Spinal Epidural Abscess

Abstract & Commentary

By Michael Rubin, MD, Professor of Clinical Neurology at Weill Cornell Medical College and Attending Neurologist at New York Presbyterian Hospital, Assistant Editor, Neurology Alert. Dr. Rubin does research for ASTA Medica and Eli Lilly.

Synopsis: Patients with spinal epidural abscess may be normothermic and have normal WBC counts. Urgent surgery was more likely to be offered to patients presenting with neurologic deficits than with pain alone. Patients treated without early surgery were significantly more likely to deteriorate and suffer poor outcomes.

Source: Curry WT et al. Spinal Epidural Abscess: Clinical Presentation, Management, and Outcome. Surg Neurol. 2005;63;364-371.

Spinal epidural abscess is a rare hospital admission, perhaps 1 in 10,000, and mortality remains high, up to 31%. Records of patients admitted to the Massachusetts General Hospital with this diagnosis between 1995 and 2001 were retrospectively reviewed to determine its clinical characteristics and assess whether outcome could be foretold based on presentation and treatment. Only those with pathologic or radiographic evidence of spinal epidural abscess were included, whereas those with discitis or osteomyelitis alone were excluded. Patients were grouped based on antibiotic or surgical treatment and worsening status was based on physician’s notes in the chart. Statistical analysis included Student t test and Pearson chi square test.

Fourty-eight patients, 30 men and 18 women, mean age 61 years (range, 31-84 years), were seen during the study period. Intravenous drug abuse was identified most often (27%, n = 13) as a risk factor. Nonspinal infection (21%, n = 10), diabetes, alcoholism, spinal procedures or trauma, HIV, and chronic steroid use were associated in the remainder. Weakness or sphincteric dysfunction (57%, n = 27), fever > 101 (48%, n = 23), and radicular or axial pain (35%, n = 17) were the most common presenting features. Normal peripheral white blood count did not exclude the diagnosis, and erythrocyte sedimentation rates (ESR) were rarely obtained. Blood cultures were positive in 60% (n = 30), with S. aureus the most commonly identified organism (63%, n = 29). Heterogeneously enhancing epidural collections were the typical MRI finding, iso/hypointense on T1 and hyperintense on T2 weighted images, most often in the lumbosacral (46%, n = 22) or cervical region (23%, n = 11), spanning anywhere from 1 to 13 levels. Osteomyelitis or discitis was evident in 73% in the adjacent disc or vertebral body. Fifty-two percent (n = 25) underwent urgent surgery, generally those with neurologic deficits, and 48% (n = 23) initially received antibiotics alone, usually those with only pain or fever. Of the latter, 23% (n = 11) required delayed surgery. On discharge, 37.5% (n = 18) were neurologically improved, 33% (n = 16) were unchanged, and 29% (n = 14) had worsened, compared to status on admission. Of those improved, 83% (n = 15) had undergone surgery, whereas among those who deteriorated, 86% (n = 12) had received antibiotics initially. Of the unchanged patients, 50% each (n = 8) had received antibiotics or undergone surgery. Fever and elevated white count may be absent in patients with spinal epidural abscess, and those who receive early surgery are likely to do better than those initially treated with antibiotics alone.

Commentary

A recent series confirms the notion that surgically treated patients with spinal epidural abscess do well (Surg Neurol. 2005;63;S1:26-S1:29). Among 24 patients, 17 men and 7 women, mean age was 47.5 years (range, 17-73 years), with spinal epidural abscess between January 1986 and December 2003; 21 (87.5%) underwent surgical drainage of the abscess. Sixty-two percent were immunocompromised as a result of concomitant illness, including diabetes or infection, with intravenous drug abuse, spinal trauma, cancer, and gunshot wound as other predisposing factors. Presenting complaints included back pain (100%), muscle weakness (66.6%), paresthesiae (38%), or sphincteric dysfunction (33.3%). Causative organisms included S. aureus (n = 14, 58.3%), tuberculosis (n = 3, 12.5%), E. coli, and S. epidermidis (1 each, 4.2%). Normal function was regained in 62.5% (n = 15), with 4 remaining with neurologic disability. Early surgery combined with antibiotic therapy appears to be the treatment of choice for spinal epidural abscess.