There is no current consensus on the optimal placement of EVD during LVT resection surgery. Placement of a prophylactic EVD is used to drain residual hematoma clots and bloody CSF, as well as to monitor and regulate intracranial pressure. Drainage placement can also prevent intracranial hypertension caused by acute hydrocephalus. Intraoperative EVD placement is most convenient for surgeons because the tube can be placed through the surgical channel. By contrast, for patients without prophylactic EVD who develop acute hydrocephalus after resection, the ventricular puncture site for EVD placement is selected in the emergency unit, which increases the risks of brain injury and other morbidities. Nevertheless, there are still risks of intraoperative EVD placement, including intracranial infection, increased risk of CSF leakage, and potential risk of excessive drainage. The aim of the present study was to identify patients at high-risk of acute hydrocephalus after LVT surgery for guidance of prophylactic EVD placement and to analyse the risk factors for post-resection VP-shunt placement.
To the best of our knowledge ,this regression analysis is the first to identify the characteristics of tumor location and other risk factors for hydrocephalus after LVT resection. We found that tumor invasion of the anterior part of the ventricle was an independent risk factor for postoperative EVD caused by acute symptomatic hydrocephalus. Deling et al. reported that hydrocephalus tends to develop after an LVT resection in which the tumor basement is located at the lateral ventricular wall, dorsal thalamus, choroid plexus,or third ventricle (near the foramen of Monro)(6), although statistical confirmation was not performed. Anatomically, the posterior internal choroid artery expands radially through the foramen of Monro and is the main blood supply vessel of the anterior part of the ventricle(21). Dring resection of tumors located in or invading the anterior part of the lateral ventricle, damage to these branching vessels may increase brain tissue swelling around the midbrain aqueduct after surgery, thereby narrowing the CSF pathway. For tumors invading the anterior ventricle wall or the aqueduct of the lateral ventricle, postoperative tissue adhesion may cause obstruction(22). Ktari, O et al. reported that postoperative obstructive hydrocephalus can be caused by displacement of intraventricular hemostatic materials and the inflammatory reaction associated with Gelfoam residue, with a surrounding marked giant cell reaction with underlying fibrosis, thrombosis of small superficial vessels, and reactive microglial(14).
In the present study, postoperative hemorrhage was also an independent risk factor for postoperative EVD caused by acute symptomatic hydrocephalus. Postoperative hemorrhage is a serious complication of LVT surgery. which typically manifests as intraventricular hemorrhage, while approximately 50% of intraventricular hemorrhage patients develop hydrocephalus(3, 11). Importantly, blood can stimulates the production of CSF(22), while the mass effect of the hematoma can obstruct the CSF pathway and cause symptoms of intracranial hypertension, which requires emergency CSF drainage(4, 9).
We found that incomplete resection was not a risk factor for postoperative EVD. Clinically, complete tumor resection is the main surgical goal. However, some LVTs are difficult to completely resect because of their extensive blood supply, unclear boundaries, or tight adhesion with normal brain tissue. To protect normal brain tissue and blood vessels and avoid severe postoperative intracranial edema and intracranial hypertension, our typical surgical goal is to achieve decompression and improve CSF circulation(18). Although residual tumors are a cause of recurrence, slow-growing tumors do not generally cause acute intraranial hypertension. For patients with incomplete resection, regular follow-up and review are required. If necessary, a secondary surgery or VP-shunt placement can be performed.
In the present study, presence of a malignant tumor was the only independent risk factor for VP-shunt placement after LVT surgery. Of the eleven patients with a VP-shunt, ten had a malignant tumor. For patients with subtentorial ventricle tumors, pediatric patients have a higher incidence of malignant tumors (e.g., medulloblastoma) and a higher rate of post-resection hydrocephalus(1, 13, 15, 24). The types and corresponding basements of supratentorial LVTs tend to differ with age. For example, choroid plexus papilloma, ependymoma, and central neurocytoma mainly occur in pediatric and juvenile people, and are mostly benign. By contrast, meningiomas and gliomas are most common in adults. Malignant tumors may impair CSF absorption because of leptomeningeal metastases at the subarachnoid level and the high CSF protein content produced by disseminated tumor cells(2, 17, 20). The high invasiveness of malignant tumors makes them difficult to resect. Thus, they can rapidly relapse after surgery to produce a mass effect and cause obstructive hydrocephalus. Interestingly, patients with radiation-induced brain atrophy can exhibit mildly elevated CSF pressure because of impaired CSF flow and reduced reabsorption caused by fibrosis of the arachnoid granulations(23). A VP-shunt is an alternative treatment for recurrent malignant LVT with symptomatic hydrocephalus.
In the present study, two patients with LVTs located at the occipital angle of the lateral ventricle developed isolated hydrocephalus after resection- one patient had a glioblastoma that was difficult to completely resect. while the other patient with complete resection showed brain tissue still adherence and postoperative obstruction. Ma et al. reported that excessive CSF loss by ventricular drainage can cause intracranial hemorrhage and ventricular wall adhesion, increasing the risk of localized hydrocephalus(18). However, the meningioma patient in that study did not receive EVD during surgery. Based on preoperative and postoperative MRI findings, we considered that this was related to the ventricle morphology around the tumor. The tumor with a large preoperative volume expanded the local ventricle and surrounding brain tissues, while the ventricular opening around the tumor was relatively narrow. After removal of the mass effect caused by the tumor, the surrounding brain tissue collapsed. The wide basement of the tumor resulted in a large surgical area in the ventricle, which aggravated postoperative peritumor brain tissue edema, leading to compression and adhesion of the narrow part of the ventricle and development of isolated hydrocephalus. For such wrapped tumors, we suggest timely postoperative imaging examination and enhanced dehydration treatment. We also recommend that the distal end of the shunt tube be placed across the ventricle stenosis, with particular attention paid to postoperative management of EVD to maintain ideal intracranial pressure.