Neurosurg Focus 17 (6):E2, 2004 Diagnosis and management of adult pyogenic osteomyelitis of the cervical spine FRANK L. ACOSTA JR., M.D., CYNTHIA T. CHIN, M.D., ALFREDO QUIÑONES-HINOJOSA, M.D., CHRISTOPHER P. AMES, M.D., PHILIP R. WEINSTEIN, M.D., AND DEAN CHOU, M.D. Departments of Neurological Surgery and Radiology, University of California, San Francisco, California Establishing the diagnosis of cervical osteomyelitis in a timely fashion is critical to prevent catastrophic neurolog- ical injury. In the modern imaging era, magnetic resonance imaging in particular has facilitated the diagnosis of cer- vical osteomyelitis, even before the onset of neurological signs or symptoms. Nevertheless, despite advancements in diagnosis, disagreement remains regarding appropriate surgical treatment. The role of instrumentation and type of graft material after cervical decompression remain controversial. The authors describe the epidemiological features, patho- genesis, and diagnostic evaluation, and the surgical and nonsurgical interventions that can be used to treat osteomyelitis of the cervical spine. They also review the current debate about the role of instrumentation in preventing spinal defor- mity after surgical decompression for cervical osteomyelitis. Based on this review, the authors conclude that nonsur- gical therapy is appropriate if neurological signs or symptoms, instability, deformity, or spinal cord compression are absent. Surgical decompression, debridement, stabilization, and deformity correction are the goals once the decision to perform surgery has been made. The roles of autogenous graft, instrumentation, and allograft have not been clearly delineated with Class I data, but the authors believe that spinal stability and decompression override creating an envi- ronment that can be completely sterilized by antibiotic drugs. KEY WORDS • cervical spine • osteomyelitis • instability • fixation According to Dimar, et al.,15 Hippocrates was the first to cervical spine make cervical osteomyelitis a unique entity. describe osteomyelitis of the spine in 400 BCE. In 1864, A small epidural infection can cause a neurological def- as discussed in Wiltse,67 Boudof described draining an ab- icit. Bone destruction and ligamentous laxity can manifest scess of the cervical spine via an anterior approach. In the as severe instability, deformity, or a neurological deficit.13 same historical review, Wiltse reported Wright’s account Establishing the diagnosis of cervical osteomyelitis in a of draining a tuberculous abscess through the pharynx in timely fashion is critical to prevent catastrophic neurolog- 1930. Although the advent of antibiotic therapy enabled ical injury.15,41 In the modern imaging era, MR imaging in early stages of vertebral osteomyelitis to be managed particular has facilitated the diagnosis of cervical osteo- without surgery, more advanced disease with spinal in- myelitis even before the onset of neurological signs or stability, cord compression, and neurological deficits re- symptoms. Nevertheless, despite advancements in diagno- quired surgical decompression and stabilization.7,54 None- sis, there remains disagreement regarding appropriate sur- theless, anterior approaches to the cervical spine were gical treatment. The role of instrumentation and type of seldom used until Robinson and Smith50 described a tech- graft material after cervical decompression remain contro- nique for anterior cervical disc removal and fusion in versial. We describe the epidemiological features, patho- 1955. Current surgical treatment options include anterior genesis, diagnostic evaluation, and surgical and nonsurgi- or posterior decompression with or without fusion, and cal interventions that can be used to treat osteomyelitis of with or without instrumentation.16,24,35,36,39,40 The fact that the cervical spine. We also review the current debate about there exist several alternative surgical approaches high- the role of instrumentation in preventing spinal deformity lights the lack of a consensus on the optimal operative after surgical decompression for cervical osteomyelitis. treatment for cervical vertebral osteomyelitis. The large diameter of the cervical spinal cord relative to the spinal canal and the significant range of motion of the EPIDEMIOLOGY AND ETIOLOGY Vertebral osteomyelitis accounts for approximately 1 13,57 Abbreviations used in this paper: CRP = C-reactive protein; to 7% of all bone infections. Whereas the thoracic CT = computerized tomography ; ESR = erythrocyte sedimentation and lumbar spine are affected in 35 and 50% of cases, rate; MR = magnetic resonance; VB = vertebral body; WBC = respectively, the cervical region is affected in 3 to 10% of white blood cell. cases.25,38,57,60 Although relatively rare, cervical osteomye- Neurosurg. Focus / Volume 17 / December, 2004 1 Unauthenticated | Downloaded 09/30/21 08:57 AM UTC F. L. Acosta, et al. litis nonetheless poses management challenges to the TABLE 1 spine surgeon, given the location of the disease process. Literature review of the microorganisms identified in cultures Pyogenic vertebral osteomyelitis refers to bacterial in- obtained in patients with cervical osteomyelitis fections of the spine that cause purulence and a predomi- nantly neutrophilic response.64 It encompasses a spectrum Study, No. of Patients (%) of pathological conditions, including discitis, spondylitis, Schimmer, Shad, Spies, Dimar, and spondylodiscitis.25 Epidural abscess often complicates Microorganism et al. et al. et al.* et al. these disease processes.25 There appears to be an increas- S. aureus 8 (53) 4 (80) 1 (33) 3 (60) ing incidence of spinal infections in recent years; this dis- coagulase-negative 0 1 (20) 0 0 ease is now estimated to occur in approximately 1 per Staphylococci 100,000 persons annually.10,29 This rise can be attributed to E. coli 2 (13) 0 0 0 the increasing prevalence of elderly and immunocompro- Klebsiella pneumoniae 1 (7) 0 0 0 mised individuals in the population.13 Cervical osteomy- Mycobacterium 1 (7) 0 0 0 elitis most often affects patients in the fifth through sev- tuberculosis 38,57 Streptococcus sp. 1 (7) 0 0 0 enth decades of life. Patients with diabetes, a history of none isolated 2 (13) 0 1 (33) 2 (40) intravenous drug abuse, chronic immunosuppression, or polymicrobial 0 0 1 (33) 0 human immunodeficiency virus are particularly suscepti- total no. of patients 15 5 3 5 ble to vertebral osteomyelitis.5,13,23,26,44,54 Cervical * All affected patients in this study had osteomyelitis of the C1–2 com- osteomyelitis has been reported to occur in up to 27% of plex. intravenous drug abusers.56,60 The most common mechanism for spread to the cervi- cal spine is through a hematogenous route. Remote infec- PATHOGENESIS tions anywhere in the body can seed the spine. Patients with primary pulmonary tuberculosis can present with tu- The unique vascular supply to the intervertebral disc berculous osteomyelitis of the spine.11,69 Urinary tract in- space in general, and to the cervical spine in particular, fections, respiratory tract infections, and intravenous drug can be used to explain the pathogenesis of cervical osteo- abuse are very common sources of spinal osteomyeli- myelitis. The spine is inoculated with infectious organ- tis.54,55 Moreover, the cervical spine is particularly suscep- isms through the arterial blood supply, direct inoculation tible to infection that spreads from adjacent tissues, or that during an invasive procedure, direct extension from an occurs from contamination after invasive diagnostic or adjacent nidus of infection, or retrogradely through the therapeutic procedures. For example, osteomyelitis of the vertebral venous plexus.64 Infection through the arterial cervical spine has been reported to occur after trache- blood supply likely accounts for most cases; periosteal ar- otomy,45 pharyngeal surgery,17 tonsillectomy,14 cervical teries can carry bacteria into the small metaphysial nutri- discography,73 and in association with Zenker diverticu- ent arteries to which they give rise, setting up a nidus of lum.22 Cervical spinal infection has also been reported to infection and causing avascular necrosis of the metaph- occur after cervical spine trauma.32,37 Hematogenous seed- ysis. The intervertebral disc, supplied by these same ves- ing, though, remains the most common route for spread of sels, also becomes infected and necrotic. Inoculation of a infection to the cervical spine.13,57,71 metaphysial artery can therefore lead to infection of both the disc space and adjacent vertebrae.14,32,73 Accordingly, it is believed that discitis and vertebral osteomyelitis are dif- 25 MICROBIOLOGY ferent stages of the same disease process. Spontaneous infection of the disc space rarely occurs.13 The predominant organism in almost all studies is Infectious organisms within the genitourinary or gas- Staphylococcus aureus, accounting for approximately 40 trointestinal systems can spread to the spine through to 80% of all spinal infections.25,29 Other Gram-positive or- epidural veins.59 This type of transvenous inoculation is ganisms such as S. epidermidis and Streptococcus species believed to be the major mechanism in the development of are the second most common ones.18,25 Since the introduc- rare infections involving the posterior elements of the tion of antibiotics, though, there has been a relative in- spine.2,64 Moreover, infection within the disc space or adja- crease in infections caused by Gram-negative bacteria cent VBs can be transmitted to the epidural