Spinal epidural abscess in adolescence: case report

Spinal epidural abscess (SEA) is a rare infectious emergency and capable of causing severe neurological deficits, especially in childhood. The mortality rate in adults varies from 5 to 23%, but in children the rates are even lower. This report aims to contribute to the scientific field by discussing a case of SEA in pediatrics. It is a teenager, 17 years old, presenting fever, low back pain and sebaceous cyst infected on her back for three days. She reports a history of drainage two days ago and a cesarean section with spinal anesthesia a year ago. Magnetic resonance imaging (MRI) of the lumbar showed posterior L1-L4 epidural collection. Epidural abscess drainage surgery was performed, with L3-L4 laminectomy, and positive culture for Methicillin-resistant Staphylococcus aureus (MRSA), sensitive to Vancomycin and Rifampicin. She was discharged after 21 days of intravenous Vancomycin, with a prescription for oral Rifampicin for three weeks. Previous skin infection is considered a classic precedent of SEA, suggesting that the patients condition was preceded by furunculosis. The microorganism responsible for 86% of SEA cases in childhood is Staphylococcus aureus . Back pain after spinal anesthesia, fever, skin infection and possible condition of immunosuppression indicated investigation for SEA. Gadolinium-contrast MRI corresponds to the gold standard diagnostic approach for SEA. The suspicion of the disease in pediatrics is extremely important in front of fever, back pain and spinal sensitivity, and should receive due attention and investigation before an indicative clinic.


INTRODUCTION
Spinal epidural abscess (ESA) is considered an infrequent, potentially serious infectious emergency, capable of causing severe neurological deficits, resulting from compression of the abscess in the spinal cord or nerve roots, which can lead to ischemia, especially if there is a delay in the diagnosis, and an early clinical and surgical approach is essential for a better prognosis [1][2][3] .
It is characterized by a purulent collection, located between the dura mater and the vertebral canal, which may manifest as a sebaceous cyst and extend along the entire length of the spinal cord 4,5 .
Its incidence varies, in the literature, from one case per 100,000 individuals to 0.2 to three cases in 10,000 hospital admissions, consensually being considered a rare condition, especially in childhood 1,4,6,7 . The mortality rate in adults ranges from 5 to 23%, but in children, morbidity and mortality is lower 6 .
The present report aims to contribute to the scientific scope with the discussion of a case of ESA in pediatrics, improving data already found in the literature.

CASE DESCRIPTION
Adolescent, female, 17 years old, hospitalized complaining of fever (38.5ºC), headache, low back pain radiating to the abdomen and infected sebaceous cyst in the upper third of the posterior part of the thorax, which had started three days ago. He informs that he performed the cyst drainage procedure manually, at home, five days ago and, in the emergency room, 48 hours before admission, with a prescription of oral Cefadroxil (500mg every 12hrs). During hospitalization, he reported onset of intermittent local low back pain two months after cesarean section, which occurred a year ago, with spinal anesthesia.
On physical examination, he weighed 115 kg, BMI 39.7 (above P97), facial pain, tachypnea, with diffuse lumbar and abdominal pain on palpation, more pronounced in the right hypochondrium.
On the fifth day of hospitalization, she had a blood count with Hb 11.9g/dL; Ht 35%; leukocytes (12,000/mm 3 , 4% rods, 70% segmented), CRP 109mg/dL, ESR 101mm. The headache and abdominal pain improved, remaining afebrile; but with persistence of low back pain. Therefore, magnetic resonance imaging of the lumbar spine was requested with a posterior epidural collection from L1 to L4, lateralized to the left and insinuating itself into the ipsilateral neural foramina of L2-L3 and L3-L4; presenting intense peripheral/dural impregnation by the contrast medium (epiputitis), compressing and deforming the dural sac and roots of the cauda equina, measuring approximately 10x1.5cm in the longitudinal and anteroposterior axes.
Evaluated by the neurosurgeon, on the sixth day of hospitalization, who observed grade 4 paraparesis and neurogenic bladder, in addition to limitation and pain on flexion and extension of the spine on physical examination. Therefore, drainage surgery of the epidural abscess was performed with laminectomy of L3 and L4 on the same date. The secretion culture was positive for Methicillin-resistant Staphylococcus aureus (MRSA), sensitive to Vancomycin and Rifampicin.
Discharge after 21 days of intravenous Vancomycin (500mg every 6 hours), with prescription of oral Rifampicin (300mg every 12 hours) for three weeks.
Three months after the procedure, she had mild low back pain, with complete resolution of the epidural collection ( Figure 1).

DISCUSSION
Among the predisposing factors for the development of SEA are spinal trauma, spinal anesthesia or epidural block, previous neurosurgery, congenital spinal anomalies, previous skin infection/osteomyelitis, cancer, abusive use of intravenous drugs, history of acupuncture, diabetes mellitus, chronic renal failure , recurrent urinary tract infection, alcoholism and immunodeficiency 2,5,6,8,9 . Such factors were found in only 35 to 67% of pediatric patients with ESA 3 .
Regional anesthesia is becoming more common in children. One should evaluate the advent of possible complications, such as bacterial infections due to catheter contamination, which correspond to 16 to 25% of cases of spinal anesthesia, and other more serious and less common ones, such as meningitis, epidural abscess and sepsis10. Wiegele et al. (2018) 10 also report that subcutaneous insertion of the catheter or at a higher point, between L5-S1, may lead to a lower risk for these infections.
It is rare for ESA to appear in immunocompetent children who do not have risk factors 8 , which suggests that the patient had an immunodeficiency condition due to her obesity condition, which, together with her history of spinal cord anesthesia, favored the development of the ESA.
Previous skin infection is considered a classic preceding presentation of ESA, despite occurring in only 15% of cases 8 . The most common route of dissemination in children is hematogenous, followed by contiguity 2 . Therefore, it is suggested that the patient's ESA condition was preceded by spinal column furunculosis.
The microorganism responsible for 50-90% of cases of ESA is Staphylococcus aureus, both methicillin-sensitive (MSSA) and resistant (MRSA) strains 9 , being the most common etiological agent in pediatric infections, in 86% of cases. cases6. Recent studies have observed an increase in MRSA etiologies in children without risk factors 2,5 . Consistent with reports in the literature, MRSA was found in the secretion culture of the patient in question.
It is recommended that Vancomycin be the antibiotic of choice for the treatment of ESA, with a duration of 4 to 6 weeks, as was done in the patient. Early treatment is essential for better control of the infection 2,4 .
The classic presentation of SEA consists of the triad of back pain, fever and neurological deficit. However, only a minority of patients will manifest it, especially the pediatric age group, which usually does not have risk factors or a clear clinical picture 2,3 .
Severe pain located in the back is the most frequent and often underestimated symptom, and a more accurate investigation should always be carried out, with laboratory and radiological exams 1,4 . The high incidence of back pain in the population, associated with the rare occurrence of SEA, makes its early diagnosis difficult 4 . Furthermore, ESA should also be suspected in febrile children with abdominal or hip pain, after ruling out other etiologies, as there are reports of acute abdominal pain disguising a possible ESA 4,11 . Post-spinal anesthesia back pain and fever, together with subsequent skin infection and possible immunosuppression condition, indicated investigation for ESA.
The neurological symptoms of AEE are divided into four stages: (1) low back pain at the level of the affected spinal region, fever and local tenderness; (2) radicular pain, neck stiffness and altered reflexes; (3) motor weakness, sensory deficit and bladder and bowel dysfunction and (4) paralysis, with possible permanent sequelae, rarely reversible after surgical approach 4,6,9 . Our patient was in stage 3, due to the presence of neurogenic bladder, grade 4 paraparesis and persistence of back pain even with flexion/extension of the spine, characterizing a picture of bladder dysfunction, motor weakness and spinal stenosis due to an inflammatory process.
The ESA has a rapid progression, with evolution from radicular symptoms to neuromuscular weakness in around three to four days and from weakness to paraplegia in 24 hours. In children, the diagnosis is often delayed until neurological signs manifest, 75% of the time. It is important to consider the diagnosis of SEA in patients who have back pain, fever and spinal cord sensitivity, with or without an altered neurological examination, in order to prevent neurological sequelae, paralysis, sepsis and death 4,8 .
The diagnosis is made by clinical suspicion, accompanied by an increase in ESR and CRP and neurological imaging showing the abscess 2 , with all these elements present in the case.
Magnetic resonance imaging (MRI) with gadolinium contrast is the gold standard diagnostic approach for SEA, with 91% sensitivity and specificity, in addition to being relevant for follow-up 1,3,6,12 . Intravenous contrast-enhanced tomography has very low sensitivity for the detection of SEA and should only be requested if MRI is not available3. The MRI requested for the patient was essential for diagnostic confirmation.
Treatment is traditionally based on surgical decompression and drainage, plus antibiotic therapy 1,3,6 . Recent reports demonstrate that the use of antibiotics alone can produce satisfactory regression of the condition 2 . Sugawara et al. (2019) 3 recommend only clinical treatment, initially, in pediatric patients who do not have risk factors and who have been diagnosed before the onset of neurological symptoms, inferring that, for the patient, both surgical and clinical approaches were necessary.
Children have better resolution of the ESA, compared to adults, since, for them, the condition is aggravated by risk factors. In a study with a case series of 34 children with ESA, none evolved to death and only 18% had neurological sequelae 11 , a fact that is in line with the good resolution of the patient's condition.

CONCLUSION
ESA is uncommon in pediatrics and requires early diagnosis and treatment in order to provide the patient with a better prognosis. The suspicion of SAA in pediatrics is extremely important in the face of fever, back pain and radicular symptoms. Being the gold standard method, MRI has the ability to reveal the extent of the lesion and confirms the clinical suspicion. The initiation of antibiotic therapy, complementary to surgical drainage, are safe and efficient approaches for the prevention of neurological sequelae. Therefore, the AEE should receive due attention and investigation in the face of indicative clinical signs.