Infections Flashcards
Spinal Epidural Abscess - Anatomy
epidural space is between dura mater and bone.
Dura adherent to the bone above foramen magnum.
True epidural space exist below foramen magnum posterior and lateral to the cord.
smaller in cervical area
larger in sacral area
fat, arteries, venous plexus
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What 2 types of epidural abscess is there?
1) Intracranial (IEA)
2) Spinal (SEA)
Ration 9:1 (Spinal:Intracranial)
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What causes spinal epidural abscesses?
— pathogenesis —
- Hematogenous spread.
- Direct extention from surrounding tissue
- Direct inoculation (procedures)
- Spinal epidural catheters are an important risk factor:
—> Contamination during insertion (face mask, sterile technique)
—> Hematogenous seeding
—. Ascending from skin
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Risk factors for spinal epidural abscess (SEA)?
- Bacteremia, any cause
dental infx. Infected catheters.
infective endocarditis. - Spinal Intervention: 0.5-3% risk w/ epidural catheter.
- Paraspinal injection of corticosteroids
- Vertebral osteomyelitis
- Other: Alcoholism. Diabetes. HIV. Trauma. Tattooing. Acupuncture. Continuous bone / soft tissue infection. Immunocompromised.
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What are common organisms causing spinal epidural abscessed?
> 60% MSSA / MRSA.
Gram(-)Bacilli. Strep. Coag neg staph.
Anaerobes. Fungi / parasites.
TB frequent cause in resource limited settings.
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What causes cord compromise in SEA (Spinal Epidural Abscess)?
- direct compression
- thrombosis / thromboflebitis
- interrupting arterial blood supply
- bacterial toxins
- inflammatory mediators.
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Clinical Presentation of SEA (spinal epidural abscess).
Fever + Back Pain + Neuro deficits (classic triad, only small proportion of patients fit this on initial presentation)
Fever (often absent initially, causing delay in diagnosis). Malaise.
Back pain 70-100% of cases.
Spinal tenderness 17-98%
Neurological deficits: reported in up to 50% of cases.
Typical progression:
Back pain (focal, severe)
—> nerve root pain (shooting, electric)
—> motor weakness, sensory changes, BB dysfunction
—> paralysis.
ONCE PARALYSIS DEVELOPS MAY QUICKLY BECOME IRREVERSIBLE.
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Lab findings for SEA (spinal epidural abscess)?
Seldom helpful.
Only 60% leukocytosis on presentation.
ESR / CRP is almost always elevated.
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Diagnosis of SEA?
(spinal epidural abscess)
HIGH INDEX OF SUSPICION:
febrile + spinal pain,
Radiculopathy / focal neuro findings.
Pain worsened w/ palpation / percussion.
Elevated CRP.
Risk factors (IVDU, chronic catheters, distant infection, older, recent spinal manipulation / procedures, immunocompromised.
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How to identify the pathogen of SEA?
(Spinal epidural abscess)
Bloodcultures x 2.
If surgery imminent collect intraoperative samples.
CT guided aspiration.
Send for aerobic + anaerobic bacteria, gram stain, fungal and mycobacterial stain and cultures.
LP for CSF —> low yield and pose risk for introducing infection.
UTD 9/2023
What imaging to order then SEA suspected?
(Spinal Epidural Abscess)
** ASAP MRI w/ contrast **
Note - CT w/ contrast acceptable is MRI not available,
Plain films may reveal changes of osteomyelitis / discitis, but rarely diagnostic.
Myelography largely obsolete.
Note - Scout lateral images of the entire spinal column may be warranted, skip lesions may be seen, and patients may not be symptomatic from all the affected area.
Note - If contrast cannot be used presence of paraspinal / bone marrow edema are common findings in SEA.
Note - Multifocal, noncontiguous SEA associated w/ delay in presentation or diagnosis, concomitant area of infections outside the spine, and ESR >95 on presentation.
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Differential Diagnosis of SEA?
(Spinal Epidural Abscess)
- disc and degenerative bone disease
- metastatic tumors
- vertebral discitis and osteomyelitis
- herpes zoster
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How do you manage SEA?
(Spinal epidural abscess).
1) reduce and resolve mass
2) eradicate causative organisms
Usually surgical drainage + antibiotic therapy.
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When is surgical intervention needed for SEA?
(Spinal Epidural Abscess)
- Acute / Progressive Neurological Deficits
- Spinal instability
- Ring enhancing lesion on MRI
- Disease progression despite antibiotic therapy.
Timing of surgery 24-36 hours from onset of paralysis.
Good neurological outcome 80% if decompression < 24 hours. 10% if > 24 hours.
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When is a conservative medical approach appropriate for management of SEA?
(Spinal Epidural Abscess)
- No risk of poor outcome (MRSA, advanced age, WCC>12.5, immunocompromised, diabetes).
- Organism known from aspirate.
- No neuro deficits.
- No cord compression in imaging
- Patient refuses surgery
- Medically unstable or unacceptable surgical risk
- Complete cord injury > 48 hours and no evidence of ascending lesion.
** no randomized trial for medical vs surgical management
Note: Medical therapy has failure rates of 8.5-17% even in ideal patients who lack risk factors.
UTD 9/2023
