Background
Infections involving the spinal canal include epidural abscesses (infection in the epidural space), meningitis (infection of the meninges), subdural abscesses (infections of the subdural space), and intramedullary abscesses (infections within the spinal cord). Because the first 3 infections are discussed elsewhere in this journal (see Epidural and Subdural Infections, Meningitis), this article addresses only intramedullary abscesses.
Intramedullary spinal cord abscesses are extremely rare lesions. Since the original description in 1830 by Hart, approximately 100 cases have been reported. Their rarity, compared with brain abscesses, has been attributed to the relatively lower volume of the spinal cord and its particular blood supply.
Pathophysiology
Mechanisms of infection include (1) hematogenous spread from an extraspinal focus of infection, (2) contiguous spread from an adjacent focus of infection, (3) direct inoculation (ie, penetrating trauma, postneurosurgery), and (4) cryptogenic mechanisms (ie, no documented extraspinal focus of infection). In a 1998 review of 25 cases, hematogenous spread accounted for 8%, contiguous spread accounted for 24%, direct inoculation accounted for 4%, and 64% were cryptogenic.[1] In children, the abscesses are associated with prior anatomic spinal canal defects, such as dermal sinus tracts, which result from the incomplete partition of epithelial ectoderm and neuroectoderm in early fetal life.
Bacteria, such as staphylococci and streptococci, are the most common organisms responsible for these infections. Infections may also be caused by viral, fungal, or parasitic organisms. A diverse list of pathogens include, but are not limited to, cysticercosis, Mycobacterium tuberculosis, Listeria monocytogenes, Toxoplasma gondii, Nocardia asteroides, Histoplasma capsulatum, brucellosis, and the tapeworm spargana.
Initially, the area of the bacterial nidus is infiltrated with polymorphonuclear cells, leading to a suppurative myelitis. This evolves into central necrosis and liquefaction, which can spread along the long spinal tracts. Although the average extent of the process before 1975 was 6 vertebral levels, the average current length appears to be 3 levels. This change may be due to earlier detection and more effective antibiotics. At the periphery of this infectious process, fibroblasts proliferate and the central purulent area eventually becomes encapsulated by fibrous granulation tissue. The most commonly affected area is the dorsal thoracic spinal cord.
Epidemiology
Frequency
International
Various reviews of the literature describe different numbers, with a range of approximately 80-100 cases since the first description in 1830. In a 2003 review, only 38 pediatric cases were identified in the medical literature since 1830.[2]
Mortality/Morbidity
Although the first reported cases had high mortality rates, prognosis has improved significantly with the advent of antibiotics.
The mortality rate without surgical intervention is practically 100%, and those patients who died despite surgery almost exclusively were affected in the preantibiotic era.
The current mortality rate (cases reported in the last 2 y) is 8-12%, although 70% of survivors had persistent neurologic deficits.
In a review of 38 pediatric cases, 20% died, 60% had residual neurologic deficits, and only 20% recovered without sequelae.[2]
Race
Ethnic preference does not appear to exist, although some geographic differences are present. All intramedullary paracoccidioidomycosis cases were reported in Brazil.
Sex
In one study in which sex was reported, spinal cord infections were 2.5 times more common in males than in females.
Age
All ages are affected though children younger than 5 years are more likely affected.
Female patients are affected mainly in the first 4 decades of life, whereas the incidence among male patients is distributed more evenly, with a peak in the third decade of life (see the image below).
Graph showing age distribution of 91 patients with intramedullary spinal cord abscess. The age or gender of 14 patients is unknown. Chan CT, Gold WL. Intramedullary abscess of the spinal cord in the antibiotic era: clinical features, microbial etiologies, trends in pathogenesis, and outcomes. Clin Infect Dis. Sep 1998;27(3):619-26. [Medline].
Simon JK, Lazareff JA, Diament MJ, Kennedy WA. Intramedullary abscess of the spinal cord in children: a case report and review of the literature. Pediatr Infect Dis J. Feb 2003;22(2):186-92. [Medline].
Menezes AH, VanGilder JC. Spinal cord abscess. In: Wilkins RH, Rengachary SS. Neurosurgery. New York: McGraw-Hill; 1985:1969.
Al Barbarawi M, Khriesat W, Qudsieh S, Qudsieh H, Loai AA. Management of intramedullary spinal cord abscess: experience with four cases, pathophysiology and outcomes. Eur Spine J. May 2009;18(5):710-7. [Medline].
Bartels RH, Gonera EG, van der Spek JA, Thijssen HO, Mullaart RA, Gabreels FJ. Intramedullary spinal cord abscess. A case report. Spine. May 15 1995;20(10):1199-204. [Medline].
Benzil DL, Epstein MH, Knuckey NW. Intramedullary epidermoid associated with an intramedullary spinal abscess secondary to a dermal sinus. Neurosurgery. Jan 1992;30(1):118-21. [Medline].
Byrne RW, von Roenn KA, Whisler WW. Intramedullary abscess: a report of two cases and a review of the literature. Neurosurgery. Aug 1994;35(2):321-6; discussion 326. [Medline].
Cokca F, Meco O, Arasil E, Unlu A. An intramedullary dermoid cyst abscess due to Brucella abortus biotype 3 at T11-L2 spinal levels. Infection. Sep-Oct 1994;22(5):359-60. [Medline].
Darouiche RO. Spinal epidural abscess. N Engl J Med. Nov 9 2006;355(19):2012-20. [Medline].
David C, Brasme L, Peruzzi P, Bertault R, Vinsonneau M, Ingrand D. Intramedullary abscess of the spinal cord in a patient with a right-to-left shunt: case report. Clin Infect Dis. Jan 1997;24(1):89-90. [Medline].
Desai KI, Muzumdar DP, Goel A. Holocord intramedullary abscess: an unusual case with review of literature. Spinal Cord. Dec 1999;37(12):866-70. [Medline].
Dev R, Husain M, Gupta A, Gupta RK. MR of multiple intraspinal abscesses associated with congenital dermal sinus. AJNR Am J Neuroradiol. Apr 1997;18(4):742-3. [Medline].
DiTullio MV Jr. Intramedullary spinal abscess: a case report with a review of 53 previously described cases. Surg Neurol. Jun 1977;7(6):351-4. [Medline].
Hanci M, Sarioglu AC, Uzan M, Islak C, Kaynar MY, Oz B. Intramedullary tuberculous abscess: a case report. Spine. Mar 15 1996;21(6):766-9. [Medline].
Hardwidge C, Palsingh J, Williams B. Pyomyelia: an intramedullary spinal abscess complicating lumbar lipoma with spina bifida. Br J Neurosurg. 1993;7(4):419-22. [Medline].
Hart J. Case of encysted abscess in the centre of the spinal cord. Dublin Hosp Rep. 1830;5:522-524.
Hoil-Parra JA, Lazareff JA. [Lumbar dermal sinus as a cause of intramedullary and subdural abscess. Report of 2 cases]. Bol Med Hosp Infant Mex. May 1993;50(5):341-6. [Medline].
Hott JS, Horn E, Sonntag VK, Coons SW, Shetter A. Intramedullary histoplasmosis spinal cord abscess in a nonendemic region: case report and review of the literature. J Spinal Disord Tech. Apr 2003;16(2):212-5. [Medline].
Lahdou JB, Gilliard C, de Coene BD, Vandercam B, Deltombe T, Hanson P. [Streptococcus milleri subacute spinal cord abscess. Apropos of a case]. Neurochirurgie. 1996;42(2):100-4. [Medline].
Lindner A, Becker G, Warmuth-Metz M, Schalke BC, Bogdahn U, Toyka KV. Magnetic resonance image findings of spinal intramedullary abscess caused by Candida albicans: case report. Neurosurgery. Feb 1995;36(2):411-2. [Medline].
Manfredi M, Bozzao L, Frasconi F. Chronic intramedullary abscess of the spinal cord. Case report. J Neurosurg. Sep 1970;33(3):352-5. [Medline].
Martin RJ, Yuan HA. Neurosurgical care of spinal epidural, subdural, and intramedullary abscesses and arachnoiditis. Orthop Clin North Am. Jan 1996;27(1):125-36. [Medline].
Miranda Carus ME, Anciones B, Castro A, Lara M, Isla A. Intramedullary spinal cord abscess. J Neurol Neurosurg Psychiatry. Mar 1992;55(3):225-6. [Medline].
Rogg JM, Benzil DL, Haas RL, Knuckey NW. Intramedullary abscess, an unusual manifestation of a dermal sinus. AJNR Am J Neuroradiol. Nov-Dec 1993;14(6):1393-5. [Medline].
Tacconi L, Arulampalam T, Johnston FG, Thomas DG. Intramedullary spinal cord abscess: case report. Neurosurgery. Oct 1995;37(4):817-9. [Medline].
Vajramani GV, Nagmoti MB, Patil CS. Neurobrucellosis presenting as an intra-medullary spinal cord abscess. Ann Clin Microbiol Antimicrob. 2005;4:14. [Medline].
Weng TI, Shih FY, Chen WJ, Lin FY. Intramedullary abscess of the spinal cord. Am J Emerg Med. Mar 2001;19(2):177-8. [Medline].

