□ CASE REPORT □Tubercular Spinal Epidural Abscess of the Lumbosacral
Region without Osseous Involvement: Comparison ofSpinal MRI and Pathological Findings ofthe Resected Tissue
QingLong Zhang 1 and Hisashi Koga 1,2Abstract
We herein present a case of tubercular spinal epidural abscess (SEA) without osseous involvement thatmimicked an acute bacterial abscess. This case manifested quite unusual findings not only radiographically,
but also clinically compared with previously reported cases of tubercular SEA.
Key words: spinal epidural abscess, tuberculosis, magnetic resonance imaging, osseous involvement(Intern Med 55: 695-698, 2016)(DOI: 10.2169/internalmedicine.55.5707)

Introduction
Spinal epidural abscess (SEA) is a rare infectious disorderthat often has a delayed diagnosis and is associated withsignificant morbidity and mortality rates. Therefore, early diagnosis is crucial for a better treatment outcome. Approximate half of all SEA cases are hematogenously seeded from
non-adjacent primary infectious sources or sepsis. Furthermore, 10-30% of SEA is directly extended from adjacentvertebral osteomyelitis and/or discitis. Although the mostfrequently identified pathogen is Staphylococcus aureus(60%), the identification of Mycobacterium is quite rare(less than 1%) (1). We herein present an extremely rare caseof tubercular SEA involving the lumbosacral region without
any other active infectious regions, even in the adjacent vertebral body and disc.

Case Report
A 77-year-old man visited our outpatient clinic in August
2014 with a 1-month history of severe pain in his right leg.
On examination, he presented sensory disturbance and motor
weakness of the right lower limb (L5-S1 nerve area). The
patient’s right Achilles reflex slightly decreased, however,other deep tendon reflexes were normal. The right Straight
Leg Raising (SLR) test was positive, however, we could notobserve any pathological reflexes, such as Babinski, Oppenheim, or Chaddock reflexes. Additionally, the patient exhibited no symptom of meningeal irritation (headache, nuchal
stiffness, and Kernig’s sign). According to these clinicalmanifestations, the patient was suspected to have lumbar
disc herniation and a CT scan was performed. CT images
revealed an isodense mass lesion in the right epidural space,compressing and distorting the dural sac and Rt S1 nerve(Fig. 1). Further MRI images revealed a relatively lowintensity mass lesion on the T1-weighted image extended
from the L5-S2 vertebral body level (Fig. 2C). The mass
was partially heterogeneous on the T2-weighted andShortTIInversion
Recovery( STIR )images(Fig. 2A, B, D, and E).
He also had a temperature of 38℃, and his laboratory investigations showed WBC 7,500 cu.mm (normal range:3,500-9,500); neutrophil 84.2% (normal range: 40-75);
erythrocyte sedimentation rate (ESR) 65 mm/1 hr (normalrange: 0-15); and C-reactive protein (CRP) 46.3 mg/L (normal range: 0-8). He had a previous history of tubercularpneumonia, however, a chest X-ray and CT scan could not
identify active tuberculosis (TB) region. Furthermore, bloodand sputum examinations did not indicate any bacterial in-１

Department of Minimally Invasive Spinal Surgery, Zhangzhou Zhengxing Hospital, China and ２Department of Orthopaedics, Iwai Orthopaedic
Medical Hospital, JapanReceived for publication May 2, 2015; Accepted for publication June 28, 2015
Correspondence to Dr. Hisashi Koga, hkoga0808@gmail.com

695

Intern Med 55: 695-698, 2016

DOI: 10.2169/internalmedicine.55.5707

AB

Figure 1. Axial CT (A, B) imaging of the L5/S1 disc (A) and cranial side of sacral spine (B). These
images show a mass lesion demonstrating isodensity (black arrowheads) in the right epidural space,compressing and distorting the dural sac and right S1 nerve root.

BAC

DE

Figure 2. Axial (A, B) and sagittal (C, D, E) MR imaging of the lumbosacral spine. T1-weighted
image (C) shows a relatively low-intensity mass lesion (white arrowheads) in the spinal canal, extending from the L5-S2 vertebral body. T2-weighted (A, B, D) and short TI inversion recovery (E) images
reveal partially heterogeneous iso-intensity.

fection, including TB.
According to the patient’s clinical course and laboratory
data, we suspected acute bacterial SEA and performed
evacuation under microendoscopic spinal surgery. Microen-doscopic spinal surgery is a novel, less invasive surgical
technique, which results in decreased pain and operative
time and achieves a faster recovery after surgery (2, 3).
Thus, this technique is the most suitable for weakened infec-696

Intern Med 55: 695-698, 2016

A

DOI: 10.2169/internalmedicine.55.5707

BFigure 3. Histopathology. Macroscopic findings of a resected capsule of the epidural abscess. Light
brown color shows the region for caseous necrosis (arrows) (A). Hematoxylin and Eosin stainingshows granulomatous inflammation with Langhans giant cells surrounding the caseous necrosis (arrows) (B).

tious disease patients and/or patients of advanced age.
During the operation we observed a tubercular abscesswith caseous necrosis, and the pathologically findings of thecapsule confirmed it was a tubercular spinal epidural abscess(Fig. 3). Additionally, we endoscopically checked the L5/S1
disc space, however, no apparent infection was observed.
Furthermore, a bacterial culture of the pus identified thepresence of Mycobacterium tuberculosis. Immediately after
the operation, the patient’s leg pain was relieved, and antiTB chemotherapy was started. Two weeks after the operation the patient was discharged from our hospital and wasable to walk without any assistance.

Discussion
A spinal tubercular infection is a relatively rare disease in
medically advanced countries. On the other hand, this pathological status is more common in developing countries.
Even in advanced countries, tuberculosis is becoming a new
threat due to its acquisition of multi-drug resistance andagainst immunocompromised individuals.
The typical infectious patterns of spinal TB are spondylodiscitis or spondylitis with disk involvement (4). The contiguous vertebrae are frequently involved. Although epiduralinvolvement and/or epidural spread are also observed in
more than 60% of all cases (5), tubercular SEA without osseous involvement is extremely rare. Only two cases havebeen previously reported. Arora et al. reported the case of animmunocompetent 35-year-old man who presented with subacute cauda equine syndrome. The patient had been diagnosed with pulmonary TB infection 15 days prior to developing neurological symptoms. Baallal et al. reported thecase of an immunocompetent 58-year-old man who presented with paraplegia (6). In both cases, it extended into
the wide vertebral levels (former: T5-S2, latter: C7-L2),
however, both cases were successfully cured by combination

therapy of surgery and anti-TB chemotherapy.
Although our case showed relative narrow segment of extension (L5-S2), it was also subsequently cured with thecombination of surgery and anti-TB chemotherapy. Generally, the onset of spinal TB is chronic (7), however, the casereported by Arora et al. and our case showed a relative acuteonset. Therefore, a subacute onset of symptoms (2-4 weeks)
might be one of the clinical characteristics of tubercular
SEA without osseous involvement. This onset is quite similar to that of other bacterial SEA, such as Staphylococcus
aureus, thus this clinical course appears to be difficult to diagnose as tubercular SEA.
Similarly, it was difficult to diagnose tubercular SEA
without osseous involvement based on the laboratory data. Anormal or slightly increased WBC count may help to suspect this pathological status because other bacterial SEA
generally show higher WBC counts (15,700 cu.mm on average) (8); the case by Arora et al. and our case did not showsuch an increased WBC count (former: 13,600, latter:7,500).
From the MRI findings described from previously reported cases and our case, an isointensity signal on T2weighted and/or STIR images is one of the discriminating
features of tubercular SEA from other bacterial SEA. Usually, the central part of other bacterial SEA exhibits a waterequivalent signal intensity on T2-weighted and/or STIR images (homogenous high-intensity signal) (9-11). This difference mainly occurred in the thick granular membrane of tubercular SEA. In our case, a thick granular membrane wasalso confirmed by the pathological examination. On theother hand, Jung et al. reported that thin and smooth enhancement of the abscess wall and a well-defined, paraspinal abnormal signal were frequently observed in tuberculous
spondylitis (12). The thick granular membrane observed during tubercular SEA confirmed in our report might protect
against the spread of infection into the vertebrae and/or disc697

Intern Med 55: 695-698, 2016

DOI: 10.2169/internalmedicine.55.5707

space, and tubercular SEA without osseous involvement
may subsequently arise from the primary epidural infection.
If we find a heterogeneous isointensity signal on the T2weighted and/or STIR images, then we should consider tubercular SEA without osseous involvement as the differential diagnosis.
Due to the recent aging society, cases of older, immunocompromised patients with a previous history pulmonary TB
are rapidly increasing. Unfortunately, the clinical, laboratorial, and imaging features of tubercular SEA without osseous involvement is not completely distinguishable fromother bacterial SEA. However, the heterogeneous isointensity signal on the T2-weighted and/or STIR images mayhelp clinicians consider the possibility of tubercular SEA.
The authors state that they have no Conflict of Interest (COI).

References
1. Sendi P, Bregenzer T, Zimmerli W. Spinal epidural abscess inclinical practice. QJM 101: 1-12, 2008.
2. Harrington JF, French P. Open versus minimally invasive lumbar
microdiscectomy: comparison of operative times, length of hospital stay, narcotic use and complications. Minim Invasive Neurosurg: MIN 51: 30-35, 2008.

3. Yeung AT, Yeung CA. Minimally invasive techniques for the management of lumbar disc herniation. Orthop Clin North Am 38:363-372, 2007.
4. Pertuiset E, Beaudreuil J, Lioté F, et al. Spinal tuberculosis inadults. A study of 103 cases in a developed country, 1980-1994.
Medicine 78: 309-320, 1999.
5. Jain AK, Sreenivasan R, Saini NS, Kumar S, Jain S, Dhammi IK.
Magnetic resonance evaluation of tubercular lesion in spine. Int
Orthop 36: 261-269, 2012.
6. Baallal H, El Mostarchid B. Multisegmental tubercular spinalepidural abscess. Pan Afr Med J 14: 2, 2013.
7. Metta H, Corti M, Redini L, Yampolsky C, Schtirbu R. Spinal
epidural abscess due to Mycobacterium tuberculosis in a patientwith AIDS: case report and review of the literature. Braz J Infect
Dis 10: 146-148, 2006.
8. Reihsaus E, Waldbaur H, Seeling W. Spinal epidural abscess: ameta-analysis of 915 patients. Neurosurg Rev 23: 175-204, 2000.
9. Patel D, Baron EM, Enochs WS, Ruth C, Harrop JS, Vaccaro AR.
Spinal epidural abscess mimicking lymphoma: a case report. Orthopedics 31: 402, 2008.
10. Sandhu FS, Dillon WP. Spinal epidural abscess: evaluation with
contrast-enhanced MR imaging. AJNR Am J Neuroradiol 12:1087-1093, 1991.
11. Stäbler A, Reiser MF. Imaging of spinal infection. Radiol Clin
North Am 39: 115-135, 2001.
12. Jung N-Y, Jee W-H, Ha K-Y, Park C-K, Byun J-Y. Discriminationof tuberculous spondylitis from pyogenic spondylitis on MRI. AJR
Am J Roentgenol 182: 1405-1410, 2004.

Ⓒ 2016 The Japanese Society of Internal Medicine
http://www.naika.or.jp/imonline/index.html

698