Perspectives Commentary on: Efficacy and Safety of Subdural Drains After Burr-Hole Evacuation of Chronic Subdural Hematomas: Systematic Review and Meta-Analysis of Randomized Controlled Trials by Alcalá-Cerra et al. pp. 1148-1157.
Wai Sang Poon, M.D. Chair Professor & Chief in Neurosurgery The Chinese University of Hong Kong Division of Neurosurgery Prince of Wales Hospital
Chronic Subdural Hematoma: To Drain or not To Drain, This Is the Question David Yuen Chung Chan1, Peter Yat Ming Woo 2, Wai Sang Poon1
I
n industrialized countries chronic subdural hematoma (CSH) is one of the most common clinical conditions encountered in daily neurosurgical practice. Among the population more than 65 years, annual incidence ranges from 8 to 58 per 100,000 (7, 11). Life expectancies has increased steadily during the past 4 decades (5, 26) and the number of people older than 65 years are expected to double by the year 2050 in Britain and North America (6, 21). A substantial portion of this population will also likely be prescribed antiplatelet or anticoagulant medication for a variety of cardiovascular diseases. A review of the long-term consequences of patients with CSH demonstrated that the 6-month and 1-year mortality rates could be as high as 26.3% and 32%, respectively, in North America (15). A comparison with a control population revealed markedly decreased median overall survival among patients with CSH of 4.4 years as opposed to 6 years (15). As a result, CSH has been suggested to be a sentinel health event akin to hip fractures in the elderly (8, 15). Chronic subdural hematomas can no longer be considered a “benign” condition, particularly when recurrence is reported at 8%e22% worldwide (19). Understandably the burden of treating patients with CSH will only increase for future generations of neurosurgeons. It is becoming increasingly pertinent that the international neurosurgical community reaches a consensus on an effective management strategy. Ever since its first detailed description by Virchow in 1857, the exact pathogenesis of CSH has remained incompletely understood (22), but studies have shown that inflammatory processes mediate their expansion or recurrence (13, 17, 20). By counteracting subdural space inflammation, we previously reported that medical treatment by dexamethasone for CSH produced favorable outcomes in selected patients (19). Due to lingering concerns of the safety of high-dose steroids, other inflammation modulating
Key words - Burr-hole - Chronic subdural hematoma - Closed-system drainage - Recurrence - Reoperation
Abbreviations and Acronyms CSH: Chronic subdural hematoma RCT: Randomized controlled trial
WORLD NEUROSURGERY 82 [6]: 1007-1009, DECEMBER 2014
medical treatments, such as hMG coA-reductase inhibitors, have recently been studied with some initial promise (24). But perhaps an equally important obstacle to achieving standardof-care surgical therapies for CSH is the diversity of management practices. Often delegated to the most junior member of the neurosurgical team, the time-honored procedure, whatever it may be, is usually firmly entrenched as part of a center’s practice. However, as evidence-based medicine becomes increasingly important, in the past 10 years we have witnessed a renaissance in the improvement and standardization of this relatively straightforward operation. An illustrative example is the popular transition from craniotomy and twist drill craniostomy for CSH evacuation to burr hole craniostomy. Such a paradigm shift in surgical technique was contributed by the findings of the landmark meta-analysis of Weigel et al. (25) that we commented on previously (12). At present, surgical discussions are focused on the placement of closedsystem subdural drains. As early as 1990, a prospective study of 38 patients reported by Wakai et al. (24) revealed the potential use of subdural drains in reducing CSH recurrence from 33% in control patients to 6%. A retrospective review of 500 patients also supported the use of subdural drains with lower reoperation rates from 19%e10% (14). To illustrate the diametric attitudes regarding subdural drain use, questionnaire surveys reported that 80% of Canadian neurosurgeons routinely place drains compared with 11% in the United Kingdom (4, 18). General opinions of their benefit remained largely unchanged until a randomized controlled trial (RCT) described their effectiveness in significantly reducing recurrence from 24% among control group patients to 9.3% (16). This was also accompanied by a considerable decrease in 6-month mortality from 18.6%e8.6% (16). Despite these compelling results, concerns regarding the relatively high rates of recurrence among the control group, incomplete patient follow-up, and the single-centre nature of the study encouraged other investigators (2, 10) to attempt to validate the findings of Santarius et al. (16) with
From the 1Department of Surgery, Division of Neurosurgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, People’s Republic of China; and 2Kwong Wah Hospital, Hong Kong, People’s Republic of China To whom correspondence should be addressed: Wai Sang Poon, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2014) 82, 6:1007-1009. http://dx.doi.org/10.1016/j.wneu.2014.09.018
www.WORLDNEUROSURGERY.org
1007
PERSPECTIVES
various degrees of success. We performed a two-center retrospective review of 313 patients starting on July 1, 2010 and ending on June 30, 2013 (unpublished data). The reoperation rate in 1 center, where subdural drains were regularly placed, was 9.0% and in another, where drains were seldom used, was 15.9% (P ¼ 0.118). In addition there are reservations that subdural drains could prolong unnecessary postoperative bed rest, increase the risk of foreign body infection, hemorrhage, and seizures (4). Therefore, in light of these conflicting observations, we applaud the timely written article by Alcala´-Cerra et al. published in this issue of WORLD NEUROSURGERY. This meta-analysis of 7 RCTs is the first of its kind exclusively investigating subdural drain placement after burr hole craniostomy by pooled analyses of the following end points: symptomatic recurrence, reoperation, poor functional outcome, mortality, and postoperative complications at 3 weeks to 6 months. The investigators concluded that of the 628 patients subdural drains significantly reduced the risk of recurrence (P ¼ 0.0005), the need for reoperation (P ¼ 0.00005), and was associated with better functional performance (P ¼ 0.04). There was also no statistically significant increased risk of medical or surgical complications associated with drain placement (P ¼ 0.33). The strength of this remarkable work lies on the investigators’ adoption of the rigorous and validated Jadad scale for trial methodology quality, the inclusion of studies with functional outcome measures, and the relative homogeneity of trial subjects (9).
However, one should temper overenthusiasm for subdural drainage with further scrutiny of the group’s meta-analysis. The investigators regarded only 3 trials as of high methodologic quality and that more than a third of patients were from the RCT by Santarius (16). Furthermore, when analyzing study end points, such as recurrence and reoperation, only 2 trials yielded positive results. It is of our opinion that due to a considerable discrepancy in sample size and effect sizes for recurrence and reoperation end points, the findings of Alcala´-Cerra et al. may not provide robust enough evidence for a definitive answer on subdural drainage. Alternatively, less conventional methods of closed-system drainage, such as subperiosteal drainage, have been proposed and found to be safe (3, 23, 27). In the first direct comparison between subperiosteal and subdural drainage, a retrospective study revealed no significant difference in recurrence and functional outcome at 3 months (3). Other less invasive methods known to reduce recurrence, such as maintaining a postoperative lying flat position and adequate intravenous hydration, also need to be controlled in future trials of this nature (1). Alcala´-Cerra’s group has persuaded us to believe that some form of drainage may prove ultimately beneficial. We highly anticipate the results of well-designed multicenter RCTs focusing on closed-system drainage with or without medical treatment. In the meanwhile, the study by Alcala´-Cerra et al. has rendered the question of whether to drain or not less of a quandary.
lib/research/key_issues/Key-Issues-The-ageingpopulation2007.pdf. Accessed September 2, 2014.
13. Lee KS: Natural history of chronic subdural haematoma. Brain Injury 18:351-358, 2004.
1. Abouzari M, Rashidi A, Rezaii J, Esfandiari K, Asadollahi M, Aleali H, Abdollahzadeh M: The role of postoperative patient posture in the recurrence of traumatic chronic subdural hematoma after burr-hole surgery. Neurosurgery 61: 794-797; discussion 797, 2007.
7. Ducruet AF, Grobelny BT, Zacharia BE, Hickman ZL, DeRosa PL, Anderson K, Sussman E, Carpenter A, Connolly ES Jr: The surgical management of chronic subdural hematoma. Neurosurgical Rev 35:155-169; discussion 169, 2012.
14. Lind CR, Lind CJ, Mee EW: Reduction in the number of repeated operations for the treatment of subacute and chronic subdural hematomas by placement of subdural drains. J Neurosurg 99: 44-46, 2003.
2. Ahmed SV, Bonny S, Chandra S: ‘Idiopathic’ chronic bilateral subdural haematoma—a separate entity or a missed cause? BMJ Case Reports, 2011; pii: bcr092011477.
8. Dumont TM, Rughani AI, Goeckes T, Tranmer BI: Chronic subdural hematoma: a sentinel health event. World Neurosurg 80:889-892, 2013.
REFERENCES
15. Miranda LB, Braxton E, Hobbs J, Quigley MR: Chronic subdural hematoma in the elderly: not a benign disease. J Neurosurg 114:72-76, 2011.
9. Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, Gavaghan DJ, McQuay HJ: Assessing the quality of reports of randomized clinical trials: is blinding necessary? Controlled Clinical Trials 17:1-12, 1996.
16. Santarius T, Kirkpatrick PJ, Ganesan D, Chia HL, Jalloh I, Smielewski P, Richards HK, Marcus H, Parker RA, Price SJ, Kirollos RW, Pickard JD, Hutchinson PJ: Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet 374:1067-1073, 2009.
4. Cenic A, Bhandari M, Reddy K: Management of chronic subdural hematoma: a national survey and literature review. Can J Neurol Sci 32:501-506, 2005.
10. Javadi A, Amirjamshidi A, Aran S, Hosseini SH: A randomized controlled trial comparing the outcome of burr-hole irrigation with and without drainage in the treatment of chronic subdural hematoma: a preliminary report. World Neurosurg 75:731-736; discussion 620-733, 2011.
17. Santarius T, Kirkpatrick PJ, Kolias AG, Hutchinson PJ: Working toward rational and evidence-based treatment of chronic subdural hematoma. Clin Neurosurg 57:112-122, 2010.
5. Department of Health, HKSAR: Life expectancy at birth (male and female) 1971e2013. 2014; Centre for Health Protection, Department of Health, The Government of the Hong Kong Special Administrative Region. Available at: http://www.chp.gov. hk/en/data/4/10/27/111.html. Accessed September 2, 2014.
11. Kudo H, Kuwamura K, Izawa I, Sawa H, Tamaki N: Chronic subdural hematoma in elderly people: present status on Awaji Island and epidemiological prospect. Neurol Med Chir (Tokyo) 32:207-209, 1992.
18. Santarius T, Lawton R, Kirkpatrick PJ, Hutchinson PJ: The management of primary chronic subdural haematoma: a questionnaire survey of practice in the United Kingdom and the Republic of Ireland. Brit J Neurosurg 22:529-534, 2008.
12. Kwan MC, Sun DT, Poon WS: Types of postoperative drainage for chronic subdural hematoma: to do it on the table or under? World Neurosurg 77:51-52, 2012.
19. Sun TF, Boet R, Poon WS: Non-surgical primary treatment of chronic subdural haematoma: preliminary results of using dexamethasone. Brit J Neurosurg 19:327-333, 2005.
3. Bellut D, Woernle CM, Burkhardt JK, Kockro RA, Bertalanffy H, Krayenbuhl N: Subdural drainage versus subperiosteal drainage in burr-hole trepanation for symptomatic chronic subdural hematomas. World Neurosurg 77:111-118, 2012.
6. Cracknell R: The ageing population. 2010; House of Commons Library Research. Available at: http://www.parliament.uk/documents/commons/
1008
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.09.018
PERSPECTIVES
20. Tanaka Y, Ohno K: Chronic subdural hematoma—an up-to-date concept. J Med Dental Sci 60:55-61, 2013. 21. Department of Commerce, U.S.: The next four decades: the older population in the United States 2010 to 2050. U.S. Census Bureau. Available at: http://www.census.gov/prod/2010pubs/p25-1138.pdf. Accessed September 2, 2014. 22. Virchow R: The subdural hematomas [in German]. Verh Phys Med Ges Wurzburg 7: 134-142, 1857. 23. Wakai S, Hashimoto K, Watanabe N, Inoh S, Ochiai C, Nagai M: Efficacy of closed-system drainage in treating chronic subdural hematoma: a prospective comparative study. Neurosurgery 26: 771-773, 1990.
24. Wang D, Li T, Tian Y, Wang S, Jin C, Wei H, Quan W, Wang J, Chen J, Dong J, Jiang R, Zhang J: Effects of atorvastatin on chronic subdural hematoma: a preliminary report from three medical centers. J Neurol Sci 336:237-242, 2014. 25. Weigel R, Schmiedek P, Krauss JK: Outcome of contemporary surgery for chronic subdural haematoma: evidence-based review. J Neurol Neurosurg Psychiatry 74:937-943, 2003. 26. World Health Organisation: World health statistics 2013. Available at: http://www.who.int/ gho/publications/world_health_statistics/EN_WHS 2013_Full.pdf. Accessed September 2, 2014. 27. Zumofen D, Regli L, Levivier M, Krayenbuhl N: Chronic subdural hematomas treated by burr hole
WORLD NEUROSURGERY 82 [6]: 1007-1009, DECEMBER 2014
trepanation and a subperiostal drainage system. Neurosurgery 64:1116-1121; discussion 1121-1112, 2009.
David Yuen Chung Chan, Peter Yat Ming Woo are co-first authors. Citation: World Neurosurg. (2014) 82, 6:1007-1009. http://dx.doi.org/10.1016/j.wneu.2014.09.018 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2014 Elsevier Inc. All rights reserved.
www.WORLDNEUROSURGERY.org
1009
Wai Sang Poon, M.D. Chair Professor & Chief in Neurosurgery The Chinese University of Hong Kong Division of Neurosurgery Prince of Wales Hospital
Chronic Subdural Hematoma: To Drain or not To Drain, This Is the Question David Yuen Chung Chan1, Peter Yat Ming Woo 2, Wai Sang Poon1
I
n industrialized countries chronic subdural hematoma (CSH) is one of the most common clinical conditions encountered in daily neurosurgical practice. Among the population more than 65 years, annual incidence ranges from 8 to 58 per 100,000 (7, 11). Life expectancies has increased steadily during the past 4 decades (5, 26) and the number of people older than 65 years are expected to double by the year 2050 in Britain and North America (6, 21). A substantial portion of this population will also likely be prescribed antiplatelet or anticoagulant medication for a variety of cardiovascular diseases. A review of the long-term consequences of patients with CSH demonstrated that the 6-month and 1-year mortality rates could be as high as 26.3% and 32%, respectively, in North America (15). A comparison with a control population revealed markedly decreased median overall survival among patients with CSH of 4.4 years as opposed to 6 years (15). As a result, CSH has been suggested to be a sentinel health event akin to hip fractures in the elderly (8, 15). Chronic subdural hematomas can no longer be considered a “benign” condition, particularly when recurrence is reported at 8%e22% worldwide (19). Understandably the burden of treating patients with CSH will only increase for future generations of neurosurgeons. It is becoming increasingly pertinent that the international neurosurgical community reaches a consensus on an effective management strategy. Ever since its first detailed description by Virchow in 1857, the exact pathogenesis of CSH has remained incompletely understood (22), but studies have shown that inflammatory processes mediate their expansion or recurrence (13, 17, 20). By counteracting subdural space inflammation, we previously reported that medical treatment by dexamethasone for CSH produced favorable outcomes in selected patients (19). Due to lingering concerns of the safety of high-dose steroids, other inflammation modulating
Key words - Burr-hole - Chronic subdural hematoma - Closed-system drainage - Recurrence - Reoperation
Abbreviations and Acronyms CSH: Chronic subdural hematoma RCT: Randomized controlled trial
WORLD NEUROSURGERY 82 [6]: 1007-1009, DECEMBER 2014
medical treatments, such as hMG coA-reductase inhibitors, have recently been studied with some initial promise (24). But perhaps an equally important obstacle to achieving standardof-care surgical therapies for CSH is the diversity of management practices. Often delegated to the most junior member of the neurosurgical team, the time-honored procedure, whatever it may be, is usually firmly entrenched as part of a center’s practice. However, as evidence-based medicine becomes increasingly important, in the past 10 years we have witnessed a renaissance in the improvement and standardization of this relatively straightforward operation. An illustrative example is the popular transition from craniotomy and twist drill craniostomy for CSH evacuation to burr hole craniostomy. Such a paradigm shift in surgical technique was contributed by the findings of the landmark meta-analysis of Weigel et al. (25) that we commented on previously (12). At present, surgical discussions are focused on the placement of closedsystem subdural drains. As early as 1990, a prospective study of 38 patients reported by Wakai et al. (24) revealed the potential use of subdural drains in reducing CSH recurrence from 33% in control patients to 6%. A retrospective review of 500 patients also supported the use of subdural drains with lower reoperation rates from 19%e10% (14). To illustrate the diametric attitudes regarding subdural drain use, questionnaire surveys reported that 80% of Canadian neurosurgeons routinely place drains compared with 11% in the United Kingdom (4, 18). General opinions of their benefit remained largely unchanged until a randomized controlled trial (RCT) described their effectiveness in significantly reducing recurrence from 24% among control group patients to 9.3% (16). This was also accompanied by a considerable decrease in 6-month mortality from 18.6%e8.6% (16). Despite these compelling results, concerns regarding the relatively high rates of recurrence among the control group, incomplete patient follow-up, and the single-centre nature of the study encouraged other investigators (2, 10) to attempt to validate the findings of Santarius et al. (16) with
From the 1Department of Surgery, Division of Neurosurgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, People’s Republic of China; and 2Kwong Wah Hospital, Hong Kong, People’s Republic of China To whom correspondence should be addressed: Wai Sang Poon, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2014) 82, 6:1007-1009. http://dx.doi.org/10.1016/j.wneu.2014.09.018
www.WORLDNEUROSURGERY.org
1007
PERSPECTIVES
various degrees of success. We performed a two-center retrospective review of 313 patients starting on July 1, 2010 and ending on June 30, 2013 (unpublished data). The reoperation rate in 1 center, where subdural drains were regularly placed, was 9.0% and in another, where drains were seldom used, was 15.9% (P ¼ 0.118). In addition there are reservations that subdural drains could prolong unnecessary postoperative bed rest, increase the risk of foreign body infection, hemorrhage, and seizures (4). Therefore, in light of these conflicting observations, we applaud the timely written article by Alcala´-Cerra et al. published in this issue of WORLD NEUROSURGERY. This meta-analysis of 7 RCTs is the first of its kind exclusively investigating subdural drain placement after burr hole craniostomy by pooled analyses of the following end points: symptomatic recurrence, reoperation, poor functional outcome, mortality, and postoperative complications at 3 weeks to 6 months. The investigators concluded that of the 628 patients subdural drains significantly reduced the risk of recurrence (P ¼ 0.0005), the need for reoperation (P ¼ 0.00005), and was associated with better functional performance (P ¼ 0.04). There was also no statistically significant increased risk of medical or surgical complications associated with drain placement (P ¼ 0.33). The strength of this remarkable work lies on the investigators’ adoption of the rigorous and validated Jadad scale for trial methodology quality, the inclusion of studies with functional outcome measures, and the relative homogeneity of trial subjects (9).
However, one should temper overenthusiasm for subdural drainage with further scrutiny of the group’s meta-analysis. The investigators regarded only 3 trials as of high methodologic quality and that more than a third of patients were from the RCT by Santarius (16). Furthermore, when analyzing study end points, such as recurrence and reoperation, only 2 trials yielded positive results. It is of our opinion that due to a considerable discrepancy in sample size and effect sizes for recurrence and reoperation end points, the findings of Alcala´-Cerra et al. may not provide robust enough evidence for a definitive answer on subdural drainage. Alternatively, less conventional methods of closed-system drainage, such as subperiosteal drainage, have been proposed and found to be safe (3, 23, 27). In the first direct comparison between subperiosteal and subdural drainage, a retrospective study revealed no significant difference in recurrence and functional outcome at 3 months (3). Other less invasive methods known to reduce recurrence, such as maintaining a postoperative lying flat position and adequate intravenous hydration, also need to be controlled in future trials of this nature (1). Alcala´-Cerra’s group has persuaded us to believe that some form of drainage may prove ultimately beneficial. We highly anticipate the results of well-designed multicenter RCTs focusing on closed-system drainage with or without medical treatment. In the meanwhile, the study by Alcala´-Cerra et al. has rendered the question of whether to drain or not less of a quandary.
lib/research/key_issues/Key-Issues-The-ageingpopulation2007.pdf. Accessed September 2, 2014.
13. Lee KS: Natural history of chronic subdural haematoma. Brain Injury 18:351-358, 2004.
1. Abouzari M, Rashidi A, Rezaii J, Esfandiari K, Asadollahi M, Aleali H, Abdollahzadeh M: The role of postoperative patient posture in the recurrence of traumatic chronic subdural hematoma after burr-hole surgery. Neurosurgery 61: 794-797; discussion 797, 2007.
7. Ducruet AF, Grobelny BT, Zacharia BE, Hickman ZL, DeRosa PL, Anderson K, Sussman E, Carpenter A, Connolly ES Jr: The surgical management of chronic subdural hematoma. Neurosurgical Rev 35:155-169; discussion 169, 2012.
14. Lind CR, Lind CJ, Mee EW: Reduction in the number of repeated operations for the treatment of subacute and chronic subdural hematomas by placement of subdural drains. J Neurosurg 99: 44-46, 2003.
2. Ahmed SV, Bonny S, Chandra S: ‘Idiopathic’ chronic bilateral subdural haematoma—a separate entity or a missed cause? BMJ Case Reports, 2011; pii: bcr092011477.
8. Dumont TM, Rughani AI, Goeckes T, Tranmer BI: Chronic subdural hematoma: a sentinel health event. World Neurosurg 80:889-892, 2013.
REFERENCES
15. Miranda LB, Braxton E, Hobbs J, Quigley MR: Chronic subdural hematoma in the elderly: not a benign disease. J Neurosurg 114:72-76, 2011.
9. Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, Gavaghan DJ, McQuay HJ: Assessing the quality of reports of randomized clinical trials: is blinding necessary? Controlled Clinical Trials 17:1-12, 1996.
16. Santarius T, Kirkpatrick PJ, Ganesan D, Chia HL, Jalloh I, Smielewski P, Richards HK, Marcus H, Parker RA, Price SJ, Kirollos RW, Pickard JD, Hutchinson PJ: Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet 374:1067-1073, 2009.
4. Cenic A, Bhandari M, Reddy K: Management of chronic subdural hematoma: a national survey and literature review. Can J Neurol Sci 32:501-506, 2005.
10. Javadi A, Amirjamshidi A, Aran S, Hosseini SH: A randomized controlled trial comparing the outcome of burr-hole irrigation with and without drainage in the treatment of chronic subdural hematoma: a preliminary report. World Neurosurg 75:731-736; discussion 620-733, 2011.
17. Santarius T, Kirkpatrick PJ, Kolias AG, Hutchinson PJ: Working toward rational and evidence-based treatment of chronic subdural hematoma. Clin Neurosurg 57:112-122, 2010.
5. Department of Health, HKSAR: Life expectancy at birth (male and female) 1971e2013. 2014; Centre for Health Protection, Department of Health, The Government of the Hong Kong Special Administrative Region. Available at: http://www.chp.gov. hk/en/data/4/10/27/111.html. Accessed September 2, 2014.
11. Kudo H, Kuwamura K, Izawa I, Sawa H, Tamaki N: Chronic subdural hematoma in elderly people: present status on Awaji Island and epidemiological prospect. Neurol Med Chir (Tokyo) 32:207-209, 1992.
18. Santarius T, Lawton R, Kirkpatrick PJ, Hutchinson PJ: The management of primary chronic subdural haematoma: a questionnaire survey of practice in the United Kingdom and the Republic of Ireland. Brit J Neurosurg 22:529-534, 2008.
12. Kwan MC, Sun DT, Poon WS: Types of postoperative drainage for chronic subdural hematoma: to do it on the table or under? World Neurosurg 77:51-52, 2012.
19. Sun TF, Boet R, Poon WS: Non-surgical primary treatment of chronic subdural haematoma: preliminary results of using dexamethasone. Brit J Neurosurg 19:327-333, 2005.
3. Bellut D, Woernle CM, Burkhardt JK, Kockro RA, Bertalanffy H, Krayenbuhl N: Subdural drainage versus subperiosteal drainage in burr-hole trepanation for symptomatic chronic subdural hematomas. World Neurosurg 77:111-118, 2012.
6. Cracknell R: The ageing population. 2010; House of Commons Library Research. Available at: http://www.parliament.uk/documents/commons/
1008
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.09.018
PERSPECTIVES
20. Tanaka Y, Ohno K: Chronic subdural hematoma—an up-to-date concept. J Med Dental Sci 60:55-61, 2013. 21. Department of Commerce, U.S.: The next four decades: the older population in the United States 2010 to 2050. U.S. Census Bureau. Available at: http://www.census.gov/prod/2010pubs/p25-1138.pdf. Accessed September 2, 2014. 22. Virchow R: The subdural hematomas [in German]. Verh Phys Med Ges Wurzburg 7: 134-142, 1857. 23. Wakai S, Hashimoto K, Watanabe N, Inoh S, Ochiai C, Nagai M: Efficacy of closed-system drainage in treating chronic subdural hematoma: a prospective comparative study. Neurosurgery 26: 771-773, 1990.
24. Wang D, Li T, Tian Y, Wang S, Jin C, Wei H, Quan W, Wang J, Chen J, Dong J, Jiang R, Zhang J: Effects of atorvastatin on chronic subdural hematoma: a preliminary report from three medical centers. J Neurol Sci 336:237-242, 2014. 25. Weigel R, Schmiedek P, Krauss JK: Outcome of contemporary surgery for chronic subdural haematoma: evidence-based review. J Neurol Neurosurg Psychiatry 74:937-943, 2003. 26. World Health Organisation: World health statistics 2013. Available at: http://www.who.int/ gho/publications/world_health_statistics/EN_WHS 2013_Full.pdf. Accessed September 2, 2014. 27. Zumofen D, Regli L, Levivier M, Krayenbuhl N: Chronic subdural hematomas treated by burr hole
WORLD NEUROSURGERY 82 [6]: 1007-1009, DECEMBER 2014
trepanation and a subperiostal drainage system. Neurosurgery 64:1116-1121; discussion 1121-1112, 2009.
David Yuen Chung Chan, Peter Yat Ming Woo are co-first authors. Citation: World Neurosurg. (2014) 82, 6:1007-1009. http://dx.doi.org/10.1016/j.wneu.2014.09.018 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2014 Elsevier Inc. All rights reserved.
www.WORLDNEUROSURGERY.org
1009
