Tendinous and Capsular Lesions
The shoulder joint is composed of two synovial cavities: the subacromial–subdeltoid bursa and the glenohumeral joint. In rotator cuff diseases, subacromial synovitis is responsible for the generation of shoulder pain, and its severity may correlate with the intensity of pain. During inflammation, the so-called hyperalgesia occurs, which is characterized by intensified pain with a reduced threshold to somatic stimulation.
Pigmented villonodular (PVN) synovitis is one of a group of benign, proliferative lesions arising from the synovium of joints, bursae, and tendon sheaths.340 Traditionally, these lesions have been identified as a benign giant cell tumor of the tendon sheath, hemorrhagic villous synovitis, and proliferative synovitis.341 PVN synovitis in the knee and hand has been described frequently, but its occurrence at the shoulder is rare.
The cause of PVN synovitis is unclear, but it may be related to inflammation or trauma. The lesions develop slowly, and patients usually present with a gradual onset of pain at the affected joint.340 A palpable, tender, soft-tissue mass may be present. PVN synovitis is regarded as a locally aggressive but benign tumor. Early diagnosis and treatment are essential to preserve joint function and integrity. The treatment of choice is complete synovectomy or bursectomy, or arthroscopic synovectomy.340
Shoulder subluxation can be caused by trauma, overuse, or hemiplegia. The traumatic and overuse causes of shoulder subluxation, which can often be diagnosed on the basis of history and physical examination, are described in Chapter 16. The most common complaints are of instability, restricted activities, and pain. Strength and range of motion are usually normal. The most common significant finding on physical examination is apprehension.
Shoulder pain is a common complication of hemiplegia. One of the most commonly cited causes of shoulder pain in hemiplegia is shoulder subluxation. Shoulder subluxation occurs in hemiplegia because of the paralysis of active restraints, which play a critical role in maintaining glenohumeral joint integrity. In this population, glenohumeral joint subluxation may inhibit functional recovery by limiting glenohumeral range of motion.
Unfortunately, the available options for preventing and treating shoulder subluxation in the hemiplegic population are limited. Armboards and laptrays have not been shown to be effective and may lead to an overcorrection of inferior subluxation.342 This overcorrection may predispose the involved shoulder to impingement syndromes. The use of slings remains controversial. Slings may cause lateral subluxation, contribute to the deleterious effects of joint immobilization, or promote undesirable synergistic patterns of muscle activation.342 Intramuscular neuromuscular electrical stimulation (NMES) delivered via percutaneously placed electrodes may address the limitations of transcutaneous systems in the treatment of shoulder subluxation and pain.342
In contrast to the hip, in which the ball-and-socket joint is deep and well stabilized, the articular surface of the shoulder rests in the shallow glenoid cavity. Ninety-five percent of shoulder dislocations occur in the anterior direction and result in stretching and detachment of the anterior capsule and labrum.343 Dislocation of the shoulder is a common and often disabling injury, resulting in damage to nerves, blood vessels, and the rotator cuff muscles. Most shoulder dislocations are traumatic in origin. The most common mechanisms are a fall on an outstretched hand, a blow against the anterior arm when the limb is extended and externally rotated, or, rarely, a blow to the back of the shoulder.
Traumatic shoulder dislocations are accompanied by extreme pain that worsens as the supporting musculature goes into spasm.344 Generally, patients present with the arm somewhat abducted and externally rotated, often grasped tightly by the opposite hand to minimize movement.344
The examination of a patient who has recently dislocated the shoulder is often difficult because of associated pain and muscle guarding. It is important to attempt to examine for axillary nerve function (deltoid power and overlying sensation), supraspinatus power, and glenohumeral range of motion.345 Axillary nerve palsy and avulsion of the supraspinatus are common complications of a dislocated shoulder. Associated fractures may be present. Vascular compromise is uncommon in this injury, but when it occurs, rapid surgical referral is necessary to save the limb.344
RA affects the joints in a characteristic and symmetric fashion. In addition to the smaller joints, RA can affect the larger joints, including the shoulders. It results in pain and stiffness, which are usually greatest in the morning. 346–348 This condition should be considered when patients have symmetric involvement of the shoulder, morning stiffness, constitutional signs, and physical signs of joint inflammation.349 Synovial inflammation of the subacromial–subdeltoid bursae can occur, resulting in pain on abduction to approximately 90 degrees in both shoulders.349 Chronic inflammation or long-term corticosteroid use, or both, may also result in rotator cuff tearing, another viable cause of pain and function loss in the patient with RA. This should be suspected when significant weakness is noted on abduction or external rotation of the shoulder.349 The clinician should also look for other signs of inflammatory arthritis, which include synovial thickening of the MCP joints and thickening at, and loss of range of motion of, the wrists. The rheumatoid factor is often negative in older patients with RA.349
Polymyalgia rheumatica is another cause of shoulder pain in older individuals. These patients have pain in the shoulder and hip girdle muscles, profound morning stiffness, and malaise.349 This condition can be difficult to distinguish from RA in older people.
Septic arthritis of the shoulder is uncommon but can occur in patients who are debilitated from generalized disease,350 in those taking immunosuppressive medications, or in combination with an underlying shoulder disease process, such as rotator cuff tearing351 or RA.352,353
Diabetic patients are at higher risk of developing monoarticular steroid-sensitive arthritis.354 A condition of unknown etiology, it can affect the rotator cuff and the glenohumeral joint capsule.355 As the name suggests, the condition is provoked by the patient's reaction to hydrocortisone.
Diagnosis requires joint aspiration and bacteriological testing. Monoarticular arthritis, which usually resolves spontaneously in 2 years with medical intervention,356 is an absolute contraindication to capsular stretching.357
Intrinsic glenohumeral arthritis is an infrequent cause of shoulder pain, but loss of glenohumeral motion is often seen in patients with periarticular syndromes (see Chap. 16).349 Although the rotator cuff often is intact, the subscapularis muscle often is shortened, limiting external rotation.358 X-ray findings include358
- flattening posterior erosion of the glenoid and an enlarged or deformed humeral head359,360;
- inferiorly located osteophytes;
- acromioclavicular arthritic changes.359
The most commonly involved bones with acute hematogenous osteomyelitis in order of frequency are femur, tibia, humerus, fibula, radius, phalanges, calcaneus, ulna, ischium, metatarsals, and vertebral bodies.361 Patients with sickle-cell disease are at an increased risk of bacterial infections, and osteomyelitis is the second most common infection in these patients.362
Patients usually present with fever, malaise, irritability, pain, and localized tenderness at the site of infection. Muscle guarding may also be a feature, as well as decreased movement and pain of the affected limb and adjacent joints. These symptoms may be accompanied by edema and erythema over the involved area.
Cat-scratch disease is generally a benign, self-limited infectious disease in immunocompetent patients. It is caused by Bartonella henselae, a small, Gram-negative, argyrophilic, nonacid-fast, pleomorphic bacillus.363 Domestic cats, especially kittens, serve as a reservoir for B. henselae.363 In general, patients present with a history of a scratch, bite, or close contact with a kitten or cat. Often a red-brown nontender papule develops at the region of the inoculation within 3–10 days and may persist for several weeks. Most patients develop tender regional lymphadenopathy, particularly in the axilla, and many develop fever.
The differential diagnosis of all painful shoulders includes tumors of a wide variety. Evaluation of a shoulder tumor has several areas in common with other musculoskeletal neoplasms. Thorough evaluation of patients requires not only routine radiography but also radionuclide imaging, CT scanning, magnetic resonance imaging (MRI), and angiography. The typical clinical features of a bone tumor include variable pain, which is often worse at night and markedly unresponsive to salicylates. Surgical treatment of shoulder tumors depends on the patient's age and the type, extent, and aggressiveness of the tumor.
Nontraumatic avascular necrosis of the humeral head may be idiopathic or associated with the systemic use of corticosteroids, dysbaric conditions (blockage of the blood vessels by a bubble of nitrogen coming out of solution), transplantation, systemic illness, alcoholism, sickle-cell disease, hyperuricemia, pancreatitis, lymphoma, or Gaucher disease.353,364–367
Diagnosis is through imaging, particularly MRI, which detects the pathology at its earliest stage.
Gout is a metabolic disease characterized by recurrent episodes of acute arthritis that can manifest in the shoulder joints.
Referred pain from the cervical region may be experienced in the shoulder or interpreted as a distal sensation.368
Referral sources for this region include the heart,369 pleura, lung tissue, diaphragmatic pain,370 lymph nodes of the neck, shoulder, chest, and breast tissue.370
Pain in the shoulder area can be caused by direct or referred pain from an underlying malignancy, such as a Pancoast tumor (see “Tumor”).370 The scapula and humerus are frequently sites of metastases in tumors of the kidney, breast, lung, and prostate.349 These patients have persistent pain that is unaffected by movement but is associated with fatigue, weight loss, and other constitutional signs. A history of gradually progressive pain, starting as a mild ache but developing into persistent severe pain, should initiate a search for a malignancy.349 Severe shoulder pain in a patient with a normal physical examination of the shoulder and cervical spine should increase the suspicion of a malignancy.
Intrinsic neck pathology can cause referred pain to the head, anterior and posterior chest wall, shoulder girdle, and upper limb.368 In the case of radiculopathy, muscle function might be affected directly. Cervical spine symptoms are usually affected by head position, with neck extension causing an exacerbation and flexion producing some relief.349
Intracerebral and Intraspinal Conditions
Subclavian Steal Syndrome
This condition (see Chap. 24) results in signs and symptoms of cerebral ischemia and upper arm pain. Ischemia is the result of subclavian artery stenosis proximal to the origin of the vertebral artery and, subsequently, “steals” of blood from the cerebral circulation of the Circle of Willis and basilar vessel (see Chap. 24).
The symptoms of subclavian steal syndrome are usually precipitated or aggravated by arm exercises.371
Pain, either acute or chronic, occurs in more than 65% of patients with MS372 during all stages of the disease. Chronic pain may be characterized by dysesthetic extremities, back and shoulder pain, and pain secondary to spasticity.166 Complications of disuse, such as frozen shoulder and osteoporosis, are other painful syndromes that may develop.166
Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS), commonly referred to as Lou Gehrig's disease, is a neurodegenerative disorder that causes rapid loss of motor neurons in the brain and spinal cord, leading to paralysis and death. Diagnosis is based solely on clinical data. The diagnosis of ALS depends upon the recognition of a characteristic constellation of symptoms and signs and supportive electrophysiological findings. For clinically definite ALS diagnosis, UMN and LMN signs in bulbar and two spinal regions or in three spinal regions are required. The LMN weakness and muscle atrophy involves both peripheral nerve and myotomal distributions. The clinical hallmark of ALS is the coexistence of muscle atrophy, weakness, fasciculations, and cramps (caused by LMN degeneration), together with hyperactive or inappropriately brisk muscle stretch reflexes, pyramidal tract signs, and increased muscle tone (due to corticospinal tract involvement).373 Muscle cramps are often already present before other symptoms develop. Most patients present with asymmetrical, distal weakness of the arm or leg. ALS is a progressive disease. The symptoms usually progress first in the affected extremity and then gradually spread to adjacent muscle groups and remote ipsilateral or contralateral regions. Although disability is usually limited in the early stages, ALS progresses relentlessly. Most patients are ultimately unable to walk, care for themselves, speak, and swallow.373 However, there is usually no clinical involvement of parts of the CNS other than the motor pathways.373
Respiratory weakness due to high cervical (phrenic nerve, C4) and thoracic spinal cord involvement is the most common cause of death in ALS, often in conjunction with aspiration pneumonia.373
Guillain–Barré syndrome (GBS) is challenging to identify because of its multitude of presentations and manifestations. GBS may be defined as a postinfectious, acute, paralytic peripheral neuropathy. It can affect any age group, although there is a peak incidence in young adults. GBS appears to be an inflammatory or immune-mediated condition.
The majority of patients describe an antecedent febrile illness. Upper respiratory infections are seen in 50% of cases and are caused by a variety of viruses. The illness is usually an acute respiratory or gastrointestinal condition that lasts for several days and then resolves. This is followed in 1–2 weeks by the development of a progressive ascending weakness or paralysis, which is usually symmetric. The progression of the weakness or paralysis can be gradual (1–3 weeks) or rapid (1–2 days). The patient reports difficulty or instability with walking, arising from a chair, and ascending or descending stairs. Associated signs and symptoms include cranial nerve involvement (facial weakness), paresthesias, sensory deficits, difficulty in breathing, diminished muscle stretch reflexes, autonomic dysfunction (tachycardia and vasomotor symptoms), oropharyngeal weakness, and ocular involvement.374
The differential diagnosis for GBS is quite large and includes the spectrum of illnesses causing acute or subacute paralysis. These include spinal cord compression (myelopathy), UMN disorders, poliomyelitis, transverse myelitis, polyneuropathy, SLE, polyarteritis nodosa, myasthenia gravis, and sarcoidosis.374
All patients with suspected GBS should be hospitalized for vigilant monitoring because of the high risk of respiratory failure, which occurs in approximately one-third of patients.374
Syringomyelia is a disease that produces fluid-containing cysts (syrinx) within the spinal cord, often associated with stenosis of the foramen magnum. The syrinx can occur within the spinal cord (syringomyelia) or brain stem (syringobulbia). Syringomyelia has been found in association with various disorders, including spinal column or brain stem abnormalities (scoliosis, Klippel–Feil syndrome, Chiari I malformation), intramedullary tumors, and traumatic degeneration of the spinal cord. Chiari I malformation is the most common condition in patients with syringomyelia.
Painful dysesthesias, which have been described variously as burning pain, pins-and-needles sensations, and stretching or pressure of the skin, occur in up to 40% of patients with syringomyelia.375 The pain tends to arise in a dermatomal pattern and is accompanied, in most cases, by hyperesthesia.
Radiologic features that suggest syringomyelia include an increase in the width and depth of the cervical canal, bony abnormalities at the craniovertebral junction, diastematomyelia, and occipitalization of the atlas.
The extraspinal causes of shoulder pain include tumor, clay shoveler fracture, brachial plexopathy, and herpes zoster.
Pancoast syndrome is a constellation of characteristic symptoms and signs that includes shoulder and arm pain along the distribution of the eighth cervical nerve trunk and first and second thoracic nerve trunks, Horner syndrome (see Chap. 3), and weakness and atrophy of the muscles of the hand, most commonly caused by local extension of an apical lung tumor at the superior thoracic inlet.376,377 These tumors are called superior pulmonary sulcus tumors or Pancoast tumors.
The most common initial symptom is shoulder pain due to the localization of the Pancoast tumors in the superior pulmonary sulcus. Pain can radiate up to the head and neck or down to the medial aspect of the scapula, axilla, anterior part of the chest, or ipsilateral arm, often along the distribution of the ulnar nerve.378 This radicular causalgic pain is often difficult to treat. Sensory loss and motor deficit in the upper extremity may also occur. Weakness and atrophy of the intrinsic muscles of the hand are not uncommon, along with pain and paresthesia of the medial aspect of the arm, forearm, and fourth and fifth digits along the distribution of the ulnar nerve, caused by extension of the tumor to the C8 and T1 nerve roots.378
The differential diagnosis of Pancoast syndrome includes other primary thoracic neoplasms, metastatic and hematologic conditions, infectious diseases, thoracic outlet syndromes, and pulmonary amyloid nodules.378
Clay shoveler fracture is a rare condition. The condition was first described by McKellar379 and was based on a few cases reported, found in English men, who spent long hours digging heavy clay. It has since been described in power lifters.380 The condition is characterized by a traction fracture of the lower cervical or upper thoracic spine due to an excessive pull of the trapezius, rhomboid muscles during heavy work. Typically, the patient reports a sudden onset of sharp neck, shoulder, and arm pain and exhibits limited active bilateral elevation to around 150 degrees. Passive elevation remains unaffected. Other conditions that mimic these symptoms include a fracture of the first rib, mononeuritis of the long thoracic nerve, mononeuritis of the accessory nerve, a C5 root palsy, or a total rupture of the supraspinatus.357
Idiopathic brachial plexopathy (IBP) is a syndrome of shoulder pain and weakness. IBP has a number of pseudonyms, including neuralgic amyotrophy, Parsonage–Turner syndrome, and idiopathic brachial neuritis. The initial symptom typically seen with IBP is sudden, sharp, and throbbing pain in the shoulder girdle, followed by weakness in the scapular and proximal arm muscles. Sensory loss is usually not prominent. The pain usually subsides within 24 hours to 3 weeks, and the weakness and atrophy are recognized as the pain resolves. Weakness is maximal within 2–3 weeks of the onset of symptoms and often is accompanied by muscle wasting and scapular winging. Slow resolution of the weakness follows in nearly all patients, but recovery may be incomplete.
Herpes zoster is characterized by deep, boring, or stabbing thoracic and arm pain. Varicella zoster virus infection is unique because of its two clinical manifestations: varicella (chickenpox) and herpes zoster (shingles). After an individual has chickenpox, the virus lies dormant in the posterior (dorsal) root ganglia and sensory ganglia of cranial nerves. Herpes zoster occurs if the virus becomes reactivated, causing an acute, painful infection of a sensory nerve and its corresponding cutaneous area of innervation. Herpes zoster, therefore, occurs only in individuals previously infected with the chickenpox virus.
Postherpetic neuralgia is the most common complication of herpes zoster. It arises from inflammatory injury to sensory nerves, ganglia, and nerve roots and from maladaptive responses to pain signaling and the likely inability of pain receptors to return to normal after the inflammation subsides. The nerve dysfunction can result in hyperesthesia, hypoesthesia, dysesthesia, and allodynia (pain as the result of innocuous stimuli, such as clothing touching the affected skin).
The characteristic rash begins as erythematous macules and papules that progress to vesicles within 24 hours, then to pustules (3–4 days), and finally to crusts (7–10 days). The most common distribution of herpes zoster is unilateral involvement of the thoracic dermatome, followed by the cranial, cervical, and lumbar dermatomes. Involvement of the maxillary division of the trigeminal nerve causes vesicles of the uvula and tonsillar area. Involvement of the mandibular branch produces vesicles on the floor of the mouth, buccal membranes, and the anterior part of the tongue. Herpes zoster near or involving the eyes is considered an emergency, because this potentially serious development can lead to blindness.
In general, the diagnosis of herpes zoster is based on the history and the clinical examination, which shows the characteristic painful, grouped vesicular rash in a dermatomal distribution. Acute herpes-zoster infection is a self-limiting condition, and the primary treatment goals are to reduce and manage the acute pain and modify the duration of the rash and inflammation.