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African Journal of Neurological Sciences
Pan African Association of Neurological Sciences
ISSN: 1015-8618
Vol. 20, Num. 1, 2001, pp. 14-16
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African Journal of Neurological Sciences, Vol. 20, No. 1, 2001, pp. 14-16
LUMBAR PUNCTURE IN BRAIN ABSCESS OR SUBDURAL EMPYEMA: NOT
AN INNOCUOUS PROCEDURE.
Syed S. NADVI, Narendra NATHOO, James R. van DELLEN
Department of Neurosurgery, Nelson R. Mandela School of Medicine, University
of Natal and Wentworth Hospital, Durban, South Africa.
Correspondence to: Dr. N. Nathoo Department of NeurosurgeryWentworth
Hospital, P/Bag JACOBS 4026 South Africa, E-mail: nathoo@wwh.und.ac.za
Code Number: ns01004
ABSTRACT
Background: Many authors have strongly cautioned against the
performance of lumbar puncture in patients with suspected or likely infective
intracranial mass lesions due to the dubious value of the CSF analysis so
obtained, and due to the inherent danger of clinical deterioration precipitated
by a pressure cone. Objective: To assess the role of lumbar
puncture (LP) in aiding diagnosis and influencing outcome in patients with
intracranial brain abscess or subdural empyema. Methods: The records
of patients admitted with space occupying intracranial infective mass lesions
(brain abscess and subdural empyema) to the neurosurgical unit at Wentworth
Hospital, Durban, over a 15 year period, were retrospectively reviewed. Of the
1411 patients admitted with intracranial suppurative disorders (brain abscess =
712) and subdural empyemas (699), 422 (29.9%) underwent diagnostic LP prior to
referral to our unit. The records of these 422 patients were studied in more
detail with regard to the result of the LP and it's effect on patient
outcome. Results of the LP were analysed in order to determine the contribution
of LP to the diagnosis. The impact of the LP on patient outcome was
assessed. Results: The cerebrospinal fluid (CSF) examination was
normal in 66 (15.6%) and equivocal in 283 (67.1%). Bacterial meningitis was
diagnosed in 73 (17.3%) and organisms cultured in 42 (10.0%). As suspected, 272
patients (64.5%) underwent clinical deterioration following lumbar puncture. In
81 patients (19.2%) the clinical deterioration was directly attributable to the
lumbar puncture and 20 patients (4.7%) died as a result of
LP. Conclusion: In patients with brain abscess or subdural empyema,
LP contributes little to diagnosis while significantly increasing the risk of
clinical deterioration and even death. Patients suspected of harbouring
infective intracranial mass lesions should undergo computed tomography (CT)
prior to LP or should be placed onto empiric antibiotic therapy until a CT scan
can be obtained. Keywords: cerebrospinal fluid, intracranial brain
abscess, lumbar puncture, subdural empyema,
RÉSUMÉ
Introduction: plusieurs auteurs ont insisté
sur le caractère inutile et dangereux de pratiquer une ponction lombaire
(PL) lorsque l'on suspecte un processus expansif intracrânien d'origine
infecteuse à cause du risque d'engagement.. Objectif:
évaluer le rôle de la PL au plan diagnostique et étudier son
influence sur l'évolution des abcès et empyèmes sous -
duraux intra-crâniens. Méthodes: les dossiers des
patients hospitalisés pour des lésions infectieuses
intracrâniennes pendant 15 ans et admis dans le département de
neurochirurgie du Wentworth Hospital, Durban ont été
étudiés rétrospectivement. Sur les 1411 patients
hospitalisés pour suppuration intracrânienne (abrès
cérébraux = 712) et empyèmes sous - duraux (699), 422
(29,9%) ont subi une PL avant d'être admis dans notre service. Les
dossiers de ces 422 patients ont été
étudiés. Résultats: le liquide
cérébro-spinal (LCS)était normal dans 66 cas (15,6%) et
équivoque dans 283 cas (67,1%). Une méningite bactérienne a
été diagnostiquée dans 73 cas (17,3%) avec présence
de germes dans 42 cas (10%). 272 patients (64,5%) eurent une
détérioration clinique après la PL. Chez 81 patients
(19,2%) l'aggravation clinique était en rapport avec la PL. 20 patients
(4,7%) décédèrent à cause de la
PL. Conclusion: Chez les patients ayant un abcès ou un
empyème sous - dural intra-crânien la PL accroit de façon
significative le risque de détérioration clinique voire la mort.
Tout patient suspect de processus exapnsif intra-crânien doit
bénéficier du CT-scan avant la de pratiquer une PL ou devra
bénéficier d'un traitement antibiotique empirique avant la
réalisation du CT-scan. Mots clés: abcès
intracrânien, empyéme sous-dural intra-crânien, liquide
cérébro-spinal, ponction
lombaire,. INTRODUCTION Computed tomography (CT)
was first introduced in South Africa at the neurosurgical unit at Wentworth
Hospital, Durban in 1975, and despite it's increasing availability, lumbar
puncture (LP) appears still to be commonly performed in our region as a first
diagnostic procedure in patients with brain abscess or subdural empyema. In a
15-year review of patients with brain abscess and subdural empyema treated at
our institution between 1983 and 1997, nearly a third had undergone a diagnostic
lumbar puncture prior to CT. We therefore evaluated the diagnostic role of
lumbar puncture in these patients as well as it's impact on patient
outcome. PATIENTS & METHODS During the 15-year period,
January 1983 to December 1997, patients with brain abscess and subdural empyema
admitted to our neurosurgical unit were evaluated. The neurosurgical unit at
Wentworth Hospital in Durban is the sole referral centre for the Province of
KwaZulu-Natal and half of the Eastern Cape Province. The diagnosis of
brain abscess or subdural empyema was made on conventional CT criteria in all
cases and definitively at surgery in almost all (97.8%) [1, 23]. The
investigative procedures which these patients underwent were retrospectively
reviewed. Patients undergoing diagnostic lumbar puncture prior to CT were
identified and their case notes were carefully analysed with respect to the
contribution of cerebrospinal fluid (CSF) analysis to diagnosis and to the
impact of lumbar puncture on outcome. RESULTS During the
15-year period, a total of 4623 patients with all forms of intracranial
infection were admitted to our neurosurgical unit at Wentworth Hospital in
Durban, South Africa. Of these, 1411 patients were diagnosed as harbouring
purulent infective intracranial mass lesions, in particular 712 with brain
abscess and 699 with subdural empyema.
One hundred and forty-two of these 712 patients with brain abscess (19.9%)
and 280 of the 699 patients with subdural empyema (40.1%) had undergone diagnostic
lumbar puncture prior to CT and, importantly, prior to referral to our unit.
Overall, 422 patients (29.9%) were subjected to lumbar puncture as the first
diagnostic procedure, prior to CT. [Table 1]
TABLE I - INFECTIVE INTRACRANIAL LESIONS
IN 422
PATIENTS UNDERGOING LUMBAR PUNCTURE PRIOR TO
CT
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BRAIN ABSCESS
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142
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SUPRATENTORIAL
INFRATENTORIAL
|
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SUBDURAL EMPYEMA
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280
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SUPRATENTORIAL
INFRATENTORIAL
|
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TOTAL
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422
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422
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CSF analysis from lumbar puncture revealed a normal CSF in 66 patients (15.6%),
bacterial meningitis in a minority 73 (17.3%) and a pleocytosis in 283 (67.1%).
In the latter case bacterial meningitis could not be proven and an organism
could not be cultured. Typically, the CSF in such a situation revealed white
cell counts < 500/cm3 with a predominance of polymorphs, an elevated
protein level and, either normal or moderately depressed CSF glucose levels.
Overall, therefore the CSF examination was either normal or non-diagnostic in
349 patients (82.7%). An organism was cultured in 42 of the 422 patients (10.0%)
and this was predominantly in the group of infant patients with subdural empyema
secondary to bacterial meningitis (83.3%). Of great concern and of significance
the CSF pressure was only measured in 25 patients (5.9%) and when measured was
raised (>20cm) in 15 (60%). [Table 2] As might have been expected 272 patients
(64.5%) experienced clinical deterioration (drop in Glasgow Coma Scale (GCS)
or development of a new focal sign) at some time following lumbar puncture.
However, only in 81 patients (19.2%) could the deterioration predominantly be
attributable to lumbar puncture. Twenty of the 81 patients died (4.7%). The
fatalities predominantly occurred in patients with abscesses (hemispheric in
10 and cerebellar in 7). In the case of subdural empyema only three cases existed.
[Table 3]
TABLE 2 - CSF ANALYSIS IN 422 PATIENTS
UNDERGOING LUMBAR PUNCTURE
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CSF EXAMINATION
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No.
|
Percentage
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NORMAL
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66
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15.6
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BACTERIAL MENINGITIS
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73
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17.3
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EQUIVOCAL (NON-DIAGNOSTIC)
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283
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67.1
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ORGANISM CULTURED
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42
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10.0
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PRESSURE MEASURED
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25
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5.9
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TABLE 3 - CLINICAL DETERIORATION FOLLOWING LUMBAR
PUNCTURE IN 422 PATIENTS
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No.
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Percentage
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DETERIORATION ASSOCIATED WITH LUMBAR PUNCTURE
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272
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64.5
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DETERIORATION DUE TO LUMBAR PUNCTURE
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81
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19.2
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FATALITIES ATTRIBUTED TO LUMBAR PUNCTURE
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20
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4.7
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DISCUSSION Many authors, including one of the present group
[18] have strongly cautioned against the performance of lumbar puncture in
patients with suspected or likely infective intracranial mass lesions due to the
dubious value of the CSF analysis so obtained, and due to the inherent danger of
clinical deterioration precipitated by a pressure cone
[6-10,12,13,20-22]. The diagnostic value of CSF findings from lumbar
puncture have proved to be limited. Carey et al found that approximately
one-third of patients with proven brain abscess did not show any significant CSF
pleocytosis, two-thirds had elevated protein levels, and glucose levels were
lowered in one-quarter [3]. Gregory et al noted that in three-quarters
of brain abscesses, the CSF glucose level was normal, while Yang in an
authoritative series of 400 brain abscesses reported that the CSF white cell
count was not necessarily elevated, being < 10/mm3 in 21% of cases
[21, 22]. Kratimenos et al in a series of 14 patients with multiple
brain abscesses noted that the CSF obtained by lumbar puncture did not yield any
positive cultures [14]. Galbraith et al and Kaufman et al reported
similar findings regarding CSF analysis in patients with subdural empyema
[9,13]. It has been proposed that the arachnoid is a significant, hardy
layer that protects the CSF from the subdural, extra-arachnoidal collection of
pus in patients with subdural empyema. In patients presenting in a delayed
fashion, the CSF may however exhibit an equivocal neighbourhood pattern due to
prolonged contact of the pus with the arachnoid leading to arachnoiditis with
resultant CSF changes .[9, 13] In our series of 422 patients, CSF examination
was normal or non-contributory in over 80% of cases. It has been our alarming
experience that a normal or equivocal CSF examination often lulls the referring
physician into complacency, who then treats the patient as one with viral
meningitis or partially treated bacterial meningitis, leading to a delay in
diagnosis and appropriate treatment. The dangers of lumbar puncture in
patients with infective intracranial mass lesions have been well documented by
many [8,9,10,12,13,18]. Gregory (1967), Duffy (1969) and Garfield (1969) have
all described clinical deterioration following lumbar puncture[8,10,12].
Garfield described deterioration in the level of consciousness in the ensuing 48
hours in 41 of 140 patients who underwent lumbar puncture [10]. Carey could
attribute the deaths of 5 patients (5%) to lumbar puncture. [3] Chun et
al described the death of 4 of 27 patients (14.8%) who died within 24 hours
of undergoing lumbar puncture [5]. Large series of patients with brain
abscess or subdural empyema undergoing diagnostic lumbar puncture have
previously been reported. In 1960, Bonnal et al reported 208 cases and,
more recently, Yang reported 173 cases [21,22]. Both authors cautioned that
lumbar puncture was of limited value and was hazardous. In our series, 20
deaths could be directly attributed to lumbar puncture (4.7%). Seven of the
deaths were in patients harbouring cerebellar abscesses where supratentorial
hydrocephalus has been documented as a concomitant adverse prognostic factor.
[15] One of the 14 patients with infratentorial subdural empyema also died.
Associated supratentorial hydrocephalus probably also being a contributory
factor in the precipitation of the pressure cone [16]. In addition to pressure
cone, lumbar puncture may rarely also precipitate intracerebral or subdural
haemorrhage [17,19]. We support the view of Ciarallo et al who
cautioned against injudicious lumbar puncture in patients with periorbital
cellulitis [4]. We also concur with Garfield who advised that a lumbar puncture
should not be performed in patients with meningeal irritation when a convulsion
has occurred, or if papilloedema, hemisphere or cerebellar signs are present
[10]. Gower et al have recently described contra-indications to lumbar
puncture as defined by CT, which would support the clinical view [11]. In
addition to Garfield's contra-indications to performance of lumbar
puncture, we would recommend that a patient with meningeal signs and who also
exhibits evidence of trauma, sinusitis or mastoiditis not undergo lumbar
puncture but should rather be firstly investigated by CT. In the absence of
readily available CT facilities, we strongly recommend that such a patient be
commenced on empirical, high-dose, intravenous antibiotics until such time that
a CT is obtained. CT is becoming an increasingly accessible modality in our
region, with 8 public sector CT scanners already installed in the Province of
KwaZulu-Natal, with 6 teleradiologically linked to Wentworth Hospital. Our
report of 422 cases, which also represents the largest series reported to date,
supports the view that lumbar puncture is of limited use in diagnosis of brain
abscess and subdural empyema and, more over, is inherently dangerous and
therefore students and practitioners should be advised, and taught, on the
dangers. It is hoped that with the ever increasing availability of CT, the
iatrogenic conversion of a patient with an eminently treatable brain abscess or
subdural empyema into one with secondary irreversible brainstem damage from
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Copyright 2001 - African Journal of Neurological Sciences
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