Delayed intramedullary abscess in operated case of spinal lipoma.

Intramedullary abscess is a rare condition with high rate of mortality and morbidity. We are presenting a case of delayed intramedullary abscess in an operated case of spinal lipoma, after 2 years of primary surgery. To best of our knowledge this only second case of intramedullary abscess in a case of spinal lipoma without dermal sinus.

Introduction

Intramedullary spinal cord abscess is a rare condition. Only case reports are available in literature. Early identification and diagnosis are very important as this condition has a high rate of morbidity and mortality.[1] In preantibiotic era, hematogenous spread was most common cause, but now a day, most of patients are reported with dermal sinus, especially in pediatric population.[12] We are reporting a case of delayed intramedullary abscess in an operated case of spinal lipoma in a 3-year-old child. We believe to our knowledge, this only second case of intramedullary abscess associated with spinal lipoma without dermal sinus.

Case Report

A 3-year-old male child had been born at term after a normal delivery. At the age of 1 year, he underwent surgery for lumbosacral lipomeningocele. At that time, he presented with congenital swelling in the lumbosacral region without any neurological deficit. On examination, there was 3 cm × 3 cm size eccentric swelling (more on the right side) present in the lumbosacral region with intact overlying skin without any dermal sinus. On magnetic resonance imaging (MRI) of the lumbar spine (LS), there was evidence of dorsal spinal and subcutaneous lipoma with L2–L3 vertebral posterior arch defect. The Patient underwent excision of the spinal and subcutaneous lipoma [Figure 1a–c]. Postoperative period was uneventful, and the patient was discharged on postoperative day 7 without any neurological deficit.

Figure 1

(a) T1 weighted MRI sagittal magnetic resonance imaging showing posterior arch defect at L2 and L3 level with dorsal spinal and subcutaneous lipoma. (b and c) T1-W1 and T2-W2 magnetic resonance imaging axial cuts, respectively, showing posterior arch defect in vertebra with dorsal spinal lipoma, which is in continuity with subcutaneous lipoma

After approximately 2 years of the primary surgery patient now presented with history of fever for last 1 month and lower limb weakness and seizures for last 15 days. The patient was asymptomatic in intervening period. On admission, the patient was conscious but drowsy; there was Grade 0 power in both lower limbs with the presence of neck rigidity. MRI of the LS was suggestive of peripheral contrast enhancing lesion extending from D10 to L5 with diffuse expansion of cord suggestive of intramedullary abscess [Figure 2a and b] With impression of intramedullary abscess, the patient was taken for surgery; exploration of previous incision with D12 and L1 laminectomy was done. Limited midline myelotomy was done with drainage of pus, and canal was irrigated with saline.

Figure 2

(a) Follow-up magnetic resonance imaging at 3 years, T2-W1 sagittal cuts showing diffuse expansion of cord at thoracolumbar region. (b) Contrast magnetic resonance imaging sagittal cuts showing peripheral contrast enhancing loculated intramedullary lesions

Postoperatively, the patient was given broad-spectrum intravenous antibiotics for 2 weeks followed by 6 weeks of oral antibiotics. Culture sensitivity of pus was sterile. The patient was discharged on postoperative day 10 with improvement in consciousness of the patient with slight improvement in power of the right lower limbs (up to Grade 1) and no improvement in the left lower limb. At 6 weeks follow-up, the patient was doing well with no significant improvement in power in comparison to immediate postoperative period.

Discussion

Intramedullary spinal cord abscess is a rare neurosurgical condition. Byrne et al. in their review found mean age of presentation was 36.4 years with M:F ratio of 5:2. They also found that there was bimodal age distribution in these patients, with predominance of patients age younger than 25 years and older than 50.[3] Simon et al. in their review of pediatric patients found slight male predominance with median age of 36 months.[4] According to Morandi et al., 25% of spinal cord abscesses have occurred in children <5 years old, and the thoracic region is the most frequently involved.[5] Our patients presented at 3 years of age with intramedullary abscess; he was initially operated for spinal lipoma at the age of 1 year.

The clinical features depend on location of abscess. New onset neurological deficit is most common presenting feature with local pain and fever. Depending on duration of presenting features, these cases divided into three groups, acute (<1 week), subacute (1–6 weeks), and chronic (>6 weeks).[67] The patient presenting with acute symptoms usually presents with sudden onset neurological deficits, fever, and leukocytosis, and on other hand, chronic patient presents with gradually progressive ascending paraparesis with or without fever and leukocytosis. The most common complaint reported at the time of admission usually are motor impairment (80%) followed by sensory loss (43%), sphincter disturbances (36%), fever (23%), and dorsal pain (10%).[7] Our patient presented in subacute phase with history of fever for 1 month and lower limb weakness for 15 days. Menezes et al. in their review observed poor outcome in patients who presented with acute symptoms with high mortality rate.[6]

Most common cause of intramedullary abscess in adult is hematogenous, and in children, most commonly this condition is secondary to spinal dysraphism, of which dermal sinus is most common.[127] Major causes of intramedullary abscess are hematogenous (58%), contiguous spread (28%), and unknown origin.[2] Before use of broad-spectrum antibiotics, intramedullary abscess was more common with hematogenous spread from distant primary infective site such as lung. However, with use of better antibiotic, this condition is now more reported with dermal sinus or other spinal dysraphism. Till now, 18 cases of intramedullary abscess secondary to dermal sinus have reported in literature, and to our best knowledge, only one case reported in operated case of spinal lipoma.[57891011] Both our case and previously reported case had delayed presentation after surgery for spinal lipoma.

In literature, the thoracolumbar region of spinal cord found to be most common region involved in abscess formation due to relatively less blood supply to this junctional zone.[23710] In various authors observed that in hematogenous spread abscess starts in the thoracic region and in cases of spinal dysraphism abscess start in the lumbar region. As abscess enlarges, it spreads along fiber tract and involves adjacent regions. The most common organism in cases of spinal abscess is staphylococci and streptococci.[1] Few cases of intramedullary abscess with mycobacterium have been reported in literature.[9]

MRI with contrast is gold standard investigation before surgical planning. Whole spine screening should be done as abscess may extend along fiber tract, may involve more than one region, or may become holocord. In MRI, these lesions characteristically show cystic cavitation with peripheral contrast enhancement. Localized abscess with variable enhancement may resemble intramedullary tumor. MRI enables to identify the extent of the vertebral column involvement, the presence of epidural and subdural infections or concomitant dermal sinus, epidermoid, or intramedullary tumors, and the extent of the spinal cord abnormality.

In preantibiotic era, prognosis of this condition was poor with high mortality rate. The mortality rate was drastically reduced from 10 to 20% due to improvement in antimicrobial agents.[10] Despite a marked decline in mortality rate, the neurological outcome remains disappointing. A complete neurological recovery is achieved in only 20% of patients with intramedullary abscess.[10] Younger patients found to have better outcome, and poor outcome was likely to occur after acute spinal cord abscess.

If left untreated or delay in treatment intramedullary abscess can involve whole spinal cord or even brain, which leads poor prognosis of the patient. On diagnosis of intramedullary abscess, starting of suitable antibiotic and prompt surgical evacuation of abscess by laminectomy and limited myelotomy is considered treatment of choice. In cases of extensive abscess involving long segment of spinal cord limited laminectomy and myelotomy with irrigation, to drain abscess can achieve effective results. Any concomitant spinal abnormality or dysraphism should also be treated during surgery.[12]

Our case, to the best of our knowledge, is only second case described in literature that developed intramedullary abscess after the treatment of spinal lipoma without dermal sinus. This 3-year-old patient who discharge uneventfully after the first surgery, presented with new neurological deficit, fever, and seizure after 22 months of primary surgery. The patient was asymptomatic in intervening period with history any febrile illness. Hardwidge et al. report another case of intramedullary abscess in an operated case of spinal lipoma, in their report patient too presented with delayed (after 16 years of primary surgery) neurological deficits.[5] Pathophysiology of developed of delayed intramedullary abscess not clearly defined like in cases of dermal sinus where contiguous spread of infection can lead to abscess formation. As more cases of intramedullary abscess being reported with dermal sinus, serious thought should be given to excise these lesions prophylactically whenever diagnosed.

Conclusion

Intramedullary spinal abscess is rare condition, and it should be suspected in any patient with dermal sinus or other dysraphism presented with rapid progression of neurological deficits with history of febrile illness. Whole spine MRI screening is necessary before planning treatment. Early surgical evacuation and broad-spectrum antibiotic should be started early and are treatment of choice. Despite adequate treatment rate of neurological deficits is high. Predisposing conditions such as dermal sinus should be treated in every child when diagnosed to reduce risk of this disabling condition.

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Conflicts of interest

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