0
Special Feature |

Radiological Case of the Month FREE

[+] Author Affiliations

Section Editor: Beverly P. Wood, MD

More Author Information
Arch Pediatr Adolesc Med. 2002;156(3):294. doi:.
Text Size: A A A
Published online

DENOUEMENT AND DISCUSSION: INTRACRANIAL HYPERTENSION AND REDUCED CEREBRAL BLOOD FLOW IN MENINGOCOCCAL MENINGITIS

Figure 1. Computed tomographic scan showing an extraventricular drain and cerebral edema. The anterior horn of the right lateral ventricle appears smaller than the left but is within normal limits. The xenon flow study shows the left hemisphere with normal perfusion and flow from 30 to 60 mL/100 mg of tissue per minute. The right frontal/parietal cortex is hypoperfused with flows of 20 mL/100 mg of tissue per minute, with sparing of the occipital region on posterior parietal lobes, where flows are 30 to 50 mL/100 mg of tissue per minute.

Stable xenon CT cerebral blood flow (CBF) determination is effective to evaluate brain perfusion after traumatic brain injury. Stable (nonradioactive) xenon gas is inhaled and acts as a tracer. The CT scan is obtained with specialized software, and the attenuation of the signal reflects the perfusion within the brain while the regional blood flow is quantitated. The scans are performed when arterial PCO2 and mean arterial blood pressure are known. Measurement of CBF coupled with information about ICP have been used to guide clinical management of traumatic brain injury. Xenon CT has been used in the evaluation of CBF in nontraumatic brain injury1 but its efficacy in guiding therapy is not as well established.

Neurologic injury in bacterial meningitis is due to several factors, such as elevated ICP, vasculitis, sinus thrombosis, alterations in CBF, defective autoregulation of CBF, or alterations in cerebral metabolism.2 Elevated ICP may be due to cerebral edema,3 increased CSF volume,4,5 or increased cerebral blood volume.6 Cerebral blood flow is elevated, normal, or decreased during the course of bacterial meningitis.1 Many patients with bacterial meningitis have intact CBF/PCO2 reactivity; hence, hyperventilation may further reduce CBF in patients whose CBF is already below normal.1 Our patient likely had cerebral edema and decreased compliance, which was not evident on the initial CT. Since his CBF was low, increased cerebral blood volume was not a factor in the increased ICP.

Computed tomography and magnetic resonance imaging have demonstrated a wide variety of cerebral abnormalities in children with bacterial meningitis. The incidence of abnormality varies among series, and recent studies have shown a low incidence of cerebral edema without any relationship to neurologic examination or outcome4,7. While CT scans are useful if they reveal specific focal abnormalities or edema to indicate the presence of elevated ICP, a normal CT scan does not preclude increased ICP.

If the physical examination or initial imaging study suggests that ICP is elevated, internal ICP monitoring should be considered. If ICP is found to be elevated, a xenon CT aids in determining the treatment strategy by delineating the pattern of CBF. In our case, since the patient had decreased CBF, the treatment strategy focused on improving cerebral perfusion pressure and minimizing cerebral metabolic needs while avoiding hyperventilation (which would have decreased already compromised blood flow). While there is no direct evidence that this treatment strategy improves outcome, there is evidence that patients with lower cerebral perfusion pressure (mean arterial pressure − ICP) have poorer outcomes, and that patients with low CBF have poorer outcomes.1 The only way to manipulate CBF and cerebral perfusion pressure is with simultaneous monitoring of arterial blood pressure and ICP, paired with quantitative CBF to guide management.

Accepted for publication June 15, 1999.

Corresponding author: Laura M. Ibsen, MD, Oregon Health Sciences University, Division of Pediatric Critical Care Medicine, Department of Pediatrics, 3181 SW Sam Jackson Park Rd, Portland, OR 97201-3098.

Ashwal  SStringer  WTomasi  L  et al.  Cerebral blood flow and carbon dioxide reactivity in children with bacterial meningitis. J Pediatr. 1990;117523- 530
Berkowitz  I Update: meningitis. Crit Care Med. 1993;21S316- S318
Horwitz  SJBoxerbaum  BO'Bell  J Cerebral herniation in bacterial meningitis in childhood. Ann Neurol. 1980;7524- 528
Cabral  DAFlodmark  OFarrel  KSpeert  DP Prospective study of computed tomography in acute bacterial meningitis. J Pediatr. 1987;111201- 205
Tauber  MGKhayam-Gashi  HSande  MA Effects of ampicillin and corticosteroids on brain water content, cerebrospinal fluid pressure, and cerebrospinal fluid lactate levels in experimental pneumococcal meningitis. J Infect Dis. 1985;151528- 524
Tureen  J Cerebral blood flow and metabolism in experimental meningitis. Pediatr Infect Dis J. 1989;8917- 919
Kline  MWKaplan  SL Computed tomography in bacterial meningitis of childhood. Pediatr Infect Dis J. 1988;7855- 857

Tables

References

Ashwal  SStringer  WTomasi  L  et al.  Cerebral blood flow and carbon dioxide reactivity in children with bacterial meningitis. J Pediatr. 1990;117523- 530
Berkowitz  I Update: meningitis. Crit Care Med. 1993;21S316- S318
Horwitz  SJBoxerbaum  BO'Bell  J Cerebral herniation in bacterial meningitis in childhood. Ann Neurol. 1980;7524- 528
Cabral  DAFlodmark  OFarrel  KSpeert  DP Prospective study of computed tomography in acute bacterial meningitis. J Pediatr. 1987;111201- 205
Tauber  MGKhayam-Gashi  HSande  MA Effects of ampicillin and corticosteroids on brain water content, cerebrospinal fluid pressure, and cerebrospinal fluid lactate levels in experimental pneumococcal meningitis. J Infect Dis. 1985;151528- 524
Tureen  J Cerebral blood flow and metabolism in experimental meningitis. Pediatr Infect Dis J. 1989;8917- 919
Kline  MWKaplan  SL Computed tomography in bacterial meningitis of childhood. Pediatr Infect Dis J. 1988;7855- 857

Correspondence

CME
Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
Submit a Comment

Multimedia

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Topics