JSUR Journal

Introduction

First introduced by Werner Hacke in 1996, Malignant Middle Cerebral Artery (MCA) infarction is a term used to describe a space-occupying mass effect resulting from cerebral edema following MCA infarction. [1] Patients with malignant MCA infarction typically have a poor prognosis, high mortality rate, and poor quality of life. [2] Therefore, early diagnosis and aggressive therapy, including decompressive surgery, are essential to reduce brain herniation and subsequent brainstem compression [3]. Decompressive Craniectomy (DC) is typically performed in patients with large cerebral infarctions. Multiple large-scale, multicenter, randomized, prospective studies have indicated the benefits of DC in patients with malignant MCA infarction. [4-6] Long-term benefits have also been documented at 3-year followup. [7] Generally, performing decompressive surgery within 48 h of stroke onset reduces the mortality rate and improves patients’ functional outcomes. [8] Ultra-early DC before neurological deterioration also improves the neurological sequelae of patients with malignant MCA infarction. For instance, in patients who underwent DC within 6 h of symptom onset, low rates of mortality, vegetative state, and severe disability were observed. [9] Strokectomy refers to the partial resection of an infarcted brain tissue. It is performed either as an adjuvant procedure to DC or as a standalone surgical alternative. Strokectomy alleviates cerebral edema and enables the immediate replacement of the cranial bone. However, the resected tissue may progressively cause subsequent edema. Therefore, the necessity of strokectomy has long been debated. In addition, strokectomy has not been frequently performed, and malignant MCA infarctions are uncommon. Therefore, few cases requiring strokectomy for malignant MCA infarction have been reported in the literature. [10] In a retrospective study, Kostov et al. [11] reported similar neurological outcomes between patients who underwent strokectomy alone and patients who underwent DC alone. Nevertheless, the benefits of strokectomy in terms of overall survival and neurological outcomes have remained controversial [12].

In this study, we investigated the potential benefits of strokectomy and DC for patients with malignant MCA infarction. We reviewed the data of 27 patients with malignant MCA infarction, of whom 9 underwent DC alone (DC alone group) and 18 underwent a combination of DC and strokectomy (DC+S group).

Materials and Methods

Study Design

This retrospective study was conducted at a single hospital in Taiwan (National Taiwan University Hospital). All patients who underwent craniectomies for malignant MCA infarction from January 2003 to December 2022 were included in the study, and their data were reviewed. The study protocol was approved by the Institutional Review Board of National Taiwan University Hospital (202011049RINC). Clinical records, imaging data, outcome scores, and neurological symptoms were analyzed. In addition, the clinical outcomes, mainly the modified Rankin scale (mRS) score at 3-month follow-up, and mortality rates of the DC+S group were compared to those of the DC only group. Patients with bilateral hemisphere infarctions were excluded from the study.

Surgical Procedure

At our institute, all patients with MCA infarction, regardless of whether they have undergone thrombolytic agent therapy, intraarterial thrombectomy, or both, are admitted to the Neurology Intensive Care Unit. Discussion pertaining to aggressive treatment is then held by unit staff with the patient and their family. If the patient agrees to undergo aggressive treatment, their dosage of dual antiplatelet agents is reduced to enable possible surgical intervention. Other medications, such as mannitol, glycerol, and hypertonic saline, are administered in accordance with established guidelines. [3,13-20] Once malignant MCA infarction with uncal herniation is radiologically confirmed, often through emergent Computed Tomography (CT), a neurosurgeon is informed, and emergent surgery is arranged. As a standard surgical procedure, DC is performed on the ipsilateral side of the malignant MCA infarction. A reversed question-mark incision is made, starting anteriorly to the tragus, extending posteriorly and rostrally, and turning anteriorly until the frontal hairline. A large craniotomy window is used to cover the entire MCA region. The dura is then opened in either a C-shape or cruciate manner and reflected. Ischemic tissue is identified as nonviable blanched brain tissue that is swollen with no clear pulsation. [21] Subsequently, subpial resection is performed using suction and bipolar forceps. Because infarcted brain tissue exhibits marked cytotoxic edema and undergoes liquefactive necrosis, this tissue is easy to remove with suction without disturbing viable brain parenchyma. Dura augmentation is then performed using either an autologous fascia graft or dura substitutes, and an Intracranial Pressure (ICP) monitor is placed at the subdural space. A skull graft is preserved in a tissue bank at our institute. For better decompression, the temporalis muscle is often resected. After surgery, the patient is transferred to the Intensive Care Unit (ICU), and a CT scan is performed within 48 h of surgery or as clinically required. ICP data are collected using a Philips IntelliSpace Critical Care and Anesthesia critical care information system and recorded on an hourly basis. A total of 24 ICP values are collected every day. The highest value is recorded and converted into daily-based ICP data.

Figure 1 shows the case of malignant right MCA infarction in a 52-year-old man. Although emergent intra-arterial thrombectomy was performed, progressive brain swelling with a midline shift was observed. Therefore, emergent DC without strokectomy was performed 24 h after the onset of stroke. However, the patient’s ICP increased, and bedside sonography revealed an increased pulsatility index with enlarged hemorrhagic transformation. Follow-up brain CT also revealed progressive brain edema with an increased midline shift (Figure 1B). Therefore, right frontotemporoparietal strokectomy was performed. Follow-up brain CT revealed complete correction of the midline shift (Figure 1C). The patient remained clearly conscious on poststrokectomy day 1 and was extubated on poststrokectomy day 12.

Figure 1: Malignant right MCA infarction in a 52-year-old man. (A) At initial presentation, axial CT revealed a right dense MCA sign. (B) After emergent DC without strokectomy, follow-up brain CT revealed progressive brain edema with an increased midline shift. (C) After the patient underwent a right strokectomy, follow-up brain CT revealed complete correction of the midline shift.

Outcome Measurement and Statistical Analysis

Patient outcomes were measured using the mRS both preoperatively and 3 months postoperatively. All statistical analyses were conducted using SAS software version 9.4 (SAS Institute, Cary, NC, USA). Two-tailed Student’s t tests were used for metric variables, Mann-Whitney U test was used for ordinal variables, and Fisher’s exact test was used for categorical variables. A P value less than .05 was considered statistically significant. Patients with missing data of 1 variable were excluded only from the corresponding statistical analysis but not from the entire study.

Results

A total of 31 patients with MCA infarction underwent DCs at National Taiwan University Hospital from 2003 to 2022. Only 1 patient with M2 territory infarction and hemorrhagic transformation did not meet the criteria for malignant MCA infarction. Specifically, this patient had a final Alberta Stroke Program Early CT Score (ASPECTS) of 6 on noncontrast brain CT and a minimal midline shift. Therefore, this patient was excluded from the study. Another 3 patients with bilateral hemisphere infarction were excluded from the study (Figure 2). A total of 27 patients were included in this study, of whom 18 underwent a combination of DC and strokectomy (DC+S group) and 9 underwent DC alone (DC alone group). Table 1 presents a summary of the patients’ clinical characteristics. The mean age of the strokectomy group was significantly lower than that of the control group (58.1 vs. 68.9, P = .02). However, no difference was observed between the 2 groups in terms of gender, infarction side, initial National Institutes of Health Stroke Scale (NIHSS) score (24.6 vs. 25.4), or ASPECTS (0 vs. 0) on noncontrast CT. Compared with the control group, the number of patients who underwent thrombolytic therapy and intra-arterial thrombectomy was higher in the strokectomy group.

Figure 2: Flowchart of patients included in the study.

*denoted p<0.05. **denoted p<0.01. F:female. IA:intra-arterial. L:left. M:male. mRS:modified Rankin scale. R:right. rtPA: recombinant tissue plasminogen activator.

Table 1: Characteristics and comparison between patients who underwent decompressive craniectomies alone (DC alone) and decompressive craniectomies + strokectomy (DC+S).

Figure 3 shows the primary mRS outcomes at 3 months of follow-up. In the DC+S group, 3 patients had an mRS score of 3, 8 patients had an mRS score of 4, and 7 patients had an mRS score of 5. In the DC alone group, 3 patients had an mRS score of 4, 3 patients had an mRS score of 5, and 3 patients had an mRS score of 6. Mann–Whitney U test revealed a statistically significant difference between the 2 groups (P = .0425). When the 2 groups were dichotomized into either favorable outcomes (mRS score ≤3) or unfavorable outcomes (mRS score >3), no statistical significance was observed (3/15 vs. 0/9). Similarly, when the 2 groups were dichotomized into either severe disability (mRS score >4) or moderate disability (mRS score ≤4), no significant difference was observed (7/11 vs. 6/3). In the DC alone group, 1 patient had central nervous system (CNS) infection, but the results were not significantly different. In the DC+S group, 2 patients had shunt-dependent hydrocephalus, but the results were also nonsignificant.