Journal of Neurology, Neurosurgery, and Psychiatry 1987;50:1071-1074

Short report

Contraindications to lumbar puncture as defined bycomputed cranial tomographyDJ GOWER,* AL BAKER,t WO BELL,* MR BALLt

From the Section on Neurosurgery, Departments ofSurgery,* and Radiology,t Wake Forest University MedicalCenter, Bowman Gray School ofMedicine, Winston-Salem, North Carolina, U.S.A.

SUMMARY Papilloedema is not always an adequate predictor of potential complications fromlumbar puncture, and many clinicians are using computed tomography (CT) before lumbar punc-ture in an effort to identify more accurately the "at risk" patient. This paper identifies the followinganatomical criteria defined by CT scanning that correlate with unequal pressures between intra-cranial compartments and predispose a patient to herniation following decompression of the spinalcompartment: lateral shift of midline structures, loss of the suprachiasmatic and basilar cisterns,obliteration of the fourth ventricle, or obliteration of the superior cerebellar and quadrigeminalplate cisterns with sparing of the ambient cisterns. These criteria should be considered to becontraindications to lumbar puncture.

Lumbar puncture was originally described byQuincke in 1891, and it has since proved to be ahighly effective diagnostic procedure.' In 1909,Harvey Cushing recognized that patients withunequal pressures between intracranial compart-ments who underwent lumbar puncture were at riskfor cerebral herniation and death.2 This group ofpatients was best identified at that time by the pres-ence of a "choked disk" (papilloedema), and hisfinding resulted in the axiom that papilloedema was acontraindication to lumbar puncture.More recently, some authors have suggested that

papilloedema is not always an adequate predictor ofcomplications from lumbar puncture,3 and many cli-nicians now turn to computed tomography (CT)before performing lumbar puncture. Most wouldagree that a "normal" CT scan indicates a patient atminimal risk for herniation, but a scan that showssome type of abnormalities, such as nonobstructivehydrocephalus, atrophy, or meningeal enhancement,may not clearly answer the question, "Is this patientsafe to tap?".The purpose of this paper is twofold: first, to report

Address for reprint requests: Dr DJ Gower, Section on Neuro-surgery, Bowman Gray School of Medicine, 300 South HawthorneRoad, Winston-Salem, NC 27103, USA.

Received 12 August 1986 and in revised form 24 November 1956.Accepted 28 November 1986

a case of death following lumbar puncture with pre-morbid CT definition of the intracranial anatomy andsecond, to suggest to the clinician criteria that mayhelp to identify by CT those patients who are indeedat increased risk for complications from lumbarpuncture.

Case Report

A 29 year old man developed a severe headache with asso-ciated nausea and vomiting on one day, and was lethargic onthe next day. When examined in a local emergency room, hehad a stiff neck, temperature of 40°C, peripheral white bloodcell count of 28,000 per mm3, and mild left hemiparesis. Adiagnostic lumbar puncture was performed for suspectedmeningitis. The cerebrospinal fluid had 80 white blood cellsper mm3 (16% polymorphonuclear cells), glucose of97 mg/dl, and protein of 118 mg/dl. The patient was beingtransported to the x-ray suite for an admission chest radio-graph when he became unresponsive and developed fixedand dilated pupils with decerebrate posturing and respira-tory compromise. An emergency CT scan was done anddemonstrated a right thalamic mass lesion with shift of themidline structures (fig 1). He was transferred to our institu-tion where he was treated aggressively for increased intra-cranial pressure with hyperventilation and mannitol, and forsuspected purulent cerebritis with broad-spectrum antibio-tics. He was declared brain dead 24 hours after admission,and life support systems were withdrawn at the family'srequest. Postmortem examination of the brain demonstrateda non-typed fungal cerebritis in the right thalamus. Nosource of fungal emboli was found.

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Gower, Baker, Bell, Ball

9''~~~~~~~~~~~~~~~~~~~~~...:.Fig 1 Infused CT scan that demonstrates midline shift and uncal herniation withdisplacement of the right posterior cerebral artery.

CT evidence of unequal intracranial pressuresShifts of brain parenchyma between intracranialcompartments in a patient with unequal intracranialpressures may compress neural structures againstbony or dural prominences. Two common forms ofneural compression occur: one when the medial por-tion of the temporal lobe herniates into the tentorialnotch and compresses the midbrain, peduncle, andthird nerve (uncal herniation); the other at theforamen magnum when the cerebellar tonsils com-press the medulla (tonsillar herniation). Fluid shiftsand pressure changes between compartments mayoccur whenever lumbar puncture is performed. Thelowering of the spinal compartment pressure by thetap and removal of cerebrospinal fluid will causesome downward movement of the transtentorial ortonsillar structures, and for this reason all patientsundergoing lumbar punctures are, theoretically, atsome risk of cerebral herniation. Those predisposedby having unequal intracranial pressures and shift ofcerebral tissue into close proximity to a compartmentopening (tentorial hiatus, foramen magnum) are at amuch greater risk.Over the past 25 years, modifications of the tech-

nique of spinal puncture have significantly reducedthe risk for patients with normal intracranial ana-tomy and pressure. The "standard" needle is now 20gauge, instead of the 12- or 16-gauge needle that wasonce used.3 Lafforgue and colleagues have shownthat a smaller dural puncture site allows less cerebro-spinal fluid to extravasate into the surrounding tissuesfollowing removal of the needle,4 and current techni-ques for complete analysis of cerebrospinal fluid nowrequire only 3 to 6 ml of fluid instead of the 30 to60 ml routinely removed when the procedure was firstused.

Despite these modifications, patients with unequalintracranial pressures are still at risk for cerebralherniation regardless of needle size; moreover,identification of these patients remains difficult.Korein et al, in a review of their own patients andpatients reported in the literature between 1927 and1959,3 identified a total of 1053 who had undergonelumbar puncture. Four hundred and eighteen hadpapilloedema, of whom only five (1 2%) had a "poss-ible complication" within the first 48 hours followinglumbar puncture. This study confirmed a growingsuspicion that the presence of papilloedema alone

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Contraindications to lumbar puncture as defined by computed cranial tomography(although in some cases an indicator of increasedintracranial pressure) may not be an adequate pre-dictor of cerebral herniation following lumbarpuncture.

While CT scanning frequently eliminates the needfor diagnostic lumbar puncture by providing a firmdiagnosis, such as subarachnoid haemorrhage orbrain tumour,5 two clear indications for lumbarpuncture remain: suspected purulent or carcino-matous meningitis, and suspected spinal cord com-pression from metastatic disease requiring myelo-graphy. For patients in both of these categories, amass lesion from a brain abscess or an intra-parenchymal metastatic lesion may make lumbarpuncture treacherous.

Although the CT scan clearly defines intracranialanatomy, pressure data must be inferred from thestructural information it provides. Thus, someauthors have recommended that lumbar puncture beattempted only if the CT scan is "normal".6 We agreethat all patients should have both uninfused andinfused CT scans before lumbar puncture, butlimiting lumbar puncture to those with "normal"scans may not be necessary. We suggest the followingCT criteria that are anatomical correlates to unequalintracranial pressures and should be considered

contraindications to a proposed diagnostic lumbartap.

(1) CT evidence ofunequal pressures across the midline(falx cerebri)The presence of unequal supratentorial pressures iseasily identified by lateral shift of the midline struc-tures (septum pellucidum, third ventricle).7 Asym-metry of the lateral ventricles alone may not be anaccurate sign, since ipsilateral ventricular dilatationmay occur secondary to stroke, or coaptation of afrontal horn may represent a normal anatomical vari-ant. Following lumbar puncture unequal supra-tentorial pressures would most likely lead to com-pression of the ipsilateral temporal lobe, leading to anuncal herniation.

(2) CT evidence of unequal pressures between thesupratentorial and infratentorial compartmentsUnequal pressures across the tentorium may be sub-divided into an elevated pressure cephalad to the ten-torium pushing structures into the posterior fossa oran elevated pressure caudad to the tentorium pushingstructures upward as well as through the foramenmagnum.

Symmetrical supratentorial pressures higher than

]

Fig 2 (left) Normal uninfused CT scan demonstrating the basilar cisterns (1 = suprasellar cistern, 2 = ambientcistern, 3 = quadrigeminal plate cistern), and (right) an example of upward transtentorial herniation with obliterationof the quadrigeminal plate cistern (3) and sparing of the ambient cistern (2).

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infratentorial pressure are identified by loss of thesuprachiasmatic and circummesencephalic cisterns(basilar cisterns) (fig 2, right). The ventricular systemmay be symmetrically small as in diffuse cerebraloedema, or the lateral ventricles including the tempo-ral horns may be enlarged as in obstructive (non-communicating) hydrocephalus. Decompression ofthe spinal and posterior fossa compartments fromlumbar puncture may cause the medial temporallobes to impact into the tentorial hiatus bilaterally(bilateral uncal herniation).We believe the strongest contraindication to lum-

bar puncture is a posterior fossa mass. Any increasein pressure in the posterior fossa may move the cere-bellar tonsils into the region of the foramen magnum,predisposing the patient to tonsillar herniation when-ever even a small amount of cerebrospinal fluid isremoved from the spinal compartment. Unfor-tunately, the posterior fossa and foramen magnumare difficult areas to image by computed tomography,and direct demonstration of the posterior fossa massmay be compromised by bone and motion artifact,isodensity, volume averaging from thick slices, or fail-ure to infuse the patient. An asymmetrical lesion suchas a cerebellar hemispherical mass may shift thefourth ventricle laterally; anterior and posterior com-partment masses may compress the fourth ventricleand shift it anteriorly or posteriorly. Shifts of thefourth ventricle produced by low and high posteriorfossa masses may be difficult to image in the axialplane. In many cases, a posterior fossa mass effectmust be deduced from other, indirect evidence, suchas obliteration of the fourth ventricle, symmetricalobstructive hydrocephalus, or upward transtentorialherniation of the cerebellar vermis. Upward hernia-tion obliterates the superior cerebellar cistern and thequadrigeminal plate cistern caudal to the midbrainwhile sparing the ambient cisterns lateral to the mid-

Gower, Baker, Bell, Ball

brain (fig 2, left). Upward herniation may be a verysubtle finding on the CT scan, and a high index ofsuspicion is required.

In summary, we have presented a case of cerebralherniation following lumbar puncture, and have sug-gested criteria that may help guide the clinicianassessing data obtained from an "abnormal" CT scanto define more accurately the risk-to-benefit ratio forlumbar puncture.

The authors thank Judith MacMillan for editorialassistance, as well as Alma Doub and Libby Childressfor manuscript preparation.

References

I Wood JH. Cerebrospinal fluid: techniques of access andanalytical interpretation. In: Wilkins RH, RengacharySS, eds. Neurosurgery Vol 1. New York, McGraw-HillBook Company, 1985;161-74.

2 Cushing H. Some aspects of the pathological physiologyof intracranial tumors. Boston Med Surg J1909;161:71-80.

3 Korein J, Cravioto H, Leicach M. Revaluation of lum-bar puncture. A study of 129 patients with papil-loedema or intracranial hypertension. Neurology1959;9:290-7.

4 Lafforgue JL, de Coninck L, Cales J, Bagot M, SabathieM. A propos de la ponction lombaire: indications etlimites. Cah Anesth. 1984;32:113-7.

5 Humphreys RP. Computed tomography and the earlydiagnostic lumbar puncture. Can Med Assoc J1979;121:150-1.

6 Plum F, Posner JB. The diagnosis ofstupor and coma, 3rded. (Contemporary neurology series, 19.) Philadel-phia, F.A. Davis Company, 1980;1 14-6.

7 Sadhu VK, Sampson J, Haar FL, Pinto RS, Handel SF.Correlation between computed tomography and intra-cranial pressure monitoring in acute head traumapatients. Radiology 1979;133:507-9.

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