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Collections under which this article appears: Other Infectious Diseases Other Neurology Radiological diagnosis Other Pediatrics Neurosurgery

BMJ 2001;323:501-503 ( 1 September )

Clinical review

Lesson of the week

Recurrent bacterial meningitis: the need for sensitive imaging

Sensitive imaging is needed in children with recurrent bacterial meningitis to detect cranial anatomical defects

Enitan D Carrol, specialist registrar ^a, Amir H Latif, specialist registrar ^b, Siraj A Misbah, consultant immunologist ^b, Terence J Flood, consultant ^a, Mario Abinun, consultant ^a, Julia E Clark, consultant ^a, Robert E Pugh, consultant ^c, Andrew J Cant, consultant ^a. 

^a Department of Paediatric Infectious Diseases and Immunology, Newcastle General Hospital, Newcastle upon Tyne NE4 6BE, ^b Department of Clinical Biochemistry and Immunology, Leeds General Infirmary, Leeds LS1 3EX, ^c Department of Paediatrics, Leighton Hospital, Crewe, Cheshire CW1 4QJ

Correspondence to: E D Carrol, Institute of Child Health, Royal Liverpool Children's Hospital, Alder Hey, Liverpool L12 2AP edcarrol@liv.ac.uk

Recurrent bacterial meningitis in childhood is unusual and should prompt a search for immune deficiency. A variety of immunological defects may predispose to recurrent meningitis, including antibody or complement deficiency and hyposplenism. It is equally important to consider cranial anatomical defects such as skull fractures, particularly those affecting the base of the brain and extending to the sinuses and petrous pyramids.¹ Craniospinal dermal sinuses, neurenteric or dermoid cysts, occult intranasal encephaloceles, or transethmoidmeningoceles are also potential portals of entry for pathogens into the subarachnoid space. ^{2 3}

Encephaloceles may occur anywhere in the midline and arise from failure of closure of the embryonic neuraxis, creating a defect in the dura and cranium with or without protrusion of brain and meningeal tissue. Basal ethmoidal encephaloceles may extend into the nose and be mistaken for nasal polyps² or into ethmoid sinuses or orbits.

Sometimes there may be a delay in establishing a diagnosis owing to a failure to consider anatomical defects or the use of insufficiently sensitive imaging procedures. We describe two children with recurrent bacterial meningitis due to cranial anatomical defects in whom diagnosis was delayed.

Case reports

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Case 1
A 9 year old boy presented with pneumococcal meningitis. Although he required ventilation, he responded rapidly to intravenous cefotaxime and penicillin. A year later he presented with a second attack, but no organism was identified in either cerebrospinal fluid or blood. A detailed immunological investigation was unremarkable (table) except for a moderately low concentration of pneumococcal antibodies (12 U/l; median 34, interquartile range 20-49). Because this was a second episode of meningitis and because he responded modestly to test immunisation with pneumovax (post-immunisation antibody level 34 U/ml), antibiotic prophylaxis was started. Abdominal ultrasonography showed a normal sized spleen, and there was no evidence of Howell-Jolly bodies in his peripheral blood.

Fifteen months before his first episode of meningitis, the patient had injured his head in a road traffic incident. A cranial anatomical defect was considered at this stage, but his original skull radiographs and cranial tomograms showed no abnormality. In the absence of a history of cerebrospinal fluid rhinorrhoea, more detailed imaging was not considered useful. He continued to remain well at follow up. Penicillin prophylaxis was stopped 18 months after his second episode of meningitis.

A third episode of meningitis occurred when he was 12, six weeks after stopping penicillin prophylaxis. Unencapsulated Haemophilus influenzae was cultured from his cerebrospinal fluid. A coronal thin section tomogram of the skull showed a small linear bony defect at the right ethmoid plate (fig 1). This was repaired through a right frontal craniotomy. He has since remained well without antibiotic prophylaxis.

Case 2
A 4 month old boy was admitted with irritability and poor feeding. He was febrile, poorly perfused, and had a full anterior fontanelle. After fluid resuscitation and a septic screen, he was treated with intravenous cefotaxime. Culture of his cerebrospinal fluid grew Streptococcus pneumoniae, and blood cultures were sterile. He had made a complete recovery at follow up six weeks later, and hearing assessment was normal.

Two months later he was readmitted with lethargy, poor feeding, fever, and rapid breathing. Intravenous cefotaxime was started. Cultures of blood and cerebrospinal fluid again grew S pneumoniae. Ultrasonography showed a normal spleen.

He was treated for 18 days and discharged home with penicillin prophylaxis. The table lists the immunological investigations performed before discharge. Two weeks later, lymphocyte subset analysis and lymphocyte proliferation responses gave normal results, with normal immunoglobulin and subclass levels. A cranial tomogram showed a bony defect in the crista galli, lying anteriorly between the upper nasal cavity and the base of the frontal area (fig 2). This was repaired endoscopically. At review six months later he was doing well and his neurological development was normal.

Discussion

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Cranial antomical anomalies should be investigated in patients with recurrent bacterial meningitis and a thorough immunological investigation performed to identify antibody or complement deficiencies and hyposplenism. Prophylactic penicillin and pneumococcal vaccination may fail to prevent recurrent meningitis in patients with a bony defect of the skull or spine.

Deficiency of the IgG₂ subclass is not rare in young children and often resolves spontaneously. It is not commonly associated with recurrent bacterial meningitis, although a case of recurrent pneumococcal meningitis in a 3 year old boy with low concentrations of IgG₂ specific pneumococcal antibodies has been described.⁴ Furthermore, children with humoral immunodeficiencies often have infections in other sites such as ears, lung, and skin. The presence of a minor antibody deficiency should not preclude the search for a cranial defect.

In case 1 lack of cerebrospinal fluid rhinorrhoea and apparently normal results on imaging led to a delay in diagnosis, although the history of head injury was a clue to the diagnosis. In case 2 there was no clinical evidence of leaking cerebrospinal fluid. A minor antibody deficiency could have confused matters, although a defect was still searched for. Mollaret's meningitis (recurrent aseptic meningitis associated with herpes simplex virus) was not considered in these cases because of its viral aetiology and presentation as recurrent episodes of apparent aseptic meningitis.⁵ We are unaware of Mollaret's meningitis in children with cranial anatomical defects.

Thin section cranial computed tomography offers a relatively easy, reliable, and non-invasive method of delineating anatomical defects in recurrent meningitis.⁶ S pneumoniae is usually implicated, and treatment includes surgical repair of the underlying defect. Axial cranial computed tomography may fail to identify defects in the basal ethmoidal area and cribiform plate and so give false reassurances, whereas coronal thin sections show detailed anatomy of the anterior cranial fossa and identify most skull defects. Prompt recognition and repair of the defect, with dural closure, prevents further episodes of meningitis and ensures a good outcome for neurological development.

Acknowledgments

   Contributors: EDC, AHL, SAM, TJF, MA, JEC, REP, and AJC jointly wrote the paper. EDC and AHL coordinated the collection of clinical and laboratory data on the patients. SAM and AJC will act as guarantors for the paper.

Footnotes

Funding: None.

Competing interests: None declared.

References

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1.	Sponsel C, Park JW. Recurrent pneumococcal meningitis. Search for occult skull fracture. Postgrad Med 1994; 95: 109-110[Medline], 197.
2.	Choudhury AR, Taylor JC. Primary intranasal encephalocele. Report of four cases. J Neurosurg 1982; 57: 552-555[Medline].
3.	Castano-Duque CH, Monfort L, Muntane A, de Miquel MA, Pons-Irazazabal LC, Lopez-Moreno JL. Trans-ethmoid meningocele diagnoses in adults. Description of one case. Rev Neurol 1997; 25: 230-233[Medline].
4.	Ohga S, Okada K, Asahi T, Ueda K, Sakiyama Y, Matsumoto S. Recurrent pneumococcal meningitis in a patient with transient IgG subclass deficiency. Acta Paediatr Jpn 1995; 37: 196-200[Medline].
5.	Tang YW, Cleavinger PJ, Haijing L, Mitchell PS, Smith TF, Persing DH. Analysis of candidate-host immunogenetic determinants in herpes simplex virus-associated Mollaret's meningitis. Clin Infect Dis 2000; 30: 176-178[Medline].
6.	Steele RW, McConnell JR, Jacobs RF, Mawk JR. Recurrent bacterial meningitis: coronal thin-section cranial computed tomography to delineate anatomic defects. Pediatrics 1985; 76: 950-953[Abstract].

(Accepted 8 March 2001)

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