Introduction
Hemangioblastomas are rare and vascular-rich benign tumors of the central nervous system that account for 2% of all intracranial tumors (1,2). Hemangioblastomas frequently occur in the posterior cranial fossa, most commonly in the cerebellum (3). Based on the radiological features examined by magnetic resonance imaging (MRI), most hemangioblastomas are classified into three categories: i) Large cysts with reinforcing cystic walls or small nodules, ii) a combination of solid and cystic features and iii) completely solid tumors (4,5). Despite the progressive development of neurosurgical techniques, surgical resection of solid hemangioblastomas remains a great challenge (6). How to reduce the risk of intraoperative hemorrhage, postoperative complications and high mortality remains a concern.
Recent advancements in imaging techniques and preoperative planning have improved the identification and characterization of hemangioblastomas, allowing for more precise surgical interventions (7,8). The integration of intraoperative MRI and neuronavigation systems has enhanced the surgeon's ability to achieve complete resection while minimizing damage to surrounding brain tissue (9,10). Additionally, the use of functional MRI and tractography has helped in preserving critical neurological functions by mapping out vital brain structures and their relationship to the tumor (11).
However, the highly vascular nature of these tumors continues to pose significant challenges, particularly in managing intraoperative bleeding (12). Preoperative embolization has been employed as a strategy to reduce intraoperative blood loss by decreasing the blood supply to the tumor (13). This technique, coupled with advanced anesthetic management and meticulous surgical techniques, has contributed to improved surgical outcomes (14).
Moreover, understanding the molecular and genetic underpinnings of hemangioblastomas has opened new avenues for targeted therapies (15). For instance, studies have identified mutations in the VHL gene associated with sporadic hemangioblastomas, suggesting potential therapeutic targets (16). The VHL protein plays a crucial role in regulating hypoxia-inducible factors (HIFs), and disruptions in this pathway can lead to tumor development (17). Targeted therapies aimed at this pathway are being explored, offering hope for non-surgical treatment options (18).
These advancements underscore the importance of a multidisciplinary approach, combining neurosurgery, neuro-oncology and genetics, to optimize patient outcomes (19). Collaborative efforts involving neurosurgeons, radiologists, pathologists and geneticists are essential in developing personalized treatment plans that address the unique characteristics of each tumor and patient (20).
Therefore, in the present study, the clinical data of patients with sporadic cerebellar hemangioblastoma were collected and retrospectively analyzed, including clinical characteristics, radiographic features, postoperative recurrence and prognosis, in order to determine the appropriate surgical treatment strategy for sporadic cerebellar hemangioblastoma. This comprehensive analysis aims to provide insight into improving surgical techniques, reducing complications and enhancing long-term prognosis for patients with this challenging condition. By identifying factors associated with favorable outcomes and potential complications, the study seeks to refine surgical approaches and inform clinical decision-making, ultimately leading to better management of sporadic cerebellar hemangioblastomas.
Discussion
Hemangioblastomas are benign tumors of the central nervous system that frequently occur in the posterior cranial fossa, particularly the cerebellum. Hemangioblastomas tend to be sporadic and the clinical presentation and treatment strategy differ from those of patients with combined VLH disease (23-25). In addition, the composition of the tumor has been reported to be an important factor affecting the postoperative prognosis of hemangioblastoma (5). Solid hemangioblastomas have a higher risk of intraoperative hemorrhage and postoperative complications compared to cystic hemangioblastomas (26). Studies have indicated that patients with solid hemangioblastoma have a worse prognosis than patients with cystic hemangioblastoma (26,27).
Due to the lack of characteristic clinical manifestations, CT and MRI examinations have become the main diagnostic methods for hemangioblastoma. According to the imaging features of sporadic cerebellar hemangioblastomas, it can be categorized into three types: Large cysts with reinforcing cystic walls or small nodules, a combination of solid and cystic, and completely solid tumors (5). Among them, the type of cyst with small nodules was the most common. Of the 76 cases included in the present study, 57 patients had cystic tumors confirmed by MIR imaging, accounting for 75.0% of all cases.
In the present study, the diameter of cystic hemangioblastomas was measured by combining the respective lengths of the cysts and nodules. Studies have indicated that the size of the tumor correlates with the clinical presentation of the patient (22,28). In the present study, the mean diameter of the lesion was 37.9±11.1 mm and it produced a significant mass effect in the posterior cranial fossa, leading to preoperative hydrocephalus. Among the 57 patients with cystic tumor, 16 patients presented with obstructive hydrocephalus, whose clinical symptoms included headache, vertigo, cerebellar ataxia and nausea or vomiting. In the present study, 54 cystic tumors were completely resected and the clinical symptoms of these patients improved significantly after surgery. A total of three cases of cystic tumors were partially resected and underwent postoperative radiotherapy; however, all of them recurred at different time-points. Therefore, it was concluded that in cases of cystic hemangioblastoma, complete resection significantly reduces the rate of tumor recurrence. Drainage of cystic fluid and removal of reinforcing tumor nodules have also been shown to be the most appropriate treatment for cystic hemangioblastoma (22). As long as the tumor can be completely removed, most patients' symptoms will remain stable or ameliorative (29). Failure to completely resect the tumor usually leads to tumor recurrence (30). Therefore, the present analysis suggests that complete resection of the tumor at the time of initial surgery is essential to reduce the incidence of tumor recurrence and complications.
In addition, the present study included four cystic cases, which showed large non-enhancing cysts and surrounding enhancing cystic walls on enhanced MRI scans. Since intraoperative pathology confirmed that the reinforcing walls of the cystic tumors also contained tumor tissue, it was ultimately decided to carefully separate the tumor walls from the surrounding brain tissue and resect them completely, while preserving the critical neurological functional areas surrounding the cystic tumors as much as possible. Previous studies have also reported that the resection strategy for such cystic cases should be modified and refer to the surgical access for solid tumors, and that all components of the tumor, including the wall nodules and the cyst itself, must be removed (4,31,32). In addition, because the significantly enhanced cystic tumor wall may be rich in capillaries, it has been suggested that preoperative needle aspiration biopsy should be avoided due to concerns about tumor hemorrhage (33,34). Therefore, it is vital in the surgical management of such cystic tumors to perform intraoperative pathology to determine clear tumor boundaries and thereby completely resect the enhanced cystic wall.
Solid hemangioblastomas show marked enhancement on MRI enhancement scans, which is the distinguishing imaging feature of solid cases. Therefore, the diagnosis of solid hemangioblastoma is not particularly difficult. However, the specific surgical treatment strategy for this type of tumor is still controversial.
Certain studies have argued that surgical outcomes for patients with solid hemangioblastomas are poor regardless of whether they have VHL or not (3,20). However, other studies have shown that surgical outcomes in patients with solid hemangioblastomas are not significantly different from those in cystic patients (35,36). In the present study, the majority of patients with solid hemangioblastomas achieved favorable clinical outcomes without serious complications or progression. Of the 11 patients with solid hemangioblastomas, 8 underwent endovascular embolization prior to surgical resection. During embolization, first, the primary tumor-supplying artery was carefully identified by multi-angle microangiography. Furthermore, it was ensured that the arteries selected for embolization would not affect the blood supply to important functional brain areas. The materials used for solid tumor embolization included a variety of substances, such as Onxy-18, flocculated sponge fragments and filament segments. Consistent with previous reports, we have made preliminary observations that the operative time for removal of solid hemangioblastoma was significantly shortened and intraoperative bleeding was more easily controlled after preoperative endovascular embolization (37). After several follow-ups, 8 cases were free of complications and recurrence. However, in three solid cases without preoperative endovascular embolization, postoperative cranial CT examination after complete tumor resection showed peripheral hemorrhage of 15-20 ml around the fourth ventricle. We believe that one of the most important reasons for the poor prognosis of these three patients may have been inadequate intraoperative hemostasis, which made intraoperative bleeding difficult to control in the absence of preoperative vascular embolization.
The safety and necessity of preoperative interventional embolization of solid hemangioblastomas is still controversial (35). Certain studies have shown that preoperative embolization is associated with high intracranial pressure and cerebral infarction (7,8). However, in the present study, eight patients with preoperative embolization had no serious complications. Of these patients, two developed mild postoperative headache, which gradually resolved the next day. During tumor resection, the numerous surgical techniques available appear to influence patient prognosis. First, the blood-supplying artery, the passing artery and the draining vein must be correctly determined. In general, the supplying artery and draining vein can be identified by looking at the vessel diameter, color, pulse or intraoperative ultrasound. In difficult cases, temporary closure clips are used to close the vessel to determine the nature of the vessel. If there is swelling of the tumor, it is a draining vein; otherwise, it is a supplying artery. In cases of solid tumor adjacent to the brainstem, separation of the tumor-brainstem interface is critical to the success of the procedure. Since there is often a thin layer of edematous brain tissue between the tumor and the brainstem, the tumor should be cauterized along the brain tissue interface with low-power bipolar electrocoagulation under neurophysiological monitoring and the operative field should be continuously irrigated to minimize heat conduction injury. Furthermore, the movements should be gentle so as to not cause brainstem displacement by excessive intraoperative pulling of the tumor. Most importantly, it was required to perform complete tumor resection instead of removing the tumor piece by piece, which could lead to intraoperative bleeding and unpredictable consequences. The conclusion of the present study is consistent with those of previous studies, namely that preoperative embolization of solid hemangioblastomas is safe and necessary, and complete tumor resection results in a good prognosis (37,38).
In the present study, there were only 76 patients. Next, multicenter case reports should be collected and a detailed prognostic analysis for each type of case should be performed.
In conclusion, total microsurgical resection is essential to improve the health status of patients with sporadic cerebellar cystic hemangioblastoma. In addition, as the safety of vascular intervention techniques continues to improve, preoperative embolization of arteries supplying solid hemangioblastomas can reduce intraoperative bleeding and improve prognosis.