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Spinal Epidural Abscess: Causes, Symptoms, Signs, Tests, Investigations, Treatment, Complications

Vertebral column is formed by 33 vertebrae and 24 discs. The 33 vertebrae are distributed in neck (7 vertebrae), thorax (12 vertebrae), lumbar (5 vertebrae), sacrum (5 vertebrae) and coccygeal segments (4 vertebrae). Intervertebral discs are absent in five sacral and four coccygeal vertebrae, which are fused. Twenty-four discs lie between vertebrae in neck, thorax and lumbar segment. Spinal canal is a cylindrical hollow structure surrounded by vertebrae, disc and ligaments. The cylindrical spinal canal is stretched between base of the skull and sacrum. Vertebral column protects spinal cord, which lies within spinal canal. Three tough fibrous membranes known as pia, arachnoid and dura mater surrounds spinal cord. The spinal cord is also surrounded by a fluid or water known as cerebrospinal fluid. Cerebrospinal fluid lies between pia and arachnoid mater. Spinal cord is protected from injury by vertebral column, three tough fibrous membrane and cerebrospinal fluid.

Spinal epidural space lies between the dura mater and bones of vertebral column. Spinal epidural space is spread from neck below the skull to sacrum. Epidural abscess is one of the rare causes of back pain. Epidural abscess is caused by bacterial infection of epidural soft tissue. Epidural abscess is a purulent secretion, which spreads in to epidural space. Large epidural abscess spreads over several segments. Collection of epidural pus when retained in epidural space causes pressure symptoms. Pressure symptoms are generated by expansion of abscess in epidural space, which eventually causes mild to harsh compression of spinal cord and spinal nerve. Epidural abscess is a rare medical condition and often leads to hospital admission. The published scientific data suggests number of cases admitted in the hospital with diagnosis of epidural abscess are 0.2 to 2.5 cases per 10,000 hospital admission.1

The annual incidence of spinal epidural abscess has risen in the past 2-3 decades from 0.2-1 cases per 10,000 hospital admissions to 2.5-3 per 10,000 admissions. The rising incidence of spinal epidural abscess is because of increased cases of Intravenous illicit drug use and increased diagnostic or therapeutic spinal procedures. Distribution of symptoms and signs caused by spinal epidural abscess depends on location of abscess in neck, mid back and lower back.

Spinal Epidural Abscess

Causes Of Spinal Epidural Abscess

Hematological And Lymphatic Spread-

  • Urinary tract Infection 
  • Respiratory infection 
  • Ear Infection
  • Chronic sinusitis

Spread Of Abscess From Adjacent Tissue

  • Osteomyelitis- Bone infection
  • Psoas Abscess
  • Infected Intravenous Cannula or I. V. Injections- Several patients receive intravenous fluid and medications daily in hospital and doctors office. Contaminated needle, cannula, I.V. Fluid and medication transmit infection and bacteria into patient’s blood. The distant deposits of the seeds of the bacteria in epidural space causes infection and abscess formation.
  • I.V. Drug Abuse- The contaminated needle and syringes are the source of infection.2 

Invasive Procedures-A Cause For Spinal Epidural Abscess

  • Epidural Anesthesia- Needle is inserted in neck, mid back or lower back
  • Spinal Anesthesia- Needle is inserted in lower back
  • Epidural Corticosteroid Injection- Procedure is performed in neck, mid back or lower back
  • Epidural catheter placement for normal baby delivery or pain- Catheter is inserted in lower back
  • Spinal Myelogram and Intrathecal Catheter Placement- Procedure is performed in lower back.
  • Discogram and disc therapy.3

Spinal Epidural Abscess Caused By Back Injury

  • Sports Injury- Causes abscess mostly in neck and lower back 
  • Domestic Fall- Mostly causes trauma of lower back resulting in epidural abscess.
  • Automobile or Car Accident- Results in injuries of lower back and neck 
  • Work Injury- Work injury causes mostly injury of lower back and neck.

Soft Tissue Injury –

  • Epidural soft tissue injury causes epidural bleeding, which is followed by epidural abscess if not treated appropriately.

Skeletal Injury-

  • Fracture of vertebrae
  • Dislocation of the vertebrae and facet joint causes spondylolisthesis and epidural bleeding, which often is followed by infection and abscess formation.

Spinal Epidural Abscess Caused By Surgery

  • Discography 
  • Cheonucleosis 
  • Discectomy
  • Laminectomy 
  • Spinal Instrumentation and Fusion.

Symptoms Of Spinal Epidural Abscess

Non- Specific Symptoms Of Spinal Epidural Abscess

  • Loss of appetite
  • Lethargy
  • Nausea and Vomiting

Specific Symptoms Of Spinal Epidural Abscess


  • Mild to Moderate Fever– Patient often suffers with mild to moderate fever following initial epidural infection. 
  • Hyperpyrexia– High fever above 102 degrees Fahrenheit is observed during initial phase of epidural infection and if epidural abscess is associated with meningitis. 

Back Pain-

  • Back pain is mostly localized over midline and paravertebral dermatome. 
  • Pain is mostly localized over spinous process and radiates into surrounding tissue. 
  • Depending on location of abscess, pain is observed over the spine of neck, mid back or lower back.
  • Patient may complaint of radicular pain that radiates into neck, arms, chest wall or leg when pain is caused by pressure or pinch of the spinal nerve in neck, mid back or lower back. 

Tingling and Numbness-

  • Neck Abscess– Tingling and numbness is observed in upper extremity and often in entire lower body.
  • Mid Thoracic Abscess– Tingling and numbness is observed in chest wall and lower extremities.
  • Lower Back Abscess– Tingling and numbness is observed in only lower extremities.


  • Neck Abscess– Patient complaints of muscle weakness in upper extremity and often in entire lower body.
  • Mid Thoracic Abscess– Patient complaints of muscle weakness in lower extremity, back muscles and abdominal muscles.
  • Lower Back Abscess– Patient complaints of weakness in leg muscles and lower back muscles.

Signs Of Spinal Epidural Abscess


  • Symptoms of paraplegia of lower extremities are observed when epidural abscess in mid and lower back causes compression or pressure over spinal cord in thoracic or lumbar segment. 
  • Paraplegic patient is unable to move both lower extremities. Partial or complete recovery is observed when spinal cord compression is relieved following surgical treatment. 


  • Quadriplegia is a medical condition that results in paralysis of all four extremities. 
  • Quadriplegia is caused by compression of spinal cord by epidural abscess in neck above level of 5th cervical vertebrae. 
  • Quadriplegic patient is unable to move all four extremities. 
  • Symptoms and signs are reversible if pressure over the spinal cord is removed by surgery. 

Bowel And Bladder Incontinence

  • Sacral parasympathetic nerves passes to urinary bladder and lower large colon through 2nd to 5th sacral nerve.
  • Spinal cord ends at 2nd lumbar vertebrae and divides into lumbar and sacral nerve below 2nd lumbar vertebrae. 

Neck Rigidity Or Stiff Neck

  • Neck rigidity or stiff neck is observed in patients suffering with spinal meningitis or meningitis.

Spinal Tenderness

  • Percussion or palpation of spine and paravertebral area suggests tenderness and pain at neck; mid back or lower back depending on level of vertebral column where abscess is located. 

Reflex Abnormalities

  • Patient suffering with paraplegia and quadriplegia has loss of joint stretch reflexes. 
  • Stretching of muscles stimulates the muscle spindle, which sends the reflex impulses to muscles to contract. 

Associated Symptoms Of Spinal Epidural Abscess

The patient suffering with spinal epidural abscess may also show a symptoms and signs of systemic infections of other organs.

Urinary Tract Infection

  • Burning urine
  • Increased frequency of urine
  • Foul smelling urine

Respiratory Infection

  • Fever
  • Cough with or without expectoration
  • History of shortness of breath

Ear Infection

  • Fever
  • Complaint of ear pain
  • Purulent discharge from ear


  • Fever
  • Complaint of headache
  • Purulent nasal discharge

Tests And Investigations To Diagnose Spinal Epidural Abscess

Blood Examination

  • Increase White blood cell (WBC) count.

Microscopic Study and Culture of Blood Samples

  • Microscopic study of blood smear after gram stain. Bacterial presence is tested for gram positive or negative bacteria. 

Blood Culture-

  • Blood samples are cultured under aerobic and anaerobic conditions. 
  • The bacterial growths are classified as aerobic or anaerobic bacteria. 

Erythrocyte Sedimentation Rate (ESR)

  • ESR is increased during infection and presence of abscess. 
  • ESR test is performed to check the prognosis following treatment.

Urine Examination

  • Proteinuria– Protein contents in urine are increased
  • Microscopic Test and Culture– Bacterial presence is observed.

Sputum Examination

  • Microscopic Test and Culture– Bacterial presence is observed.


  • Microscopic Study Of Pus– Biopsy material is obtained following needle aspiration or drainage of abscess. The pus is smeared on slide and tested with gram stain. Bacterial presence is classified as gram positive or negative bacteria. 
  • Culture Of Abscess– Sample of pus is cultured under aerobic and anaerobic conditions. The bacterial growths are classified as aerobic or anaerobic bacteria. 
  • Special Stains And Cultures– Mycobacteria and fungi are tested with special stain and cultured using specific cultural media. 

Radiological Examination


  • Diagnosis Of Fracture And Dislocation– Plain X-ray is helpful to diagnose fracture or dislocation of vertebral column. 
  • Diagnosis Of Osteomyelitis And Bone Infection– Plain X-Ray also helps to diagnose osteomyelitis or infection of the bone.

Magnetic Resonance Imaging (MRI)-

  • Diagnosis of Soft Tissue Abnormalities– MRI shows the details of the soft tissue like spinal cord, ligaments, tendon, muscles, nerves and skeletal system much better than CT scan or plain X-Ray. 
  • Diagnosis of Fluid Collection– Details of presence of fluid or pus in epidural space is observed in 3 dimensions when MRI is targeted to epidural abscess. 
  • The diagnostic sensitivity of MRI is 90%-95%. Gadolinium dye is injected prior to MRI to enhance images of spinal epidural abscess and bony infection like osteomyelitis. 

Computerized Tomography-

  • CT scan gives 3 dimensional images like MRI. Patient is exposed to multiple X-Ray images and radiations. 
  • CT scan defines bony abnormalities better than MRI.

CT Myelogram-

  • Myelogram involves injection of radio-opaque contrast dye in CSF, which is followed by CT scan of back. 
  • The spinal needle is inserted in epidural space and through the needle 15 to 20 cc of dye is injected in CSF. 
  • The spread of dye is studied. Epidural abscess often causes narrowing of the subarachnoid space and obstruct spread of dye towards head or foot depending on the level of lesion and dye injection. 
  • Dye study also helps to evaluate the spread of abscess and pressure on spinal cord.

Treatment For Spinal Epidural Abscess

Medical Treatment

  • Anti-inflammatory
  • Analgesics
  • Antibiotics:
    • Early antibiotic treatment is important to prevent neurological deficiency.Y
    • Intravenous- 1 to 6 weeks
    • Oral- 4 to 12 weeks

Surgery For Spinal Epidural Abscess-

  • Early surgical management has better prognosis than surgical treatment, which follows medical management.5
  • CT guided needle aspiration of abscess
  • Debridement of abscess cavity
  • Laminectomy

Complications Of Spinal Epidural Abscess

  • Bone Infection
  • Meningitis
  • Nerve damage
  • Spinal cord infection and abscess
  • Diskitis
  • Endocarditis
  • Psoas abscess 
  • Vertebral osteomyelitis


1. Spinal epidural abscess.

Johnson KG.

Crit Care Nurs Clin North Am. 2013 Sep;25(3):389-97.

2. Diagnosis and management of primary pyogenic spinal infections in intravenous recreational drug users.

Ziu M1, Dengler B, Cordell D, Bartanusz V.

Neurosurg Focus. 2014 Aug;37(2):E3.

3. Epidural abscess and cauda equina syndrome after percutaneous intradiscal therapy in degenerative lumbar disc disease.

Subach BR1, Copay AG, Martin MM, Schuler TC, DeWolfe DS.

Spine J. 2012 Nov;12(11):e1-4.

4. Spinal epidural abscess and paralytic mechanisms.

Shah NH1, Roos KL.

Curr Opin Neurol. 2013 Jun;26(3):314-7.

5. Spinal epidural abscesses: risk factors, medical versus surgical management, a retrospective review of 128 cases.

Patel AR1, Alton TB2, Bransford RJ1, Lee MJ1, Bellabarba CB1, Chapman JR1.

Spine J. 2014 Feb 1;14(2):326-30.

Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:December 28, 2018

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