- Neck and low back pain is one of the most common reasons that people miss work; however, most back or neck pain results from musculoligamentous strain that resolves with conservative therapy. Persistent axial skeletal pain or radicular pain is more likely to result from a surgical lesion and requires a more extensive diagnostic evaluation. Assessment begins with a history and physical examination, followed by appropriate laboratory investigations and diagnostic imaging.
- The history investigates the onset of pain and its characteristics, location, and aggravating and alleviating factors. Discussion should include similar episodes of pain, associated symptoms, and related systemic complaints. Medical, family, and social histories elucidate conditions associated with spine problems. A comprehensive physical examination of all systems is essential. Anterior neck pathologic conditions, thoracic disease, and abdominal ailments can manifest as visceral pain referred to the neck and back, and systemic disease may first manifest in the spine. Evaluation of the spine includes inspection, palpation, and range-of-motion testing. A detailed neurological examination may document physical evidence of dysfunction of the brain, spinal cord, peripheral nerves, and/or muscles. When a neurological deficit is present, its characteristics help establish the diagnosis.
- Clinical findings guide laboratory and imaging investigations. Standard laboratory studies include a complete blood count, electrolyte panel, glucose measurement, and coagulation panel. Measurements of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level, and blood cultures help diagnose an infection; serum and urine studies explore for neoplasia; immunologic markers indicate inflammatory diseases; and endocrine and metabolic studies investigate primary metabolic bone diseases.
- Classically, imaging begins with plain radiographs: anteroposterior, lateral, and flexion-extension views, as well as coned-down views of transitional areas. Magnetic resonance imaging (MRI) or computed tomography (CT) of the spine should follow to further define underlying pathology. MRI is better for imaging soft tissues and changes in tissue hydration, and CT is better for imaging bony detail. CT myelography often better delineates the neural elements in relation to the bony anatomy. Bone scans and bone density determination are occasionally required.
- The laboratory work and radiologic imaging may provide a definitive diagnosis, or pathologic evaluation of abnormal tissue may be required. Once a definitive diagnosis has been obtained, medical or surgical treatment can proceed.
- Patients presenting with spine or radicular pain associated with fever and weight loss are at increased risk of having an infectious process. The presentation of patients with neoplastic processes can be similar. The presence of fever with spine or radicular pain should lead the physician to look for an axial skeletal infection first. Neurological deficits can occur, but they usually manifest weeks to months after the onset of pain and systemic symptoms. Vertebral osteomyelitis, discitis, epidural abscess, and granulomatous processes are the most common potential infectious conditions.
- Vertebral osteomyelitis typically results from a pyogenic infection of the vertebral column. It is the most commonly encountered infection of the axial skeleton, accounting for 2% to 19% of all cases of osteomyelitis. Osteomyelitis may be the result of trauma, extension from adjacent structures, or hematogenous spread. A definitive source of infection is found in less than 50% of cases. The most common foci are genitourinary, soft tissue, and respiratory, or the infection may be traced to intravenous drug abuse. The organisms most commonly isolated are gram-positive cocci, constituting 60% to 70% of all cases. Staphylococcus aureus is the most prevalent, representing up to 60% of all positive culture results. Gram-negative rods are found predominantly in parenteral drug abusers or immunocompromised patients. The lumbar spine is most often involved, followed by the thoracic spine and cervical spine. The vertebral body is involved in more than 95% of cases. Less than 5% of cases involve the posterior elements.
- Vertebral osteomyelitis has a male predominance. Predisposing conditions include advanced age, diabetes mellitus, steroid therapy, and intravenous drug abuse. The most common symptom is insidious, diffuse back pain, which is seen in about 90% of patients; fever occurs in 50% to 70% of patients. Other symptoms include weight loss, radicular pain, myelopathy, spine deformity, and meningeal irritation. Diagnosis can be delayed owing to the nonspecificity of presenting symptoms. Mean time to diagnosis is 6 to 8 weeks, with a range of 2 weeks to 5 months. Neurological compromise and decreased mobility are late complications. Diagnosis is based on pertinent laboratory findings: elevated ESR and CRP, positive blood and bone culture results, elevated white blood cell count, and radiologic studies. The sensitivity and specificity of MRI make it the “gold standard” for detecting osteomyelitis. Bone scans are useful for diagnosis because of their high sensitivity, but other inflammatory processes or neoplasia can mimic infection on bone scans. CT reveals the extent of bony destruction.
- Management is based on biopsy results from percutaneous aspiration and bone biopsy using CT or fluoroscopic guidance. Treatment entails bed rest and broad-spectrum antibiotics, followed by definitive antimicrobial therapy based on culture results. Decompression with or without fixation may be required if there is extensive bony involvement or if neurological sequelae occur from excessive bony destruction or abscess formation.
- A spinal epidural abscess usually results from a pyogenic infection of the epidural space. Although uncommon (reported incidence: 0.2 to 1.2 cases per 10,000 hospital admissions), its clinical importance overshadows its rarity. Approximately 50% of spinal epidural abscesses result from hematogenous spread of infection to the epidural space. Other causes include direct extension of a preexisting osteomyelitis or discitis and direct inoculation from surgical manipulation or trauma. The organisms of spinal epidural abscesses mirror those found in vertebral osteomyelitis. Gram-positive cocci are the most prevalent, with S. aureus isolated in 60% to 65% of cultures with positive results; other staphylococcal and streptococcal species are the next most common organisms isolated. Thoracic involvement is slightly more common than lumbar involvement, followed by cervical involvement. Posterior location predominates in about two thirds of cases. An anterior abscess often results from direct extension of a ventrally located discitis or vertebral osteomyelitis.
- Adults are primarily affected, and there is no sex predominance; spinal epidural abscess is rare in children. Axial skeletal pain is a common initial complaint. The pain may develop a radicular component, and sensory or motor dysfunction of the affected nerve root can occur. If a spinal epidural abscess remains untreated, paraplegia or quadriplegia ensues. The incidence of fever, leukocytosis, and neurological compromise is higher than in vertebral osteomyelitis. Laboratory studies include ESR, CRP concentration, and white blood cell count, which are elevated in most patients. MRI is the diagnostic procedure of choice. T1-weighted images reveal a hypointense epidural mass that enhances with administration of a contrast agent. On T2-weighted images, the mass is hyperintense. Early diagnosis is important because patients with spinal epidural abscess can deteriorate rapidly, even when receiving intravenous antibiotics. Treatment for spinal epidural abscess is surgical evacuation and administration of the appropriate antibiotics.
- Discitis represents two entirely different entities in adults and children. Pediatric discitis classically manifests spontaneously. Adult discitis is most often encountered after discectomy, although it can occur spontaneously. Less often, adult discitis results from hematogenous spread secondary to intravenous drug abuse or debilitating disease. Early detection is important to prevent discitis from progressing to vertebral osteomyelitis or epidural abscess.
- In children, discitis is a relatively benign disease due to a chronic inflammatory disorder, viral infection, or low-grade bacterial infection. The vascular network throughout the cartilaginous end plate and disk predisposes children to discitis. This network functions as a site for bacterial colonization and disappears in late adolescence. Postoperative discitis in adults results from bacterial contamination during surgical manipulation. Gram-positive cocci, staphylococcal and streptococcal species, predominate in both pediatric and adult cultures. Biopsies and blood cultures can be nondiagnostic in 20% to 50% of patients. The lumbar spine is affected more frequently than the thoracic or cervical spine in both children and adults.
- Patients present with back pain and painful ambulation. In adults, the onset of pain at the surgical level 1 to 3 weeks after surgery signals the possibility of an infection. Typically, ESR and CRP concentration are elevated. MRI is the most sensitive and specific modality for detecting infection and determining the efficacy of treatment. MR images show evidence of the infection sooner than plain radiography does. ESR measurement is a sensitive test for detecting the infection and following the progression of treatment. Management consists of CT- or fluoroscopy-guided biopsy and culture, bed rest, and a course of intravenous and then oral antibiotic therapy. The prognosis of uncomplicated cases is excellent.
- Granulomatous infections initiate a chronic granulomatous response. Infections with fungal, spirochetal, and other organisms such as Actinomyces, Nocardia , Brucella , and Mycobacterium tuberculosis can produce granulomatous disease of the axial skeleton.
- Although rare in developed countries, tuberculous spondylitis is globally the most common granulomatous infection affecting the axial skeleton. Historically, tuberculous spondylitis (Pott's disease) is usually caused by M. tuberculosis, but other mycobacteria can also infect the axial spine. Infection results from hematogenous spread of mycobacteria from a pulmonary or genitourinary source. The infection spreads across the disk space, along the posterior or anterior longitudinal ligament, and tends to spare the disk space. The skeleton is affected in about 1% of all cases; of those, 50% to 60% involve the axial skeleton. The thoracolumbar spine is affected most frequently; involvement of the cervical spine and sacrum is rare.
- Currently, individuals infected with the human immunodeficiency virus (HIV) account for most tubercular infections in the United States, and drug-resistant strains are being seen more frequently. Clinical presentation involves bone pain over the affected spinal level with fever, malaise, and weight loss. Vertebral collapse, spine deformity, epidural abscess, and subarachnoid seeding after dural erosion are late sequelae. In the progressive stages of the disease, kyphosis and epidural abscesses are common. Neurological sequelae occur in 10% to 50% of patients with active disease. In 20% of cases, tuberculous spondylitis causes paraparesis.
- Plain radiography, MRI, and CT myelography evaluate disease progression and guide surgical planning. MRI evaluates the involvement of soft tissue and abscess formation. CT provides bony detail. Treatment is based on positive biopsy or culture results, degree of kyphosis, extent of neurological compromise, and refractoriness of the disease. Decompression and débridement, combined with antibiotic therapy, are the accepted treatment modalities when a neurological deficit evolves. Prognosis relates to patient age, extent of systemic disease, and preoperative neurological status.
- Actinomyces israelii , an anaerobic gram-positive bacterium, can cause purulent abscesses, external draining sinuses, and characteristic sulfur granules on microscopic examination. Infection is seen mostly in the cervical spine, secondary to direct extension from a preexisting mandible or supraclavicular infection. Nocardia asteroides , a gram-positive bacterium, can be a rare cause of back pain when the spinal column is involved. Nocardia spreads hematogenously from a pulmonary focus, and osteomyelitis due to this agent has occasionally been reported.
- Fungal infections of the axial skeleton are rare and occur by spore inhalation, with resultant pulmonary seeding and systemic spread. Spinal osseous involvement in patients with disseminated coccidioidomycotic and blastomycotic infection occurs in 10% to 50% of cases. The incidence of axial skeletal involvement with candidiasis or aspergillosis is low. Both fungal infections tend to occur in immunocompromised hosts. Other rare granulomatous diseases of the axial skeleton include parasitic infections such as syphilis and echinococcosis.