Advanced Clinical Updates

It's a rare adult who hasn't suffered from sciatica at one time or another. Yet when these people seek care, most clinicians immediately think of disk disease or entrapment of the nerve root in the lateral recess(spinal stenosis). Many physicians unfortunately tend to overlook some of the common nodiskogenic causes of low back pain with radiation to the leg, there by subjecting there patients to unnecessary influence of therapeutic procedures.

Sciatica may well be a symptom of disk disease or root entrapment, but it may also portend a host of other common disorders. Many physicians consider low back pain and sciatica may receive only generic treatment: bedrest, muscle relaxants, analgesics, and physical therapy. If these do not work, the patient often often seeks a second option, and a diagnostic workup continues. Sooner or later -- and as costs mount -- procedures that exact considerable expense and/or misery and that frequently prove unnecessary.1

The truth is that most causes of sciatica lend themselves to specific and less costly therapy. Physicians who look for the non-diskogenic causes of sciatica can often clinch the diagnosis--and relieve the patient's pain-- on the spot. However, estimated 8 million Americans who are victims of low back pain and sciatica currently incur $5-6 billion dollars annually in diagnostic and therapeutic costs, not to mention $14 million billion per year in days lost from work, worker's compensation, disability payments, and litigation. 2

Dr. Namey's article helps physicians diagnose and treat the nine entities most commonly confused with disk disease or nerve root entrapment in a cost- effective manner. He emphasizes the clinical features of these disordersand help distinguish among them with a minumum of expensive and evasive tests. For each entity reviwed, Dr.Namey addresses on question of how to provide specific therapy in an out patient setting and return the patient to optimum function.

-Editor's note

The Non Diskogenic Causes of Sciatica

To provide specific therapy for patients presenting with sciatica, physicians must consider a host of other syndromes that frequently mimic lumbar disk disease and go unrecognized. These conditions -- sacroiliitis, piriformis syndrome, iliolumbar syndrome, quadratus lumborum syndrome, trochanteric bursitis, ischiogluteal bursitis, facet syndrome, meralgia parasthetica, and fibrositis syndrome -- may exist seperately or in tandem with another back disorder. Each of these conditions(with the exception of meralgia parasthetica) occurs more commonly than a herniated nucleus pulposis.

Patients may also present with more than one underlying cause of sciatica. Degenerative disk disease often accompanies the lateral entrapment syndrome. Likewise sacroiliitis, spondylitis, and paraspinal spasm sometimes occur in the same patient. Most physicians are also aware that the back pain can mask psychological problems. Patients who are anxious, covertly depressed, or suffering from intrapersonal conflicts often present with a chief complaint of back pain.

Sacroiliitis: Poosibile Harbinger of the Seronegative Spondyloarthropathies

At least 2-3% of the population suffers from sacroiliitis, a frequent initial manifestation of one of the seronegative Spondyloarthropathies. Most patients however, do not develop manifestations of overt spine disease other than "lumbago", an old term for sacroiliitis.
Pathogenesis: Sacroiliitis presents most commonly in young people who are HLA-B27 positive and/or have ankylosing spondylitis, psoriatic arthritis, Reiter's disease, or arthritis related to inflammotory bowel disease.3,4 Reiter's disease commonly causes sacroiliitis in young men, which frequently precedes or follows heel pain, plantar fasciitis, metarsalgia, or knee problems.5 A recent history of venereal infection(gonorrhea, Chlamydia, or both) is significant. Also women with sacroiliitis often have an episode of cystitis, cervicitis(possibly asymptomatic), or tubal infection.6

The piriformisis muscle is frequently the major site of pain in sacroiliitis(due to inflammation of its insertion into the lower third of the SI joint). Thus, piriformis syndrome may also occur secondaryto sacroiliitis, causing classic manifestations of sciatica and complicating diagnosis(see below).

Diagnosis: Though sacroiliitis' onset is usually subacute, patients often attribute its symptoms to trauma or work related activities ("the simplest cause and effect" phenomenon). Clinical manifestations may refer to either or both SI joint(s), depending on whether inflammation is unilateral or bilateral. With unilateral disease, right-sided involvement is more common. 7

Patients describe pain in the low back, buttocks, and/or the lateral thigh, referred leg pain that may radiate as far as the ankle and, occasionally sensory changes. Pain and stiffness upon arising, later relieved by activity(such as showering), is an important clue to the disorder. Severe pain may awaken the patient spontaneously.

The family history is also significant, since the tendency to develop sacroiliitis is inherited. Look for a family history of "back problems" or related disease, such as colitis, psoriasis, or peripheral arthritis.

Physical examination reveals tenderness over the sacroiliac joints. Frequently, anterior spinal flexion is decreased and this is best documented by Schober test.*8 Stressing the sacroiliac joint with lateral compression of the pelvis is painful, and the second stage of the two-stage Patrick's test is frequently positive(Fig. 2). These maneuvers are not specific for sacroiliitis, however.

Either the erythrocyte sedimentation rate(ESR) and/or C-reactive protein (CRP) levels are usually elevated, serving as markers of the degree of inflammation. Always obtain both of these studies before ruling out sacroiliitis.

Radiographs may reveal erosions, sclerosis, bony bridging, and even fusion of the sacroiliac joints, but these changes are raely overt in the early stages of disease.9 Physicians who suspect sacroiliitis in the fcae of normal x-rays should order a bone scan. Enhanced uptake of technetium phosphates in the sacroilic joints indicates active sacroiliitis, and clearly active but asymptomatic sacoiliitis may also be evident.10

Management: Clinical management of sacroiliitis is threefold: identifying and treating the underlying disease, administering nonsteroidal anti-inflammotory drugs(NSAIDs) and, in some cases, injecting the affected sacroiliac joints and/or piriformis muscle with corticosteroids and local anesthetics(see below).

Identifying Piriformis Syndrome

Distinguishing piriformis syndrome--spasm, irritation, or inflammation of the piriformis muscle-- from a herniated nucleus pulposus often proves confusing, since sciatica is common to both entities.11 The piriformis muscle arises from the pelvic surface of sacrum at the sacroiliac capsule, crosses the sciatic nerve at the sciatic notch, and inserts on the upper border of the greater trochanter of the femur(Fig.3). It externally rotates the femur and abducts the thigh when limb is flexed.

Pathogenesis. Sacroiliitis, direct trauma, and arthritis of the hip joint are among the most common causes of piriformis syndrome12. Mechanisms of Injury can include 1) inflammation of the muscle's insertion into the SI joint, 2) trauma of the muscle(a fall on the buttocks), or 3)spraining the hip attachment(via a fall on ice where the legs slides out laterally). The piriformis can also be myofascial "trigger point" in the fibrositis syndrome(see below). All of these factors can cause sciatica because of the muscle's anatomic relationship to the sciatic nerve.

Diagnosis. Patients with piriformis syndrome frequently give a history of either 1) a minor twisting injury that occurs while lifting or carrying a heavy weight or 2)direct trauma to the buttock, such as fall. As with a herniated lumbar disk, patients may complain of severe buttock pain that radiates down the back of the thigh to the knee and sometimes, as far as ankle, foot, or toes.13, 14 Spasm of the left piriformis muscle can cause "rectal" pain, particularly with defecation or constipation. Women may also complain of perineal pain and dyspareunia or more commonly, pain when separating the legs prior to intercourse.

Though straight-leg raising and patrick's tests also are positive in lumbar disk disease, other physical findings are specific to piriformis syndrome. Look for 1) pain and weakness on resisted abduction/external rotation of the thigh and 2) persistent external rotation of the leg when the patient lies supine on the table14. The affected extremity frequently reveals tonic external rotation of the affected extremity relative to the contalateral side("positive pyriformis sign")(Fig. 4). Also look for the tenderness on palpation of the muscle medial to the trochanter. Demonstrate pain on muscle contraction by asking the patient to sit on the examination table with knees apart, ankles together, and to attempt to resist the physician's attempt to bring the knees together.13

On rectal examination, the piriformis muscle is usually exquisitely tender. Digital pressure applied to the unaffected side should not cause discomfort, but pressure to the involved piriformis muscle elicits a painful sciatic radiation.

Management Injection of the piriformis muscle is both diagnostic and therapeutic. Before begining the procedure, assemble a tray containing 1% Lidocaine and either 1) combination of 0.75% bupivacaine HCI(Marcaine) and one of the hydrocortisone derivatives or 2) Sarapin®* (an aqueous distillate Sarracenia purpurea, the pitcher plant, which blocks pain fiber transmission, but not sensory or motor function). Also have on hand a 4 to 6-inch gauge spinal needle and appropriate prepping material.

Position the patient with affected side with uppermost, with hip and knees flexed. Insert one finger of the non-dominant hand in the patient's rectum over the tender muscle between the sacrum and ischial spine. With the other hand introduce the needle from the back, midway between the lateral aspect of the sacrum and greater trochanter. Direct the needle toward the finger in rectum until you feel it just below the mucosa. Withdraw one centimeter, and inject 2-3 ml of lidocaine to ensure the needle is not in the vicinity of sciatic nerve.(Occasionally, the piriformis muscle "twitches" when the belly of the muscle is punctured, sending a shock down the leg, but this sensation disappears immediately). Then inject 2-3 ml of bupivacaine/corticosteroid mixture or Sarapin®.

If the diagnosis of piriformis syndrome is correct, dramatic relief occurs within 10-15 minutes of injection.15 Some physicians argue, however, that the injection of piriformis "blocks" the sciatic nerve and does not necessarily discriminate between piriformis syndrome and primary sciatic neuritis. But successful injection excludes more proximal compression of the sciatic nerve(i.e., that secondary to a ruptured disk).

A caveat: Many patients experience numbness in the distribution of the sciatic nerve following injection. This abates quickly, but physicians should warn their patients about this possible effect. The patient should not leave the office unassisted and should certainly not drive.(The onset of action of Sarapin® is slower, so this effect may occur in a delayed fashion when the drug is used).

Iliolumbar Syndrome: A Commonly Unrecognized Cause of Sciatica
Iliolumbar syndrome-- also known as lumbosacral sprain--is a frequently unrecognized cause of sciatica that results from inflammation, sprain, or tear of the iliolumbar ligament. This ligament bridges the transverse process of the fifth lumbar vertebra and iliac crest(Fig. 5). People who lift heavy objects while rotating the back--lifting crates off a truck for example-- are especially prone to the iliolumbar syndrome.

Diagnosis: Patients complain of pain that varies from a constant, dull ache aggravated by activity to extreme severity. Pain is usually localized to the posterior portion of one or the both iliac crests (patients can often point to the precise site), but may spread across iliolumbar region.

A careful musculoskeletal examination usually illicits the pathognomonic signs of iliiolumbar syndrome. The most typical sign is tenderness of palpation of the posterior iliac crest on the involved side. Patients frequently have a discrepancy in leg length 1.5 cm or more, and pain and sciatica are more pronounced on the side of the longer leg16. Increasing pain with lateral bending away from the involved side is the characteristic sign of ilio lumbar syndrome.17

Patients report pain in the iliac crest or directly below on straight-leg raising. To distinguish this pain from that associated with disk herniation, the physician should flex one of the patient's hips (with the knee also flexed) through its full range while holding the opposite leg down on the table. If this maneuver causes back pain on the involved side, the test is positive. (In the root compression syndrome, it causes only minimal discomfort, or even relief, since the sciatic nerve is relaxed and exerts less pull on the nerve root).17 Neurological examination is normal in patients with iliolumbar syndrome.

Management. Local injection -- best done with a combination of 1-2% lidocaine and 1-2 ml betamethasone--should relieve pain, thus confirming the diagnosis. Many patients require atleast 2-inch needle, but some need the full length of 3 1/2-inch spinal needle, so be prepared. Before injection, spray the surface of the skin with a "freezing" spray such as ethyl chloride. Approach the patient from 1-2 cm above the insertion of iliolumbar ligament at an angle that allows you to hit its insertion directly(Fig. 6). If the presumptive diagnosis is correct, the above tests should be negative. Obviously, patients who have a leg length discrepancy must later be fitted for corrective shoes.

Quadratus Lumborum Syndrome

Diagnosis of quadratus lumborum -- a condition related to, but less common than, iliolumbar syndrome-- is relatively easy for physicians who are aware that syndrome exists. The quadratus lumborum muscle arises from iliolumbar ligament and posterior iliac crest and inserts at the lower border of the last rib and the transverse processes of the lower four lumbar vertebrae. The mechanism of injury is known, but some experts believe that the strain to the muscle on one side results in rupturing a few fibers, with hypertenocity and ischesmia.13

Diagnosis. The patient usually presents with posterior iliac tenderness with referred pain to the groin, inner or anterior thigh, and/or inner calf.15 Physical examination reveals tenderness on palpation of the affected muscle and/or when the patient bends contralateral side. Pain symptoms are virtually identical to those of iliolumabr syndrome, with two exceptions: 1) adjacent ipsilateral paraspinal muscle spasm is more common and 2) pressure in the middle of the the 12th "floating" rib on the affected side causes pain in quadratus lumborum syndrome, because quadratus attaches to this rib. This latter finding is the best discriminating feature.

Management includes injection of affected muscle and exercise. Either 1) 3-4 ml of Lidocaine or 2) Sarapin® with 1 ml of corticosteroid provides relief of pain. Inject the paraspinal area of the quadratus midway between the iliac crest attachment and floating rib (both landmarks should be identified with marking pen). Also advise patients to begin stretching of the muscle, followed by an active exercise program.

Trochanteric Bursitis

Trochanteric bursitis is a form of pelvic pain commonly misdiagnosed as a lombosacral problem or arthritis of the hip. This entity is a frequent cause of sciatica in elderly patients.18 Many such patients also have leg length discrepancy but, unlike iliolumbar syndrome, the disease occur on the "short" side. Trochanteric bursitis is also associated with osteoarthritis of ipsilateral hip.19

Diagnosis. Diffuse pain in buttock and lateral thigh with marked point tenderness over greater trochanter strongly suggests Trochanteric bursitis. Patients most commonly complain of deep, aching pain, but may relate burning and tingling as well. They often report that lying on the affected side(s) is uncomfortable, as is sitting with affected leg crossed over. Activity aggrevates pain and, though rest relieves it, the pain pradoxically worsens at night. In the elderly, referred pain may suggest an L5 nerve radiculopathy.

To examine for point tenderness, have the patient assume the lateral recumbent position with the painful side upper most. Palpate the lateral aspect of the thigh from below the greater trochanter. Moving proximally, palpate the bony edge of the trochanter which, along with the bone above it, is covered with trochanteric bursa. If firm pressure over bursa causes pain and the other bony prominences are not painful, make the presumptive diagnosis of trochanteric bursitis.18

Significant radiographic findings include periosteal "fluffing" on the lateral aspect of the involved greater trochanter. Occasionally, one may see calcification within the bursa itself.

Management. Consists of injecting a local anesthetic and a corticosteroid into the point of maximal tenderness at the trochanteric bursa(Fig. 7). First palpate the "fall-off" point of the greater trochanter. The point to inject lies 1-2 cm below the line, between anterior and posterior aspects of the femur. (It's helpful to "draw" the femur and the fall-off on the patient's skin). Inject the bursa with 1-2 ml of corticosteroids with1-2 ml of lidocaine.

Ischiogluteal Bursitis: The Classical Pain in The Arse

Suspect ischiogluteal bursitis in patients with the pain localized primarily to the buttock. Non-orthopedic physicians often misdiagnose this entity, in particular, mistake it for a herniated lumbar disk.20

Diagnosis. Ischiogluteal bursitis has earned its nick name with good reason. Patients complain bitterly of severe, unrelenting pain the center of the buttock, which is aggravated by sitting or walking, is often accompanied by referred pain down the leg, and is unrelieved by bed rest.21 One characteristic that differentiates Ischiogluteal Bursitis from herniated lumbar disk is that the patients give a history of "tossing and turning all night" in a futile effort to find a comfortable position. Patients with a herniated disk, in contrast, lie absolutely still so as not to exacerbate pain and spasm.21

On physical examination, the patient often presents the bedraggled appearance of one who has not slept. Tenderness is maximal at the ischial tuberosity, and the patient may sit on the examining table with the affected buttock elevated to avoid pressure on it. As with a herniated lumbar disk, the straight-leg raising test is positive, but Patrick's test, which is negative in disk disease, is also positive. Rectal examination, though difficult to perform on supine patients(they cannot flex their hips acutely), should still be performed. On the lateral rectal wall on the painful side, physicians may note an area of bulging, doughly-feeling, inflamed tissue.21 Pressure on this spot may cause such excruciating pain that the patient may scream inadvertently.

Differential considerations include acute gout and pseudo gout. Both of these conditions can affect bursae and must be excluded as a precipitating cause.

Management. Patients suffering from ischiogluteal bursitis deserve the physician's best efforts at the pain relief. Initial treatment includes atleast 3 or 4 days of bed rest and NSAIDs. Advise the patient to sit on a pillow or a soft "doughnut" when out of bed.

Patients in severe pain require injection of 2 ml of corticosteroid and 2-5 ml of 1% lidocaine into the bursa, which may need to be repeated as often as every two days. Relief occurs in hours of injection, which should be done with patient in fetal position or leaning forward over a table. After the acute episode has passed, patients may experience perceived weekness of the foot and leg muscles for several weeks.

Posterior Facet Syndrome: A common Misdiagnosis

Posterior facet syndrome-instability of the back-is a much-abused and maligned diagnosis. Yet some patients suffer back pain caused by a chronic synoival inflammation and degenerative disease and instability in the facet joints, most frequently those of L4-5and L5-S1 vertebrae (Fig. 8).22 Posterior facet syndrome often accompanies degenerative disk disease and spinal stenosis13.

Diagnosis. Patients with posterior facet syndrome usually complain of maximum pain in the lower back. This pain may radiate down the posterior thigh to the knee, but rarely below the calf (in contrast to sciatica associated with lumbar disk herniation). The pain is usually lateral, despite the anatomy of the facet. It is aggravated by activity and helped somewhat by external bracing.

When examining the patient, look for limitation of spinal movements and tenderness at the lower lumbar, vertebral, and sacral regions. Lateral bending with extension of the spine often causes the most pain. Neurological examination is usually normal, but there may be slight dimunition of sensation over one or more dermatomes. Oblique and lateral radiographic views with the patient in flexion may reveal the presence of abnormal posterior facets.15

Management. Refer patients with posterior facet syndrome for specific therapy, depending on the pathophysiologic process involved. Options include injecting a local anesthetic and corticosteroid into facet joints, manipulation of the spine, or surgical fusion. Only a neurosurgeon, orthopedist, or rheumatologist trained in injection of the facet joints should attempt injection, and then only under fluoroscopy.

Meralgia Parasthetica

Meralgia parasthetica-an entrapment neuralgia of a lateral femoral cutaneous nerve-is called by a variety of disorders and can occasionally be confused with sciatica. Pressure along the nerve at any point by a tumor, infection, fetus, obesity, or traction, can produce symptoms.

Diagnosis of meralgia parasthetica usually poses little difficulty, although pinpointing the underlying cause may prove more problematic. Patients present with burning pain and/or parasthetica-described as "pins and needles"-of the anterolateral aspect of the thigh. Symptoms are usually unilateral, but both thighs may be involved. The pain is usually associated with walking or long periods of standing and is relieved by rest. Firm pressure on the affected area may not cause discomfort, but a light brushing (such as that caused by clothing) often produces an unpleasant tingling sensation.11

Management. If the nerve is involved as it passes over the brim of the iliac crest, a lateral femoral cutaneous nerve block (just below the anterosuperior iliac spine and, Iliolingual ligament) is both diagnostic and curative. An ineffective block warrants the need for a more extensive neurological workup (including radiographs of the spine and, sometimes myelography). Patients with refractory symptoms may eventually require a surgical section or neurolysis.

Fibrositis: A Disabling But Treatable Syndrome

For a half a century, clinicians believed that all back pain was attributable to Fibrositis, a disorder characterized b musculoskeletal hyperalgesia and stiffness at characteristic trigger points (Fig. 9).23 This pain syndrome, a form of soft tissue rheumatism, is not a true inflammatory process, since it is not associated with local leukocyte infiltration or changes in blood or serum characteristic of true inflammation.20 Consider fibrositis in a patient with poor sleep, and chronic pain, particularly if the patient is anxious, appears depressed, or manifests obsessive-compulsive behavior. Though it is a painful and debilitating disorder, it responds dramatically to non-specific or local therapy.

Diagnosis. In addition to describing widespread pains, patients with fibrositis usually have 3 sleep related complaints, even if they do not admit to insomnia.23 They 1) awaken with pain, 2) feel tired upon awakening, and 3) feel fatigued during the day. If at least two of these problems are not present, fibrositis is an unlikely diagnosis. Exhaustion may be the most disabling feature of fibrositis, but patients usually emhasize the pain and minimize the sleep disturbance.24

Pain is widely distributed, but is usually predominant along broad areas of the cervical and lumbar spine and is aggravated by stimulation of "trigger points". Another cardinal feature of the disease is a history of poor relief of pain from NSAIDs. All the disorders discussed above will respond-at least in part to NSAIDs-but fibrositis does not.

Given this history, physicians unfamiliar with the signs of fibrositis may initially suspect psychiatric illness. However, certain cardinal features are reproducible from patient to patient with fibrositis and should always be sought.25 At least 16 points of maximum tenderness ("trigger points") exist, which may be unknoiwn to the patient. There may be marked areas in skin tenderness, particularly over the scapular area. Reactive Hyperemia-visible evidence of pain in the region-is often present.

Management of fibrositis multifold. Most patients respond to direct injection of the trigger points with either lidocaine or lidocaine with corticosteroid. Steroids alone prove of little value, since the condition is not true inflammation, but including lidocaine helps to alleviate the pain of the injection.

Patients with depression or sleep disturbances may benefit from low tricyclic antidepressants, L-tryptophan, and/or psychiatric referral. Amitryptiline (Elavil, Endep) 50-75 mg or Doxepin (Sinequan, Adapin) 25-50 mg, given at bedtime, may also induce sleep in patients unable or unwilling to take antidepressants.

Finally, exercise has several benefits: it alleviates stress, promotes sleep, and generates a feeling of well-being. Aerobic exercise, particularly if done in the morning, helps patients feel better and aids sleep, which is essential to the correction of this disorder.

Helping the Patient Avoid Further Disability

In addition to specific therapy, all patients with sciatica benefit from some general measures. Encouraging aerobic activity is important, and swimming, dancing, and walking are all excellent forms of exercise. Also encourage patients to strengthen their abdominal muscles by performing modified sit-ups and by keeping these muscles taut while standing. Instruction in proper methods of lifting, bending, and carrying will also help patients avoid exacerbation of back pain.

Most non-diskogenic causes of sciatica-except fibrositis-respond favorably to a two-week course of NSAIDs. The main problem with these drugs is patient compliance: most people will not take medication several times daily for two weeks. To obviate this, prescribe a drug that requires only once or twice-daily dosing (see table). Most patients can tolerate a 7-14 day course of NSAIDs, particularly if they take them with food or milk to avoid adverse gastrointestinal effects. Of the NSAIDs, salsalate (Disalcid) is the least irritating to the GI tract. Also, advise patients not to take aspirin in any form concurrently.

Narcotics have little place in the management of non-diskogenic sciatica. In most studies, they are inferior to NSAIDs for relief of this type of pain.