Acute onset intramedullary spinal cord abscess with spinal artery occlusion: a case report and review

Abstract

Intramedullary spinal cord abscess (ISCA) without meningitis is an extremely rare entity in the central nervous system, and it is often difficult to diagnose immediately, and no definitive imaging findings have been established. We experienced the case of a 61-year-old male who presented with a sudden onset back pain without fever following rapidly worsening paraparesis for 3 days, who subsequently become unable to walk. According to the initial MRI and 3D-CTA, the presumptive diagnosis was spinal infarction due to spinal artery embolism. However, his symptoms did not improve, despite the gradual changes in MRI following antiplatelet therapy. He underwent a biopsy in an attempt to prevent the lesion from progressing toward the upper spinal cord. The pathological examination revealed an intramedullary abscess, so we performed a midline myelotomy and drained the pus from the abscess. After surgery, MRI showed improvement, but the patient’s paraplegia persisted. To the best of our knowledge, this is the first case report of spinal cord abscess with the confirmation of spinal artery occlusion on angiography, which could have been caused by a bacterial embolism. We herein discuss its possible etiology and also review recent reports on ISCA.

Introduction

An intramedullary spinal cord abscess (ISCA) is an uncommon entity described initially by Hart [28] in 1830. Since then, more than 120 cases have been reported by several reviews. The mortality of this entity has improved by the use of antibiotic agents, adequate radiographical diagnosis and immediate surgery. The first review of the literature [3] published between 1830 and 1944 reported a 90% mortality rate, while a recent review by Kurita et al. [34] of the literature published between 1998 and 2007 reported only 4% mortality.

Our case presented with an acute onset of paraparesis with a presumptive diagnosis of spinal infarction developing chronologically on magnetic resonance imaging (MRI), and the definitive diagnosis of an intramedullary abscess was finally made based on the findings of a biopsy. Following our case report, we present a review of the recent world literature and an analysis of the 54 cases reported between 1977 and 2009, including their diagnosis, pathogenesis and treatment approaches and outcomes.

Case report

A 61-year-old male with drug-controlled diabetes mellitus was admitted to another hospital with sudden onset lumbago, where he was diagnosed with lumbar spondylosis and prescribed analgesics. However, progressive paraparesis and urinary retention developed 3 days later, and he was transferred to our hospital. On admission, he could not walk due to severe paraparesis, of grade 1/5 power in both lower limbs. He had hypesthesia below the T10 (thoracic10th) level, and was afebrile. Nuchal rigidity was not obviously present. There was no history of infection, trauma, fever, or surgery of the thoraco-lumbar spine. The results of his laboratory studies were as follows: white blood cell (WBC) count 7,500 mm⁻³ with a normal differential, C-reactive protein (CRP) 0.67 mg/l, and hemoglobin A_1c 6.9. MRI revealed intramedullary high intensity on the ventral aspect of the spinal cord at the T10-11 level on sagittal T2WI, and axial T2WI demonstrated high intensity chiefly on the bilateral anterior two-thirds of the gray matter (Fig. 1a, b). A diffusion-weighted image had bi-modal distribution of high intensity with peaks at the same level and conus, although there was difficulty with regard to its visual accuracy for a definitive diagnosis (Fig. 1c). Three-dimensional computed tomography angiography (3D-CTA) revealed the interruption of the spinal artery, which branched off from the intercostal artery at the level of the T10-11 on the right side, and there was no obvious Adamkiewicz artery or aortic dissection (Fig. 2). Therefore, we initially diagnosed spinal infarction caused by atherosclerotic or embolic occlusion of the spinal artery on the background of diabetes mellitus.

Fig. 1.

MR T2-weighted sagittal (a), axial (b: T10) and diffusion-weighted (c) images showing an anterior intramedullary high signal at the lower thoracic and conus level

Fig. 2.

3D-CTA showing the interruption of the spinal artery branching off from the intercostal artery in the spinal canal at the thoracic 10-11 level. No obvious Adamkiewicz artery or aortic dissection was recognized. Coronal image (a), magnification of a (b), and an axial image (c)

Two days later, the high intracordal T2WI signal had spread over the initial lesion (Fig. 3a), and therefore we administered more antiplatelet agents to prevent the development of spinal ischemia. However, the patient’s symptoms in his lower extremities had worsened to paraplegia at that point, although he was afebrile and had no signs of inflammation. A subsequent Gd-DTPA image 10 days after onset showed distinct enhancement in the initial lesion, which could not be observed at first (Fig. 3b). Finally, MRI 1 month after onset showed local cord expansion in a ‘hump’-like configuration at the T10/11 level (Fig. 3c), and some infectious disease, intramedullary tumor or demyelinating disease was suspected. Subsequent cerebro-spinal fluid (CSF) and blood cultures were sterile, the CSF cytodiagnosis was also negative, and a cardiovascular physician did not find any evidence of infectious endocarditis on the cardiac echo, and therefore a biopsy was performed in order to make a definitive diagnosis and to select the optimal treatment to prevent such inflammation from spreading to the cervical region.

Fig. 3.

T2-weighted image on day 2 (a), the Gd-DTPA image on day 10 (b), and a T2-weighted image on day 30 (c) showing the chronological development of the lesion, which finally transformed to the dorsal mass-like `hump`

The patient underwent a laminectomy at T11-L1 and intradural exploration. The spinal cord was expanded. A yellowish soft mass exophyting through the dorsal aspect of the cord rostral adjacent conus medullaris coated with thin pia (Fig. 4a) was taken piece by piece, and intraoperative histopathological examination revealed an abscess. Purulent fluid was encountered by midline myelotomy from T11 to the conus. The cavity was irrigated with saline, and the wound was closed in layers. No drains were placed in the abscess cavity.

Fig. 4.

a Intraoperative view of the lesion showing the exophyting abscess coated by only the thin pia. b A histopathological examination showing the degenerative fibrinous matrix, macrophages, granulocytes, and no tumor cells (Papanicolaou stain ×80)

Pathological evaluation of the surgical specimen showed degenerative fibrinous matrix, macrophages, granulocytes, and no tumorous cells, thus indicating a definitive diagnosis of spinal abscess (Fig. 4b). The intraoperative pus culture was also sterile.

A temporal high fever developed on one postoperative day, but it subsided once antibiotics were instituted intrathecally, and the patient was given a 5-week postoperative regimen of antibiotics intravenously assuming gram-positive rods. MRI T2WI findings on postoperative day 35 showed a decreasing high signal in the spinal cord (Fig. 5), but the patient’s paraplegia persisted. He was thereafter transferred to another hospital to undergo rehabilitation.

Fig. 5.

A T2-weighted image after treatment showing the decrease in the intracordal high signal

Review

A MEDLINE search of the literature was conducted using the keywords “intramedullary”, “spinal cord”, and “abscess”. Fifty-four cases of ISCA were identified between the years of 1977 and 2009 (Table 1) [1, 2, 4–10, 12–24, 26, 27, 29–43, 45–56].

Table 1.

Clinical data about intramedullary spinal cord abscesses in the published literature

Case	Author	Age	Sex	Onset	T2WI high	Gd-DTPA	DWI	Op	Anti-biotics	Prognosis	Causes of abscess
1	Our case	61	M	Acute	T10-conus	Homogenius	High	+	+	Poor	Embo. to A-K a.
2	DiTullio [19]	0	F	Acute	nm	nm	nm	+	+	Poor	Dermal sinus
3	Kurita [34]	58	M	Acute	C1-T1	Ring	nm	+	+	Good	Cryptogenic
4	Menezes [39]	48	M	Subacute	nm	nm	nm	+	+	Good	Cryptogenic
5	Maheswaran [36]	1	M	Acute	nm	nm	nm	+	+	Good	Dermal sinus
6	Marwah [37]	3	F	Chronic	nm	nm	nm	+	+	Good	Cryptogenic
7	Fortuna [24]	21	M	Chronic	nm	nm	nm	+	+	Good	Trauma
8	Chu [13]	69	M	Subacute	C2-7	Ring	nm	–	+	Poor	Cryptogenic
9	Novati [45]	24	M	Acute	C3	Ring	nm	–	+	Good	Sepsis
10	Vajramani [53]	40	F	Chronic	T10-conus	nm	nm	+	+	Poor	Sepsis
11	Helvaci [29]	15	F	Acute	T11,12	nm	nm	+	+	Good	Sepsis
12	Mukunda [43]	52	M	Subacute	L1	nm	nm	+	+	Good	Cryptogenic
13	Applebee [3]	47	F	Acute	T8	Ring	nm	+	+	Poor	Sepsis
14	Chidambaram [12]	3	M	Acute	T12-S1	Ring	nm	+	–	Good	Cryptogenic
15	Crema [15]	66	M	nm	T3-6	Ring	nm	–	+	Poor	Spondylodiskitis
16	Derkinderen [17]	50	M	Subacute	C1-6	nm	nm	+	+	Poor	Surgery
17	Desai [18]	22	F	Acute	C1-conus	Ring	nm	nm	+	Poor	Cryptogenic
18	Durmaz [20]	59	M	Acute	C2-4	Ring	nm	+	+	Dead	Sepsis
19	Elmaci [21]	49	F	Chronic	C2, 3	Ring	nm	+	+	Poor	Sepsis
20	Guzel [26]	1	nm	Subacute	T3-11	Ring	nm	+	+	Poor	Cryptogenic
21	Lascux [35]	56	M	Acute	nm	Ring	nm	–	+	Good	Sepsis
22	Morandi [40]	4	M	Acute	T-L	Ring	nm	+	+	Good	Dermal sinus
23	Morimoto [41]	0	F	nm	L2-conus	Ring	nm	+	+	Good	Dermal sinus
24	Simon [49]	1	M	Subacute	T12-conus	Ring	nm	+	+	Poor	Dermal sinus
25	Sverzut [50]	42	M	Subacute	C1-T3	Ring	nm	+	+	Poor	Cryptogenic
26	Tsurubuchi [52]	1	F	Subacute	Medulla-conus	Ring	nm	+	+	Good	Dermal sinus
27	Weng [55]	28	M	Subacute	nm	Ring	nm	+	+	Good	Cryptogenic
28	Yuceer [56]	4	M	Subacute	nm	Homogenius	nm	+	+	Good	Sepsis
29	Vora [54]	54	M	Subacute	Medulla-C6	Ring	nm	+	+	Dead	Sepsis
30	Bean [6]	15	M	Acute	nm	nm	nm	+	+	Good	Dermal sinus
31	Maurice-Williams [38]	21	M	Chronic	nm	nm	nm	+	+	Good	Dermal sinus
32	Maurice-Williams [38]	20	F	Subacute	nm	nm	nm	+	+	Good	Dermal sinus
33	Blacklock [8]	71	M	Acute	nm	nm	nm	+	+	Good	Cryptogenic
34	Carus [10]	61	M	Chronic	T7-10	nm	nm	+	+	Poor	Cryptogenic
35	Koppel [32]	50	M	Acute	C4-7	nm	nm	+	+	Poor	Cryptogenic
36	Benzil [7]	2	F	Acute	nm	Ring	nm	+	+	Good	Dermal sinus
37	Rogg [47]	2	F	Acute	nm	Ring	nm	+	+	Good	Dermal sinus
38	Babu [4]	72	M	Acute	nm	Homogenius	nm	+	+	Poor	Cryptogenic
39	Amacher [1]	0	M	nm	nm	Ring	nm	+	nm	Poor	Dermal sinus
40	Tewari [51]	11	M	Chronic	nm	nm	nm	+	nm	Poor	Cryptogenic
41	Erlich [22]	59	M	Acute	C4-6	nm	nm	+	+	Dead	Sepsis
42	King [31]	50	M	Subacute	Medulla-C6	Ring	nm	+	nm	Dead	Sepsis
43	Hardwidge [27]	26	M	Subacute	nm	nm	nm	+	+	Good	Dermal sinus
44	Cokca [14]	17	M	Subacute	nm	nm	nm	+	+	Good	Dermal sinus
45	Byrne [9]	55	F	Chronic	Conus	Spotty	nm	+	+	Poor	Cryptogenic
46	Byrne [9]	68	M	Chronic	Conus	Spotty	nm	+	+	Poor	Cryptogenic
47	Bartels [5]	5	M	Acute	T8	Ring	nm	+	+	Good	Cryptogenic
48	Pfadenhauer [46]	73	M	Acute	T10-11	Spotty	nm	–	+	Poor	Sepsis
49	Morrison [42]	32	M	Acute	nm	nm	nm	+	+	Good	Sepsis
50	David [16]	27	M	Acute	nm	Ring	nm	+	+	nm	Cryptogenic
51	Kurisu [33]	1	M	Chronic	Conus	Ring	nm	+	+	Good	Dermal sinus
52	Seizeur [48]	69	nm	Chronic	T10	Homogenius	nm	+	nm	Good	Cryptogenic
53	Hott [30]	nm	nm	Acute	C2-T5	Ring	nm	+	+	Poor	Sepsis
54	Fernandez [23]	nm	nm	nm	nm	nm	nm	nm	nm	nm	IE

C cervical, T thoracic, L lumbar, nm not mentioned

Of the 54 patients, 37 (68.5%) were males, 13 (24.1%) females, and 4 were not described in the literature. The age at presentation ranged from 0 to 73 years. The median age at presentation was 32 years and its distribution had three peaks: in infants, in the second decade, and in the fifth decade. Nine patients were under 2 years old, and all but one of these (15%) was associated with a congenital dermal sinus [1, 7, 19, 33, 36, 41, 47, 49, 52]. Symptoms at the time of presentation were back pain, neck stiffness, paralysis, sensory disturbance, and urinary dysfunction among others, which sometimes was caused by meningitis or encephalitis, but a fever at the initial presentation was only seen in 23 (43.4%) of the 54 cases. The duration from the onset of symptoms to admission was acute (less than 1 week) in 24 patients, subacute in 9, chronic (more than 6 weeks) in 17, and not mentioned in 4 cases (44.4, 16.7, 31.5, 7.4%, respectively). With regard to background medical conditions, 5 patients (including our case) had diabetes mellitus [8, 10, 13, 20], 1 had human immunodeficiency virus [35] and 2 were heroin addicts [32, 50] (11.1, 1.9, 3.8%, respectively).

With regard to the cause of infection, 21 (38.9%) patients had cryptogenic sources including our case, 15 (27.8%) were related to a dermal sinus infection (with a past history of dermal sinus surgery in 9 of these), 14 (25.9%) suffered from apparent sepsis due to listeria, nocardia, brucellosis, or oral flora, 3 (5.6%) were extended from contiguous lesions, such as diskitis, trauma, or from surgery, and only 1 (1.9%) case had infectious endocarditis [23].

Imaging studies, such as plain radiography, myelography, computed tomography scans and MRI were performed for all patients. MRI results with administration of contrast material were available for 33 cases, and the findings were ring-enhancing margins with a central low signal in 26, poorly or well-defined marginal enhancement in 4, or spotty enhancement in 3 cases.

Twenty-six (47.6%) patients were treated within a week from onset and 48 (88.8%) underwent surgery, including drainage in 42 (77.8%) and additional removal of dermoid or epidermoid tissue related to a dermal sinus in 6 (11.1%). The other five patients were treated with antibiotics alone [13, 15, 35, 45, 46]. The treatment method was not mentioned in one case [23]. In total, antibiotics were used in 47 patients, not used in 1 [12], and their use was not mentioned for six patients (87.0, 1.9, 11.1%, respectively), and the period of antibiotic administration ranged from 2 weeks to 2 months.

The clinical outcomes were recorded for all but two patients. Four (7.4%) patients died because of abscess rupture inducing meningitis and brain abscess [22], listeria meningoencephalitis [31], central nervous system nocardiosis involving the bilateral hemisphere, cerebellum, and upper cervical spinal cord due to diabetes mellitus (despite a two-stage operation) [20], or sepsis after irradiation for a misdiagnosed metastasis of post-gastroesophageal surgery [54]. We divided the other cases into two groups according to their prognosis, which was good in 26 (48.1%) patients and poor in 21 patients (38.9%). Of the 26 patients in the good prognosis group, 8 (14.8%) patients fully recovered and 18 (33.3%) were able to walk without a cane with minimal neurological sequelae. Of these, all but 1 (96.2%) had received antibiotics, 24 (92.3%) underwent surgery, and the duration from onset to first treatment (surgery or antibiotics) ranged from 0 to 60 (mean 15.2) days. Twenty-one patients in the bad prognosis group had severe residual or persistent neurological deficits, such as paraparesis and paraplegia. Of these, the treatment strategy was not described for three patients, 17 (81.0%) had received antibiotics, and 15 (71.4%) underwent surgery. The duration from onset to first treatment ranged from 2 to 120 (mean 25.3) days. There was no significant difference between the good and poor prognosis groups with regard to the time until treatment (P = 0.26).

Discussion

ISCA are rare, accounting for about 120 cases identified in the literature, including those mainly derived from the dermal sinus in pediatric cases, and adults with infectious diseases of other origins. We believe that these are different entities, because the pathology of spina bifida was more complex, with concomitant other lesions (such as lipomas), which potentially led to a poorer prognosis. One review reported that 68% of children who had ISCA when they were younger than 5 had a preexisting spinal cord defect, whereas only 15% of those presenting at age 5 years or older had a preexisting defect, which was significantly lower [26]. Our review also revealed that there was a peak of age distribution in infants, and all of them except one had a dermal sinus.

Murphy et al. [44] described that the chronological changes of MRI findings in the spinal cord reveal the same progression that has been documented in the brain. In the early stage of infectious myelitis, MRI shows high signals in T2WI with poorly defined enhancement on postcontrast T1WI. Approximately 1 week after the initiation of treatment, the lesion became less diffusely hyperintense on T2WI, with more clearly defined marginal enhancement on postcontrast T1WI. Our case showed no enhancement at first, a slightly homogeneous enhancement at 10 days after admission, and finally an obvious enhancement of the lesion at 1 month after admission without the infusion of any antibiotics. The radiological differential diagnosis in the early stage includes spinal infarction, intramedullary abscess, low grade astrocytoma, and demyelinating diseases, such as neuromyelitis optica, and multiple sclerosis.

Spinal cord ischemia may occur in association with arterial spasms in the pia or occlusion of other spinal arteries [25]. Mori et al. [57] noted the case of an elderly female with sudden onset of hemiparesis whose MRI showed acute infarction (DWI/high, T2WI/isointensity) who then developed multiple brain abscesses (Gd-DTPA/ring enhancement) at 1 month after admission. There was no evidence of infectious endocarditis (IE) on cardiac echo, however, since she demonstrated both fever and Osler’s node, they concluded that she had a bacterial embolism based on IE. Thus, cases of ‘stroke-like’ sudden onset brain abscess have been reported by some authors. On the other hand, an acute onset ISCA with apparent IE has so far only been reported by one author [23]. However, there has been no past description showing radiographical confirmation of an embolism of the spinal artery that resulted in an intramedullary abscess that was confirmed by MRI and then was treated via surgery. Our case had neither obvious findings of IE on cardiac echo nor systemic findings on close inspection. Therefore, it is difficult to disclose the embolic source. However, since his combined findings of MRI and 3D-CTA showed typical spinal infarction at first presentation and his subsequent histopathological findings revealed an abscess in the same lesion, a bacterial embolic cluster on the background of diabetes mellitus might have occluded the branch of the artery. Diffusion-weighted imaging and 3D-CTA or conventional angiography was not available in any of the other reports. The source and biogenesis of the infection were still unknown; however, this sudden onset clinical course and radiographical findings could indicate that the bacterial embolism predisposed the patient to ISCA in the presence of diabetes mellitus without IE.

We delayed the accurate treatment of ISCA because of the initial misdiagnosis and the patient’s severe paraplegia. It might have been helpful to perform a PCR analysis of his cerebrospinal fluid to detect lower levels of bacteria or bacteria that are difficult to culture. Generally, early drainage and the infusion of antibiotics result in a good prognosis [11]. Simon et al. [49] reported that the good prognosis group in children without neurological sequelae had significantly more surgical drainage procedures performed within 5 days after onset of symptoms as compared with the children with a poor prognosis who developed neurological sequelae. Our review also revealed that the good clinical course group had earlier treatment than the poor group, but the difference was not significant. Recently, Kurita et al. [34] noted that there was no significant difference in the frequency of neurological sequelae between surgically and non-surgically treated patients, although the number of cases in their study was small, and the abscesses were significantly more extensive in the surgically treated group. It is therefore recommended that at present, patients should be treated with an appropriate treatment strategy according to the patient’s clinical state.