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Spine FRCS > Infection > Flashcards

Infection Flashcards

Pyogenic vertebral osteomyelitis Spinal epidural abscess Tb Spine

1
Q

What is vertebral osteomyelitis aka?

A
  • Spondylodiscitis
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2
Q

Describe the epidemiology of pyogenic vertebral osteomyelitis?

A
  • usually adults
  • median age is 50-60 years
  • location
    • 50-60% lumbar spine
    • 30-40% thoracic spine
    • -10% cervical spine
  • ​risk factors
    • IV drug abuse
    • diabetes
    • recent systemic infection ( UTI/penumonia)
    • obesity
    • malignancy
    • immunodeficiency/ immunosupressive medication
    • malnutrition
    • trauma
    • smoking
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3
Q

Describe the pathogens involved?

A
  • Staph aureus- most common 50-65%
  • staph epidermis
  • gram negative infections- GI/Resp tract
  • pseudomonas- iv drug use
  • salmonella- sickle cell disease
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4
Q

What is the pathology of pyogenic vertebral osteomyelitis?

A
  • Haematogenous seeding
    • thru arterial /venous to endplates and intervertebral discs
  • Direct Inoculation
    • thru trauma, open fractures, surgery
  • Contiguous spread from local infection
    • retropharyngeal/ retroperitoneal abscess
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5
Q

What is the incidence of neurological invovlement in pyogenic vertebral osteomyelitis?

A
  • neurological deficit involvement in 10-20%
  • resulting from
    • direct infectious involvement of neural elements
    • compression due to epidural abscess
    • compression from instability of the spine
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6
Q

what is an epidural abscess?

A
  • Collection of pus/ inflammatory granulation tissue between dura mater and surrounding adipose tissue
  • usually associated with vertebral osteomyelitis
  • present in 18% pts with spondylodiskitis
  • 50% pt with epidural abscess will have neurological symptoms
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7
Q

describe the signs & symptoms of pyogenic vertebral osteomyelitis?

A
  • Hx of UTI, Pneumonia, skin infection, organ transplant

Symptoms

  • Fever- only present in 1/3rd pts
  • Pain
    • often severe/ insidious in onset
    • worse with activity & unrelenting
    • awakens at night- infection/malignancy
  • Neurology -10-20%
    • radiculopathy
    • myelopathy
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8
Q

What investigations are useful in pyogenic vertebral osteomyelitis?

A

xrays

  • findings often delayed by weeks
  • paraspinous soft tissue swelling- loss of poas shadow
    • seen first few days
  • Disc space narrowing and disc destruction
    • seen at 7-10 days
    • disc destruction atypical of neoplasm
  • Endplate erosion/ sclerosis
    • ​10-21 days
    • local osteopenia

CT

  • Useful to show bony abnormalities, abcess formation, extent of bony involvement

MRI

  • With GADOLINIUM contrast
    • gold standard for dx and tx
    • most sensitive 96%
    • most specific 93%
    • most speciifc to differentiate from tumour
    • findings include
      • paraspinal and epidural inflammation
      • disc and endplate enhancement with gadolinium
      • T2 weighted hyperintensity of disk/ endplate

Bone Scan

  • Technetium Tc99m Bone scans
  • pt who can’t obtain MRI
  • 90% sensitive but lack specificity
  • combined Tc99m with gallium 67 more specific and sensitive than Tc99m alone
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9
Q

what laboratory tests are useful in pyogenic vertebral osteomyelitis?

A
  • WBC- only elevated in 50%
  • ESR- elevated 90% cases, monitored, less reliable than crp
  • CRP- elevated 90%, monitor success of tx
  • Blood Cultures
    • ​when positive 85% accurate for isolating organism
  • Ct guided or open biopsy
    • BC negative and no indications for immediate surgery
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10
Q

What is DDX of pyogenic vertebral osteomyelitis?

A
  • Spinal tumours
  • MRI gadollium contrast most specific modality to differentiate tumour
    • disc space involvement
    • end plate erosion
    • significant inflammation
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11
Q

What is the tx of pyogenic vertebral osteomyelitis?

A

Non operative

  • Bracing and long term antibiotics 6-12 weeks
    • most cases
    • bracing improves pain & prevent deformity
    • if pt ill start broad spectrum antibiotics
      • vancomycin ( pencillin R & gram positive)
      • 3rd gen cephalosporins ( gram neg )
      • change when known sensitiviites
      • direct iv antib for 4-6 wks then convert PO

Operative

  • Neurological decompression, surgical debridement and spinal stabilization
  • Anterior debridement + strut grafting +/- posterior instrumentation- gold standard
    • ​refractory cases
    • neurological deficits
    • progressive deformity & gross spinal instability
  • ​Posterior debridement and decompression
    • usually ineffective for debridment
      *
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12
Q

What are the goals of surgical tx of pyogenic vertebral osteomyelitis?

A

Anterior debridement, stru graft +/- poterior instrumentation

  • Identify organism
  • eliminate infection
  • prevent or remove neurological deficits
  • maintain spinal stability

strut graft

  • autogenous tricortical iliac crest, rib or fibula- safe and efective in presence of acute infection
  • better incorportation cf allograft
  • improved deformity correction with ti mesh cages filled with autograft

Instrumentation

  • contraversial in presence of acute infection
  • some i& d wiht staged instrumentation
  • single stage w bone graft + insrumentation
  • posterior instrumentation - when severe kyphotic deformity/ multilevel
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13
Q

What is a spinal epidural abscess?

A
  • A collection of pus or inflammatory granulation tissue between the dura mater and surrounding adipose tissue
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14
Q

what is the epidemiology of spinal abscess?

A
  • Usually seen in adults >60 years of age
  • locations
    • usually thoracolumbar spine
  • risk factors
    • Iv drug abuse
    • immunodeficiency
    • maligancy
    • immunosuppresive medication
    • recent spinal procedure
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15
Q

What is the pathophysiology of epidural abscess?

A
  • Haematogenous spread- 50%
  • spread from discitis- 33%

Pathogens

  • Staph aureus- most common 50-65%
  • Gram negative - E coli- 18%
  • Pseudomonas common in iv drug abusers
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16
Q

Do pts with epidural abscess have neurological deficits?

A
  • 33% pt with epidural abscess have neurological symptoms
  • 4-22% incidence of permanent paralysis
    • direct compression/infract in spinal cord
17
Q

What associated conditions are with epidural abscess?

A
  • Vertebral osteomyelitis and discitis
  • present in 18% of pt with spondylodiscitis
  • image shows extensive destruction of the lumbar spine extending over three vertebral segments with associated epidural abcess necessitating surgical decompression and fusion.
18
Q

What is the prognosis with epidural abscess?

A
  • Preop degree of neurological deficit most important indicator of clinical outcome
  • mortality 5%
  • Early diagnosis essential
19
Q

What are the signs and symptoms of epidural abscess?

A

Symptoms

  • Fever present ii 50%
  • systemic illness more profound than vertebral osteomyelitis
  • Pain- severe insidious in onset, occurs 87%

Signs

  • Neurological deficit - 33%
  • radiculopathy or myelopathy

Labs

  • WCC leukocytosis 22,000 cells/mm3
  • ESR elevated >90% cases
  • CRP elevated in 90% cases
20
Q

What imaging is useful in dx of epidural abscess?

A

Xrays

  • usually normal

CT

  • poorly sensitive for epidural abscess

Ct myelogram

  • 90% sensitive but invasive

MRI w gadolinlium

  • investigation of choice
  • show extent of abscess, presence of vertrebral osteomyelitis, allow visualisation of neurological compression
  • gadolinium allows differentiation of PUS from CSF
  • Ring of enhancing lesion is pathognomonic for abscess
21
Q

What is the tx of epidura abscess?

A

Non operative

  • bracing and iv antibiotics
    • small abscess with minima compression on neural elements
    • no neurological deficits
    • pt of close clinical follow up
    • historically surgcial emergency
    • Recent trend towards non op mx as new studies show non op tx effective in pts without neurological deficit

Surgery

  • Surgical decompression +/- spinal stabilisation
    • for neurological deficits
    • spinal cord compression on imaging MRI >50% compression of thecal sac
    • presistent infecton despite Antib for 6 weeks
    • progressive deformity or instability
    • post op antib for 2-4 wks if no bony involvement
    • 6 weeks if bony involvement
22
Q

Describe the surgical techniques of decompression of epidural abcess?

A
  • Decompressive laminectomy
    • most common form of operative tx
    • when abscess is posterior and there is no contiguous spondylodiscitis
  • Anterior debridement and strut grafting when
    • abcess is located anteriorly
    • anterior vertebral body & discs involved- preence of spondylodiscitis
    • see picture-shows anterior debridement, corpectomy, fibular strut grafting, and Kaneda instrumentation.
23
Q

What is the epidemiology of spinal TB ?

A
  • Increasing in US to increasing immunocompromised population
  • HIV positive population - cd4 counts 50-200

location

  • 15% pt with TB will have extrapulmonary
  • spine, esp thoracicspine most common extrapulmonary site
  • 5% TB pts have spine involvement
24
Q

What is the pathoanatomy of spinal TB?

A
  • Early infection
    • begins in metaphyseal body
    • spreads under ALL
    • leads to
      • contiguous multilevel involvement
      • skip lesions/ non contiguous segment 15%
      • paraspinal abscess 50%
        • usually anterior & quite large
      • usually doesn’t involve disc space- pyogenic vertebral OM does!
  • Chronic infection
    • ​severe kyphosis
    • sinus formation
    • Pott’s paraplegia
      • ​spinal cord injury caused by abscess/bony sequestra or meningomyelitis
25
Q

What are the signs and symptoms of TB spine?

A

Symptoms

  • onset insidious than pyogenic infection
    • chronic illness
    • malaise
    • night sweats
    • weight loss
    • back pain
      • late symptom, after bony destruction

Signs

  • Kyphotic deformity
  • neurological deficits
26
Q

What imaging is helpful in dx of TB spine?

A
  • CXR
    • 66% abnormal
    • ordered for any pt suspected of TB
  • Spine xrays
    • early infection
      • involvement of anterior vertebral body with sparing of disc space
    • late infection
      • disc space desctruction, lucency & compression of adj vertebral bodies
  • MRI with gadolinium
    • prefered for dx and tx
  • Nuclear medicine studies
    • Obtain with combination of technetium & gallium
    • shown to have highest sensitivity for detecting infection
27
Q

What lab studies are helpful in dx of tb spine?

A
  • WBC normal
  • ESR- usually elevated, normal in 25%
  • PPD- purified derivative of tuberculin
    • positive in 80%
  • CT guided biopsy with culture and staining
    • tested for acid fast bacilli on Lowenstein- Jensen medium
    • Ziehl neilson stain- red snappers- see pic
    • mycobacteria may take 10 wks to grow in culture
    • PCR faster identification 95% sensitivity/93% accuracy
28
Q

What are the dx of tb spine?

A
  • Atypical bacteria
    • actinomyces israeii
    • nocardia asteriods
    • brucella
  • Fungi
    • Coccidoides immitis
    • Blastomyces dermatitidis
    • Cryptococcus neoformans
    • Aspergillosis
  • Spirochetes
    • Treponema pallidum
29
Q

What is the tx of TB spine?

A

Non operative

  • Isoniazid, rifampicin, pyrazanamide therapy
    • meds mainstay of tx
    • tx for 9-18 months
    • ethanbutol and streptomycin added for part of tx
  • Spinal orthosis
    • for pain control & prevent deformity

Surgery

  • Anterior debridement +uninstrumentation strut grafting + posterior stabilising indications
    • neurological deficit
    • advanced spinal instability/progressive kyphosis
    • adv disease with caseation prevent access by antibiotics
    • failure of non op tx after 3-6/12
30
Q

What are the advantages of surgical tx?

A
  • Less progressive kyphosis
  • earlier healing
  • decrease sinus formation
  • pts with neurological deficits, early debridement and decompression lead to improved neurological recovery
31
Q

What is the epidemiology of paediatric disc space infections?

A
  • More common than adults
  • more common in Males
  • effects children <5 years
  • Lumbar spine most common 50-60%
32
Q

What is the pathoanatomy of paediatric disc space infections?

A
  • Blood vessels extend from cartilagenous end plate through nucleus propulsus in children
    • ​allows direct innoculation of disc
    • infection may spread from endplate, thru disc to vertebral body
  • ​In adults blood supply only travels to annulus fibrosis so limiting disc space infection
33
Q

What are the typical organisms in disc space infections in children?

A
  • Staph aureus- most common 80%
  • Tuberculosis
  • Salmonella in sickle cell anaemia pts
34
Q

What is the symptoms and signs of a chid with spinal disc infection?

A

Symptoms

  • Toddler
    • refusing to sit/walk/painful limp
    • loss of appetite
    • fever (25% will be febrile)
    • abdominal pain
  • older children
    • point tenderness back pain

Signs

  • Limited rom
  • localised/tenderness of back
35
Q

What is seen on imaging?

A

xrays

  • radiographic findings are unreliable
  • early manifestation at 1 week
  • normal
  • loss of lumbar lordosis- earliest sign
  • disc space narrowing 10-21 days post infection
  • end plate erosion 10-21 days post infection

MRI

  • diagnostic test of choice

Labs

  • CRP/ESR/WCC- high normal or elevated
36
Q

What is the tx of disc space infection?

A

Non operative

  • Bedrest, immobilisation, antibiotics 4-6 weeks
    • with early infection, NO ABSCESS, or displacment of thecal sac
    • antibiotics target staph aureus 7-10 days
    • Watch serial labs for response
    • CT biopsy if no improvement- rule out TB

Surgery

  • Surgical debridement and antibiotic treatment
    • for late infections
    • parapsinal abscess in presence of neurological defecit
    • aim to get cultures then antibiotics and brace
      *
37
Q

What are the complications of paediatric spinal disc infections?

A
  • Long term narrowing of disc space
  • Fusion between vertebra
  • back pain
38
Q
A

Spine FRCS (20 decks)

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