British Journal of Neurosurgery (1992) 6 , 249-254

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SHORT REPORT

Solitary brainstem abscess successfully treated by microsurgical aspiration ZAIN ALABEDEEN B. JAMJOOM

Division of Neurosurgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia

Abstract A case of pyogenic pontine abscess detected by computerized tomography scan in a 10-year-old boy is presented. While on broad-spectrum antimicrobial treatment, he deteriorated and developed new symptoms of respiratory distress. Microsurgical exposure of the abscess and aspiration of pus resulted in rapid improvement in his neurological state and radiological resolution of the lesion. The aim of this article is to emphasize the importance of prompt diagnosis and the role of surgical drainage of pus in the management of brainstem abscesses.

Key words: Pyogenic abscess, brainstem, antibiotic therapy, open drainage, cornputmized tomography.

Introduction

15 days earlier after a short episode of fever, headache and malaise. When the patient was Solitary pyogenic abscess of the brainstem is a admitted to a local hospital 5 days after onset rare occurrence, and until a decade ago, it was of his illness, he was apyrexial and had no signs frequently not recognized during life.',* This, of meningeal irritation. However, he had lefttogether with an old neurosurgical dogma that side abducens and facial palsies as well as a brainstem lesions were inoperable, contributed right hemiparesis and an extensor right plantar to the uniformly fatal outcome of this disease. reflex. During the following days these sympIn recent years, however, new neuroimaging toms deteriorated and difficulty of swallowing methods and improved neurosurgical techand speech ensued. A lumbar puncture reniques have resulted in a few case reports of vealed clear, colorless cerebrospinal fluid with s~rvival.~-'~ a normal cell count and protein content. The This article describes a case of solitary blood investigations were unremarkable apart pontine abscess with excellent recovery folfrom a slight increase of the erythrocyte lowing microsurgical exposure of the lesion sedimentation rate to 20 mm in the first hour. and drainage of the pus under direct vision. A cranial computerized tomography (CT) scan disclosed a low density area in the pons with Case report smooth ring enhancement after intravenous A 10-year-old boy was admitted to the Neuro- contrast injection (Fig. 1). A brainstem abscess surgical Department of the King Khalid was considered to be the most likely diagnosis, University Hospital because of diplopia, diffi- but a cystic tumor or a tuberculoma could not culty in swallowing and weakness of the left be excluded. The patient was already on a side of the body. These symptoms developed broad-spectrum antimirobial treatment con-

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Zain Alabedeen B. Jamjoom

FIG1. Preoperative computerized tomography scan before (a) and after (b) intravenous contrast injection showing a low density area in the pons with a thin ring enhancement. The fourth ventricle is markedly compressed.

sisting of mefoxin, ampicillin and amikacin, and the antituberculous drugs Rifampicin and Isoniazid at the time of transfer. On admission, the child was drowsy, apyrexial and had no meningeal signs. There were left-side abducens and facial palsies, and the gag reflex was reduced. His speech was markedly slow and dysarthric. There was a mild right hemiparesis. The tendon reflexes were increased in the lower limbs with bilaterally positive Babinski signs and ankle clonus. The systematic examination revealed no focus of active infection apart from a bad molar tooth. A tuberculin skin test was negative. As the patient’s condition had been stable for the last few days, conservative management was continued. The antiobiotic treatment was adjusted to chloramphenicol, penicillin G and metronidazole, and dexamethasone was added. Three days after admission, however, the patient became more drowsy and developed symptoms of respiratory distress with episodes of apnea. A repeat cranial C T scan showed no change in the size of the lesion and there was no hydrocephalus. The patient was taken to surgery and a small midline suboccipital craniotomy was performed. The cerebellum and cistema magna appeared unremarkable. Under the operating microscope, the fourth

ventricle was entered through a small incision in the midportion of the cerebellar vermis. There was a large swelling in the floor of the fourth ventricle, more on the left side, with a prominent vessel on its top (Fig. 2). The swelling was punctured with a 20 gauge cannula at the site of maximal fluctuation. There was no resistance on entering the abscess cavity, and approximately 6 ml of nonviscous yellow-greenish pus was aspirated. The swelling collapsed immediately. Microscopic examination revealed a few Grampositive cocci, but bacterial cultures were negative. The patient’s neurological state improved gradually. A C T scan 1 week after operation showed a tiny residual enhancement in the pons (Fig. 3). Because of slight bone marrow depression the chloramphenicol and metronidazole were discontinued 2 weeks after the start. The antibiotic therapy was continued postoperatively with intravenous penicillin and cefsulodin for 6 weeks. On discharge, the patient had an abducens palsy and a residual facial weakness. He returned to school 1 month later, and his performance has been excellent. The last follow-up examination 5 months after surgery revealed a mild squint without diplopia and elevated tendon reflexes of both legs, but

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Solitary brainstem abscess

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FIG. 4. Enhanced C T scan 5 months postoperatively c o n h s complete resolution of the abscess.

FIG. 2. A view of the floor of the fourth ventricle through a small incision in the vermis showing a large swelling with prominent vascularity.

no Babinski signs. A repeat CT scan confirmed total resolution of the abscess (Fig. 4).

FIG. 3. Enhanced CT scan 1 week after operation. There is a small residual ring structure in the pons. The fourth ventricle can be seen in normal position.

Discussion The rarity of solitary pyogenic abscess involving the brainstem is attested by the observation

made by Weickhardt and Davis: who found only four such cases among some 330,000 autopsy files of the US Armed Forces Institute of Pathology. Russell and Shawl1 estimated that solitary brainstem abscess constitutes less than 4% of all posterior fassa abscesses and probably less than 1% of all intracranial abscesses. According to Kashiwage et aL5 only 60 cases have been reported in the literature. Since then only a few case reports have been added.3.7&10 Most brainstem abscesses develop either by hematogenous metastasis from remote foci of infection, usually in the lungs, or by direct extension from an adjacent structure, mostly the ears, accounting for 34 and 29% of all reported cases, respectively.2 It is remarkable that the infective source remains unknown in 37% of brainstem abscesses, compared with 10-18% of brain abscesses in other locations. 14-1 Prior to the advent of the CT scan, early diagnosis and management of brainstem abscess constituted a formidable challenge. Patients with brainstem abscess most commonly present with cranial nerve deficits, especially facial weakness, dysphagia and abducens palsy, together with hemiparesis, headache and fever.2 However, classical brainstem syndromes that would allow a precise anatomical localization are rather infrequent. Moreover,

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Zain Alabedeen B. Jamjoom

the clinical picture is often complicated by co- quired, however, a ventriculo-atrial shunt for existing basal meningitis and dural thrombo- obstructive hydrocephalus." All three patients phlebitis. The clinical course has been rapidly made a good recovery with no or only a mild progressive deterioration ending uniformly in neurological deficit. death, usually within a week or two after the The other 11 survivors underwent evacuaonset of ~ y m p t o m s . ' * ~ JThis ~ J ~ led Hulme in tion of pus in addition to antimicrobial ther- l ~ evacuation of pus was 1961 to conclude that: "Hitherto the diagnosis a ~ y . ~ - ~ J O The has been made only at necropsy; it seems achieved by open surgery in seven patients and unlikely, however, that any effective surgical CT-guided stereotactic aspiration in the reintervention would be practicable even if the maining four,'J0 Two of the surgical cases condition were recognized during life .".I presented with obstructive hydrocephalus and Since that time, however, the prognosis has ventriculo-peritoneal (VP) shunts needed to improved, mainly due to the introduction of be inserted before the diagnosis of brainstem C T scan, more potent antibiotics and micro- abscess was e~tablished.~."In a third patient, a surgical and stereotactic techniques. VP shunt was performed for delayed commuThe first two cases of survival with brain- nicating hydrocephalus.6 stem abscess were reported in 1974.4J2Both The results of surgical management of patients underwent surgical evacuation of the brainstem abscess have been more variable. abscess with good functional recovery in one Excellent outcome with mild residual neurolocase, thus confirming that brainstem abscess is gical deficit was reported in all four cases who amenable to treatment if an early diagnosis can were treated by stereotactic aspiration7J0 and four of the seven patients who had open be made. With the cranial C T scan, identification and surgery (Refs 3, 5, 12, and present case). Of localization of intra-axial brainstem lesions the remaining three cases, the outcome was have been greatly facilitated. On CT, pyogenic poor only in one patient in whom drainage and ~ abscess in the brainstem has, as elsewhere in extirpation of the abscess was p ~ r s u e d .In the brain, a fairly characteristic appearance contrast, multiple aspirations did not seem to consisting of central hypodensity surrounded interfere with a good by a smooth ring enhancement after intraveThe question of the optimal treatment for nous contrast i n j e ~ t i o n . ~ It * ~has J ~ been esti- brainstem abscess remains open. The lack of mated that, when allied to the clinical data, C T an accurate bacteriological diagnosis is a source scan enables a confident and correct diagnosis of uncertainty regarding the outcome of conof abscess in 73% of cases.I5However, signs of servative management alone. Progressive neuinfection may be absent in half of the patients rological deterioration, as in our case, and with brain a b s c e ~ s , ~ ~and J ~ Jthe ~ white cell enlargement of abscesses despite antibiotic count in cerebrospinal fluid (CSF) may be therapy have also been observed by several normal in up to 40% of the c a s e ~ . ~The ~ ~ risk ~ O authors in other intracranial location^.^^-^^ We of lumbar puncture in brain abscess victims therefore suggest that a trial of antimicrobial should also not be underestimated.20,21Based treatment in brainstem abscess may be justifiaon the C T scan alone differentiation between ble as long as the patient's clinical condition is an abscess and a glioma of the brainstem may stable and close neurological observation with prove very difficult if not impo~sible.~ C T monitoring is available. However, surgical T o date, 14 patients, including the present evacuation of the pus should be carried out case, have survived brainstem absces~es.~-'~without delay at the first sign of clinical Only in one case was the lesion located in the deterioration or C T evidence of enlargement. Although C T stereotaxy and ultrasoundmedulla oblongata: the remaining abscesses involved the pons and midbrain. Three pa- guided needle aspiration seem to be the less t i e n t ~ * ,were ~ * ~ managed ~ conservatively with invasive procedures, open operation and aspiantimicrobial drugs alone, one of which re- ration of pus under direct vision is not

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Solitary brainstem abscess

necessarily associated with a higher morbidity if the microsurgical technique is applied through a small, carefully planned craniotomy. An open microsurgical approach offers the following advantages: (1) the abscess is penetrated at the point of highest fluctuation ensuring the least possible damage to the brainstem; and (2) there is direct visual control of the collapse of the abscess indicating complete evacuation of the pus. Address for correspondence: Dr Z. B. Jamjoom, Division of Neurosurgery, College of Medicine, King Saud University, PO Box 2925, Riyadh 1 1461, Saudi Arabia.

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10 Rossitch E Jr, Alexander E, Schiff SJ, Bullard DE. The use of computed tomography-guided stereotactic techniques in the treatment of brain stem abscesses. Clin Neurol Neurosurg 1988; 90365-8. 11 Russell JA, Shaw MDM. Chronic abscess of the brainstem. J Neurol Neurosurg Psychiatry 1977; 40:625-9. 12 VanGilder JC, Allen WE, Lesser RA. Pontine abscess: survival following surgical drainage. J Neurosurg 1974; 40:386-90. 13 Vaquero J, Cabezudo JM, Leunda G. Nonsurgical resolution of a brain-stem abscess. J Neurosurg 1980; 53:726-7. 14 McClelland CJ, Craig BF, Alan Crockard H. Brain abscesses in Northern Ireland a 30 year community review. J Neurol Neurosurg Psychiat 1987;41:1043-7. 15 Miller ES, Dias PS, Uttley D. CT scanning in the management of intracranial abscess: a review of 100 cases. Br J Neurosurg 1988;2:439-46. 16 Rosenblum ML, Hoff JT, Norman D, Weinstein PR, Pitts L. Decreased mortality from brain abscesses since advent of computerized tomography. J Neurosurg 1978;49:658-68. 17 Yang S. Brain abscess: a review of 400 cases. J Neurosurg 1981: 55:794-9. 18 Murphy MJ, Bienton DW, Aschenbrener CA, Van Gilder JC. Locked-in syndrome caused by a solitary pontine abscess. J Neurol Neurosurg Psychiatry 1979; 421062-5. 19 Robert CM Jr, Stem WE, Brown WJ,Greenfield MA, Bentson JR. With special note upon the employment of thorium dioxide. Surg Neurol 1975; 3:153-60. 20 Morgan H, Wood MW, Murphey F. Experience with 88 consecutive cases of brain abscess. J Neurosurg 1973;38~698-703. 21 Carey ME, Chou SN, French LA. Experience with brain abscess. J Neurosurg 1972; 36:l-9. 22 Black P, Graybill JR, Charache P. Penetration of brain abscess by systematically administered antibiotics. J Neurosurg 1973;38705-9. 23 Dyste GN, Hitchon PW, Menezes AH, VanGilder JC, Green GM. Stereotaxic surgery in the treatment of multiple brain abscesses.J Neurosurg 1988;69:188-98. 24 Rosenblum ML, Hoff JT, Norman D, Edwards MS, Berg BO. Nonoperative treatment of brain abscesses in selected high-risk patients. J Neurosurg 1980; 52217-25.

Solitary brainstem abscess successfully treated by microsurgical aspiration.

A case of pyogenic pontine abscess detected by computerized tomography scan in a 10-year-old boy is presented. While on broad-spectrum antimicrobial t...
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