in patients with a systemic in \202 ammatory condition such as RA or polyarticular JIA, is mild anemia with normal red cell indices, high or high-normal platelets, and increased acu te phase response. Lymphopenia frequently accompanies autoimmune disease. Neutrophils are r aised in infection, with steroids, and in systemic JIA or adult onset Still \200\231s disea se. Blood urea, electrolytes, creatinine, and urate will detect hyperuricemia and renal impairm ent associated with gout (see Chapter 15). Blood calcium, phosphate, albumin, vitamin D, an d alkaline phosphatase ( PTH) will screen for metabolic bone disease. \200 Rheumatoid f actor (RF) and anti-citrullinated protein antibody (ACPA) tests such as anti-cyclic citrull inated peptide (CCP) may be useful for diagnosing rheumatoid arthritis. Antinuclear antibod y (ANA) and a screen of extractable nuclear antibodies (ENAs) may be helpful for the evalua tion of a number of disorders, including systemic lupus erythematosus (SLE), Sjogren \200 \231s, and scleroderma. In children with JIA, a positive ANA is associated with an increased risk of uveitis. Other investigations to consider: serum angiotensin converting enzyme (sACE) for sarcoidosi s, glycosylated hemoglobin in diabetics, serum and urinary protein electrophoresis for myel oma. Other diagnostic procedures \200 Nerve conduction studies are useful to evaluate upper li mb neuropathies. Joint/bursa \202 uid aspiration is mandatory in suspected cases of sepsis and should be s ent for culture and microscopy. Crystal arthropathy should also be considered. Treatment of wrist and hand disorders Treatment for speci \201 c diseases is considered in Part 2. Management of the soft tissue lesions in the hand and wrist, like elsewhere, combi nes periods of rest and splinting with active physical therapy, avoidance of repetitive act ivity, and analgesia. In most cases, the condition will resolve CHAPTER 2 Regional musculoskeletal conditions 56 spontaneously, but severe or persistent pain and disability may warrant input from a hand o ccupational therapist, local steroid injections, or occa- sionally surgical soft tissue dec ompression. \200 Conditions that respond to local steroid therapy include: tenosynovitis, e.g., De Quervain \200\231s \200 tendon nodules and ganglia \200 \202 exor tenosynovitis (and trigger \201 nger) \200 Dupuytren \200\231s contracture \200 carpal tunnel syndrome \200 synovitis: radiocarpal and radioulnar at the wrist, MCPs and PIPs, \201 rst carpometacarpal (CMC). The accuracy of needle placement is likely to be improved by US guidance; however, greater ef \201 cacy from such an approach over blind injection has not yet been shown. See Corticosteroid Injection Therapy and Principles of Rehabilitation at the end of this chapter. Functional evaluation (from a physical and occupational therapist) is likely to be of use i n cases of polyarthropathy. Early use of splints, orthotics, and exercises may lead to grea ter functional ability and a decrease in symptoms. Surgical options for the hand and wrist may include: fusion or resection of the carpal bones \200 ulna styloidectomy and wrist synovectomy (RA ) \200 tendon repair and transfer operations (RA) \200 synovectomy of joints and/or ten dons (RA) \200 fusion of small joints \200 PIP/MCP replacements \200 Dupuytren \200 \231s release/fasciectomy \200 carpal tunnel release \200 trapeziectomy for thumb CMC j oint OA Many of these procedures primarily reduce pain; function may not be restored. This page intentionally left blank CHAPTER 2 Regional musculoskeletal conditions 58 Upper limb peripheral nerve lesions Background \200 Upper limb peripheral nerve lesions a re common. Most are entrapment neuropathies. Occasionally, nerve trauma may present to primary care providers o r rheumatologists with (primarily) regional muscle weakness. Although not speci \201 c for its diagnosis, the triad of pain, paresthesias, and weakness is suggestive of nerve entrapment. Features may be considered more speci \201 c for nerve entrapment if there is a history of acute or overuse trauma proximal to the distribution o f the symptoms. Lesions may characteristically occur in association with speci \201 c activities, occupations, or sports (e.g., ulnar neuropathy in cyclists). \200 Accurate di agnosis relies on demonstration of the anatomic lesion. Useful in this respect is knowledge of likely sites of entrapment or damage and, in the case of entrapment, the ability to eli cit a positive Tinel sign (i.e., percussion over the site of entrapment eliciting sensory s ymptoms in the appropriate nerve distribution). Always compare examination \201 ndings in both upper limbs. \200 Nerve conduction studi es are an adjunct to clinical diagnosis. They should not be relied on to make a diagnosis i n the absence of good clinical data. MR techniques and their interpretation are becoming increasingly more sophisticated in iden tifying patterns of abnormality in these disorders. The long thoracic nerve \200 Entrapment is in the differential diagnosis of painless shou lder weakness. The nerve origin is at C5 \200\223C7, and its course runs beneath the subscapular is and into the serratus anterior. Muscle paralysis is often painless and implies loss of the last 30 of overhead arm extens ion, disrupted scapular rhythm, and scapula winging. Winging is demonstrated by inspection from behind with the patient pressing against a wall with an outstretched arm. Damage to the nerve occurs typically from an anterior direct blow or brachial plexus injury . Damage sometimes occurs after carrying heavy backpacks (e.g., army recruits) or after sur gical resection of a cervical rib. It can also occur spontaneously after infection. There is no speci \201 c treatment. The suprascapular nerve \200 The nerve origin is at roots C4 \200\223C6; its course is la teral and deep to the trapezius, through the suprascapular notch, terminating in the supras pinatus and posteriorly in the infraspinatus. It carries pain \201 bers from the glenohum eral joint and AC joint. Impingement of the nerve at the suprascapular notch should be considered in a patient complaining of shoulder pain despite a normal examination and imagi ng tests. Injury to the nerve often gives diffuse shoulder pain, although painless paralysis of the muscles can occur. UPPER LIMB PERIPHERAL NERVE LESIONS 59 Injury is often thought to occur from repeated stretching of the nerve at the notch. Weight lifters are prone to bilateral injury and volleyball players prone to dominant side injury. Compression by ganglia or tumors occurs and can be con \201 rmed by MR. Ulnar nerve The ulnar nerve originates from C8 and T1. It lies along the medial side of the brachial artery in the upper arm, then above the medial humeral epicondyle where it passes posteriorly, piercing the medial intermuscular septum. It then runs behind the elbow in a groove between the olecranon and medial epicondyle, covered by a \201 brous sheath and ar cuate ligament (cubital tunnel). Following the line of the ulna in the \202 exor compartm ent of the forearm, branches supply the \202 exor digitorum profundus (FDP) and the \202 exor carpi ulnaris (FCU). The nerve enters the hand on the ulnar side dividing into su per \201 cial (palmaris brevis and skin over the medial one and a half digits) and deep (s mall muscles of the hand) branches. \200 Lesions are usually due to entrapment. \200 Th e ulnar nerve is occasionally damaged in the relatively exposed cubital tunnel (cubital tun nel syndrome) resulting in pain and paresthesias along the medial forearm, wrist, and fourt h/ \201 fth digits. Damage may occur from direct trauma, compression, or recurrent subluxa tion. The Tinel test at the elbow may be positive and there might be sensory loss over the palmar aspect of the \201 fth digit. There are a number of sites where entrapment of the ulnar nerve may occur around the wrist, either proximal to the volar carpal ligament or beneath it or the pisohamate ligament. Ext ernal compression, acute or recurrent trauma, and ganglia are the usual causes. Symptoms ha ve been noted in cyclists, users of jack hammers or vibrating tools, and in avid videogame players. Entrapment of the purely sensory cutaneous branch can occur from excessive compute r mouse use. Motor weakness may be most evident by observing general muscle wasting in the hand (hypothe nar eminence, interossei, adductor pollicis) and \202 exion deformity of the fourth and \201 fth digits \200\224the latter caused by third and fourth lumbrical weakness (see Plat e 6). Flexion of the wrist with ulnar deviation (FCU) and thumb adduction may be weak (adductor p ollicis weakness will be evident if you ask the patient to run the thumb across the base of the \201 ngers as normally it can sweep across smoothly). \200\234Froment \200\231s sign \200\235 also signi \201 es weakness of the adductor polli cis and is demonstrated by a weakness in holding paper between the thumb and the index \201 nger when both are in the sagittal plane. Discrimination of a wrist site from an elbow site of nerve entrapment is helped by the site of a positive Tinel test, preservation of power of wrist \202 exion/medial deviation (FC U) in a wrist lesion, and electrophysiology. Rest, analgesia, and occasionally local steroids are helpful. A review of posture, repetiti ve activity, and a biomechanical assessment with changes in activities and technique are re commended. Surgical decompression may also be necessary. CHAPTER 2 Regional musculoskeletal conditions 60 Radial nerve The nerve origin is at roots C5 \200\223C8, and its course runs anterior to su b- scapularis, and then passes behind the humerus in a groove that runs between the long an d medial heads of triceps. It then winds anteriorly around the humeral shaft to lie between brachialis and brachioradialis. In the \202 exor compartment of the arm it divides at th e level of the lateral epicondyle into super \201 cial branch (cutaneous/sensory) and the posterior interosseous nerve (PIN), which runs through the supinator muscle into the forear m to supply the extensor compartment muscles. \200 Entrapment needs to be considered in t hose cases of shoulder or upper arm trauma where subsequent presentation includes arm and wrist weakness. Compression of the radial nerve in the upper arm causes stiffness in the dorsal arm and for earm, weakness of the wrist, and little \201 nger extension. The triceps is usually unaff ected as nerve supply to the muscle leaves the radial nerve proximally. Transient compression of the nerve at the site of the medial head of triceps has been described in tennis players. Compression can occur as the nerve pierces the lateral intermuscular septum just distal to the radial head and also where the PIN pierces the supinator. At this lower site, compression is often a consequence of trauma, may be associated with a positive Tinel test and local tenderness, and the pain may be repr oduced by extreme passive forearm pronation combined with wrist \202 exion. Symptoms may mimic those of lateral epicondylitis. Surgical exploration may be necessary to con \201 rm a diagnosis. Median nerve The nerve origin is from the C6 \200\223T1 nerve roots. Starting at the brachi al plexus, it runs together with the brachial artery in the upper arm (supply- ing nothing) , then enters the forearm between the two heads of pronator teres (from the medial humeral epicondyle and coronoid process of the ulna). It runs deep in the forearm, dividing into me dian and anterior inter- osseous branches. The median branch enters the hand beneath the \202 exor retinaculum on the radial side of the wrist. All pronator and \202 exor muscles in the forearm (except FCU and the medial half of FDP) are supplied by the two branches. T he median nerve supplies sensory nerves to the radial side of the hand. \200 Entrapment s yndrome at the wrist is very common. \200 In the rare pronator syndrome, trauma, swelling , or masses between the two pronator heads can cause entrapment, giving lower arm pain, par esthesias, and weakness of forearm pronation. There is local tenderness and reproduction of pain from resisted forearm pronation or wrist \202 exion. Pain in CTS is often present at night and relieved by exercising the hand. Daytime symptoms can persist. Pain can be referred up the arm, even to the shoulder. Sensory symptoms are con \201 ned to the radial three and a half digits. UPPER LIMB PERIPHERAL NERVE LESIONS 61 Clumsiness is a common early feature of CTS. \200 Symptoms reproduced by a positive Tinel \200\231s sign (percussion over the volar aspect of the wrist, with the wrist hyperextende d) and Phalen \200\231s maneuver (volar aspect of the wrist rested on the back of a chair a nd the hand allowed to fall loosely under gravity, held for one minute) indicates nerve com pression. A severe or chronic lesion is associated with sensory testing abnormality (see Figure 2.10) and motor weakness of the abductor pollicis brevis (APB), opponens pollicis, and the \201 rst and second lumbricals. Nerve conduction studies are indicated if the diagnosis is uncertain, the condition is prog ressive, motor neuron disease is suspected (thenar muscle wasting marked/progressive with m inimal sensory symptoms), dual pathology is suspected, surgical decompression is being cons idered, and in cases of surgical failure. False negative results occur in 10% of cases. MR appears to be more sensitive than US for detecting abnormalities involving the median nerve in or around the carpal tunnel. Etiology of CTS is debated but probably multifactorial. The following are associated: Colles \200\231 fracture, trauma, carpal OA, diabetes, in \202 ammatory jo int/tendon disease (e.g., RA, scleroderma), ganglia, menopause and pregnancy. Hypothyroidis m, acromegaly, amyloid, and benign tumors are also associated with CTS. Treatment of carpal tunnel syndrome \200 Night splinting may be curative, especially earl y in the condition. \200 NSAIDs are helpful if there is underlying in \202 ammatory dise ase. \200 Local steroid injections are of value. If partial remission is achieved, consider repeating the injection (see Plate 15). Surgical decompression is indicated when there is failure of conservative therapy, progressive/persistent neurologic changes, or muscle atrophy/weakness . Failure of surgical release of the carpal tunnel requires further consideration of underlying causes such as a ganglion or other soft tissue lesion. Reconsid er also whether there really is a mechanical/ local or perhaps a more subtle cause (e.g., m ononeuritis or peripheral neuropathy, entrapment at the pronator or nerve root lesion). 6 2 C H A P T E R (a) (b) C3 C3 2 R e g i o n a l C4 C4 T2 T2 C5 C5 T3 T3 T4 C6 T2 T5 m u s c u l o s k e l e t a l C6 T3 T3 (c) T2 C5 T1 C7 C5 C7 C7 c o n d i t i o n s C6 C6 C8 C8 (d) Fig. 2.10 Approximate distribution of dermatomes on the anterior (a) and posterior (b) aspe cts of the (right) upper limb. Approximate area of sensory change in lesions of the median (c) and ulnar (d) nerves. This page intentionally left blank CHAPTER 2 Regional musculoskeletal conditions 64 Thoracic back and chest pain Background \200 The typical thoracic spine (T1 \200\223T12) moves less than the lumbar and cervical vertebrae. Segmental movement in any direction is a bout 6 . However, given the number of segments, this can add up to appreciable mobility ov erall. Less segmental movement results in reduced frequency of problems overall (only 6% of patients attending a spinal clinic have thoracic spine problems). Ribs (1 \200\22310) articulate posteriorly with vertebrae at two points: the articular face t of the rib head with the costovertebral facet on each vertebral body and the articular fa cet of the rib tubercle with the costotransverse facet on each vertebral lateral process. T hese are both synovial joints. Ribs 11 and 12 do not have costotransverse joints. \200 Th e ribs, each continuous with its costal cartilage, articulate anteriorly by a synovial join t with the manubrium (1 \200\2232), sternum (2 \200\2237), each costal cartilage above (8 \200\22310), or do not articulate (11/12 \200\224 \202 oating ribs). A massive block of spinal extensor muscles is responsible for maintaining the body against gravity. Some extend over some distance (e.g., the spinalis th oracis from the upper thoracic to the mid-lumbar spinous processes). Dermatomes are circumferential and extend from T2 at the clavicles to T10 at the umbilicus. However, up to \201 ve nerve roots may contribute innervation of any one point in a truncal dermatome. Taking a history The interpretation of cardiac, esophageal, or pleural chest pain as mus- c uloskeletal in origin is a common occurrence. It may result in missing a serious condition (see Tables 2.8 and 2.9). \200 A review of the patterns of quality and radiation of cardi ac and esophageal pain in the clinical context should always be considered. Pleuritic pain is common. Chronic pulmonary emboli may be underdiagnosed, and have serious consequences. Any in \202 ammatory, infective, or in \201 ltrative pleural lesion will be painful. Lesions con \201 ned to pulmonary parenchyma do not produce pain. \200 Pericardial pain can be misinterpreted as musculoskeletal or pleuritic. \200 Mediastinal abnormalities can produce pain that is often referred. The interpretation of neurogenic or musculoskeletal c hest pains as car- diogenic, esophageal, or pleural is a common occurrence and may lead to unnecessary investigations. Take a good history (see Table 2.10). \200 Thoracic spine les ions can result in referred anterolateral chest pain. \200 Costovertebral and costotransv erse joint dysfunction is relatively common and is generally age-related but can occur in a nyone with spinal deformity. It may produce thoracic spine pain alone or result in an exten sive pattern of radiation of pain over the back, lateral, and anterior chest wall. Lower cervical spine lesions can refer pain to the anterior chest wall. THORACIC BACK AND CHEST PAIN 65 Table 2.8 Characteristics of chest pain from non-neurologic and nonmusculoskeletal patholog y Process Characteristics of pain Angina Gradual onset often related to exercise, a heavy meal, or emotion. Squeezing, strangling, o r constriction in chest, can be aching or burning in nature. Commonly substernal but radiat es to any of anterior chest, interscapular area, arms (mainly left), shoulders, teeth, and abdomen. Reduces with rest and sublingual nitrates Myocardial infarction Similar to above regarding quality and distribution. Longer duration. Less easily relieved Pericardial in \202 ammation Sharp or steady substernal pain. Can be referred to shoulder tip, anterior chest, upper abd omen, or back. Often has a pleural component and is altered by change in position \200\224s harper more left-sided when supine but eased by leaning forward Aortic dissection Acute onset with extremely severe peak. Felt in center of chest or back. Lasts for hours Pleuritic in \202 ammation Common. Sharp, knifelike, super \201 cial. Aggravated by deep inspiration, sneezing, or co ughing. If accompanied by hemoptysis consider pulmonary embolism Mediastinal conditions Empyema or surgical emphysema may be intense and sharp and radiate from substernal to shoul der area. Associated with crepitus. Mediastinitis and tumor pain resembles pleural pain. Ma y have constant feeling of constriction/oppression Peptic disease Penetrating duodenal ulcers can cause intense, persistent midthoracic back pain Esophageal re \202 ux Persistent retrosternal burning is typical. Often postprandial, when lying or at night/earl y morning. Esophageal spasm can be similar to angina and can cause midthoracic back pain bu t re \202 ux symptoms often coexist Many painful chest conditions are associated with radiation of the pain down the left arm. This pattern is not speci \201 c for myocardial ischemia. Lower cervical pain may be referred to the interscapular region. \200 Interscapular pain may also be associated with mechanical lumbar disorders. Unlike infection, tumors, and fracture, referred pain is eased or abolished by c hanges in position or posture. If there is thoracic back pain alone and it is acute and/or severe, consider osteoporotic f racture, tumors, and infection. \200 Osteoporotic vertebral collapse is common in postmen opausal women. An acute, nonminimal-trauma-associated severe pain is typical. CHAPTER 2 Regional musculoskeletal conditions 66 Table 2.9 Painful neurologic and musculoskeletal conditions of the thoracic spine and chest wall Thoracic vertebral disease Osteoporotic or pathological fracture Tumors, e.g., osteoid osteoma, metastasis Osteomyelitis Paget \200\231s disease Osteomalacia, rickets Costovertebral joint dysfunction Nerve irritation Root irritation/compression from disc prolapse or osteophyte at exit foramen, from structur e distal to exit foramen, or from neuroma Biomechanical/ degenerative Scoliosis (nonstructural compensatory, structural) Diffuse idiopathic skeletal hyperostosis (DISH) Calcium pyrophosphate dihydrate disease (of ligamentum \202 avum) Herpes-zoster of intercostal nerve Chest wall/super \201 cial lesions Rib fracture Other rib lesions, e.g., tumors, \201 brous dysplasia, osteomalacia Costochondritis/Enthesitis Intercostal muscle tear/strain Mastitis or \201 brocystic disease of the breast Myofascial pain and \201 bromyalgia Parietal pleural in \202 ammation/infection/ in \201 ltration Spondyloarthropathy (e.g., ankylosing spondylitis) Spinal in \202 ammation Acute discitis Chronic indolent discitis Scheuermann \200\231s osteochondritis In adolescents only Fractures occur in many other situations, e.g., AS or a neoplastic bone lesion. Spinal infections should not be missed. The most common are Staphylococcus aureus, Brucella, and Mycobacterium tuberculosis (see Chapter 17). THORACIC BACK AND CHEST PAIN 67 Ask about the quality of pain \200 Musculoskeletal pain (local or referred) generally ass ociates with speci \201 c movements, positions, or postures, and it is reproducible. Pain that increases with coughing, sneezing, or deep inspiration, is suggestive of pleural lesions. Rib and intercostal lesions or costovertebral joint dysfunction may also cause thi s sort of pain. Ask about other symptoms and risk factors \200 The pain from a fracture/lesion (osteoporo tic, malignancy, infection) is often localized and extreme, waking the patient at night. Acute or chronic thoracic spine lesions may be associated with cord compression. Ask about recent change in sphincter function and progressive lower limb stiffness or heaviness. Risks for osteoporosis (see Chapter 16). \200 Systemic symptoms of fever (osteomyelitis). \200 Bone pain elsewhere (metastases, osteomalacia, Paget \200\231s disease). \200 Spi nal pain in adolescence (for an adult with kyphosis/spinal pain). \200 A positive family history is recognized in idiopathic juvenile scoliosis, osteoporosis, and generalized osteoarthritis (see Chapter 6). Depression and anxiety are important modulators of pain. However, although thoracic back and chest pains may be psychogenic, it is imprudent to settle on thi s diagnosis without excluding musculoskeletal conditions and diseases of viscera that can c ause referred pain. Examination Visual inspection Observe the patient (who has undressed down to his or her und erwear) from the back and front. Look for deformity, asymmetry, swellings, and note the res piratory pattern. \200 Any scoliosis should be noted. Nonstructural scoliosis is frequent ly due to posture, severe back or abdominal pain, leg length discrepancy, and, rarely, can be psychogenic. Structural scoliosis may be due to various lesions at any age. There is a normal mild thoracic kyphosis; however, marked kyphosis in adults (particularly postmenopausal women) might suggest multiple osteoporotic vertebral fractures or degenerati ve disc disease. A loss of normal kyphosis ( \202 at spine) may be seen in spondylitis or possibly severe muscle spasm. Loose folds of skin on the back might denote multiple vertebral fractures. Costochondral swelling occurs in some cases of costochondritis or rickets (referred to as a \200\234rickety rosary \200\235 due to the large \200\234beads \200\235 that appear belo w the surface of the skin) in children. Look for synovitis of costosternal or sternoclavicu lar joints (which is found with spondyloarthropathy). Palpation Palpate over the vertebrae, paravertebral joints, and back musculature with the p atient prone. Palpate the anterior chest wall. CHAPTER 2 Regional musculoskeletal conditions 68 Spinal osteomyelitis may be associated with obvious skin swelling and erythema, exquisite f ocal tenderness, and extensor spasm. Tumors may give similar signs, though skin erythema is not likely. \200 Costotransverse joints may be tender (4 \200\2235 cm from midline). Discomfort at any costovertebral joint and its referred pain can be elicited by individual rib manipulation (downward pressure on the rib lateral to its vertebral joints when the pat ient is prone). Identify any trigger points that reproduce myofascial pain in back muscles. Tender swelling of the sternoclavicular, costomanubrial, or sternocostal joints may suggest spondyloarthropathy or SAPHO (synovitis, acne, pustulosis ( palmoplantar), hyperostosis and (aseptic) osteomyelitis). In \202 ammation of costal cartilages is often associated with painful swelling and tenderness. Rib and intercostal lesions should be easily discriminated from re ferred pain by eliciting local tenderness. Check thoracic spinal movement Movements of the thoracic spine should be checked. Ask the p atient to sit on the couch with their arms folded in front of them. Guided by movements of the spinous processes, gauge the range of thoracic spine movement. \200 Approximate norma l ranges of movement in the aforementioned position are extension 30 , lateral \202 exion 30 , \202 exion 90 , and rotation 60 . \200 Scoliosis is often associated with rotation that is accentuated on \202 exion. Abnormal mobility will not be speci \201 c for any underlying condition, but may draw atte ntion to the major affected spinal segment. Painful segments are guarded and may appear hyp omobile. Spondylitis may become obvious if there is extensive spinal hypomobility. Chest expansion should be measured from forced expiration to complete inspiration measuring at expansion, with a tape, at the level of the xiphisternum. Normal young adult chest expansion should measure at least 3 cm. Other examination \200 Given the range of serious conditions causing chest pains, a full medical examination is important and should always be considered. Neurologic examination of the legs should be considered in anyone who is at risk of spinal cord compression. Look for increased tone, weakness, and brisk re \202 exes. Breast and axillary lymph node examination should be performed. Diagnostic procedures Radiographs \200 Lateral view radiographs generally provide more in formation about thoracic spine lesions than anteroposterior views; however, together, both views can con \201 rm osteoporosis, degenerative disease THORACIC BACK AND CHEST PAIN 69 (e.g., previous Scheuermann \200\231s osteochondritis, ochronosis, DISH), and Paget \200 \231s disease (see Chapter 16). Look for vertebral squaring (in AS) and either marginal or nonmarginal syndesmophytes as in psoriatic spondylitis (See Plate 7) or other SpA (see Chapter 8). Discriminate enthesitis from DISH at the corners of vertebrae by the presence of erosions w ith bone reaction (enthesitis) compared with bone proliferation alone (DISH). Enthesitis, a ssociated with chronic spondylodiscitis, is part of the SpA spectrum of diseases. Normal radiographs do not exclude malignancy. \200 Bone lesions can be well characterized by CT (e.g., osteoid osteoma). MR \200 MR is important in discriminating tumor from infe ction. \200 Disc lesions, spinal canal, and cord are well visualized with MR. \200 Fat suppressed or gadolinium-enhanced MR sequences may be necessary to detect enthesitis or spondylodiscitis associated with SpA. Bone scan \200 A bone scan is a sensitive test for infection and malignancy. \200 In su spected cases of (previously undiagnosed) malignancy, it is more sensitive than radiographs , can often con \201 rm the lytic or sclerotic nature of a lesion, and will identify any o ther skeletal sites of disease. \200 It is a useful investigation in patients with malign ancy who present with back pain. A lack of additional lesions strongly suggests against a s ingle spinal abnormality being malignancy related. Tomography can detect abnormality in the pars interarticularis, facet joint, and disc/vertebral body. Bone scan sensitively identi \201 es rib and, in most cases, in \202 ammatory intercostal lesions. If solitary, the differential diagnosis is of a metastasis, primary ma lignant or benign bone tumor, healed rib fracture, \201 brous dysplasia, Paget \200\231s bone disease, hyperparathyroidism, or infection. Other procedures to consider in patients with chest pain \200 CXR, then consider pulmonar y ventilation/perfusion scan and spiral CT to evaluate for pulmonary embolism. CT of the chest in patients with unexplained pleural pain. \200 ECG and an exercise stres s test for patients with possible cardiac ischemia. Transthoracic echocardiography to show thickened pericardium or an effusion associated with pericarditis. Upper gastrointestinal endoscopy in suspected cases of peptic ulceration. Diagnostic trial of a proton pump inhibitor in cases of re \202 ux esophagitis. Treatment For treatment of thoracic and chest-wall lesions, see the following section on Lo w Back Pain and Disorders in Adults and also Chapter 20. CHAPTER 2 Regional musculoskeletal conditions 70 Low back pain and disorders in adults Epidemiology \200 The lifetime prevalence of back p ain is 58%, and the greatest prevalence is between 45 and 64 years of age. Low back pain is the \201 fth most common reason for all physician visits in the United States. Two percent of the workforce in the United States is compensated for back injuries every year. The \201 nancial health care and indirect employment costs of low back pain in the United States are estimated to be more than $24 billion. Lumbar and sacral spine anatomy \200 There are normally \201 ve lumbar vertebrae. Anoma lies are not uncommon at the lumbosacral junction. The transition between the mobile lumbar spine ( \202 exion, extension, and lateral \202 exion) and \201 xed sacrum together with high weight-loading combine t o make the region highly prone to damage. The facet joints are sharply angled, effectively reducing rotation in lumbar segments. The sacroiliac joints (synovial) are held \201 rmly by a strong \201 brous capsule and tough ligaments. The amount of normal movement (essentially rotation) is normally inversely proportional to age. \200 The spinal cord ends at L1/L2. Nerves then run individually, a re normally mobile in the spinal canal, and together are termed the cauda equina. Each nerve exits its appropriate lateral intervertebral exit foramen, passing initially superior and then laterally to the disc, e.g., L4 from L4/ L5 exit forame n. However, in the spinal canal each nerve descends immediately posterior to the more proxi mal intervertebral disc before it exits. Thus, for example, L4 root symptoms can occur from either lateral herniation of the L4/5 disc or posterior herniation of the L3/L4 disc (or f rom both). Facet joint innervation is from posterior primary rami, each of which supplies the corresponding joint at its level, one higher and one lower. Basic principles of assessment \200 Low back pain can arise from damage or in \202 ammat ion of the thoracic or lumbar spines or from the posterior pelvis. Pathology in retroperitoneal abdomi nal and pelvic viscera can result in referred pain to the low back. A simple way of categorizing back pain is to consider its cause to be mechanical, in \202 ammatory, neurologic, or referred, or due to bone pathology (see Table 2.10). Over 90% of episodes of low back pain in adults are mechanical, self- limiting, and do not require investigation. Indicators for further investigation include age > 55 years, stiffness, focal pain, pain that disturbs sleep, nerve root symptoms, and chronic persistent (> 6 week s) pain. LOW BACK PAIN AND DISORDERS IN ADULTS 71 Table 2.10 Common and/or serious causes of low back pain in adults Hypermobility (see Chapter 16) Mechanical/ degenerative (very common) Facet joint arthritis Disc disease (annular tear, internal disruption, prolapse) Scoliosis/kyphosis Spinal stenosis Sacroiliitis In \202 ammatory (uncommon) AS (Chapter 8) Sacroiliitis (e.g., AS, brucellosis) Infection (rare) Osteomyelitis (e.g., Staphylococcus aureus, TB, brucellosis) (see Chapter 17) Bone disease (common) Osteoporotic fracture (see Chapter 16) Paget \200\231s disease Osteomalacia Neoplasia (rare) Secondary metastases Multiple myeloma Other Sickle cell crisis Renal disease (e.g., tumors, infection) Gynecologic disease Fibromyalgia (see Chapter 18) The low back is often a focus for those who may use pain (consciously or unconsciously) as a protective device in the face of domestic, emotional, or occupationa l stress. These stresses commonly in \202 uence the description and impact of pain but rar ely act alone in causing pain \200\224there is usually some underlying organic pathology. Taking a history Differentiate whether the pain is likely to be primarily mechanical or in \202 ammatory, due to bone pathology or referred \200 The site and extent of the pain do es not easily discriminate the cause. All disorders may be associated with mechanical defor mity and/or muscle spasm that may cause pain in a more diffuse distribution. \200 General ly, pain due to mechanical lesions is acute in onset, while patients with pain from in \202 ammatory lesions present after symptoms have been present for some time. In \202 ammatory pain is often associated with morning stiffness that can last for several hours and is eased by movement. Mechanical lesions tend to worsen with use. Many mechanica l or degenerative lesions may have an in \202 ammatory component, e.g., internal disc disr uption causing discogenic pain. CHAPTER 2 Regional musculoskeletal conditions 72 Intrinsic bone pathology often causes severe, unremitting, focal pain. Sleep is disturbed. Pain does not ease substantially with movement. About 3% of patients presenting with back pain have nonmusculoskeletal causes. A signi \201 cant proportion of women have pelvic conditions su ch as ovarian cysts or endometriosis. Pain may be cyclical. For those aged over 55 with no previous similar episodes of pain, a search for an underlying neoplastic lesion is required. Associated systemic symptoms are common in osteomyelitis and may be present if a malignancy has disseminated. Ask about pain radiation and symptoms in the legs \200 Progressive neurologic leg symptom s suggest a worsening/expanding lesion such as a tumor, infection/vertebral collapse, Paget \200\231s disease, or lumbosacral spinal stenosis. Pressure on nerves below the spinal cord (i.e., the cauda equina) suf \201 cient to cause a disturbance in perineal sensation and/or bowel/ bladder paralysi s is a neurosurgical emergency (i.e., cauda equina syndrome). Leg pain caused by nerve root irritation/compression is often clearly de \201 ned and shar p, often accompanied by numbness or paresthesias. The most commonly involved nerve roots ar e L4, L5, or S1. Pain generally radiates to below the knee and often, but not always, to th e heel and big toe. Sciatic nerve entrapment at the level of the piriformis muscle can produce identical radicular symptoms to L5 or S1 nerve root entrapment. Neurologic symptoms in the distribution of the femoral nerve (primarily anterior thigh musculature) might suggest a high lumbar nerve root lesion (L1 \200\223L3 for example). Disc prolapse is the most common cause of nerve root pain, but bony encroachment at the ner ve root exit foramen by vertebral end plate or facet joint osteophytes and/or soft tissue t hickening or \201 brosis can also lead to foraminal stenosis, which can also cause nerve root pain. Disks do not need to prolapse to cause pain. Annular tears and internal disruption (i.e., microfractures in vertebral end plates) can cause a pattern of p ain, termed discogenic pain, characterized by low back and referred buttock/posterior thigh pain aggravated by movement. Generally, all mechanical lesions of the lumbar spine can result in referred pain around th e pelvis and anterior thighs. However, pain from lumbar facet joints and probably other seg mental structures can be referred to the lower leg. Aching in the back and posterior thighs after standing is typical of, but not speci \201 c for, spondylolisthesis. There are often added spasms of acute pain, especially if there is segmental instability. The symptoms of spinal stenosis are often relieved by sitting bent slightly forward, since the spinal canal dimensions increase in this position. LOW BACK PAIN AND DISORDERS IN ADULTS 73 Sacroiliitis often causes referred pain to the buttocks and back of thighs. It occurs commonly in spondyloarthropathy (see Chapter 8). \200 Sacroiliac pain c an occur in multiparous women \200\224the condition may be associated with hypermobility. Note the description of the pain \200 Pain may be severe, whatever the cause; however, no te whether the patient \200\231s descriptors of it suggest nonorganic in \202 uences. Sharp, lancinating leg pains suggest nerve root irritation/compression (radicular pain) whereas leg pain referred from other structures within a lumbar segment is generally deep and aching. The distribution may be similar. More persistent, rather than e pisodic, radicular pain may denote stenosis of the nerve root exit foramen. A description of bilateral buttock/leg pain that worsens on walking is consistent with spin al stenosis, especially in those with normal peripheral pulses and no bruits. A change in the description of pain in someone who has an established diagnosis may be important, e.g., subacute, severe, unremitting localized pain in a patient with AS who normally has mild in \202 ammatory pain might re \202 ect a superimposed dis citis; or, acute severe unremitting sleep-disturbing pain in an elderly woman with known ch ronic mechanical pain associated with OA might suggest osteoporotic fracture. Florid descriptions of the pain and its severity are associated with psychological modulators of pain. Previous back pain and trauma, occupation, and family history \200 Scheuermann \200\231s disease (which is associated with irregular vertebral endplates) causes spinal pain in adol escence. It is a risk for spinal degeneration and kyphosis in adults. Previous trauma may have caused pars interarticularis fractures (an antecedent of spondylol isthesis), vertebral fracture (risk of further mechanical damage), or ligament rupture (sub sequent segmental instability).