Modified Computed Tomography Classification for Chronic Subdural Hematoma Features Good Interrater Agreement: A Single-Center Retrospective Cohort Study

Advances in chronic subdural hematoma and membrane imaging

Chronic subdural hematoma (cSDH) is projected to become the most common cranial neurosurgical disease by 2030. Despite medical and surgical management, recurrence rates remain high. Recently, middle meningeal artery embolization (MMAE) has emerged as a promising treatment; however, determinants of disease recurrence are not well understood, and developing novel radiographic biomarkers to assess hematomas and cSDH membranes remains an active area of research. In this narrative review, we summarize the current state-of-the-art for subdural hematoma and membrane imaging and discuss the potential role of MR and dual-energy CT imaging in predicting cSDH recurrence, surgical planning, and selecting patients for embolization treatment.

Time and Influencing Factors to Chronic Subdural Hematoma Resolution After Middle Meningeal Artery Embolization

OBJECTIVE

We sought to describe the resolution time of chronic subdural hematoma (CSDH) after middle meningeal artery embolization (MMAE) and potential variables that may affect hematoma resolution.

METHODS

A retrospective analysis was performed on CSDH patients between December 2018 and December 2021. Patient characteristics, radiologic manifestations, and data of hematoma resolution were recorded. Univariate and multivariate analyses were conducted to identify predictors of CSDH resolution time.

RESULTS

A total of 53 patients were enrolled including 53 hematomas. Only 1 participant relapsed and did not require surgical evacuation. Hematoma resolution was observed in 27 (50.9%) at 4 months and 48 (90.6%) cases at the last radiologic follow-up. The median MMAE-to-resolution time was 19 weeks (interquartile range: 8-24). The burr-hole irrigation + MMAE group showed faster hematoma resolution than MMAE alone during early follow-up periods, but no significant difference was found at 6 months. Increased thickness of residual hematoma, excessive postoperative midline shift, high-density hematoma, mixed-density hematoma, separated hematoma, and anticoagulant or antiplatelet agents used were predictive of nonresolution at 4 months as determined by univariate analysis, whereas anticoagulant or antiplatelet agents used and high-density hematoma were not significant on multivariate analysis. No significant association was noted between hematoma resolution and comorbidities or other hematoma radiologic features.

CONCLUSIONS

MMAE is an effective and minimally invasive treatment for CSDH with a lower recurrence rate. The median resolution time of CSDH following MMAE was 19 weeks (interquartile range: 8-24). Burr-hole irrigation contributed to early hematoma resolution but had no significant effect at 6 months. In addition, residual hematoma thickness, postoperative midline shift, and specific type of hematoma were associated with delayed hematoma resolution at 4 months.

Short-term follow-up pilot study of sole middle meningeal artery embolization for chronic subdural hematoma: influence of internal architecture on the radiological outcomes

PURPOSE

To identify prognostic factors with emphasis on chronic subdural hematoma (CSDH) architecture that determines short-term outcome of middle meningeal artery embolization (MMAE).

METHODS

Consecutive CSDH patients treated by MMAE (November 2019 and March 2022) were retrospectively analyzed. Four architectures were analyzed: homogeneous, laminar, separated, and trabecular types. Predictor variables from baseline CT were correlated with radiological endpoint (≥ 50% of hematoma volume reduction), time to reach the endpoint, and rate of volume reduction.

RESULTS

Study included 50 patients with 56 CSDHs (median age [first quartile, Q1; third quartile, Q3] 70.5 [60, 78.3] years; 36 were men). Separated type reached the endpoint at a lower rate on both bivariate (p = 0.02) and multivariate Cox model (0.034). Kaplan-Meier curves demonstrated that the median [Q1, Q3] time for 50% of the hematomas to reach the endpoint was 5 [4, 8], 4 [3, 5], 15 [15, 15], and 11 [4, 19] weeks for homogeneous, laminar, separated, and trabecular types, respectively. Linear mixed-effect model demonstrated a significant variation in the slope of hematoma volume reduction that was - 4.16 (95% confidence interval [CI] - 5.4, - 2.9), - 6.7 (95% CI - 8.35, - 5.1), - 2.03 (95% CI - 4.14, 0.08), and - 5.06 (95% CI - 6.8, - 3.32) ml per week for homogeneous, laminar, separated, and trabecular subtypes, respectively.

CONCLUSION

Separated CSDH is a poor prognostic type in achieving radiological endpoint and a slower rate of volume reduction. While, homogeneous and laminar types reached the endpoint faster than separated and trabecular types on short-term follow-up.

Development and validation of a recurrent prediction model for patients with unilateral chronic subdural hematoma without hematoma volumetric analysis

OBJECTIVE

Approximately 10 % of patients with chronic subdural hematoma (CSDH) undergo reoperation after initial surgery. This study aimed to develop a predictive model for the recurrence of unilateral CSDH at initial surgery without hematoma volumetric analysis.

METHODS

This single-center retrospective cohort study evaluated pre- and postoperative computed tomography (CT) images of patients with unilateral CSDH. The pre- and postoperative midline shift (MLS), residual hematoma thickness, and subdural cavity thickness (SCT) were measured. CT images were classified based on the internal architecture of the hematoma (homogenous, laminar, trabecular, separated, and gradation subtypes).

RESULTS

Total 231 patients with unilateral CSDH underwent burr hole craniostomy. After receiver operating characteristic analysis, preoperative MLS and postoperative SCT showed better areas under the curve (AUCs) (0.684 and 0.756, respectively). According to the CT classification of preoperative hematomas, the recurrence rate was significantly higher in the separated/gradation group (18/97, 18.6 %) than in the homogenous/laminar/trabecular group (10/134, 7.5 %). Four-point score was derived from the multivariate model using the preoperative MLS, postoperative SCT, and CT classification. The AUC of this model was 0.796, and the recurrence rates at 0-4 points were 1.7 %, 3.2 %, 13.3 %, 25.0 %, and 35.7 %, respectively.

CONCLUSION

Pre- and postoperative CT findings without hematoma volumetric analysis may predict CSDH recurrence.

Endoscopically observed outer membrane of chronic subdural hematoma after endovascular embolization of middle meningeal artery

Background:

Embolization of the middle meningeal artery (MMA) has been established for chronic subdural hematoma (CSDH). Neuroendoscopic observation of the outer membrane of the hematoma was carried out after embolization. The treatment mechanism of embolization is discussed, focusing on the vasculature and inflammation of the membrane.

Methods:

Four patients with recurrent CSDH were included in this study. The MMA was embolized using Embosphere® particles in three patients. The outer membrane was observed with normal and narrow band images (NBIs).

Results:

The net-like vessels were not obstructed in the whole area of the outer membrane, but in a patchy fashion of embolized areas surrounded by nonembolized areas. In two patients, the nonembolized areas showed a hemorrhagic inflammatory red color. Histopathological examination confirmed hypertrophic dura with leukocyte infiltration. Dilated dural arteries and proliferated sinusoid arteries were located in the deep and superficial border cell layers. These arteries were visualized as green and brown on NBI, respectively. In the embolized area, the red membrane turned pink, indicating ischemia and subsiding inflammatory hyperemia. In the third patient, the outer membrane was white in both the nonembolized and embolized areas in endoscopic view, and the net-like vessels were sparse in both endoscopy and histology, indicating a scar inflammatory phase. The membrane transition was not observed in the patient that did not undergo embolization.

Conclusion:

Endoscopic observation revealed that embolization of the MMA blocked both the dural and sinusoidal arteries. Ischemic transformation causing the suppression of inflammation of the outer membrane is a suggested mechanism of MMA embolization.

Morphological changes in chronic subdural hematomas following upfront middle meningeal artery embolization: sequence, timing, and association with outcomes

OBJECTIVE

Middle meningeal artery embolization (MMAE) is an increasingly utilized approach for the treatment of chronic subdural hematomas (CSDHs). The course of morphological progression of CSDHs following MMAE is poorly understood. Herein, the authors aimed to describe these morphological changes and assess their prognostic significance for the outcomes on follow-up.

METHODS

A single-institution retrospective cohort study of CSDH cases treated by upfront MMAE, without prior or adjunctive surgical evacuation, was performed. Clinical outcomes, complications, and the need for rescue surgery on follow-up were recorded. Hematomas were categorized into 6 morphological subtypes. All baseline and follow-up head CT scans were assessed for CSDH structural appearance, density, and loculation. Changes in CSDH size were quantified via 3D reconstruction for volumetric measurement.

RESULTS

Overall, 52 CSDHs in 45 patients treated with upfront MMAE were identified. Hematomas were followed for a mean of 92.9 days. Volume decreased by ≥ 50% in 79.6% of the CSDHs. The overall rescue surgery rate was 9.6%. A sequence of morphological changes after MMAE was identified. Hematomas that diverged from this sequence (5.4%) all progressed toward treatment failure and required rescue surgery. The CSDHs were categorized into early, intermediate, and late stages based on the baseline morphological appearance. Progression from early to intermediate and then to late stage took 12.7 and 30.0 days, respectively, on average. The volume of early/intermediate- and late-stage hematomas decreased by ≥ 50%, a mean of 78.2 and 47.6 days after MMAE, respectively. Early- and intermediate-stage hematomas showed a trend toward more favorable outcomes compared with late-stage hematomas. The density of homogeneous hypodense hematomas (HSDHs) transiently increased immediately after MMAE (p < 0.001). A marked decrease in density and volume 1 to 3 weeks after MMAE in HSDHs was detected, the lack of which indicated an eventual need for rescue surgery. In HSDHs, a baseline mean density of < 20 HU, and a lower density than baseline by 1 month post-MMAE were predictors of favorable outcomes. The baseline hematoma volume, axial thickness, midline shift, and loculation were not correlated with MMAE outcomes. Loculated, trabecular, and laminar hematomas, which are known to have unfavorable surgical outcomes, had MMAE outcomes similar to those of other "surgical" hematomas.

CONCLUSIONS

The current study was the first to describe the nature, sequence, and timing of morphological changes of CSDHs after MMAE treatment and has identified structural features that can predict treatment outcomes.

Risk factors of recurrence in chronic subdural hematoma and a proposed extended classification of internal architecture as a predictor of recurrence

Chronic subdural hematomas (cSDHs) constitute one of the most prevalent intracranial disease entities requiring surgical treatment. Although mostly taking a benign course, recurrence after treatment is common and associated with additional morbidity and costs. Aim of this study was to develop hematoma-specific characteristics associated with risk of recurrence. All consecutive patients treated for cSDH in a single university hospital between 2015 and 2019 were retrospectively considered for inclusion. Size, volume, and midline shift were noted alongside relevant patient-specific factors. We applied an extended morphological classification system based on internal architecture in CT imaging consisting of eight hematoma subtypes. A logistic regression model was used to assess the classification’s performance on predicting hematoma recurrence. Recurrence was observed in 122 (32.0%) of 381 included patients. Apart from postoperative depressed brain volume (OR 1.005; 95% CI 1.000 to 1.010; p = 0.048), neither demographic nor factors related to patient comorbidity affected recurrence. The extended hematoma classification was identified as a significant predictor of recurrence (OR 1.518; 95% CI 1.275 to 1.808; p < 0.001). The highest recurrence rates were observed in hematomas of the homogenous (isodense: 41.4%; hypodense: 45.0%) and sedimented (50.0%) types. Our results support that internal architecture subtypes might represent stages in the natural history of chronic subdural hematoma. Detection and treatment at a later stage of spontaneous repair can result in a reduced risk of recurrence. Based on their high risk of recurrence, we advocate follow-up after treatment of sedimented and homogenous hematomas.

External validation of prognostic models predicting outcome after chronic subdural hematoma

BACKGROUND

Several prognostic models for outcomes after chronic subdural hematoma (CSDH) treatment have been published in recent years. However, these models are not sufficiently validated for use in daily clinical practice. We aimed to assess the performance of existing prediction models for outcomes in patients diagnosed with CSDH.

METHODS

We systematically searched relevant literature databases up to February 2021 to identify prognostic models for outcome prediction in patients diagnosed with CSDH. For the external validation of prognostic models, we used a retrospective database, containing data of 2384 patients from three Dutch regions. Prognostic models were included if they predicted either mortality, hematoma recurrence, functional outcome, or quality of life. Models were excluded when predictors were absent in our database or available for < 150 patients in our database. We assessed calibration, and discrimination (quantified by the concordance index C) of the included prognostic models in our retrospective database.

RESULTS

We identified 1680 original publications of which 1656 were excluded based on title or abstract, mostly because they did not concern CSDH or did not define a prognostic model. Out of 18 identified models, three could be externally validated in our retrospective database: a model for 30-day mortality in 1656 patients, a model for 2 months, and another for 3-month hematoma recurrence both in 1733 patients. The models overestimated the proportion of patients with these outcomes by 11% (15% predicted vs. 4% observed), 1% (10% vs. 9%), and 2% (11% vs. 9%), respectively. Their discriminative ability was poor to modest (C of 0.70 [0.63-0.77]; 0.46 [0.35-0.56]; 0.59 [0.51-0.66], respectively).

CONCLUSIONS

None of the examined models showed good predictive performance for outcomes after CSDH treatment in our dataset. This study confirms the difficulty in predicting outcomes after CSDH and emphasizes the heterogeneity of CSDH patients. The importance of developing high-quality models by using unified predictors and relevant outcome measures and appropriate modeling strategies is warranted.

Derivation of a Clinical Score for Prediction of Recurrence Following Evacuation of Chronic Subdural Hematoma: A Retrospective Cohort Study at a National Referral Centre

BACKGROUND

Chronic subdural hematoma (cSDH) is a common pathology, and recurrence is a common complication, which may be predicted by certain patient and radiologic factors. Empiric radiologic surveillance has been shown to convey no benefit.

METHODS

A retrospective review of a prospectively collated database was performed. Preoperative and postoperative noncontrast computed tomography scans were reviewed. Radiologic appearance, preoperative hematoma volume, patient age, presence of bilateral hematomas, maximal hematoma thickness, and therapeutic coagulopathy were assessed as predictors. Receiver operating characteristic curve analysis, logistic regression, and LASSO regression were used to select potential predictors. A multivariate model was then fitted, and a score was derived.

RESULTS

A total of 142 patients were included. Maximal hematoma thickness >12 mm (P = 0.02) and age >65 years (P = 0.01) were found to correlate with the likelihood of recurrence. Bilateral hematomas and a hyperdense or mixed density appearance were also identified on LASSO regression. Bilateral hematomas (P = 0.19), hyperdense or mixed density (P = 0.66), maximum thickness >12 mm (P = 0.01), and age >65 years (P = 0.02) were included in the multivariate model. A 6-point score was derived. A score of >3 had a sensitivity of 89% (95% confidence interval [CI] 78%-97%) and specificity of 26% (95% CI, 17%-34%) for predicting recurrence, with recurrence significantly more likely in patients with a score of 4-6 versus those with a score of 0-3 (P = 0.02).

CONCLUSIONS

Certain radiologic findings may predict the recurrence of cSDH following evacuation. The score derived may be useful in identifying patients who might benefit from routine postoperative surveillance imaging.