Background. It is unclear whether history and physical examination findings can predict abnormalities on head computed tomography (CT) believed to indicate increased risk of lumbar-puncture- (LP-) induced brain herniation. The objectives of this study were to (1) identify head CT findings felt to be associated with increased risk of brain herniation and (2) to assess the ability of history and physical examination to predict those findings. Methods. Using a modified Delphi survey technique, an expert panel defined CT abnormalities felt to predict increased risk of LP-induced brain herniation. Presence of such findings on CT was compared with history and physical examination (H&P) variables in 47 patients. Results. No H&P variable predicted “high-risk” CT; combining H&P variables to improve sensitivity led to extremely low specificity and still failed to identify all patients with high-risk CT. Conclusions. “High-risk” CT is not uncommon in patients with clinical characteristics known to predict an absence of actual risk from LP, and thus it may not be clinically relevant. “Overdiagnosis” will be increasingly problematic as technological advances identify increasingly subtle deviations from “normal.” 1. Introduction There is substantial evidence in the medical literature that lumbar puncture (LP) is extremely safe [1–3], particularly in the setting of patients who are immunologically normal and who do not manifest abnormal mental status, papilledema, or focal neurological deficit [3–5]. Nevertheless, many clinicians are concerned that LP could lead to tonsillar herniation [6–11] in patients with increased intracranial pressure (ICP), by decreasing cerebrospinal fluid pressure in the subarachnoid space, and thus creating a pressure gradient that could displace cerebral and brainstem structures [7, 12]. There are only a small number of reports, however, suggesting catastrophic deterioration related to LP [9, 13, 14], and even the validity of these observations has been questioned [15–17]. Nevertheless, despite the substantial evidence that few, if any patients, are at risk from LP, many clinicians worry about potential harm, and it has been suggested that head computed tomography (CT) be obtained prior to LP, in the hope that it might be able to identify the few patients in whom the procedure would purportedly be dangerous [5, 18]. There are no studies, however, which define what if any findings on head CT actually do predict increased risk of tonsillar herniation following LP [3, 4, 19]. We designed this study to assess the prevalence of “high-risk” CT
References
[1]
G. Linker, N. Mirza, G. Manetti, M. Meyer, K. T. Putnam, and T. Sunderland, “Fine-needle, negative-pressure lumbar puncture: a safe technique for collecting CSF,” Neurology, vol. 59, no. 12, pp. 2008–2009, 2002.
[2]
M. K. Patel and M. A. Clarke, “Lumbar puncture and subarachnoid haemorrhage,” Postgraduate Medical Journal, vol. 62, no. 733, pp. 1021–1024, 1986.
[3]
R. Hasbun, J. Abrahams, J. Jekel, and V. J. Quagliarello, “Computed tomography of the head before lumbar puncture in adults with suspected meningitis,” The New England Journal of Medicine, vol. 345, no. 24, pp. 1727–1733, 2001.
[4]
A. K. Gopal, J. D. Whitehouse, D. L. Simel, and G. R. Corey, “Cranial computed tomography before lumbar puncture: a prospective clinical evaluation,” Archives of Internal Medicine, vol. 159, no. 22, pp. 2681–2685, 1999.
[5]
P. R. Greig and D. Goroszeniuk, “Role of computed tomography before lumbar puncture: a survey of clinical practice,” Postgraduate Medical Journal, vol. 82, no. 965, pp. 162–165, 2006.
[6]
F. Simonetti, P. Pergami, M. Ceroni, A. H. Ropper, and R. Viviani, “About the original description of cerebellar tonsil herniation by Pierre Marie,” Journal of Neurology Neurosurgery and Psychiatry, vol. 63, no. 3, p. 412, 1997.
[7]
N. H. Steigbigel, “Computed tomography of the head before a lumbar puncture in suspected meningitis—is it helpful?” The New England Journal of Medicine, vol. 345, no. 24, pp. 1768–1770, 2001.
[8]
W. Waldman and R. Laureno, “Precautions for lumbar puncture: a survey of neurologic educators,” Neurology, vol. 52, no. 6, p. 1296, 1999.
[9]
G. P. Duffy, “Lumbar puncture in the presence of raised intracranial pressure,” British Medical Journal, vol. 1, no. 641, pp. 407–409, 1969.
[10]
P. R. Dodge and M. N. Swartz, “Bacterial meningitis—a review of selected aspects. ii. special neurologic problems, postmeningitic complacations and clinicopathological correlations,” The New England Journal of Medicine, vol. 272, pp. 954–960, 1965.
[11]
S. Kastenbauer, F. Winkler, H.-W. Pfister et al., “Cranial CT before lumbar puncture in suspected meningitis (multiple letters),” The New England Journal of Medicine, vol. 346, no. 16, pp. 1248–1251, 2002.
[12]
H. van Crevel, A. Hijdra, and J. De Gans, “Lumbar puncture and the risk of herniation: when should we first perform CT,” Journal of Neurology, vol. 249, no. 2, pp. 129–137, 2002.
[13]
G. P. Duffy, “Lumbar puncture in spontaneous subarachnoid haemorrhage,” British Medical Journal, vol. 285, no. 6349, pp. 1163–1164, 1982.
[14]
D. J. Gower, A. Baker, W. Bell, and M. R. Ball, “Contraindications to lumbar puncture as defined by computed cranial tomography,” Journal of Neurology Neurosurgery and Psychiatry, vol. 50, no. 8, pp. 1071–1074, 1987.
[15]
B. D. Archer, “Computed tomography before lumbar puncture in acute meningitis: a review of the risks and benefits,” Canadian Medical Association Journal, vol. 148, no. 6, pp. 961–965, 1993.
[16]
W. J. Oliver, T. C. Shope, and L. R. Kuhns, “Fatal lumbar puncture: fact versus fiction—an approach to a clinical dilemma,” Pediatrics, vol. 112, no. 3, pp. e174–e176, 2003.
[17]
J. Zisfein and A. J. Tuchman, “Risks of lumbar puncture in the presence of intracranial mass lesions,” Mount Sinai Journal of Medicine, vol. 55, no. 4, pp. 283–287, 1988.
[18]
J. J. Perry, I. G. Stiell, G. A. Wells et al., “Attitudes and judgment of emergency physicians in the management of patients with acute headache,” Academic Emergency Medicine, vol. 12, no. 1, pp. 33–37, 2005.
[19]
N. D. Baker, H. Kharazi, L. Laurent, et al., “The efficacy of routine head computed tomography (CT scan) prior to lumbar puncture in the emergency department,” Journal of Emergency Medicine, vol. 12, no. 5, pp. 597–601, 1994.
[20]
H. A. Linstone and M. Turoff, The Delphi Method: Techniques and Applications, Addison-Wesley, Reading, Mass, USA, 1975.
[21]
N. Dalkey and O. Helmer, “An experimental application of the delphi method to the use of experts,” Management Science, vol. 9, pp. 458–467, 1963.
[22]
R. L. Custer SJ and B. R. Stewart, “The modified delphi technique—a rotational modification,” Journal of Vocational and Technical Education, vol. 15, 1999.
[23]
A. Ali, “Using the delphi technique to search for empirical measures of local planning agency power,” The Qualitative Report, vol. 10, pp. 718–744, 2005.
[24]
K. W. Brooks, “Delphi technique: expanding applications,” North Central Association Quarterly, vol. 54, pp. 377–385, 1979.
[25]
W. R. Mower, J. R. Hoffman, M. Herbert, A. B. Wolfson, C. V. Pollack Jr., and M. I. Zucker, “Developing a clinical decision instrument to rule out intracranial injuries in patients with minor head trauma: methodology of the NEXUS II investigation,” Annals of Emergency Medicine, vol. 40, no. 5, pp. 505–514, 2002.
[26]
A. Sodickson, P. F. Baeyens, K. P. Andriole et al., “Recurrent CT, cumulative radiation exposure, and associated radiation-induced cancer risks from CT of adults,” Radiology, vol. 251, no. 1, pp. 175–184, 2009.
[27]
R. T. Griffey and A. Sodickson, “Cumulative radiation exposure and cancer risk estimates in emergency department patients undergoing repeat or multiple CT,” American Journal of Roentgenology, vol. 192, no. 4, pp. 887–892, 2009.
[28]
D. H. Newman and D. L. Schriger, “Rethinking testing for pulmonary embolism: less is more,” Annals of Emergency Medicine, vol. 57, no. 6, pp. 622–627, 2011.
[29]
G. Welch, L. Schwartz, and S. Woloshin, Over-Diagnosed: Making People Sick in the Pursuit of Health, Beacon Press, Boston, Mass, USA, 2011.
[30]
L. J. Baraff, R. L. Byyny, M. A. Probst, N. Salamon, M. Linetsky, and W. R. Mower, “Prevalence of herniation and intracranial shift on cranial tomography in patients with subarachnoid hemorrhage and a normal neurologic examination,” Academic Emergency Medicine, vol. 17, no. 4, pp. 423–428, 2010.
[31]
E. R. Haut and P. J. Pronovost, “Surveillance bias in outcomes reporting,” Journal of the American Medical Association, vol. 305, no. 23, pp. 2462–2463, 2011.
[32]
F. Woudenberg, “An evaluation of delphi,” Technological Forecasting and Social Change, vol. 40, no. 2, pp. 131–150, 1991.
