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1. Rare causes

Infection, tumor, aortic aneurysm, sickle cell crisis, retroperitoneal mass, and chronic pancreatitis are among the rare causes of axial spine pain with or without

extremity pain. A thorough medical history is critical. Pain often starts suddenly, and it is severe, unrelenting, and not relieved by rest. MRI in most cases is the imaging study of choice, and treatment of the underlying pathology (e.g., surgery, radiation) usually helps to alleviate the pain.

2. No clear cause

In most cases of LBP or neck pain, the anatomic or pathologic diagnosis remains unclear. A thorough history and physical examination is essential to exclude some of the rare but serious causes. LBP and neck pain of unclear etiology is a legitimate diagnosis. In the absence of neurologic symptoms, analgesics such as

acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) can be provided.

Patients should be encouraged to continue their usual activity. If no improvement is seen within 3 weeks, physical therapy may be helpful. If axial neck pain or LBP lasts for more then 12 weeks, an attempt should be made to establish an anatomic diagnosis. The etiology of pain can be established in many cases with controlled invasive diagnostic tests with local anesthetics. Schwarzer et al. found that among patients suffering from chronic LBP, 40% have discogenic pain, 15% to 20% have SI joint pain, and 5% to 10% have facet joint pain.

3. Discogenic pain

The patient with LBP or neck pain originating from the vertebral disc often presents with deep, achy, axial midline pain. Pain can be referred to shoulder or scapular regions for cervical discs, and to buttocks and posterior thigh for lumbar discs. Patients with discogenic pain are often young, are otherwise healthy, and may have jobs that require repetitive motion of the affected spine segment (such as package handlers). Onset of symptoms is usually gradual. Pain is experienced while sitting,

standing, and bending forward. The referred pain usually remains in the proximal part of the extremity. Results of physical examination are usually nonspecific, with limited range of motion at the affected segment, or pain with movement, particularly on flexion. MRI and CT scans are not usually helpful. The presence of a

high-intensity zone on MRI at the posterior aspect of the disc on sagittal plane may indicate the radial fissure of IDD. Provocative discography by injection of

radiocontrast dye is utilized to rule out axial disc pathology. Discography is usually done with fluoroscopic guidance, with a second disc as a control. A postdiscography CT scan can provide more detailed information concerning the anatomic abnormality. Treatment for discogenic pain starts with conservative therapy, including physical therapy and oral NSAIDs. Refractory patients may be considered for intradiscal electrothermal therapy (IDET) (see Chapter 13). This is a relatively new technique with some encouraging data suggesting efficacy. Surgical fusion of the spine remains an option, usually as a last resort.

Axial spine pain originating from the facet joints has a presentation similar to that of discogenic pain. In most cases, the pain starts gradually and is deep, achy, and localized around the midline; there may be some standing and sitting intolerance. Extension and lateral bending of the affected spine are usually painful.Referred pain to the shoulder, buttock, and proximal extremities is common. Most commonly, pain is the result of stress of the facet joint capsule secondary to loss of disc or vertebral height. It can be caused by degenerative change or osteoporosis, and it is also seen after decompression surgery. When pain is secondary to osteoarthritis of the facet joints, it tends to be less severe and is often described as morning stiffness. In rare cases, facet joint pain may originate from fracture or hemarthrosis following trauma. Physical examination is usually nonspecific, and sensory and motor examination is usually benign. Some patients have paraspinal tenderness and pain on extension and lateral bending. Imaging studies may help identify pathology such as loss of disc or vertebral height, spondylolisthesis, or other degenerative changes. Diagnostic local anesthetic block under fluoroscopic guidance is the most accurate way to isolate the facet joint as the source of axial spine pain (see Chapter 12). Currently, radiofrequency lesioning of the medial branches is considered the most effective long-term therapy for axial spine pain originating from the facet joints.

5. Sacroiliac joint pain

Localized lower back or upper buttock pain is the common presentation of SI joint pain. Pain referred to the posterior thigh and below the knee is rare. In most cases, the cause is unclear. Trauma, infection, and tumor are uncommon causes of SI joint pain. Physical examination may reveal localized tenderness over the joint, and Patrick's test may be positive (see preceding section, “Examination of the Spine”). Degenerative change of the joint on a radiograph is extremely common and

nonspecific and not helpful in making a diagnosis. Intra-articular injection of local anesthetic under fluoroscopic guidance with complete pain relief indicates that the SI joint is the probable source of the pain. Treatment for SI joint pain remains controversial. Currently, an intra-articular injection of steroid with local anesthetics is the most common therapy (see Chapter 12).

6. Spinal stenosis

Spinal stenosis includes both central canal narrowing and foraminal narrowing. Symptoms from central canal narrowing tend to be diffuse compared to foraminal narrowing (when the exiting nerve root often produces symptoms in a dermatomal distribution). The clinical presentation of central canal narrowing includes axial spine pain (e.g., LBP) and extremity pain. The degree of axial and extremity pain varies between individuals; pain tends to start at the spine and gradually involve the

extremities. The pain tends to be diffuse (nondermatomal) and is usually characterized as achy. It commonly worsens with walking (neurogenic claudication), especially downhill walking, and with extension of the spine. Rest and flexion of the spine usually provide temporary relief. A simple way to distinguish neurogenic from vascular claudication is to exercise patients on a bike. Patients with neurogenic claudication usually have no pain, whereas those with vascular claudication have pain while biking.

Spinal stenosis is more common in older individuals and may be associated with age-related changes of the spine. The pathophysiology includes osteophytes, facet capsular hypertrophy, and diffuse broad-based disc bulge. Foraminal narrowing can be caused by these changes as well as by loss of disc height and by

spondylolisthesis. MRI can be useful in delineating the extent and the causes of the narrowing.

In mild to moderate cases, a translaminar epidural steroid injection may be therapeutic. Most patients feel their extremity pain improve sooner then their axial pain. The injection can be repeated for a cumulative benefit. If there is no improvement from epidural steroid injections, a surgical consultation may be sought to evaluate

possible decompression surgery. Cervical spinal stenosis symptoms can involve both upper and lower extremities, and an early surgical consultation should be sought. 7. Myofascial pain

Neck pain and low back pain of myofascial origin are fairly common, especially after trauma and repetitive motion injury. Myofascial pain around the neck and low back presents as deep, achy, localized discomfort worsening with activity. Pain is thought to be caused by strain or sprain injury to the muscle. Patients are sometimes able to feel a focal area of tight muscle knot and tenderness on palpation. Patients may complain only of paraspinal muscle discomfort, or the pain may extend to the occiput, scapular, and shoulder areas, or to the buttocks and upper thigh areas. It is important to distinguish somatic referred pain (from disc or facet joint pathology) from pain of muscular origin. Physical examination may reveal a tight muscle band, tender to palpation, and may have a characteristic radiation pattern (trigger point). Various physiotherapy techniques (e.g., stretching and strengthening exercise, massage, iontophoresis) remain the initial therapy of choice (see Chapter 16). Injection of local anesthetics into the tender points may be very useful, especially if a coordinated physiotherapy program immediately follows the injection. Some physicians add steroid with local anesthetics for this injection. There is a risk of local muscle atrophy with repeated steroid injection. Myofascial pain is described in detail in Chapter 17.

8. Failed back syndrome

The diagnosis of failed back syndrome is given to patients who suffer from chronic pain after spine surgery. The surgery may have been performed only for the purpose of relieving pain, or it may have been done for other reasons including stabilization or decompression to relieve neurologic deficit. Pain may vary significantly, and it may be accompanied by neurologic deficits. The pain is often different in quality and in distribution from the patient's presurgical pain. Epidural scarring is thought to be the primary cause of persistent pain. A thorough history and physical examination are critical to distinguish the nociceptive and neuropathic components of pain. Pain along the distribution of one or more nerve roots may indicate epidural fibrosis. Nociceptive pain from facet or disc disease should be also considered. Up to 40% of postlaminectomy (lumbosacral) patients have LBP originating from facet joints. Scar tissue, early-onset arthritic change, and osteophytes may cause spinal stenosis. Therapy for failed back syndrome remains controversial. Repeat surgery may not provide the desired pain relief. For patients with neuropathic pain, epidural steroid injection via the foraminal or caudal route can be a useful and relatively benign initial intervention. Other interventional modalities, such as epidural lysis of adhesions via epiduroscopy or by catheter technique (Racz procedure), are not widely practiced because of limited evidence of efficacy. Spinal cord stimulation has been shown to be an effective mode of therapy for neuropathic pain from failed back surgery (see Chapter 13).

9. Whiplash injury

Acceleration–deceleration injury from motor vehicle accidents, commonly known as whiplash injury, frequently causes neck pain. Whiplash is estimated to occur in 1% of the general population, and the pain may become chronic in 10% to 25% of the patients. A controlled study found cervical facet joints to be the most common cause of neck pain after whiplash injury. The authors estimated that in at least 50% (possibly as high as 80%) of high-speed injuries, cervical facet joints are the source of neck pain. The most common cervical segments involved are C5-6 and C2-3. The neck has a large number of muscles, including the neck extensor, flexor, rotator, and lateral flexors. They are well innervated and a common source of neck pain.

The initial office visit should include a history of injury or risk factors for serious pathology. Physical examination has a limited role because of poor reliability and validity of identifying specific causes of pain. It may show limited range of motion, pain with movement, or tenderness over the articular pillars or paraspinous muscles. These signs are nonspecific for making pathoanatomic diagnoses. In the case of trauma, plain films may show fracture or dislocation. MRI and CT are not indicated unless there is a suggestion of impending neurologic compromise. Ronnen et al. (1996) showed that MRI is not useful for diagnosing whiplash-related injury.

Facet joints are the most common cause of neck pain. To formulate an accurate diagnosis of cervical facet joint pain, a control joint block is recommended because of the high rate of false-positive responses from a single diagnostic block. The prevalence of cervical discogenic pain is unknown. Provocative discography may help to identify discogenic pain, although cervical discography has a fairly high level of false-positive responses. A high degree of vigilance and expertise are required when using this technique to avoid infection and injury to vital structures.

V. CONCLUSION

The vast majority of the patients with back and neck pain recover within weeks. The cause of the acute pain remains undetermined in the majority of cases. Neoplasms and infections account for less than 0.7% and 0.01% cases of acute LBP, respectively. History and physical examination should focus on identifying the warning signs of serious underlying pathology. In routine cases, findings include a limited range of motion, pain with activity, and back tenderness; these signs and symptoms are nonspecific and do not help in making a definitive diagnosis. Furthermore, if serious pathology is not suspected, special investigations do not help to make a specific diagnosis. Initial treatment for acute nonspecific back and neck pain should focus on providing reassurance and encouragement, as well as adequate analgesia using simple analgesics and physical treatments, allowing patients to remain active and continue to work.

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4. Bogduk N, Aprill C. On the nature of neck pain, discography and cervical zygapophysial-joint pain Pain 1993;54:213–217.

5. Kuslich SD, Ulstrom CL, Michael CJ. The tissue origin of low back pain and sciatica: A report of pain response to tissue stimulation during operation on the lumbar spine using local anesthesia.

Orthop Clin North Am 1991;22: 181–187.

6. Maigne JY, Aivaliklis A, Pfefer F. Results of sacroiliac joint double block and value of sacroiliac pain provocation tests in 54 patients with low back pain. Spine 1996;21:1889–1892. 7. Merskey H, Bogduk N, eds. Classification of chronic pain, 2nd ed. Seattle, WA: IASP Press, 1994.

8. Ronnen HR, de Korte PJ, Brink PR, vander Bijl HR. Acute whiplash injury: Is there a role for MR imaging? A prospective study of 100 patients. Radiology 1996;201: 93—96. 9. Schwarzer AC, Wang SC, Bogduk N, et al. The false positive rate of uncontrolled diagnostic blocks of the lumbar Z-joints. Pain 1994;58:195–200.

10. Schwarzer AC, Aprill CN, Derby R, Fortin J. The prevalence and clinical features of internal disc disruption in patients with chronic low back pain. Spine 1995;20:1878–1883. 12. Walsh TR, Weinstein JN, Spratt KF, et al. Lumbar discography in normal subjects. J Bone Joint Surg 1990;72A:1081–1088.

28 Headache

The Massachusetts General Hospital Handbook of Pain Management

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Headache

F. Michael Cutrer and Pramit Bhasin I have a pain upon my forehead here.

—Othello Act 3, Scene 3, by William Shakespeare (1564–1616)