¬ drome is often included in the differ¬ ential diagnosis of nondiscogenic sci-
Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/18/2015
atic, few
cases have been reported in the literature.110 Pace and Nagle5 re¬
an atypically high incidence, 45 (6%) of 750 patients seen in a tertiary referral (refractory to conventional treatment) back pain clinic. The inci¬ dence was six times higher in females than in males, and often followed a history of hip or pelvic trauma.5 It is emphasized by many authors that the diagnosis of piriformis muscle syndrome is made strictly on clinical criteria, without the support of neuro¬ physiologic or radiologie studies.5"9 Characteristic presenting complaints are pain and paresthesias in the glu¬ teal region radiating to the hip and posterior thigh in a sciatic radicular distribution.1"9 Female patients may
port
complain of dyspareunia.5·6 Report¬ edly, there is often distinct tenderness and reproduction of the patient's pain by deep palpation over the belly of the piriformis muscle, particularly toward the sciatic notch and
on
the lateral
pelvic wall by rectal or pelvic examin¬ 8
ation.5 Pain and weakness on resisted abduction and external rotation of the thigh, "Pace's sign," have been inter¬ preted as an indication of piriformis muscle irritability.5,6 This is tested with the patient seated, abducting the legs against the resistance of the ex¬ aminer's hands. "Freiberg's sign," pain on internal rotation of the ex¬ tended thigh, may also be positive.3·6 This maneuver tightens the piriformis muscle and causes pressure on the sci¬ atic nerve at the sacrospinous liga¬ ment. Diagnostic "trigger point" injec¬
tions with a local anesthetic or steroids may confirm the diagnosis, and also be a means of therapeutic relief.5-9 The symptoms of the piriformis syn¬ drome are thought to be due to entrap¬ ment of the sciatic nerve in the region of the greater sciatic notch due to hy-
perirritability, spasm, hypertrophy, or contracture of the piriformis mus¬ cle.1"9 The piriformis muscle arises along the anterior border of the sacrum and capsule of the sacroiliac joint (Fig 2). It then runs laterally, passing through the greater sciatic fo¬ ramen, converging into a tendonous
insertion on the greater trochanter of the femur. Typically, the sciatic nerve exits the greater sciatic foramen, pass¬ ing below the belly of the piriformis muscle. However, in 15% of autopsy specimens the sciatic nerve actually passes through the belly of the mus¬ cle.11 Additionally, the inferior gluteal nerve and artery and the posterior cu¬ taneous nerve of the thigh also emerge below the inferior border of the piri¬ formis muscle after passing through the greater sciatic foramen. The pudendal nerve also exits the greater sci¬ atic foramen along the inferior border of the piriformis muscle, but quickly re-enters the pelvis through the lesser sciatic foramen. The superior gluteal nerve and artery exit the pelvis through the greater sciatic foramen, coursing above the superior border of the piriformis muscle. The superior gluteal nerve innervates the gluteus
médius, gluteus minimus, and the su¬ perior portion of the gluteus maximus. The inferior gluteal nerve courses along the undersurface of the gluteus maximus, widely innervating that muscle. The piriformis muscle itself is innervated by branches from L5, SI, and S2. Functionally, the piriformis muscle is primarily an external rota¬ tor of the hip joint when the thigh is extended and an abductor of the flexed thigh. The piriformis muscle syn¬
drome, although primarily involving
the sciatic nerve, may also include in¬ volvement of the superior gluteal nerve, inferior gluteal nerve, pudendal
nerve, and posterior cutaneous nerve of the thigh.112 Our patient had pain and associated neurologic deficit in¬ volving the sciatic, inferior gluteal, superior gluteal, pudendal, and poste¬ rior cutaneous nerves. Gluteal artery aneurysms are quite rare; approximately 100 cases have been reported.1318 The vast majority of the cases have been pseudoaneurysms
following major pelvic trauma.14"17 The superior gluteal artery is involved most commonly in penetrating trauma and the inferior gluteal artery in blunt trauma.1415 One case of a superior glu¬ teal aneurysm due to an iatrogenic in¬ jury has been reported.17 Neurologic signs and symptoms may involve not only the sciatic nerve, but also the superior gluteal, inferior gluteal, pu¬ dendal, and posterior cutaneous nerves.1318 The diagnosis of piriformis muscle syndrome and/or gluteal artery aneu¬ rysm should be considered in cases of atypical sciatica with normal radiologic studies for an intraspinal cause. This is particularly important if there is evidence of involvement of the supe¬ rior gluteal nerve (weakness of the gluteus médius and minimus muscles), inferior gluteal nerve (weakness of the gluteus maximus muscle), pudendal nerves (peroneal sensory loss, includ¬ ing the scrotum or labia majora), and/ or the posterior cutaneous nerve of the thigh. The differential diagnosis of a mass lesion in the region of the piri¬ formis muscle also includes pyogenic or tuberculous abscess, soft-tissue sar¬ coma, sciatic hernia, hygroma, chron¬ ic bursitis, lipoma, and echinoccal cyst.1416 Intramuscular injection of a
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local anesthetic and/or steroids re¬ sulting in amelioration of sciatic pain is considered a confirmatory diagnos¬ tic test for piriformis muscle syn¬ drome.6·9 It should be emphasized that
aspiration prior to diagnostic injection should always be performed to rule out other possible causes and avoid direct intravascular injection. Pelvic CT scan and magnetic resonance imaging may be helpful in evaluation of the perti¬ nent gluteal musculature and also in detecting a vascular lesion such as a gluteal artery aneurysm. References 1. Yeoman W. The relation of arthritis of the sacroiliac joint to the sciatica. Lancet. 1928; 2:1119-1122. 2. Freiberg AH, Vinkle TH. Sciatica and the sacroiliac joint. J Bone Joint Surg. 1934;16:126139. 3. Freiberg AH. Sciatic pain and its relief by operations on the muscle and fascia. Arch Surg.
1937;34:337-350.
4. Mizuguchi T. Division of the piriformis muscle for treatment of sciatica. Can J Anaesth.
1976;3:719-722. 5. Pace JB, Nagle D. Piriformis syndrome. West J Med. 1976;124:435-439. 6. Sokheim LF, Siewers P, Paus B. The piriformis muscle syndrome. Acta Orthop Scand. 1981;52:73-75. 7. Stewart JD. Focal Peripheral Neuropathies. New York, NY: Elsevier; 1987;279-280. 8. Thiele GH. Coccydynia and pain in the superior gluteal region. JAMA. 1937;109:1271-1275. 9. Wyant GM. Chronic pain syndromes and their treatment; III: the piriformis syndrome. Can Anaesth Soc J 1979;26:305-308. 10. Karl RD, Yedinak MA, et al. Scintigraphic appearance of the piriformis muscle syndrome. Clin Nucl Med. 1985;10:361-363. 11. Beaton LE, Anson BJ. The relation of the sciatic nerve and of its subdivisions to the piriformis muscle. Anat Rec. 1937;70:1-5. 12. Rusk MR. Superior gluteal nerve entrapment syndrome. Muscle Nerve. 1980;3:304-307. 13. Battle WH. A case of traumatic gluteal aneursym. Br Med J. 1898;5:1415-1416. 14. Hultborn KA, Kjellman T. Gluteal aneurysm: report of three
cases
and review of litera-
ture. Acta Chir Scand.
1963;125:318-325. 15. Meek GN, Hill RL. Surgical treatment of gluteal artery aneurysms. Am J Surg. 1968;116: 731-734. 16. Proschek R, Fowles JV, Broneau L. A case of post traumatic false aneurysm of the superior gluteal artery with compression of the sciatic nerve. Can J Surg. 1983;26:554-555. 17. Rankin RN, Youngson GG, McKenzie FN. Management of superior gluteal artery aneurysm with percutaneous balloon catheter occlusion: a
report. Surgery. 1979;85:235-237. Smyth NPD, Rizzoli HV, Ordman CW, Khourny JW, Chiucca JC. Gluteal aneurysm: case report. Arch Surg. 1965;91:1014-1020. case
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