The Ethics Committee of the Affiliated Hospital of Guizhou Medical University approved this retrospective study. The study was performed based on the WMA Declaration of Helsinki. Patients with ICH admitted to our hospital who underwent sMIS were included in our study. The recruitment period was from January 1, 2018, to June 30, 2019.
Study design and participants
A retrospective analysis was performed. The authors aimed to determine whether initial CT blend signs were associated with poor functional outcome of patients with ICH following sMIS. We collected data from patients with ICH by reviewing the medical records of the Affiliated Hospital of Guizhou Medical University. The recruitment period was from January 1, 2018, to June 30, 2019. The patients were diagnosed using a baseline CT scan within 1 hour of admission, and surgery was performed within 27 hours of admission. The eligible patients with ICH were selected according to the inclusion criteria listed below. All eligible patients were treated by sMIS and were assigned to two groups based on their haematoma features.
The inclusion criteria were as follows: (1) patients over 18 years old with a history of hypertension or hypertension observed upon admission as well as symptoms and signs meeting the diagnostic criteria for ICH, which was confirmed using a nonenhanced CT scan; (2) patients who suffered from spontaneous ICH in the supratentorial area (the basal ganglia, thalamus or cerebral lobes); (3) patients with ICH volumes between 30 ml and 50 ml; (4) patients with no contraindications for surgery; and (4) the authorized representatives of the patients provided consent for surgery.
The exclusion criteria were the same as those in previously published studies12. Patients with ICH located in the brainstem or with secondary ICH from haemorrhagic transformation from brain infarction were not included. Patients without authorized representative consent to surgery were also excluded from the study.
From January 1, 2018, to June 30, 2019, a total of 710 patients with spontaneous ICH were admitted to the Affiliated Hospital of Guizhou Medical University. Among them, 318 patients underwent sMIS. Of the 318 patients who underwent sMIS, 25 left the hospital within one week without medical orders, 21 patients experienced ICH in the brainstem, and another 30 patients displayed large-volume (over 50 mL) ICH on CT. These 76 patients were not included in the final analysis (Fig. 1).
Based on the inclusion criteria, 242 consecutive patients with spontaneous ICH were included in the present study. All patients in the present study underwent sMIS. The patients were assigned to the following groups based on their CT haematoma features: the blend sign group included 91 patients, and the nonblend sign group (control group) included 151 patients with spontaneous ICH. The baseline clinical characteristics of the patients are listed in Table 1.
The initial and follow-up CT scans (General Electric Medical Systems, Milwaukee, WI) were performed using standard clinical parameters with axial 3-mm-thick sections, a current of 225 mA, a window level of 39 and a window width of 120. The images were obtained and stored for further evaluation. The ICH for each patient was located in the supratentorial area (including the basal ganglia, thalamus or cerebral lobes). Two experts (one neurosurgical expert and one neuroimaging expert) who were blinded to the clinical information served as reviewers and independently evaluated the shape features of the haematomas. The shape of the haematoma was assessed by visual inspection16. The blend sign was determined by the criteria proposed in previously published studies13. Briefly, the haematoma blend sign was defined as follows: (1) blending of a relatively hypoattenuating area with an adjacent hyperattenuating region within a haematoma; (2) presence of a well-defined margin between the hypoattenuating area and adjacent hyperattenuating region that is easily recognized by the naked eye; (3) the haematoma should have at least an 18 Hounsfield unit difference between the 2 density regions; and (4) the relatively hypoattenuating area was not encapsulated by the hyperattenuating region.
Discrepancies about the presence of the blend signs were settled by joint discussion between the readers.
Haematoma volumes were estimated based on CT using the ABC/2 formula (t=π/6×l×s×slice) 14. The criteria for identifying the blend sign were the same as those reported in the literature13. The blend sign was composed of two parts with different densities on CT (Fig. 2).
sMIS for ICH evacuation
The sMIS procedures for ICH evacuation were the same as those used in our previously published studies 19, 22, 23. To remove the influences of surgical technical factors on the outcomes, surgical procedures were performed by two experienced neurosurgeons. Briefly, a stereotactic instrument was fixed on the patient’s skull, and a repeated CT scan was performed for each patient prior to surgery. After the repeating CT scan was performed, the patient was transferred to the operating room. Using the CT scan, the coordinates of the ICH were determined, and we punctured the skull using a 3-mm-diameter needle (with a drill integrated into the needle guard) under the guidance of the stereotactic instrument. After the drill was replaced by a blunt-tip plastic needle core, the LY-1-type puncture-needle set was inserted slightly into the haematoma. Following removal of the plastic-needle core, the liquid part of the haematoma was aspirated using a 10-ml syringe (Fig. 3). The aspiration was stopped after the first resistance was encountered, and the needle guard connected to a plastic tube was retained for several days for drainage. The patients were transferred to the intensive care unit after removing the location framework and stereotactic apparatus. Then, 50,000 units of urokinase (diluted in 2 ml of normal saline) were injected slowly every 8 hours into the residual haematoma area to dissolve the solid part of the haematoma. The needle system was closed for 2 hours before reopening to allow spontaneous drainage. The first postoperative follow-up CT scan was performed on the day following surgery, and the second postoperative CT was performed on the third day after surgery. Some patients needed a third or even a fourth postoperative follow-up CT scan. If the patients showed neurological deterioration at any time after surgery, a repeated CT scan was performed.
All patients in our study received the same medical management based on the guidelines for the treatment of hypertensive ICH15. More comprehensive measures were also taken in all patients, including the prevention of deep-venous thrombosis (DVT), the control of temperature and blood glucose, nutritional support, and the prevention of other complications. The main measures used for preventing DVT were to move the paralysed limbs slowly and to wear socks. No anticoagulants were used to prevent DVT during the hospital stay because they might induce haemorrhage.
The primary functional outcome was a good functional outcome, defined as the proportion of patients who achieved a modified Rankin Scale (mRS) score of 0–3 at discharge. The mRS was conducted by neurological experts blinded to both the study and the imaging. The secondary outcomes included the National Institutes of Health Stroke Scale (NIHSS) scores, the Glasgow Coma Scale (GCS) scores and the ICH volume changes. The outcome was considered favourable if the mRS score was 0–3 points. In contrast, if the mRS score was >3 points, the outcome was considered poor4. The GCS and NIHSS scores were assessed upon admission and at one and two weeks after surgery by experienced neurological experts. Mortality and complications were recorded during the hospital stay and were compared between the two groups.
Some patients suffered from life-threatening complications during their hospital stays. Severe cardiopulmonary complications included severe pulmonary infection, respiratory failure, and heart failure. The cardiopulmonary complications were those that occurred during their hospital stay. Exacerbations of chronic heart failure and respiratory failure, as well as community-acquired pneumonia, were not included.
Postoperative rehaemorrhaging was defined as when the ICH (hyperdensity) reappeared in the haematoma region on the follow-up CT scan after it was removed completely following surgery12. An increase in the haematoma volume of >33%16 compared with the ICH volume determined by using the previous CT scan, which showed significantly decreased ICH volume after sMIS, was also considered a case of postoperative rehaemorrhage.
On the basis of the assumption that 25% of patients would have a mRS score of 0-3 in the blend sign group versus 45% of patients would have a mRS score of 0–3 following sMIS in the control group4, we estimated that 90 patients in each group would provide 81.0% statistical power at an α level of 0.05. The permissible error d was 0.1.
A commercially available software package (SPSS, Version 22.0) was used to perform the statistical analyses. Categorical data are expressed as proportions, and continuous variables are presented as the mean and SD. Demographic, clinical, and radiological characteristics were compared between patients with shape-regular or shape-irregular ICH using Student’s t tests (for normal distribution) or nonparametric tests (if the data were not normally distributed). A difference in the GCS and NIHSS scores between different time points was analysed using the method of repeated measures. A p value less than 0.05 was considered to indicate a statistically significant difference. The independent association between the initial CT blend sign and the outcome of patients after sMIS was evaluated using binary logistic regression. The interobserver reliability of the CT blend sign was assessed by calculating the κ values. The κ values were categorized as reported in the literature12. A κ value equal to 1 indicated total agreement between the observers.