Infections of the Cervical Spine

30 Infections of the Cervical Spine



Kamal R.M. Woods, Samer Ghostine, Terrance Kim, J. Patrick Johnson




KEY POINTS



• Early diagnosis and treatment is pivotal to the management of cervical spine infections, given their propensity to cause rapid and severe neurological decline.

• Most patients with cervical spine infections complain only of vague neck pain, although fevers, radiculopathy, neck rigidity, and dysphagia may also be present.

• The diagnosis of cervical spine infection is typically made based on elevated erythrocyte sedimentation rate (ESR) and confirmatory imaging.

• In the absence of acute neurological deficit or spinal instability, pyogenic cervical osteomyelitis, and cervical discitis are usually treated with 4 to 8 weeks of intravenous antibiotics.

• Surgical treatment is recommended for cervical epidural abscesses, subdural empyemas, and intramedullary abscesses.


Introduction


Evidence from Egyptian mummies suggests that infections of the spine predate the era of written history. In his textbook On the Articulations, Hippocrates (400 bc) included reports of vertebral deformity that likely resulted from what was later described by Pott as tuberculous spondylitis. Today, infections of the spine are relatively rare clinicopathologic entities. When they do occur, however, these infections still pose both diagnostic and therapeutic challenges to clinicians.


Spine infections predominate in the lumbar region, followed by the thoracic and then the cervical regions. Nonetheless, cervical infections are particularly problematic because of their propensity to cause more rapid and severe neurological deficits. The discussion that follows will examine the most surgically relevant cervical spine infections: pyogenic vertebral osteomyelitis, spinal epidural abscess, discitis, subdural empyema, and intramedullary abscess.



Basic Science


Cervical infections may be viewed from the perspective of the infectious organism: bacterial, viral, fungal, or parasitic. Alternatively, they may be approached based on the response of the host to the inciting organism: pyogenic (“pus-forming”), or granulomatous. The classic example of a granulomatous infection is tuberculous spondylitis (Pott disease), in which the histology shows caseating central necrosis surrounded by Langhans giant cells. Granulomatous infections may also be caused by fungi, such as aspergillosis, coccidiomycosis, blastomycosis, and cryptococcosis. Parasitic infections of the cervical spine, including cysticercosis, schistosomiasis, and echinococcosis, are extremely rare, and data on their management are limited to case reports.


Overall, the most common causative agent for spinal infections in the United States is Staphylococcus aureus, which is present in more than 50% of cases. When the spine infection is associated with a genitourinary or gastrointestinal infection, Escherichia coli, Proteus, and other gram-negative bacteria are frequently responsible. Patients who have a recent history of intravenous drug abuse are more likely to be infected with Pseudomonas aeruginosaStreptococcus is a significant cause of intramedullary cervical abscesses, as it can spread through the lymphatic system from the retropharyngeal space.


There are several potential routes for the dissemination of infections to the cervical spine, including direct extension from contiguous structures, open spinal trauma or surgery, hematogenous, or lymphatic. Both venous and arterial mechanisms have been implicated in hematogenous spread. The Batson venous plexus was proposed as a valveless conduit through which infections of the pelvis, such as urinary tract infections, may spread to the spine. This venous mechanism has been largely refuted, and an alternative arterial route postulated.1 In the case of vertebral pyogenic osteomyelitis, infection is thought to seed the metaphyseal (subchondral) bone near to the anterior longitudinal ligament via a rich arterial network. The posterior spinal arteries that branch off the dorsal artery entering the intervertebral foramen are probably responsible for cervical epidural abscesses. Infections of the retropharyngeal space can enter the lymphatics and spread along the spinal nerves to communicate with the spinal subarachnoid space and Virchow-Robin space, thus leading to cervical subdural empyemas or cervical intramedullary abscesses.


Interestingly, discitis is seen in two distinct patient populations: pediatric and adult. While discitis in the pediatric population is usually caused by a hematogenous source, adult discitis occurs in patients who have undergone prior surgery involving the disc space. The reason for this clear distinction is that, as the spine ages, there are changes that take place in its vascularity. Histologic studies have shown that an end-arteriolar supply of the disc is present during infancy and childhood, and these end arteries are obliterated by the third decade of life.2



Clinical Practice Guidelines


The guidelines that govern the diagnosis and treatment of cervical spine infections may vary on a case-by-case basis. However, there are certain common themes which ought to be emphasized.



Risk Factors


Numerous risk factors for the development of cervical spine infections have been identified, including diabetes, intravenous drug usage (especially via the jugular vein), alcohol abuse, urinary tract manipulation or infection, immunocompromised state, steroid therapy, prior spine surgery, advanced age, and male gender. In the setting of diabetes, steroids, or other immunocompromised state, the diagnosis is usually delayed because of an impaired inflammatory response.



Clinical Presentation


The most common chief complaint for all cervical spine infections is vague, nonspecific neck pain of a progressive nature. With pyogenic osteomyelitis and discitis, this pain is exacerbated by neck motion, and eventually becomes extremely debilitating. Radicular pain is frequently present in epidural abscesses, and results from either direct nerve root compression or inflammation.3 If a cervical epidural abscess spreads to the retropharyngeal space, then dysphagia or even airway compromise may result.


The time course to presentation for cervical spine infections varies from acute (less than 1 week), to subacute (1 to 6 weeks), to chronic (more than 6 weeks). In the case of pediatric discitis, this pain is usually so severe at an early stage that a diagnosis is made before the infection spreads to the adjacent vertebral bodies.4 For pyogenic vertebral osteomyelitis, the presentation tends to be subacute to chronic in 90% of cases, partly because of its more insidious onset. A definitive diagnosis of pyogenic vertebral osteomyelitis is made, on average, 8 weeks to 3 months after disease onset.5 Patients who present acutely (less than 1 week) are more likely to be febrile, and to have other constitutional signs and symptoms.


Infections that result in the formation of a mass-occupying abscess have a greater chance of presenting with neurological deficit. This may be seen in vertebral osteomyelitis that extends into the epidural space, or with a primary spinal epidural abscess. Likewise, subdural empyemas and intramedullary abscesses cause neurological deficit at an early stage. In some instances of vertebral osteomyelitis, the bony quality is compromised to the extent that bony collapse may occur, leading to spinal instability and secondary neurological deficit. Sometimes, spinal epidural abscesses and subdural empyemas may cause neurological compromise that is out of proportion with the degree of compression. This is thought to be secondary to vascular compromise from venous compression, thrombosis, or thrombophlebitis.6


On physical exam, some patients with cervical infections may have local tenderness at the level of the infection, or diffusely in the cervical region. Given the paucity of other physical exam findings, such spine tenderness may seem somewhat dramatic. When the adjacent soft tissue is affected, the skin may show the typical signs of infection: erythema, swelling, warmth, induration, or even fluctuance. Meningitis may be associated with epidural abscesses and subdural empyemas, resulting in rigidity of the neck with passive flexion.

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Aug 6, 2016 | Posted by in NEUROSURGERY | Comments Off on Infections of the Cervical Spine

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