Original ArticleOpening the Internal Hematoma Membrane Does Not Alter the Recurrence Rate of Chronic Subdural Hematomas: A Prospective Randomized Trial
Introduction
Chronic subdural hematoma (CSDH) is a common condition with a reported annual incidence of 3–5.4 per 100,000 people,1, 2 characterized by the formation of neomembranes within the subdural space that enclose a liquefied hematoma.3, 4, 5, 6 Membranes usually consist of a thicker and highly vascularized outer neomembrane and a thinner inner neomembrane.6, 7, 8, 9 CSDHs are typically seen in the later stages of life1, 7, 10, 11, 12 and often in multimorbid patients.
Techniques proposed for hematoma evacuation in symptomatic patients6 include bedside twist-drill craniotomy, burr-hole craniotomy, or minicraniotomy and drainage of the hematoma blinded, under sight, or aided by an endoscope.11, 13 Large craniotomies with complete resection of hematoma membranes are usually reserved for patients with multiple membranes and recurrent hematomas.14, 15 Although it has been the subject of much debate, a recent prospective trial strongly favored the insertion of continuous closed-system drainage into the subdural space for some days after hematoma evacuation.16
Surgical evacuation is considered to be a minimally invasive procedure. Nevertheless, mortality ranges from 0% to 6% and morbidity from 0% to 76%.1 Recurrence rate after surgery of 0.35%–33% has been reported.2, 8, 10, 17 Risk factors for recurrence include a thick subdural membrane on contrast-enhanced computed tomography (CT),7 advanced age,17 coagulation disorders,17 bilateral haematomas,17 brain atrophy,17 postoperative subdural air accumulation,17 and early removal of subdural drainage.17
One factor considered pivotal for hematoma recurrence is the failure of the brain to fill the dead space resulting from hematoma evacuation in the mostly elderly population. Techniques to facilitate brain expansion include lumbar puncture and intrathecal instillation of artificial cerebrospinal fluid6, 18, 19 or replacement of hematoma with oxygen after subdural tapping,20, 21 postoperative avoidance of head elevation for the first days after hematoma drainage,17, 22 and to open the internal hematoma membrane in a radiate fashion during enlarged twist-drill craniotomy.23
The goal of our prospective randomized study was to analyze whether partial opening of the inner hematoma membrane influences the recurrence rate in patients undergoing enlarged burr-hole craniotomy for CSDH.
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Ethical Issues
All patients gave informed consent to participate in the study. The study protocol was approved by the ethics committee of the Innsbruck Medical University (UN 3065, SN 258/4.6).
Study Design
The study was conducted as a prospective, randomized, blinded trial at the Neurosurgical Department of Innsbruck Medical University between February 2008 and January 2010. The ethics committee allowed inclusion only of patients able to give fully informed consent into this study.
Patient Characteristics
We consecutively enrolled 52 eligible
Results
One patient randomized to group A was lost to follow-up and excluded from the analysis.
Fourteen patients underwent reoperation for clinical deterioration or residual hematoma during follow-up (n = 6 in group A [21%]; n = 8 in group B [28 %]). The number of reinterventions was not statistically different between both groups (P = 0.537).
Residual hematoma of ≥ one third not requiring surgery was present in 7 patients in group A (25%) and 10 patients in group B (36%) (P = 0.383) (see Table 3).
The
Discussion
The results of this study show that opening the internal hematoma membrane does not alter the rate of patients requiring revision surgery and the number of patients showing a marked residual hematoma within the first 6 weeks after evacuation of a CSDH. Opening of the internal hematoma membrane was not associated with a higher number of postoperative CT scans or increased postoperative outpatient visits.
After evacuation of a CSDH, patients are left with a dead space of different depth that is
Acknowledgments
We would like to thank Klaus Twerdy for allowing this study. We also thank Pujan Kavakebi, Jürgen Volker Anton, Richard Bauer, Nadja Loinig, and Emrah Akartuna for their intensive cooperation in the execution of the study.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.