Direct inoculation, Contiguous spread from an adjacent infection, Hematogenous seeding
Venous theory-Retrograde flow from the pelvic venous plexus tothe perivertebral venous plexus via valvelessmeningorrhachidian veins Arterial theory-Bacteria can become lodged in the end-arteriolarnetwork near the vertebral end plate
Once the infection is established adjacent to the endplate of one vertebral body, it can rupture through thatstructure into the adjoining disk and infect the nextvertebral body In the cervical spine, if the infection penetrates theprevertebral fascia, it can extend into the mediastinumor into the supraclavicular fossa
From the lumbar spine, abscess formation maytrack along the psoas muscle and into thebuttock (piriformis fossa), the perianal region,the groin, or even the popliteal fossa The extension of infection from the vertebralbody or disk into the spinal canal may result inan epidural abscess or even bacterialmeningitis
Vascular channels cross the cartilaginousgrowth plate and end within the nucleuspulposus. These channels provide pathwaysfor direct inoculation of organisms into theavascular nucleus pulposus
Direct spread of infected material into thespinal canal can produce an epidural abscessthat may compress the neural elements orcause thrombosis or infarction of the regionalvascular supply to the spinal cord
Pathologic fracture can occur, withassociated extrusion of either infectedmaterial or bony elements into the spinalcanal. Kyphosis and/or spinal instability resultingfrom destruction of the disk, vertebral bone,and posterior stabilizing structures cancause neural impingement
50% of the skeletal involvement occurs in thespine Between 10% and 61% of patients present with ordevelop a neurologic deficit The primary route of infection to the spine ishematogenous from a pulmonary or genitourinarysource, although direct spread from adjacentstructures can occur
The most common form Adjacent to the vertebral end plate andspreads around a single intervertebral disk Extension to the adjacent vertebra occurs asthe granulomatous abscess material tracksbeneath the anterior longitudinal ligament The intervertebral disk is usually spared
Central involvement occurs in the middleof the vertebral body and can be mistaken for atumor.Destruction of the vertebral body will then lead tospinal deformity
Anterior involvement begins beneath the anteriorlongitudinal ligament, causing scalloping of thevertebral body Anterior involvement can produce a spinalabscess that extends over multiple levels
Primary involvement of the posteriorstructures is uncommon Paraspinal extension with abscess formationis common and can occur at any level
Pyogenic Vertebral Osteomyelitis More common in males than in females More common in elderly populations In populations with intravenous drug abuse orimmunocompromise after organ transplantation orchemotherapy
Depends on- Location of the infection, The virulence of the organism The immune status of the host Back or neck pain is the most consistentsymptom Associated with notable paraspinal musclespasm
Usually present regardless of activity level Radicular leg or arm pain is less commonbut may be present with neurologicinvolvement Fever in 50% of patients Weight loss
A patient with a psoas abscess may havepain with hip extension Cervical abscess formation may lead totorticollis or dysphagia Radiculopathy, myelopathy,or evencomplete paralysis can occur with neuralcompression as a result of abscess,instability, or spinal deformity Direct spread of the infection into theepidural space can cause meningitis.
Staphylococcus aureus accounting for>50%. Escherichia coli, Pseudomonas and Proteusmay occur following genitourinary infectionsor procedures Intravenous drug abusers are prone toPseudomonas infections Salmonella, presumably from an intestinalsource, can cause vertebral osteomyelitis inchildren with sickle cell anemia.
WBC ESR CRP Blood cultures Malnutrition measurement-serum albuminlevel of <3 g/dL, serum transferrinmeasurement of <150 μg/dL, and an absolutelymphocyte count of <800/mL ,24-hour urinarycreatinine excretion of <10.5 mg in men or<5.8 mg in women
Closed Biopsy-using computed tomography andFluoroscopy Accuracy-70% Open biopsy-indicated when needle biopsy failsto identify an organism, when the infection isinaccessible by standard closed techniques, orwhen there is marked structural damage withneurologic Compromise Open biopsies are diagnostic in >80% of cases Laparoscopic or thoracoscopic approach-todecrease the morbidity of the procedure
Biopsies should be sent for gram stain, acid-fast stain, and aerobic,anaerobic, fungal, andTB cultures Antibiotics must not be started until the biopsyis done Histologic studies also should be done todetect metabolic or neoplastic processes Pathologic examination should be conductedto differentiate between acute and chronicinfection
Back pain is less severe than in a pyogenicinfection Weight loss, malaise, fevers,and night sweats Kyphotic deformities, Neurologic deficits, Cutaneous Sinuses Immunocompromised patients are at risk fordeveloping infections with atypical mycobacteria
Vertebral infection should be suspected when thechild has A lowgrade fever Pain, Refuses to bear weight Assumes a flexed position of the spine
White blood cell count may or may not beelevated ESR is usually mildly elevated CRP level is markedly elevated Acute infections are more likely to yieldpositive blood cultures Biopsy can be done under CT guidance; a60% to 70% yield rate for infectious lesionscan be expected
Risk factors History of intravenous drug use Diabetes Trauma Obesity Percutaneous or open procedures(eg,spinal surgery, nerve or epidural block,or diskography) HIV Renal failure
Back pain Progressive neurologic deficit, or fever. The ESR is almost always elevated. Leukocytosis may not be present
Crucial to localize the infection To assess the extent of involvement To determine the response to treatment
Radiographs may demonstrate progressiveosteolysis and end plate destruction,oftenbest seen on the anteroposterior view As the disease progresses,the disk spacenarrows and eventually collapses Plain radiographs, however, may notdemonstrate abnormal findings for up toseveral weeks after the process has begun.
Soft-tissue extension must besuspected- In the presence of an abnormal psoasshadow Widening of the mediastinum Enlargement of the retropharyngeal soft-tissue shadow. The presence of gas in the soft tissuessuggests an infection with an anaerobicorganism.
Often demonstrate vertebral destruction withrelative preservation of the disk spaces
Disk space narrowing End plate erosions Bony destruction Paravertebral soft-tissue swelling Autofusion
Technetium 99m bone scintigraphy is sensitive(~90%) but nonspecific The study is dependent on local blood flow, false-negative results have occurred in areas of relativeischemia Paediatric vertebral osteomyelitis, the technetium99m bone scan is positive in 74% to 100% of cases,facilitating earlier diagnosis of diskitis in children
Used in conjunction with technetium 99mscans, gallium 67 citrate scans have highsensitivity and specificity in detecting foci ofInfection Gallium scans also normalize during therecovery phase and may be used to followtreatment response Indium 111-labeled scans have a poorsensitivity in vertebral osteomyelitis (17%) andare not recommended
CT is useful in delineating the extent of bonydestruction and soft tissue extension and ishelpful in preoperative planning The status of the neural elements cannot beaccurately assessed without the use ofmyelographic dye, which is contraindicated insuspected infection because it places the patientat risk for developing meningitis or arachnoiditis
The modality of choice in the diagnosis andevaluation of spinal infection Provides excellent imaging of the soft tissue,neural elements, and inflammatory changes inthe bone MRI has an extremely high sensitivity (96%)and specificity (93%) Noninvasive, allows detection of paravertebraland epidural extension, and clearly visualizesneurologic structures.
The administration of gadolinium incombination with MRI improves resolutionand allows an infectious process to bedistinguished from degenerative changes ofthe end plate and intervertebral disk Even with MRI, however, granulomatousinfections can be difficult to distinguish fromtumors of the spine. Thus, a biopsy is often required to make adefinitive diagnosis
Pyogenic InfectionsThe goals for treatment of spinal infectionsshould be to establish a diagnosis andidentify the pathogen,eradicate theinfection,prevent or minimize neurologicinvolvement,maintain spinal stability, andprovide an adequate nutritional state tocombat infection
Once the organism has beenidentified,intravenous antibiotic therapyshould be initiated according to the cultureresults and sensitivities A course of 2 to 6 weeks of parenteralantibiotics is usually recommended followedby a course of oral antibiotics, depending onthe virulence of the organism, susceptibilityof the host, and other factors, such asretained hardware
Conversion to oral antibiotics shouldbe made only with Clinical improvement, Normalization of the ESR and CRP level, or Resolution of the infection as demonstratedin imaging studies.
To obtain a tissue diagnosis after a failedclosed needle biopsy or from a locationinaccessible by closed methods For drainage of an abscess that iscausing sepsis or neurologic deficit;
To treat neurologic deficit secondary tocompression either by the infection (abscessor granulation) or structural destruction For structural instability or deformity For failure of medical management toreduce persistent symptoms or elevatedlaboratory measurements.
Depends on-The location of the infection and theintended purpose of the surgery Anterior approach is most commonly used tomaximize access to the infected tissue. A posterolateral approach to the thoracic spinemay be considered in certain instances
Costotransversectomy if only culture, biopsy, orabscess drainage is necessary Endoscopic approaches avoid thoracotomy, theymay cause less morbidity in the medically fragilepatient.
Tricortical iliac crest or middle third of the Fibula Fresh-frozen allografts in combination withautogenous bone Vascularized bone grafts Titanium surgical mesh filled with autogenousbone Posterior fusion with instrumentation
The goal of nutritional supplementation is torestore the patient to the premorbid nutritionalstatus. Nutrition consultation and monitoring oflaboratory measurements are helpful inreaching a positive nitrogen balance
A four-drug regimen of isoniazid, rifampin,ethambutol, and pyrazinamide is used as first-line therapy for 6 months The response to treatment is assessed byroutine clinical examinations and radiographs
Indications for surgery in tubercular infectionsare the same as for pyogenic infections. The most common surgical technique, theHong Kong procedure, involves débridementof infected bone, decompression of the spinalcanal, and correction of the kyphoticdeformity using structural grafting
The prognosis for neurologic recovery intheface of chronic deficits is not as optimistic
Immobilization with casting or bracing Parenteral antibiotics helps for more likely toresult in rapid relief of symptoms and a lowerincidence of recurrent symptoms
Surgical drainage Conservative management-no neurologic deficit, ifthe involvement is extensive,if the patient is notexpected to survive surgery, or if paralysis hasbeen present for >48 hours so that neurologicimprovement would be unlikely
Prompt and aggressive treatment ofneurologic compression appears tofavorably affect neurologic recovery Anterior abscesses, particularly withvertebral body involvement, should haveanterior débridement.This can be doneusing either an open or endoscopicapproach Posteriorly located infections can beadequately treated by a laminectomy Followed by parenteral antibiotics accordingto C/S