Lumbar epidural abscess is localized within epidural space between first lumbar vertebrae and first sacral vertebrae.1 Spinal cord is covered by three fibrous membrane known as pia, arachnoid and dura. Pia is the innermost membrane attached to spinal cord and dura is the thickest outer most membrane that protects spinal cord. Epidural space is outside the dura membrane. Epidural space contains fatty tissue, blood vessels, lymph vessels and nerve fibers. Epidural abscess is collection of pus within epidural space. Large volume of epidural pus can spread in several levels of lumbar spinal segments and lateral space outside inter-vertebral foramina. Incidence of epidural abscess is between 0.002 of hospital admission. Lumbar epidural abscess is rare in children.
Risk Factors Causing Lumbar Epidural Abscess
- Back Injury
- Contaminated Reuse of Needles- Intravenous drug use for addiction.
- Chronic Renal Failure
- Chemotherapy for Cancer
- Cachexia in Malignancy
Causes of Lumbar Epidural Abscess
Bacterial Infections2, 3, 4
- Staphylococcus Aureus- Most common infection (about 50 to 73% of cases).
- Mycobacterium Tuberculosis
- Streptococcus Milleri
- Haemophilus Parainfluenzae
- Brucella Species
- Actinomyces Israelii.
Source of Infection
- Proximal or Infection Of Adjacent Tissue
- Osteomyelitis of Vertebrae5
- Psoas Abscess- Paravertebral infection and abscess
- Distal Infection
- Ear Infection
- Bacteremia-Bloodstream Infection
- Severe Back Injuries- Followed by bleeding and infection
- Auto Accident
- Work Accident
- Penetrating Injuries-Followed by infection
- Sharp object penetration through skin into deeper paravertebral tissue.
Infection following back surgery.
Post Epidural Injection6
Epidural steroid injection or epidural blood patch can introduce infection in epidural space, which later follows with epidural abscess.
Post Epidural Catheter Insertion
Epidural catheter is placed to deliver local anesthesia for treatment of lower back pain, labor delivery, leg pain and cancer pain.
Symptoms of Lumbar Epidural Abscess
General Symptoms of Lumbar Epidural Abscess
- Nausea and Vomiting
- Loss of Appetite
Specific Symptoms of Lumbar Epidural Abscess
- Back Pain- Pain is localized between L1 and S1 spinal segment of lower back.
- Radicular Pain- Severe leg pain observed in lower leg, dermatomal distribution of pain depends on level and volume of abscess.
- Tingling- In lower leg.
- Numbness- Follows tingling if treatment is prolonged and appropriate treatment is not provided.
- Weakness- Weakness in lower leg is a late symptoms and indicates emergency. Surgical treatment is advised to prevent permanent paralysis.
- Bowel Bladder Incontinence- Difficulties in holding urine.
- Urinary Incontinence- Difficulties in holding stool.
- Urinary Retention- Difficulties to pass urine.
Investigations Done To Diagnose Lumbar Epidural Abscess
- Complete Blood Count- White Blood Cell Count (WBC) – Increased.
- Erythrocyte Sedimentation Rate- High.
- Blood Sugar- High.
CAT Scan of Lower Back (L1 to S1)
Epidural mass of abscess seen.
MRI of Lower Back (L1 to S1)
Epidural mass of abscess seen.
Treatment for Lumbar Epidural Abscess
- Choice of Antibiotics For Treating Lumbar Epidural Abscess
- Methicillin- S aureus bacteria are sensitive to Methicillin.
- First Generation Cephalosporin.
- Combination Vancomycin Plus Aminoglycoside.
- Trimethoprim Sulphamethoxazole.
- Duration of Treatment
- Intravenous Antibiotics- 4 to 8 weeks in most cases, in case of osteomyelitis, treatment is continued longer depending on prognosis.
Surgery for Lumbar Epidural Abscess
Indications for Surgery
- Severe Numbness and Weakness.
- Paraplegia- Sudden in occurrence
- Evacuate Abscess
- Decompression of Epidural Space
- Not Responding To Intravenous Antibiotic Treatment
Prognosis of Lumbar Epidural Abscess
- Total Recovery- Diagnosis is accomplished and treatment is provided before symptoms of numbness and weakness is observed.
- Partial Recovery- Antibiotic treatment is ineffective and symptoms of numbness, weakness, bladder incontinence and bowel incontinence continue for over 8 to 12 weeks. Patient may recover with partial numbness in leg or weakness associated with muscle atrophy.
- Paraplegia- Large abscess or failure to treat with antibiotics will worsen the symptoms and eventually cause permanent damage of spinal cord resulting in paraplegia.
Complications Involving Lumbar Epidural Abscess
- Lumbar Meningitis
- Osteomyelitis of Vertebral Column5
- Back Pain
- Brain Abscess
- Cerebral Meningitis
- Numbness in Leg
- Weakness in Leg
When to See a Doctor?
Severe back pain associated with tingling and numbness.
- Lumbar Epidural Abscess
- Weakness in leg
- Spinal epidural abscess: a 10 year perspective. Hlavin ML, Kaminski KJ, Ross JS, et al. (1990) Neurosurgery 27:177–184.
- Spinal sepsis due to Streptococcus milleri: two cases and review. Gelfand MS, Bahktian BJ, Simmons BP (1991) Rev Infect Dis 13:559–563.
- Haemophilus parainfluenzae as a rare cause of epidural abscess: case report and review.Auten GM, Levy CS, Smith MA (1991) Rev Infect Dis 13:609–612.
- Spinal epidural abscess due to Actinomyces israelii.Kannangara DW, Tanaka T, Thadepalli H (1981) Neurology 31:202–204.
- Pyogenic vertebral osteomyelitis and postsurgical disc space infections.Ozuna RM, Delamarter RB (1996) Ortho Clin North Am 27:87–94
- Epidural abscess: a hazard of spinal epidural anaesthesis. North JB, Brophy BP (1979) Aust NZ J Surg 49:484–485.
- Diagnosis and management of spinal epidural abscess. Redekop GJ, Del Maestro RF (1992) Can J Neurol Sci 19:180–187.
- Spinal epidural abscess. An infectious emergency. Rockney R, Ryan R, Knuckley J (1989) Case report and review. Clin Pediatr 28:323–324.