Infections and Tumors of the Spine

Clinical Presentation

The most common presenting symptom of spinal infection is back pain or neck pain. No pathognomonic features of the pain occur with vertebral osteomyelitis or discitis, which can lead to a delay in diagnosis. Pain often is worse at night and can occur with changes in position, ambulation, and other forms of activity. The intensity of the pain varies from mild to extreme. Constitutional symptoms include anorexia, malaise, night sweats, intermittent fever, and weight loss. Spinal deformity may be a late presentation of the disease. Neurologic deficits are a serious complication but rarely are the presenting complaint. A history of an immune-suppressing disease or a recent infection, or both, is common.

Temperature elevation, if present, usually is minimal. Localized tenderness over the involved area is the most common physical sign. Sustained paraspinal spasm also is indicative of the acute process. Limitation of motion of the involved spinal segments because of pain is frequent. Torticollis may result from infection in the cervical spine, and bizarre posturing and physical positions that could be considered psychogenic in origin are possible. Other possible findings include the Kernig sign (severe tightness of the hamstring) and generalized weakness. Clinical findings in elderly and immunosuppressed individuals may be minimal.

Because of the depth of the spine, abscess formation is difficult to identify unless it points superficially. Frequently, these areas of abscess pointing are some distance from the primary process. A paraspinal abscess commonly presents as a swelling in the groin below the Poupart ligament (inguinal ligament) because of extension along the psoas muscle.

The development of neurologic signs should suggest the possibility of neural compression from abscess formation, bone collapse, or direct neural infection. Neurologic findings rarely are radicular and more frequently involve multiple myotomes and dermatomes. As might be expected, neurologic symptoms become more frequent at higher spinal levels; they are most frequent with infections in the cervical and thoracic areas and are least common with infections in the lumbar region. When neurologic symptoms appear, they can progress rapidly unless active decompression or drainage is undertaken.

Laboratory Studies

The erythrocyte sedimentation rate (ESR) is used to help identify and clinically monitor spinal infections. The ESR is not diagnostic and indicates only an inflammatory process. The ESR is elevated in 71% to 97% of children with vertebral osteomyelitis. In 37% of adults with osteomyelitis, the rate is greater than 100 mm/h, and in 67%, rates greater than 50 mm/h are noted. The ESR normally is elevated after surgery (approximately 25 mm/h), peaking at 5 days but may stay elevated for 4 weeks. Persistent elevation of the ESR 4 weeks after surgery, with associated clinical findings, indicates the presence of infection.

C-reactive protein (CRP) has proven to be a more sensitive marker for early detection of postoperative spine infections when compared with ESR. CRP levels tend to peak within the first 2 postoperative days and then decline rapidly. A continued elevation of the CRP in the immediate postoperative period (4 to 7 days) or a second rise is a strong indicator of an infection. Thelander and Larsson compared the CRP with the ESR as an indicator of infection after surgery on the spine, including microscopic and conventional disc excision and anterior and posterior spinal fusion. They noted in all patients that results of both tests were elevated initially after the surgery, but in all the patients the CRP value had returned to normal by 14 days whereas the ESR took much longer to return to normal. The CRP also can be used to monitor the antibiotic treatment of an infection because of its rapid return to normal with resolution of the infection. The ESR may be elevated for weeks in a treated infection.

More recently, procalcitonin (PCT) has been found to be a useful marker for infection generally. Aljabi et al. found PCT to be a more sensitive and specific infection marker than CRP in 200 postoperative patients. In addition, the biokinetics of PCT were not affected by the surgical procedure. Other biomarkers such as presepsin are also being evaluated to help identify infection.

Leukocytosis is not especially helpful in diagnosing spinal infection. White blood cell counts may decrease in infants and debilitated patients. High white blood cell counts may indicate areas of infection other than the spine. Blood cultures are helpful if positive, which usually occurs in times of active sepsis with a febrile illness, and may be adequate for the diagnosis and treatment of osteomyelitis, but this occurrence is rare.

Imaging Techniques

The purpose of diagnostic techniques is confirmation of the clinical impression. Because clinical findings are nonspecific, imaging findings play a key role in the diagnosis of spinal infection. In spinal infection, no single diagnostic technique is 100% effective as a confirmatory test. Culture of the organism from the infected tissue is the most definitive test, but results may be falsely negative even under the most optimal conditions. Likewise, all imaging and laboratory studies may be inconclusive, depending on the time at which they are done relative to the onset of infection.

Radiography

Plain radiographs of the involved area are the most common initial study in patients with spinal infection. Radiographic findings, which appear 2 weeks to 3 months after the onset of the infection, include disc space narrowing, vertebral end plate irregularity or loss of the normal contour of the end plate, defects in the subchondral portion of the end plate, and hypertrophic (sclerotic) bone formation ( Fig. 42.1 ). Occasionally, paravertebral soft-tissue masses may be noted with involvement of nearby areas of the spine. Late radiographic findings may include vertebral collapse, segmental kyphosis, and bony ankylosis. The sequence of events may range from 2 to 8 weeks for early findings to more than 2 years for later findings. The only definable abnormality on plain radiographs and CT scans related specifically to tuberculosis is fine calcification in the paravertebral soft-tissue space.

Differential Diagnosis

The differential diagnosis of spinal osteomyelitis should include primary and metastatic malignancies, metabolic bone diseases with pathologic fractures, and infections in contiguous and related structures, including the psoas muscle, hip joint, abdominal cavity, and genitourinary system. Rheumatoid arthritis and ankylosing spondylitis and Charcot spinal arthropathy may also cause findings resembling osteomyelitis of the spine. Acquired immunodeficiency syndrome may be another underlying factor in these infections. Myelitis from bacterial infection also has similar findings and distinctive MRI findings.

Nonoperative Treatment

Antibiotic treatment for vertebral osteomyelitis and discitis infections in adults is the primary therapy. Surgery is reserved for disease progression despite appropriate antimicrobial therapy, spinal instability with spinal cord or cauda equina compression or impending significant neural compression, and drainage of an epidural abscess. The antibiotic is chosen according to the positive stains, cultures, and sensitivities of the organism. Response to treatment is evaluated by observing clinical symptoms and serially following CRP levels and PCT levels. Failure of antibiotic therapy suggests the presence of a multiorganism infection, and repeat biopsy, including open biopsy, should be considered. Consideration should also be given to surgical debridement of sequestered bone and abscess drainage if there is no clinical improvement with antibiotic therapy.

The time for discontinuing antibiotic therapy also varies. Collert suggested that antibiotic therapy should be continued until the ESR returns to normal. Unfortunately the ESR can stay elevated for a prolonged period even in a treated infection. CRP values decline more rapidly and may be a better gauge to base discontinuance of antibiotics, but currently this factor is still being studied. Intravenous antibiotics usually are continued for about 6 weeks and are followed by oral antibiotics as indicated by the CRP, ESR, and clinical response.

With an adequate biopsy and a reliable patient who responds rapidly to antibiotics, hospitalization and bed rest usually are required only for the primary symptoms. Home-administered intravenous antibiotics allow the patient to complete treatment out of the hospital. A major risk with this technique is late pathologic fracture of the infected bone. In patients who are at risk for fracture or are in pain, a brace is used. If ambulatory therapy is chosen, thorough education and close monitoring of the patient are mandatory.

Prognosis

Even if an absolute diagnosis is not made, most spinal infections resolve symptomatically and radiographically within 9 to 24 months of onset. Recurrence of infection and periods of decreased immune response are always possible, as are delayed complications of kyphosis, paralysis, and myelopathy. These risks are greatest during the period when the infection is controlled but the bone is still soft, when the healing process has not advanced to the point where solid bone has formed around the infected tissue. Bracing is strongly recommended in these patients.

Operative Treatment

Surgical intervention is indicated when medical management has failed, when there is a neurologic deficit from either an abscess, or instability with deformity, or when a diagnosis is not otherwise possible. The location of the infection, extent of bony destruction, and presence of neurologic involvement dictate the surgical approach and the surgical objectives. Several recent studies have reported endoscopic procedures to obtain biopsy material for culture and abscess drainage with results similar to open biopsy. Posterior-only surgery is generally not indicated in patients with spondylodiscitis, although some with a significant epidural abscess component may be appropriate for posterior decompression only. Because vertebral osteomyelitis and discitis typically affect the vertebral bodies and discs, an approach that allows thorough debridement of this area and reconstruction is usually necessary. Surgical planning is nuanced, and the need for posterior stabilization is determined primarily by the stability and length of the anterior construct. In the cervical spine, an anterior-only approach often is adequate; however, supplemental posterior instrumentation may also be required, as shown by Ackshota et al. in a study of 56 patients with multilevel cervical corpectomy. The vertebral body can be accessed from an anterior or posterior approach in the thoracic or lumbar spine. Whether an anterior, posterior, or combined approach is used, the objective of surgery is to perform a thorough debridement with decompression of the neural elements and stabilization of the spine with correction of the deformity. Often this requires a corpectomy and the need for anterior reconstruction with an interbody graft or cage. The interbody graft can be an allograft or autograft bone strut, and a mesh or expandable cage can be packed with allograft or autograft. Various studies have shown that all these interbody devices are acceptable. Often supplementation with anterior and/or posterior instrumentation is needed for added stability and to correct deformity.

Infections in Children

Primary pyogenic spinal infections are uncommon in children. These infections have been divided into three clinical presentations based on the age of the child. Neonatal spondylodiscitis is rare, but the most serious form occurs between birth and 6 months and usually is due to S. aureus. This infection often is multifocal and associated with septicemia, causing some to consider it differently from spondylodiscitis in older children. The second group is infantile spondylodiscitis, which occurs from 6 months to 4 years of age. About 50% to 60% of all cases occur in this age group. Dayer et al. found that these infections are more often caused by Kingella kingae. The juvenile/adolescent group of children are those between 4 and 16 years of age. In this group S. aureus again is the most common pathogen. In children who are old enough, the syndrome frequently is associated with difficulty in walking, irritability, and sudden inability to stand or walk comfortably. Most reports indicate that the cause is hematogenous spread of a bacterial infection, although trauma also has been implicated, and males are more commonly afflicted. When positive, most blood culture reports are positive for S. aureus. Unfortunately, blood cultures are positive in only about 10% of cases. Even needle aspirations provide negative cultures in over 50% of patients, making it difficult to recommend due to the associated risks.

The average age at onset is 4 to 5 years, although the age group most commonly affected are 6 months to 4 years of age. Symptoms usually are present for 4 weeks before hospitalization, and the lumbar spine is most commonly affected. Physical findings are limited. The child may refuse to walk or may cry when walking, and spinal flexion may be limited and so painful that the child holds himself or herself erect. Physical findings directly related to the spine are rare. Neurologic findings are uncommon but are ominous when present. In older children, abdominal pain may be a presenting symptom. Other, less frequent symptoms include hamstring tightness and spinal tenderness.

Diagnosing disc space infection (vertebral osteomyelitis) in children is difficult early, and plain radiographs usually are negative. There may be a mild febrile reaction, but patients do not appear systemically ill. Laboratory investigation often reveals only a mildly elevated CRP and ESR in most patients, and patients usually are afebrile. The ESR has been found to be elevated more often than the CRP, and elevated platelet counts also are common. Polymerase chain reaction tests have become a very useful tool in the past decade, especially in diagnosing K. kingae using a throat swab . Older children are more likely to present with fever and laboratory findings of acute illness. The best test to identify the infection is MRI with and without gadolinium, or a combination of bone scanning and ⁶⁷ Ga scanning, although there is a significant radiation dose with nuclear medicine studies. These scans are not always diagnostic, and other possibilities, including inflammatory processes and tumors, may give false-positive results. Spondylodiscitis represents a continuum of disease. Most commonly the disc and the vertebrae on both sides of the disc space are affected; however, in a small portion of patients, discitis affects only the disc, and in others only vertebral osteomyelitis occurs. The treatment of discitis in children is organism-specific intravenous antibiotics and bed rest without immobilization until the child can walk and move around comfortably and then oral antibiotics for an additional period of time. Most patients are symptom free within several months. Spontaneous fusion occurs in about 25% of patients. Surgical procedures rarely are required, and persistent back pain rarely is a problem in children. Cast or brace immobilization has been recommended if pain or difficulty in walking persists; most frequently this is necessary in older children. Surgical treatment rarely is needed in children except in tuberculosis and other caseating diseases that have not responded well to antibiotics alone.

Special situations involving patients with immune suppression, suspected drug use, tumorous conditions, or poor response to conservative treatment require more vigorous evaluation by needle aspiration biopsy for culture and sensitivity. CT-guided percutaneous biopsy, with the patient under sedation, makes this a relatively safe procedure, but rates of positive culture are disappointingly low. Definitive diagnosis and organism-specific antibiotic treatment constitute the most efficient method of dealing with these infections.

Spinal Epidural Abscess (Sea)

Epidural infections have a low reported incidence of 2 to 10 cases per 10,000 hospital admissions per year and have increased with an aging population. The incidence of this infection is increased in immunosuppressed patients and intravenous drug users. Morbidity and mortality can be high with epidural infections when significant neurologic deficits are present and when the diagnosis is delayed. The neurologic risk is highest in the cervical spine and lowest in the lumbar spine below the conus. Fortunately, most SEAs occur in the lower lumbar region. The causes of infection are the same as those for osteomyelitis and discitis: direct extension from infected adjacent structures, which is by far the most common; hematogenous spread; and iatrogenic inoculation. Epidural abscess usually spans three to five vertebral segments. Longitudinal and circumferential extension of epidural infections is believed to be limited by the spinal canal anatomy. Using cryomicrotome sectioning, Hogan showed that the epidural space is discontinuous circumferentially and longitudinally. A SEA caused by direct extension from a vertebral osteomyelitis usually is on the ventral side of the canal anterior to the thecal sac, and extension from an infected facet joint often presents with an abscess posterior to the thecal sac.

The clinical findings are similar to those of osteomyelitis but with several distinct differences: (1) a more rapid development of neurologic symptoms (days instead of weeks), (2) a more acute febrile illness, and (3) signs of meningeal irritation, including radicular pain with a positive straight-leg raising test and neck rigidity. The classic progression of the disease is generalized spinal ache, nerve root pain, weakness, and finally paralysis, which can occur within 7 to 10 days. The diagnosis of SEA is based primarily on MRI with gadolinium. This study can determine the presence of contiguous spondylodiscitis or facet infection, whether the SEA is anterior or posterior to the thecal sac, and the spinal levels of involvement. Diagnosing a SEA quickly after presentation of the patient may allow medical management if there is no neurologic involvement. SEA without neurologic involvement and a known organism usually can be managed with antibiotic therapy alone, which in recent years has led to a trend away from surgical management. Medical management does require close clinical follow-up, as cases that progress to neurologic deficit have a worse prognosis. The clinical course is more important than follow-up imaging in determining a change to operative management.

There is controversy over the etiology of neurologic impairment. Some authors believe that it is the result of mechanical compression, whereas others implicate vascular changes. At least the initial neurologic deficits appear to be mechanical and usually can be reversed with decompression within 36 hours. Although progression of the process is usually slow enough to allow evaluation and preparation without endangering the patient, failure to provide prompt drainage in the cervical and thoracic spine can result in serious neurologic deficit and possibly death. Purported independent predictors of failure of nonoperative management of SEAs include age over 65 years, diabetes, methicillin-resistant S. aureus , elevated CRP, and WBC counts; however, to date these have not been validated. Nonoperative medical management demands close observation and more active intervention if necessary. Medical management should be avoided in patients with cervical SEA. Alton et al. reported a 75% failure rate and unacceptably poor motor score outcomes with medical management of cervical SEA when compared with surgical management. They recommended that all patients with cervical SEA have early decompression to optimize motor function. In addition management of contiguous infection is important. SEA resulting from spondylodiscitis with spinal instability and collapse with neurologic compromise is more likely than SEA caused by spinal instability from posterior element infection.

The primary methods of treatment are appropriate antibiotic therapy and surgical drainage. Antibiotic treatment should be based on culture results whenever possible. Blood cultures and CT-guided biopsy of the infected adjacent structures and aspiration of paraspinal abscesses are appropriate. While there are reports of SEA decompression by CT-guided aspiration, this is not our recommendation and has significant technical limitations. Antibiotics should be held until cultures are obtained in patients who are hemodynamically and neurologically stable. Most cases of SEA are caused by gram-positive bacteria, S. aureus, Staphylococcus sp., enterococci, coagulase-negative staphylococci, and streptococci. Empiric therapy should provide coverage for these organisms.

The method of surgical treatment requires an accurate assessment of the location of the abscess and the presence of an associated osteomyelitis. Acute or chronic isolated dorsal (posterior), lateral, and some ventral (anterior) infections are best treated with total laminectomy for drainage, with closure over drains or secondary closure at a later date. Epidural infections associated with osteomyelitis are best exposed by anterior or posterolateral exposures that allow treatment of the osteomyelitis and the epidural infection. Laminectomy in patients with ventral (anterior) osteomyelitis results in late deformity and collapse, so posterior instrumentation should be used.

Other intraspinal infections include subdural spinal abscess and spinal cord abscess. These infections are rare. Subdural spinal abscesses progress at a slower pace than epidural abscesses and can be confused with tumors. Treatment requires durotomy without opening the arachnoid mater, thorough debridement, and dural closure if possible. Spinal cord abscesses cause pronounced incontinence and long tract signs. They frequently are confused with intramedullary tumors and transverse myelitis. In both of these conditions, the bone scan is normal, but the ⁶⁷ Ga scan should be positive. MRI, preferably with gadolinium contrast, is extremely helpful in defining the extent of the abscess. Some spinal cord abscesses can be treated successfully with antibiotics alone. Tung et al. noted that weakness at follow-up was associated with 50% or more narrowing of the central canal, peripheral contrast enhancement, and abnormal spinal cord signal intensity. Incomplete recovery was associated with abscess size and the severity of canal narrowing.

Surgical Site Infections

Postoperative infections are usually pyogenic and occur shortly after an operation. Preventive measures should be taken to decrease the risk of infection. The most common source for surgical site infection (SSI) is contamination of the surgical wound by the patient’s endogenous skin flora, most often S. aureus . A consistent and systematic approach is necessary to minimize the risk of SSI. Patient selection criteria and medical optimization including glycemic control (hemoglobin A1c <7%), cessation of nicotine at least 4 weeks preoperatively, decreased preoperative skin bacterial burden, appropriate antibiotic prophylaxis, antiseptic skin preparation, aseptic surgical techniques, and perioperative management are among other important measures ( Table 42.1 ). Patients with instrumentation have been found to have significantly higher ESR and CRP values than patients without instrumentation, but these parameters normally decrease after surgery unless infection is present. Patients with postoperative infection usually have a renewed elevation of these parameters. Wound drainage occurs commonly at an average of 3 to 5 days after surgery; however, fever is less common. There usually is back pain and tenderness to palpation with wound erythema. Deep wound infections can occur up to 90 days postoperatively.

The Spine Patient Outcome Research Trial study of lumbar degenerative conditions showed the overall incidence of infection to be 2% after procedures for disc herniation, 2.5% after spinal stenosis surgery, and 4% after surgery for degenerative spondylolisthesis. Other studies have put the rate of infection after all spinal infections at 1.9% to 4.4%. Although this number is small, postoperative spinal infections are costly and, more important, can have a significant effect on a patient’s clinical outcome. There are conflicting data on the association of preoperative lumbar epidural steroid administration and SSI. A retrospective study by Hartveldt et al. of 5311 patients did not find an increased risk of SSI in their cohorts after lumbar epidural steroid injection (LESI). In a Medicare database review, however, Yang et al. did find an increased risk of SSI if LESI occurred within 90 days of surgery.

Procedure-related risk factors associated with postoperative infection include duration of the surgical procedure, patient hypothermia, number of people in the operating room, dural tear, blood loss, transfusion of packed red blood cells, retained wound drain, and instrumentation.

Use of topical intrawound vancomycin powder has been shown in most studies to decrease the risk of SSI. A recent meta-analysis showed that vancomycin powder is protective against SSI. Edin et al. reported no signs of tissue toxicity with vancomycin use and that it had little or no effect on osteoblasts at doses used in the surgical wound, which is usually 1 g. A systematic review by Lemans et al. found that intrawound povidone iodine irrigation led to a similar reduction in SSI and intrawound antibiotics.

Surgical treatment of wound infection involves obtaining cultures followed by initial debridement and wound irrigation, with primary closure done in layers over a drain if the wound is deemed “clean” after the procedure. The patient is started on broad-spectrum intravenous antibiotics until cultures yield a pathogen. Once the organism is obtained with sensitivities, the antibiotic may be changed. The patient stays on intravenous antibiotics usually for 6 weeks, and if there is clinical improvement and normalization of the ESR and CRP, intravenous antibiotics will be switched to oral antibiotics for roughly another 4 weeks. It is important to consult an infectious disease specialist for these patients.

Repeat irrigation and debridement of the wound with cultures and layered closure over drains is done at 48-hour intervals until the wound is without drainage and the patient is improving. Instrumentation should be assessed at the time of debridement in patients with early SSI. Well-fixed implants should be left in place. If repeat debridement is required, MRI is used to evaluate for osteomyelitis or intradiscal abscess formation. Kanayama et al. suggested that, if MRI evidence of vertebral osteomyelitis or spondylodiscitis was present, the implants should be removed. They found that with implant removal in this circumstance the infection could be better treated. Implant retention led to frequent implant failure, which made salvage more difficult because of increased bone loss and deformity from persistent infection.

Numerous authors have shown that most infections can be treated without removal of the instrumentation. Instrumentation can be removed when the fusion is solid to avoid chronic suppressive antibiotics. Bone graft pieces that are not attached to soft tissue should be removed at the time of the initial debridement. This is also our method of treatment of acute postoperative infections. Recalcitrant wounds may require negative pressure wound therapy, V-Y flaps, or free flaps when bone or implants are exposed. Recent literature has shown negative pressure wound therapy to be useful in treating postoperative spinal infections. The technique involves packing a debrided wound with gauze or foam dressing. A drain is placed over the dressing, and then the wound is sealed with a drape. The end of the drain is attached to a vacuum to produce negative pressure. The dressing is changed sterilely every 2 to 3 days until the wound can be closed.

Brucellosis

Brucellosis results in a noncaseating, acid-fast–negative granuloma caused by a gram-negative capnophilic coccobacillus. This infection occurs most frequently in individuals involved in animal husbandry and meat processing (workers in abattoirs). Pasteurization of milk and antibiotic treatment of animals have led to a significant decrease in the incidence of this disease. Symptoms include polyarthralgia, fever, malaise, afternoon or night sweats, anorexia, and headache. Psoas abscesses are found in 12% of patients. Bone involvement, most frequently of the spine, occurs in 2% to 30% of patients. The lumbar spine is the most frequently involved spinal region.

Radiographic changes of steplike erosions of the margin of the vertebral body require 2 months or more to develop. Disc space thinning and vertebral segment ankylosis by bridging are similar to changes in other forms of osteomyelitis ( Fig. 42.2 ). CT and MRI may show soft-tissue involvement. Moehring noted that ⁶⁷ Ga scanning is not helpful in sacroiliac infections. MRI may be helpful in the early identification of the disease but has not been reported for this specific infection. The diagnosis usually is indicated by Brucella titers of 1 : 80 or greater; confirmatory cultures also should be done, if possible, using special techniques. Treatment usually consists of antibiotic therapy for 4 months and close monitoring of the Brucella titers. Persistence of a titer of 1 : 160 or greater after 4 months of treatment may indicate recurrence or resistance of the infection. Indications for surgical treatment are the same as for tubercular spinal infections. Because of the indolent nature of this disease, it can be mistaken for a degenerative process. Nas et al. recommended 6 months of antibiotic therapy (rifampicin and doxycycline) with surgery for spinal cord compression, instability, or radiculopathy.

Fungal Infections

Fungal infections generally are noncaseating, acid-fast–negative infections. They usually occur as opportunistic infections in immunocompromised patients. Difficulty in diagnosis often leads to delayed treatment. Symptoms usually develop slowly. Pain is less prominent as a physical symptom than in other forms of spinal osteomyelitis. Laboratory and radiographic findings are similar to those of pyogenic infections. Tubercular infection and tumors are the primary differential diagnoses. Direct culture by biopsy is the only method of absolute determination of the infecting organism.

Aspergillus and Candida infections were the most common fungal pathogens in a review by Ganesh et al. Aspergillus is an opportunistic infection and the most common fungus affecting the spine. Pain, tenderness, and an elevated ESR and CRP are the most common symptoms, but white blood cell elevations are rare. Ganesh et al. found that half of patients with spinal aspergillosis had undergone a recent surgery and 71% had lung infection with Aspergillus . In addition, 75% of patients with candidiasis had undergone recent surgery and almost a quarter had a malignancy. The lumbar spine is the area most commonly involved with fungal infection. Mortality is quite high with these opportunistic infections. With aspergillosis, there was 26% mortality with surgical and medical management, while mortality was 60% with medical management alone. With Candida infections they reported no mortality with combined treatment and 29% mortality with medical management alone. About 37% of patients presented with neurologic deficits; half of these recovered completely and most of the remaining patients had a residual deficit. Some of the case reports did not specify neurologic recovery status. Medical management is complex in these patients and infectious disease consultation is needed. The operative indications are significant neurologic deficit, spinal instability, and failure to respond to medical management. Imaging with MRI is crucial, and CT is helpful to best characterize bone destruction.

Tuberculosis

Despite spinal tuberculosis being one of the oldest diseases known, dating back to 3400 BCE and being described by Pott in 1779, it remains a relevant problem throughout the world. The worldwide incidence is over 10 million cases/year. Before the advent of effective chemotherapy, time and surgery for paralysis were the only treatment options. Laminectomy initially was performed for paralysis, but the results were disappointing until Ménard accidentally opened an abscess and the patient improved. Many patients treated in this manner died as a result of a secondary bacterial infection, and the practice was abandoned. Posterior spinal fusion, as described by Hibbs and Albee, was the preferred operation to prevent deformity and promote healing by internal immobilization. The first radical debridement and bone grafting procedure for abscess formation was reported in 1934. After the development of satisfactory chemotherapeutic agents, more aggressive surgery was attempted, including costotransversectomy with bone grafting and radical debridement as popularized by Hodgson.

Tubercular bone and joint infections currently account for 2% to 3% of all reported cases of Mycobacterium tuberculosis . Spinal tubercular infections account for one third to one half of the bone and joint infections. The thoracolumbar spine is the most commonly infected area. The incidence of infection seems to increase with age, but males and females are almost equally infected. With current medical management, surgical treatment is not commonly needed, outcomes are generally good, and neurologic deficits often improve.

Pathologically, the infection is characterized by acid-fast–positive, caseating granulomas with or without purulence. Tubercles composed of monocytes and epithelioid cells, forming minute masses with central caseation in the presence of Langerhans-type giant cells, are typical on microscopic examination. Abscesses expand, following the path of least resistance, and contain necrotic debris. Skin sinuses form, drain, and heal spontaneously. Bone reaction to the infection varies from intense reaction to no reaction. In the spine the infection spares the intervertebral discs and spreads beneath the anterior and posterior longitudinal ligaments. Epidural infection is more likely to result in permanent neurologic damage. Spinal tuberculosis involves the anterior vertebral body initially. Progressive bone destruction leads to the characteristic gibbus deformity. Spread occurs under the anterior longitudinal ligament, initially sparing the discs of adults but not of children because of disc vascularity in young children.

Slowly progressive constitutional symptoms are predominant in the early stages of the disease, including weakness, malaise, night sweats, fever, and weight loss. Back pain is present in 70% at presentation. Progressive pain is a late symptom associated with bone collapse and paralysis. About 30% of patients present with neurologic deficits in less developed countries but less commonly in the United States and other developed countries. Cervical involvement can cause hoarseness because of recurrent laryngeal nerve paralysis, dysphagia, and respiratory stridor (known as Millar asthma ). These symptoms may result from anterior abscess formation in the neck. Sudden death has been reported with cervical disease after erosion into the great vessels. Neurologic signs usually occur late and may wax and wane. Motor function and rectal tone are good prognostic predictors.

Laboratory studies suggest chronic disease. Findings include anemia, hypoproteinemia, and mild elevation of ESR and CRP. ESR has been found to be normal in over 50% of patients. Skin testing may be helpful but is not diagnostic. The test is contraindicated in patients with prior tuberculous infection because of the risk of skin slough from an intense reaction and is not useful in patients with suspected reactivation of the disease. Early radiographic findings include a subtle decrease in one or more disc spaces and localized osteopenia. Later findings include vertebral collapse, called “concertina collapse” by Seddon because of its resemblance to an accordion. CT and MRI show bone involvement and paraspinal abscess formation. MRI is preferred because it can demonstrate epidural abscess formation.

Definitive diagnosis depends on culture of the organism and requires biopsy of the lesion. Percutaneous techniques with radiographic or CT control usually are adequate. Percutaneous thoracoscopic, laparoscopic, or endoscopic biopsy are other reported options. Open biopsy may be required if needle biopsy is dangerous or nonproductive or if other open procedures are required.

Delayed diagnosis and missed diagnosis are common. Differential diagnoses include pyogenic and fungal infections, secondary metastatic disease, primary tumors of bone (e.g., osteosarcoma, chondrosarcoma, myeloma, eosinophilic granuloma, and aneurysmal bone cyst [ABC]), sarcoidosis, giant cell tumors (GCTs) of bone, and bone deformities such as Scheuermann disease.

Cervical Spine

If the cervical spine is involved, the abscess may be present retropharyngeally, in the posterior triangle of the neck, or supraclavicular area. The tuberculous detritus may also gravitate downward under the prevertebral fascia to form a mediastinal abscess.