Answer to Case of the Month #3. Pyogenic discitis. Staphylococcal discitis complicated by bilateral psoas abscesses.
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Sixteen patients with discitis from January 1980 through December 1983 underwent 18 CT scans for initial evaluation. In six scans the study produced a false negative result (sensitivity 63%, 11/16). In three of these six the scan was performed at the wrong disc level, and in three the error was interpretive. During the same time period 6 patients had a CT diagnosis of discitis which proved incorrect (positive predictive value 63%), three of which had fractures, two had normal post discectomy changes, and one had a neuropathic arthropathy. These studies were reviewed in a blinded fashion along with 30 CT scans of post operative patients without clinical or laboratory evidence of discitis. The CT findings in the discitis patients were: (a) anterior paravertebral soft tissue swelling with obliteration of paravertebral fat planes, (b) fragmentation or erosions of vertebral end plates, and (c) paravertebral fluid collection (abscess). Both (a) and (b) were seen in 13/15 patients, (a) alone in 1/15, (b) alone in 1/15, and all three (a, b, c) in 2/15. The CT scan is diagnostic of discitis in those with all three findings. In those patients with only (a) or both (a) and (b), the CT can be suggestive of discitis in the proper clinical setting when correlated with plain film findings: however, these CT findings are also observed in other conditions. Involvement of the spinal canal by inflammatory mass was seen in 6/16 patients with discitis. Low attenuation (hypodensity) of the affected disc was not observed.
Infection after intradiscal injections has been recognised as a distinct entity, but discitis after discography has often been attributed to an aseptic process or a chemical reaction to the contrast material. We examined the hypothesis that discitis after discography is always due to infection, and report a clinical review and an experimental study. Part I. We reviewed the case records and radiographs of 432 patients who had undergone lumbar discography. When an 18-gauge needle without a stilette had been used, discitis was diagnosed in 2.7% of 222 patients but stiletted needles and a two-needle technique at each level reduced the incidence to 0.7%. Seven patients with discitis after discography had undergone anterior discectomy and fusion; in them the histopathological findings were of a chronic inflammatory response. Bacteria were isolated from the discs of three of the four patients who had open biopsy less than six weeks from the time of discography. These findings suggest that bacteria were initiators rather than promoters of the response. Part II. Multiple level lumbar discography was carried out in mature sheep, injecting contrast material with or without various concentrations of bacteria. Radiographs were taken and the discs and end-plates were examined histologically and cultured for bacteria at intervals after injection. None of the controls showed any evidence of discitis but all sheep injected with bacteria had typical radiological and histopathological changes by six weeks, though cultures were almost all negative. However, at one and two weeks after injection, but usually not after three weeks, bacteria could be isolated. We suggest that all cases of discitis after discography are initiated by infection, and that a very strict aseptic technique should be used for all injections into intervertebral discs.
The role of antibiotics in the treatment of iatrogenic discitis remains controversial. This study was carried out to assess the ability of cephazolin (a first-generation cephalosporin) to penetrate the intervertebral disc and to establish the role of intravenous antibiotics in the prevention and treatment of iatrogenic discitis. Six sheep had 1 g of intravenous antibiotic administered between 30 minutes and 120 minutes before being killed. Two adjacent lumbar intervertebral discs were harvested and assayed for antibiotic concentration. Cephazolin could only be detected in the animals killed at 30 minutes. Intravenous cephazolin was administered 30 minutes before bacterial inoculation in 46 discs of nine sheep. In five animals, the bacterial suspension contained radiographic contrast and, in four sheep, reconstituted chymopapain. No evidence of discitis was found at any level at death. Eight sheep were treated with intravenous cephazolin commencing 1, 2, or 3 weeks after bacterial intradiscal inoculation and for periods of up to 21 days. All discs developed discitis, and the lesions appeared to be similar, irrespective of time between inoculation and the commencement, duration, and dosage of antibiotic therapy. Our study supports the use of a suitable broad-spectrum antibiotic during any surgical procedure that invades the intervertebral disc. Antibiotics, however, are unable to arrest the progression of discitis once it is established
Two major types of postoperative discitis have been previously described: septic discitis and "avascular" or "chemical" discitis. Percutaneous discal biopsy is an important way of distinguishing these entities. In a retrospective study of 25 cases of postoperative discitis, three groups have been analyzed with bacteriologic and histologic tests: a group of nine patients (group A) with positive discal bacteriologic cultures; a group of eight patients (group B) with typical septic histologic tests but negative bacteriologic discal procedures; and a group of eight patients (group C) in whom the histologic picture was reminiscent of a mechanical process. No group was unique in any clinical and radiologic parameter. Group A and group B were quite similar in biological features, but group C had erythrocyte sedimentation rate and C-reactive protein serum levels significantly lower than groups A and B (P less than 0.01). After 4 weeks, these differences were still present. This study confirms that there are two main features of postoperative discitis that can be recognized by histologic and biological tests, allowing for different treatments.
Although infection following intradiscal injections has been recognized as a distinct entity, discitis following chemonucleolysis has been often attributed to a chemical reaction from chymopapain. In the first part of this study the effect of chymopapain and Conray 280 on a wide range of bacteria was measured in vitro. Chymopapain was found to have a bactericidal effect on all bacteria tested, which was more pronounced with gram positive organisms, whereas Conray 280 showed very little if any antibacterial effect after 48 hours. The aim of the second part of the study was to test the hypothesis that discitis following intradiscal chymopapain injection is due to infection and not to a chemical reaction. Multiple level lumbar intradiscal injections were carried out in eight mature sheep. Sixteen discs in four sheep were injected with a mixture of reconstituted chymopapain and a Staphylococcus epidermidis suspension. Sixteen discs in another four sheep were injected with reconstituted chymopapain only. All sheep were sacrificed at 6 weeks and the discs and end-plates were examined radiologically, and by histopathology and nuclear material was cultured for bacteria. None of the controls showed any evidence of discitis, whereas all sheep injected with bacteria had typical radiologic and histopathologic changes of discitis. However, in most cases in which end-plate lesions were well established there was no evidence of bacteria at sacrifice. These findings support the opinion that discitis following intradiscal injection is always due to infection introduced by the needle tip.
Septic discitis refers to a primary suppurative process involving the intervertebral disc space and occurs as a result of hematogenous invasion or contamination by pyogenic organisms. A case of septic discitis is described in a 77-year-old woman following an episode of Escherichia coli urosepsis. Despite bed rest, an orthosis, and appropriate antibiotics, the patient ultimately had to undergo surgical disc removal. The diagnosis of septic discitis is often made in the context of other diseases that share common clinical and laboratory findings. Magnetic resonance imaging appears well suited for diagnostic confirmation of septic discitis. Needle biopsy and aspiration results should be used to determine the appropriate choice of antibiotic for this disease process.
Although well described in the orthopaedic literature and some orthopaedic textbooks, postoperative discitis is regularly missed or diagnosed late. Six cases of discitis were studied in detail with special reference to the clinical presentation. All patients with discitis had an erythrocyte sedimentation rate (ESR) greater than 50 at 2 or more weeks after surgery. A prospective study of 26 patients undergoing uncomplicated discectomy or fusion was made. ESRs were measured preoperatively and at 1,2, and 6 weeks after operation. Any patient with increasing back pain and an ESR greater than 52 or more weeks after surgery should be considered to have discitis until proven otherwise. If the ESR is measured routinely preoperatively and at 2 weeks postoperatively, this condition should not be missed.
A series of nine patients with post-discography discitis were evaluated to help delineate the clinical course. The most consistent sign was the marked exacerbation of neck or back pain. This then was followed by an elevated sedimentation rate at an average of 20 days, followed by a positive bone scan at an average of 33 days. Of note is that seven patients initially had negative bone scans at an average of 18 days. Five out of nine patients had changes on plain roentgenograms between 14 and 51 days after discography. Magnetic resonance imaging was performed in six patients; two of these patients were scanned twice. Three scans were negative and five were positive (2 patients initially had negative scans that later became positive). The course of lumbar discitis ranged from 8 to 11 weeks, and cervical discitis from 6 to 7 weeks, with the latter usually resulting in spontaneous fusion.
Discitis after discography is due to bacterial penetration into the intervertebral disc by a contaminated needle and has an incidence of 1% to 4%. We have examined the prophylactic role of cephazolin administered at the time of discography. An experimental study in sheep using radiographic contrast containing Staphylococcus epidermidis showed that either adding the antibiotic to the intradiscal suspension or giving it intravenously 30 minutes before intradiscal inoculation of bacteria prevented any radiographic, macroscopic or histological signs of discitis; all the intervertebral disc cultures were negative. In a prospective clinical study of 127 consecutive patients having lumbar discography, the injected contrast contained cephazolin 1 mg per ml. None of the patients developed clinical or radiographic signs of discitis. We recommend the use of a suitable broad spectrum antibiotic in a single prophylactic dose whenever the intervertebral disc is entered.
The roentgenologic course of postoperative discitis is described in 111 patients examined with laminar tomography. The earliest lesion was blurring of the end plate or minor destructions, leading to cavitation of the vertebral body. Mean time from operation to the first clinical symptoms was 3 weeks. Mean time from operation to first radiologic lesions was 2 months, from operation to maximal lesions 4 months, and to the first radiologic sign of healing 5.5 months. A follow-up study was carried out and the radiologic findings were compared to those of a matched control group. A significantly higher incidence of decrease in disc height, intercorporal fusion and major osteophytes was found in the discitis group. The usefulness of laminar tomography, CT, MRI and isotope studies in the diagnosis of discitis is discussed. It is concluded that laminar tomography is a good alternative, when MRI is not available.
Nine cases of recorded discitis are presented, in which scintigraphy played an important part in the diagnosis. The patients (five men (aged 21-75 years) and four women (aged 40-73 years)) had a history of back pain varying in duration from two days to three months. Final diagnosis was confirmed microbiologically (seven patients) or radiographically (two patients). Bone scintigraphy was a valuable diagnostic procedure for discitis with earlier detection than plain radiography in three patients and similar initial detection to that of third generation computed tomography. Single photon emission computed tomographic imaging increased diagnostic confidence by indicating the involvement of the adjacent vertebral bodies rather than of the pedicles or spinous processes.
111 cases of postoperative discitis during 1968-1986 were analyzed retrospectively. The diagnosis was confirmed by lumbar tomography. Low back pain appeared at an average of 16 days postoperatively. Laboratory findings were of minor value in the diagnosis since elevated ESR, white blood cell count, and body temperature were inconstant findings. Compared with a matched control group, there was a higher incidence of chronic low back pain and vocational handicap in the discitis patients. There was no difference in the consumption of analgetics, the subjective evaluation of the final outcome, spinal mobility or neurologic findings.
The authors report our experience on 19 cases of discitis developed after operations for herniated lumbar disc. Because of the negativity of the neuroradiological studies in the acute stage, the recognition of the typical syndrome (severe back pain, spasm of the paravertebral lumbar muscles, limited spinal motility, fever) beginning 3-30 days post-operatively and the study of some laboratory tests (elevated Erythrocyte sedimentation rate (ESR) and midly to moderately elevated white blood cells (WBC) are very important for diagnosis. The first radiographic findings (disc space narrowing, ecc.) are detectable only 4 to 6 weeks after the first symptoms; other X-ray findings are not seen post-operatively before 6 months-2 years. The CT-scan is diagnostic of discitis only when the following three specific signs are present: a) anterior paravertebral soft tissue swelling with obliteration of paravertebral fat planes; b) fragmentation or erosion of vertebral end plates; c) paravertebral fluid collection (abscess). In our experience a period of immobilization of the spine with a plaster body jackets and the use of adequate antibiotic therapy are the more effective treatment. Undoubtedly the discits are the results of an infection that must be prevented adhering to the aseptic principles not only during surgery but also during the procedures performed in the radiology suite.
The diagnosis of septic discitis, or vertebral osteomyelitis, in able-bodied adults is difficult to make and often delayed. Here, the clinical findings and events leading to diagnosis and complications of septic discitis occurring in a patient with quadriplegia after urinary tract manipulation are presented. The diagnosis was delayed nine weeks from onset of fever (11 weeks after urologic manipulation), despite a variety of radiologic procedures and repeated blood and urine cultures. The patient's symptoms recurred five weeks after IV antibiotics were discontinued and while he was still taking oral cephalexin. He underwent open debridement and further IV and IM tobramycin, recovering without complication. The patient died five months later, reportedly of bowel obstruction and pneumonia. A review of the literature revealed only one other case report, of a patient with paraplegia, who also presented a diagnostic problem and died one year after diagnosis.
A 29-year-old male presented with a two month history of intermittent low back pain following a febrile illness. Two planar bone scans performed with Tc-99m MDP were normal despite roentgenographic and SPECT scintigraphic evidence of discitis. This case demonstrates the increased sensitivity of SPECT in the diagnosis of discitis.
Thirty-nine children with suspected pathology involving the vertebral column were investigated haematologically, radiographically, and by bone scintigraphy using technetium 99M pyrophosphate. Fifteen children were shown to have inflammatory disease of the vertebrae. A further six suffered from Scheuermann's disease, two from benign tumours, and the remainder from miscellaneous diseases not specifically involving bony pathology. The nuclide scan was abnormal in all cases of discitis and osteomyelitis, and in the two tumours. All of the other conditions were associated with a normal bone scan. This finding is of considerable diagnostic importance, and leads support to the theory that discitis is due to bacterial infection.
Three cases of discitis in early childhood presented with acute refusal to walk or change in gait pattern without neurologic deficits. In all three, a Gowers' sign was observed, although none had muscular weakness. The diagnosis of discitis was confirmed by the characteristic radiographic findings on survey lumbosacral films and/or by a hot spot at the L3 level on technetium bone scan.