Abstract

Background: Brainstem abscess is a rare condition with a variety of treatment approaches. In this paper, we report an unusual case of a brainstem abscess with a positive outcome in an immunocompetent patient who was treated with antibiotic therapy.

Case Description: A 22-year-old female presented with bilateral tetraparesis that was worse on the left hemibody, appendicular tremor, and left upper eyelid ptosis. Brain magnetic resonance imaging showed an abscess in the pons and midbrain due to possible nocardiosis. She was treated with dexamethasone, phenytoin, vancomycin, and meropenem for 8 weeks and trimethoprim-sulfamethoxazole for 6 weeks. The brain injury decreased, and the patient’s neurological status significantly improved.

Conclusion: Brainstem abscess may be treated conservatively, leading to improvement of the clinical condition and decreased lesion size on imaging.

Keywords: Antibiotic therapy, Brain abscess, Brainstem, Nocardia infections

INTRODUCTION

Brainstem abscess is an uncommon and severe condition.[ 2 , 7 , 15 ] The pons and midbrain are more commonly affected than other brain regions.[ 4 , 13 ] This condition is frequently associated with HIV and diabetes.[ 12 ] The most common causative microorganisms identified are Streptococcus spp., Staphylococcus spp., Listeria spp., Mycobacterium tuberculosis, Cytomegalovirus, Nocardia spp., Toxoplasma gondii, and Haemophilus influenzae type b (Hib).[ 12 , 16 , 25 ]

The clinical manifestations depend on the size and stage of the infection. Symptoms include fever, headache, vomiting (due to an increase in intracranial pressure), tetraparesis, and diplopia, with or without sepsis.[ 9 , 12 , 15 , 16 ] Treatment depends on the clinical presentation, the affected area, and the etiology of infection.[ 7 ]

CASE REPORT

A 22-year-old immunocompetent female was referred to Ophir Loyola Hospital presenting a 6-day history of tetraparesis, which was worst in the left hemibody, appendicular tremor, and left upper eyelid ptosis. On admission, the Glasgow coma scale (GCS) was 13, and she presented tetraparesis, which was worst in left hemibody, ataxia, hypoesthesia of the left side of the face and the left hemibody, left upper eyelid ptosis, right 6^th cranial nerve paresis, right peripheral facial paralysis, vertigo, and nausea. She could not walk and was using a nasogastric tube. No other alterations were observed. Magnetic resonance imaging (MRI) of the brain showed an encapsulated lesion with peripheral contrast in the brainstem (pons and midbrain), suggestive of abscess; after spectrometric study, the lesion measured 18.7 mm axially and 23.2 mm sagittally [ Figure 1 ]. In addition, chest computed tomography (CT) showed a right pulmonary intraparenchymal lesion suggestive of fungus, and biopsy of the collected pulmonary fragment demonstrated pulmonary tissue and bronchial mucosa without significant histological changes and with no granulomas or atypia. All bacterial cultures and serological tests were negative. The liquor was cloudy and purulent, with 15872 cells, 85 erythrocytes, 100% polymorphonuclear leukocytes, and total protein: 149 mg/dL. Therapy with vancomycin (2 g/day), meropenem (3 g/day), and dexamethasone was introduced. On the 4^th day of hospitalization, phenytoin was added to the therapeutic regimen. Every 15 days, MRI of the brain was performed to monitor evolution, and the images indicated a gradual decrease in the size of the abscess.

Figure 1:

(a) Magnetic resonance imaging showing contrast (gadolinium) lesions in the pons and midbrain in the sagittal orientation before antibiotic treatment. (b) Magnetic resonance imaging showing contrast (gadolinium) lesions in the pons and midbrain in the axial orientations before antibiotic treatment.

On the 42^nd day of hospitalization, the patient underwent a new chest CT that showed improvement in lung injury, and a presumptive diagnosis of nocardiosis was established by a pneumologist. Thus, trimethoprim-sulfamethoxazole (160 mg + 800 mg) was added to the antibiotic regimen.

On the 49^th day of hospitalization, after 8 weeks of vancomycin and meropenem and 2 weeks of trimethoprim- sulfamethoxazole, the patient was discharged. On physical examination, she was conscious and oriented, with GCS 15 and normal reflexes, presenting retardation of movement of the arm, strength graduated on 4/5 of the left arm, and hypoesthesia of the left hemibody. In addition, the patient presented with right 6^th cranial nerve paresis and right peripheral facial paralysis and did not walk. The image examination showed a lesion measuring 4.9 mm (axially) × 11 mm (sagittally) [ Figure 2 ]. The patient was prescribed outpatient treatment with ciprofloxacin (500 mg/day) for 2 weeks and prednisone (40 mg/day) for 2 months, and trimethoprim-sulfamethoxazole (160 mg + 800 mg) was maintained for more 30 days.

Figure 2:

(a) Magnetic resonance imaging showing contrast (gadolinium) lesions in the pons and midbrain in the sagittal orientation after antibiotic treatment. (b) Magnetic resonance imaging showing contrast (gadolinium) lesions in the pons and midbrain in the axial orientation after antibiotic treatment.

After 2 weeks, she returned to the neurosurgery ambulatory service; she was walking with support and had right 6^th cranial nerve paresis, right peripheral facial paralysis, diplopia, and GCS 15.

DISCUSSION

Here, we described the evolution of a case of a female patient who was treated at the neurosurgery service of a hospital for brainstem abscess after pulmonary nocardiosis. She was treated with antibiotic therapy, which resulted in improvement of neurological condition and neuroimaging, with a decrease in lesion size of 13.8 mm axially and 12.2 mm sagittally.

Drug therapy must be considered the first choice for brainstem abscesses, principally due to the difficulty of surgical access.[ 19 , 26 ]

We found 14 case reports describing antibiotic therapy for the treatment of brainstem abscess.[ 6 , 8 - 11 , 14 , 17 - 20 , 22 - 24 , 26 ] A summary is shown in [ Table 1 ]. The outcomes of those case reports support our outcome.

Table 1:

Clinical summary of patients with brainstem abscess treated with antibiotics only.

Empirical treatment with broad-spectrum antibiotics must be started immediately and maintained for 6 to 8 weeks or more, with sequential brain MRI to monitor the effectiveness of the treatment every 2 weeks.[ 2 , 9 , 12 , 13 , 15 ] The antibiotic used may be vancomycin or meropenem at high doses.[ 26 ] After diagnosis or presumed diagnosis of microorganisms that might cause symptoms, the drug must be reviewed.

Infections caused by nocardia may affect the skin, lung, and lymph nodes and may disseminate to the central nervous system (CNS).[ 5 , 21 ] Chest images may demonstrate a single or multiple nodules or a cavity.[ 3 ] The treatment recommended by experts is trimethoprim-sulfamethoxazole for 12 months in cases of brainstem abscess.[ 1 , 3 ]

In this case report and literature review, we showed that conservative treatment of brainstem abscess may lead to a positive outcome.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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