Middle Meningeal Artery Embolization for Chronic Subdural Hematoma

Factors affecting the postoperative recurrence of chronic subdural hematomas (CSDHs) have not been sufficiently investigated. The authors have attempted to determine features of CSDHs that are associated with a high or low recurrence rate on the basis of the natural history of these lesions and their intracranial extension. One hundred six patients (82 men and 24 women) harboring 126 CSDHs who were treated at Tokyo Kosei Nenkin Hospital between January 1989 and April 1998 were studied. Types of CSDHs were classified according to hematoma density and internal architecture, and the intracranial extension of the hematomas were investigated. The postoperative recurrence rate was calculated for each factor. Based on the internal architecture and density of each hematoma, the CSDHs were classified into four types, including homogeneous, laminar, separated, and trabecular types. The recurrence rate associated with the separated type was high, whereas that associated with the trabecular type was low. Chronic subdural hematomas are believed to develop initially as the homogeneous type, after which they sometimes progress to the laminar type. A mature CSDH is represented by the separated stage and the hematoma eventually passes through the trabecular stage during absorption. Based on the intracranial extension of each hematoma, CSDHs were classified into three types, including convexity, cranial base, and interhemispheric types. The recurrence rate of cranial base CSDHs was high and that of convexity CSDHs was low. Classification of CSDHs according to the internal architecture and intracranial extension may be useful for predicting the risk of postoperative recurrence.

Although factorial trials have become common, standards for the analysis and reporting of such trials have not been established and, despite concerns about the possibility of unrecognized interactions between therapies in factorial trials, the magnitude of this potential problem is unknown. To examine the rationale, methods, and analysis of randomized factorial trials. We searched MEDLINE, EMBASE, and the Cochrane Controlled Trials Register using the terms factorial, interaction, 2 x 2, 2 by 2, and incremental to identify factorial randomized trials published from January 2000 to July 2002. To identify trials missed by the electronic search, we performed a hand search of English-language trials in a defined topic area (using the term myocardial ischemia [exp]) listed in MEDLINE (1966-2002), EMBASE (1980-2002), and the Cochrane Controlled Trials Register, as well as all trials in any topic area published in December 2000, excluding trials reporting only continuous surrogate end points. The final set of 33 eligible publications described 29 unique trials. Two investigators independently identified factorial trials, generated a list of items affecting validity of results, and abstracted these items from each trial. The sensitivity of electronic searching for identifying factorial trials was 76%. Our 3-pronged search strategy identified 44 factorial trials with clinically important binary outcomes: 36 (82%) were done for reasons of efficiency (testing 2 interventions in the same patient population), and 8 (18%) were done to assess the incremental benefits of combining the 2 treatments. All but 1 of the trials reported treatment effects by comparing all patients who received treatment A (ie, those receiving either A alone or both A and B) vs all those not receiving treatment A (ie, those receiving either B alone or neither A nor B). Twenty-nine of the 44 trials (66%) reported the data from each of the treatment groups separately; 26 trials (59%) reported testing for interactions between the treatments. Only 2 of 31 (6%) comparisons demonstrated a statistically significant interaction between the 2 treatments. Accurate interpretation of factorial trials depends on the transparent reporting of data for each treatment cell. Despite concerns about unrecognized interactions, our findings suggest that investigators are appropriately restricting their use of the factorial design to those situations in which 2 (or more) treatments do not have the potential for substantive interaction.

In this paper the authors systematically evaluate the results of different surgical procedures for chronic subdural hematoma (CSDH).