Longitudinal Pulse-Synchronous Bouncing During Catheter Angiography-A Phenomenon Specific to Spinal Hemangioblastomas.

BACKGROUND: Spinal hemangioblastomas are often evaluated with catheter angiography for both workup and treatment planning. We report a unique longitudinal pulse-synchronous bouncing phenomenon observed during their angiographic evaluation and consider the association of pulse-synchronous bouncing with syringomyelia, another pathologic feature associated with hemangioblastomas. METHODS: Preoperative spinal angiograms and associated magnetic resonance imagings (MRIs) obtained over a 16-year period at a single institution were retrospectively evaluated. Magnetic resonance imaging (MRI) parameters included lesion and syrinx location and size. Angiograms were evaluated for bouncing phenomena. Student's t-test and Chi square test compared characteristics between groups. Linear regression analyses evaluated maximum amplitude of dynamic motion and any associated syrinx. RESULTS: Nineteen hemangioblastoma patients had preoperative angiograms available for review. Eight exhibited bouncing behavior. Between the dynamic and nondynamic cohorts, there was no difference in presence or volume of syrinxes. Lesions in the dynamic cohort trended towards a cervical location (75% vs. 36.3%, P = 0.10). No significant correlation was found between bouncing amplitude and syrinx size (R2 = 0.023). Dural contact may be related to this dynamic behavior since other high-flow lesions like AVMs do not demonstrate this phenomenon, and AVMs are pial-based and more likely to contact stationary dura. Here, there were fewer lesions abutting the thecal sac in the dynamic cohort (50% vs. 81.8%, P = 0.14). CONCLUSIONS: Though no significant relationship was established between this bouncing behavior and syrinx formation, noted trends included a greater range of motion for cervical lesions and limited motion in tumors abutting the thecal sac.

Prognostic Factors of Spinal Intramedullary Hemangioblastoma : Analysis of Surgical Outcomes and Tumor Characteristics.

Objective: Spinal intramedullary hemangioblastoma is a rare and highly vascularized benign tumor. The characteristics of the tumor, its corresponding location, and surgical outcomes remain unknown. The purpose of this study was to identify risk factors and strategies for neurologic deterioration following hemangioblastoma surgery. Methods: A comprehensive retrospective analysis was undertaken to evaluate patients who underwent surgical intervention for intramedullary hemangioblastoma at our institution from 1993 to 2022. Patients with at least one year of follow-up data were included. The analysis covered patient demographics, pre- and post-operative Modified McCormick Scale (MMCS), tumor location, and tumor size. Results: This study included 25 cases. One-year after surgery, neurological deterioration was observed in 5 (20.0%) cases, and neurological improvement was found in 9 (36.0%) cases. Five cases were ventrally located, and twelve cases were dorsally located. Ventrally located cases were larger in tumor axial size (p = 0.029) than dorsal location tumors, resulting in poorer follow-up MMCS and a higher prevalence of von Hippel-Lindau syndrome (VHL) (p = 0.042). Three of them were confirmed to be supplied by the anterior spinal artery. In the case of dorsally located cases, there was no neurologic deterioration. Conclusion: In intramedullary spinal cord hemangioblastomas, cases located ventrally had a higher incidence of neurological deterioration following surgery than those located dorsally or in intramedullary extramedullary cases. Ventrally located hemangioblastomas were larger than those in other locations. They were mainly supplied by the anterior spinal artery in VHL patients.

Preoperative angiographic considerations and neurological outcome after surgical treatment of intradural spinal hemangioblastoma: a multicenter retrospective case series.

PURPOSE: Intradural spinal hemangioblastomas are rare highly hypervascularized benign neoplasms. Surgical resection remains the treatment of choice, with a significant risk of postoperative neurological deterioration. Due to the tumor infrequency, scientific evidence is scarce and limited to case reports and small case series. METHODS: We performed a retrospective multicenter study including five high-volume neurosurgical centers analyzing patients surgically treated for spinal hemangioblastomas between 2006 and 2021. We assessed clinical status, surgical data, preoperative angiograms, and embolization when available. Follow-up records were analyzed, and logistic regression performed to assess possible risk factors for neurological deterioration. RESULTS: We included 60 patients in Germany and Austria. Preoperative angiography was performed in 30% of the cases; 10% of the patients underwent preoperative embolization. Posterior tumor location and presence of a syrinx favored gross total tumor resection (93.8% vs. 83.3% and 97.1% vs. 84%). Preoperative embolization was not associated with postoperative worsening. The clinical outcome revealed a transient postoperative neurological deterioration in 38.3%, depending on symptom duration and preoperative modified McCormick grading, but patients recovered in most cases until follow-up. CONCLUSION: Spinal hemangioblastoma patients significantly benefit from early surgical treatment with only transient postoperative deterioration and complete recovery until follow-up. The performance of preoperative angiograms remains subject to center disparities.

Von Hippel-Lindau disease with intracranial hemorrhage due to arteriovenous anastomosis via multiple spinal hemangioblastomas: illustrative case.

BACKGROUND: Some spinal hemangioblastomas (HBLs) resemble spinal vascular malformations. Intracranial subarachnoid hemorrhage (SAH) secondary to spinal HBL has rarely been reported. OBSERVATIONS: A 67-year-old man with a prolonged von Hippel-Lindau disease (VHL) history presented with sudden headache and vomiting. Cranial and cervical computed tomography (CT) revealed severe infratentorial, supratentorial, and cervical SAH. Cranial CT angiography and magnetic resonance imaging revealed a mismatch in hemorrhage and intracranial tumor localization, with no vascular lesions that could lead to intracranial SAH. Cervical CT angiography revealed abnormal blood vessels originating from 5 spinal tumors suspected to be HBLs. We considered that the SAH was caused by venous reflex from vascular malformation-like spinal HBLs. Transarterial embolization (TAE) of the feeding artery of HBLs was performed to improve symptoms and reduce rebleeding risk. Nine months after TAE, angiography showed no venous reflux into the intracranial space. Ten months later, the authors excised the T1-2 tumor because the patient complained of progressive paralysis of the right upper extremity. LESSONS: In HBL with prolonged VHL, intracranial hemorrhage due to venous regurgitation via a mimicked vascular malformation may occur. Reducing venous reflux with TAE may improve symptoms and prevent rebleeding.

Radiologic Characteristics of Spinal Hemangioblastomas in von Hippel Lindau Disease as Guidance in Clinical Interventions.

OBJECTIVE: Hemangioblastomas in the central nervous system are the most common manifestation of von Hippel-Lindau (VHL) disease. Because the growth rate of hemangioblastomas is unpredictable, regular follow-up is mandatory, focusing on clinical symptoms and imaging of the central nervous system. However, clinical symptoms may be subtle and nonspecific, and data about the relationship between the radiologic findings and clinical symptoms are sparse. This study aims to evaluate if and how findings of magnetic resonance imaging (MRI) regarding spinal hemangioblastomas are associated with symptoms of VHL disease, with special attention to peritumoral edema and spinal cysts. METHODS: Serial spinal MRI scans of 43 genetically or clinically established VHL patients with at least 2 years of follow-up were reevaluated to examine the volume, growth rate, and location of spinal hemangioblastomas and the presence, size, and growth rate of peritumoral edema and cysts. Findings were compared with clinical symptoms using the Fisher exact test. RESULTS: We observed a total of 77 spinal hemangioblastomas in 28 patients. Eight of the 28 patients showed peritumoral edema and spinal cysts, and 1 patient showed peritumoral edema without cyst formation; 6 of these 9 patients showed clinical symptoms. Both peritumoral edema and spinal cysts were associated with clinical symptoms (P = 0.023 and P = 0.011, respectively). CONCLUSIONS: The presence of peritumoral edema and/or spinal cysts shown on MRI in VHL patients with spinal hemangioblastomas is associated with symptoms in more than half of the patients and may alert the clinician to intensify clinical and radiologic surveillance.

Chronological Progression and Management of Syringobulbia Caused by Spinal Hemangioblastoma: A Case Series and Review of the Literature.

BACKGROUND: Syringomyelia often accompanies spinal hemangioblastoma (SHB). It often shows progression to the medulla oblongata, dubbed as "syringobulbia", which presents critical symptoms such as dysphagia and respiratory compromise. Appropriate management of chronological syringomyelia progression toward syringobulbia is not set in stone. This study aims to unravel the clinical and chronological behavior of syringobulbia and its management. METHODS: A single-institution case series study of 5 patients operated for SHB with syringobulbia was conducted. Serial preoperative magnetic resonance imaging scans were analyzed in further details, especially focusing on the chronological progression of syringomyelia. A literature review was performed to describe clinical/imaging characteristics. RESULTS: Chronological imaging analyses revealed that despite the relatively steady progression of syringomyelia over years, it accelerated when developing syringobulbia. Intramedullary signal change ("presyringomyelia") was observed in the area where syringomyelia subsequently occurred. Literature review yielded another 15 cases of SHB with syringobulbia, totaling 20 cases. Bulbar dysfunction was seen in 4 cases (20%). Gross total resection was performed in all cases except 1, which underwent just syringotomy. Rapid postoperative symptom improvement was observed in all cases, as well as immediate imaging resolution of syringomyelia. CONCLUSIONS: The symptoms associated with syringobulbia often become life-threatening. Notably, its resolution may be near-synchronous to surgical resection of the spinal lesion. The speed of progression of syringomyelia is usually steady, but it may accelerate when extending to syringobulbia. Regular imaging follow-up is thus highly recommended to determine the best timing of intervention when presyringomyelia and syringomyelia are ascending toward the medulla oblongata.

Thoracic epidural analgesia in a patient with von Hippel-Lindau disease.

von Hippel-Lindau disease (VHLD) is an autosomal dominant disorder characterized by central nervous system hemangioblastomas and renal tumors. Here, we report a case of thoracic epidural placement in a 35-year-old woman with VHLD presenting for left open heminephrectomy for renal masses. We also reviewed the literature on this topic.

Spinal extradural hemangioblastoma: A systematic review of characteristics and outcomes.

Extradural spinal nerve root hemangioblastoma is a rare entity with very few cases reported in the literature. A comprehensive picture of the treatments and outcomes of the same is thus not available. A systematic search was done according to PRISMA guidelines. Search criteria included terms: spinal extradural hemangioblastoma, extradural hemangioblastoma, and spinal root hemangioblastoma. The parameters considered were treatment, motor, and sensory outcome, association with von-Hippel-Lindau (VHL) syndrome. Twenty-two studies (19 full text articles) were available for the review. A total of 39 cases of extradural spinal nerve root hemangioblastoma have been reported. These cases had a median age of 44 years with male predominance (2:1) and up to 48% occur in the thoracic level, similar to our case. Thirty-six percent of patients were associated with VHL syndrome. Surgical resection was the primary modality of treatment with embolization used in selected cases (20%). They had mean follow-up of 23 (±11) months. The prognosis was better than the intradural counterpart with no motor deficit and sensory deficit in only 9%. Preoperative identification of the extradural nature of this pathology and complete excision at the first surgery offers excellent outcomes compared to intradural lesion. Targeted embolization may be used in cases anticipated with high blood loss.

Sporadic and Von-Hippel Lindau disease-associated spinal hemangioblastomas: institutional experience on their similarities and differences.

INTRODUCTION: Hemangioblastomas are uncommon tumors of the central nervous system that can be seen in Von Hippel-Lindau (VHL) disease. Despite their benign histology, hemangioblastomas can cause substantial morbidity due to involvement of critical structures. In order to better understand the clinical behavior of spinal cord hemangioblastomas, we have analyzed the clinical, pathologic, radiologic characteristics and management of sporadic and VHL-associated cases at our institution. METHODS: We performed a database search to identify all spinal hemangioblastomas at our institution between 1997 and 2016. Tumor characteristics were analyzed for sporadic and VHL-associated tumors separately in order to understand the differences in groups. RESULTS: We included 20 patients with VHL-associated spinal hemangioblastomas, and 22 patients with sporadic spinal hemangioblastomas. VHL-associated patients were significantly younger at time of presentation compared to sporadic patients (p < 0.0025). Thirty-two patients (76.2%) presented with focal weakness, 34 (81.0%) with sensory loss, and 22 (52.4%) with pain. VHL patients were more likely to present with multiple symptoms (p < 0.001). Median follow-up time was 20.9 months, during which 17 tumors recurred. The median recurrence free interval was 44 months. There were no differences in gross total resection rates between sporadic and VHL-associated cases (p = 0.197). VHL-associated cases had a higher rate of repeat surgery for recurrence (14 patients-73.6%) compared to sporadic cases (3 patients-13.6%; p < 0.001). CONCLUSION: VHL-associated spinal hemangioblastomas differ from sporadic tumors in terms of age, presenting symptoms, multifocality, and rate of recurrence. Recurrences seem to be unrelated to the extent of resection, indicating the need for life-long follow up for VHL patients.

Clinical analysis of syringomyelia resulting from spinal hemangioblastoma in a single series of 38 consecutive patients.

OBJECTIVE: Syringomyelia was predominantly caused by Chiari malformation or intramedullary ependymoma. The goal of this study was to identify factors related to clinical outcomes and spinal hemangioblastoma (SH)-induced syringomyelia formation in a single series of patients. PATIENT AND METHODS: Thirty-eight patients with SH were treated with microsurgery from January 2013 to December 2018. Clinical features and related factors were retrospectively analyzed in SH patients with and without syringomyelia. RESULTS: Out of the total number of SH patients, 21 presented with remarkable syringomyelia, resulting in an incidence of 55.26% (21/38).Gross total resection was achieved in 36 cases (94.73%), and subtotal resection was obtained in 2 patients (5.27%). Neurological symptoms improved in 34 patients, remained stable in 2 patients and were aggravated in 2 cases during follow-up. In addition, there was a notable difference between the location of tumors and syringomyelia (P < 0.05). Syringomyelia occurred more frequently in the cervical segment than in any other spinal segment. Moreover, there was an association between symptom duration and clinical prognosis (P < 0.05). Ordinal regression analysis showed that the prognosis of middle duration groups (6-12 months) was better than early groups (0-6 months, p < 0.05, OR 20.21, 95%CI 2.34-336.97) and late groups (>12 months, p < 0.05, OR 11.54, 95%CI 1.30-102.21). Syringomyelia collapse or reduction occurred between two weeks and 15 months after surgery. An improvement of spinal function grade after surgery was more significant in syringomyelia reduction groups (p < 0.05). CONCLUSIONS: The prevalence of syringomyelia due to SH is considerably high, and the initial clinical presentation of syringomyelia resulting from SH should be emphasized. Satisfactory outcomes were achieved by effective surgery in affected patients.

Pregnancy-induced growth of a spinal hemangioblastoma: presumed mechanisms and their implications for therapeutic approaches.

Hemangioblastomas are benign tumors of the central nervous system (CNS) that may occur either sporadically or as part of von Hippel-Lindau (VHL) disease, in which they coexist with a series of other tumors outside the CNS. Because of their low mitosis rate, hemangioblastomas usually have slow-growing and late manifestations, but may cause sudden neurological symptoms if tumor hemorrhage occurs. Few studies have evaluated the impact of pregnancy on the evolution of hemangioblastomas. Some authors have reported tumor growth in women with VHL disease, but no such association was observed by others. The influence of pregnancy on sporadic hemangioblastomas remains largely unexplored. We report here the case of a pregnant woman whose first manifestation of sporadic spinal hemangioblastoma was life-threatening, rapidly progressive dysautonomia. In addition, we discuss the role of pregnancy in the triggering of symptoms, as well as the possibility of medically indicated delivery for the management of these tumors.

Rapid Worsening of Symptoms and High Cell Proliferative Activity in Intra- and Extramedullary Spinal Hemangioblastoma: A Need for Earlier Surgery.

STUDY DESIGN: A retrospective analysis of a prospective database. OBJECTIVE: To compare preoperative symptoms, ambulatory ability, intraoperative spinal cord monitoring, and pathologic cell proliferation activity between intramedullary only and intramedullary plus extramedullary hemangioblastomas, with the goal of determining the optimal timing for surgery. METHODS: The subjects were 28 patients (intramedullary only in 23 cases [group I] and intramedullary plus extramedullary in 5 cases [group IE]) who underwent surgery for spinal hemangioblastoma. Preoperative symptoms, ambulatory ability on the McCormick scale, intraoperative spinal cord monitoring, and pathologic findings using Ki67 were compared between the groups. RESULTS: In group IE, preoperative motor paralysis was significantly higher (100 versus 26%, p < 0.005), the mean period from initial symptoms to motor paralysis was significantly shorter (3.5 versus 11.9 months, p < 0.05), and intraoperative spinal cord monitoring aggravation was higher (65 versus 6%, p < 0.05). All 5 patients without total resection in group I underwent reoperation. Ki67 activity was higher in group IE (15% versus 1%, p < 0.05). Preoperative ambulatory ability was significantly poorer in group IE (p < 0.05), but all cases in this group improved after surgery, and postoperative ambulatory ability did not differ significantly between the two groups. CONCLUSIONS: Intramedullary plus extramedullary spinal hemangioblastoma is characterized by rapid preoperative progression of symptoms over a short period, severe spinal cord damage including preoperative motor paralysis, and poor gait ability compared with an intramedullary tumor only. Earlier surgery with intraoperative spinal cord monitoring is recommended for total resection and good surgical outcome especially for an IE tumor compared with an intramedullary tumor.

Intramedullary hemangioblastoma: Microsurgical resection technique.

Spinal hemangioblastomas are benign and highly vascular tumors accounting for 1-5% of intramedullary spinal tumors in surgical series. Surgery is curative in sporadic cases. We present the description of a surgical technique to safely resect an intramedullary hemangioblastoma. A dorsal midline myelotomy provides an excellent exposure of the tumor and identification of the feeding arteries. Interruption of these arteries and precise dissection of the tumor from the cord tissue followed by division of the venous drainage allow the in toto excision of the tumor. Closure of the dorsal myelotomy may be achieved with sequential fusion of the pial and arachnoid edges using a "welding" technique.

Relationship between Spinal Hemangioblastoma Location and Age.

STUDY DESIGN: Retrospective case series. PURPOSE: To investigate the relationship between tumor location and clinical characteristics. OVERVIEW OF LITERATURE: Hemangioblastoma is a rare disease that develops in the central nervous system. Magnetic resonance imaging (MRI) is useful to evaluate hemangioblastomas. Hemangioblastoma's location is designated as intramedullary, intramedullary+extramedullary, or extramedullary by MRI. METHODS: We analyzed 11 patients who underwent surgery for spinal hemangioblastoma. Using T1 contrast axial MRI data, the cases were divided into three groups (intramedullary, intramedullary+extramedullary, and extramedullary). Patient demographics, MRI findings, and preoperative neurological status were analyzed and compared for each group. RESULTS: The average age of patients with intramedullary, intramedullary+extramedullary, and extramedullary hemangioblastoma was 34.0, 64.4, and 67.5 years, respectively. Patients in the intramedullary hemangioblastoma group were younger than the other groups. Extramedullary cases had a smaller syrinx compared to the other groups. CONCLUSIONS: Age may play an important role in the hemangioblastoma tumor location and the subsequent diagnosis by an MRI.

Relationship between Spinal Hemangioblastoma Location and Age

STUDY DESIGN: Retrospective case series. PURPOSE: To investigate the relationship between tumor location and clinical characteristics. OVERVIEW OF LITERATURE: Hemangioblastoma is a rare disease that develops in the central nervous system. Magnetic resonance imaging (MRI) is useful to evaluate hemangioblastomas. Hemangioblastoma's location is designated as intramedullary, intramedullary+extramedullary, or extramedullary by MRI. METHODS: We analyzed 11 patients who underwent surgery for spinal hemangioblastoma. Using T1 contrast axial MRI data, the cases were divided into three groups (intramedullary, intramedullary+extramedullary, and extramedullary). Patient demographics, MRI findings, and preoperative neurological status were analyzed and compared for each group. RESULTS: The average age of patients with intramedullary, intramedullary+extramedullary, and extramedullary hemangioblastoma was 34.0, 64.4, and 67.5 years, respectively. Patients in the intramedullary hemangioblastoma group were younger than the other groups. Extramedullary cases had a smaller syrinx compared to the other groups. CONCLUSIONS: Age may play an important role in the hemangioblastoma tumor location and the subsequent diagnosis by an MRI.

Multiple spinal hemangioblastomas complicated with postoperative remote cerebellar hemorrhage: review of the literature of two rare entities.

BACKGROUND: Multiple spinal hemangioblastomas constitute a rare pathology; most patients have von Hippel-Lindau disease. In the literature, spinal surgery has been complicated with remote intracranial hemorrhage in a very few cases. METHODS: A 51-year-old woman, with no pertinent familial past medical history, presented with low back pain. Medullary magnetic resonance imaging revealed 3 spinal extramedullary tumors. The tumor at the L4 level appeared as a dumbbell-shaped neurinoma-like mass with enlarged vessels nearby. Medullary angiography excluded a dural fistula. Surgery was performed in 2 stages for all lesions. The day after lumbar surgery, the patient became comatose because of a remote cerebellar hemorrhage associated with hydrocephalus. She underwent external ventricular drainage and posterior fossa craniectomy. RESULTS: The patient recovered fully at 35 days except for a slight disorientation and diplopia. Histology of all lesions revealed hemangioblastomas. Discussion of this case concerns radiologic features of spinal hemangioblastomas, diagnosis of von Hippel-Lindau disease, and pathophysiology of hemorrhagic complications following spinal surgery. CONCLUSIONS: This case report includes 2 rare entities, of which every spinal surgeon should be aware.

Early microsurgical treatment for spinal hemangioblastomas improves outcome in patients with von Hippel-Lindau disease.

BACKGROUND: Spinal hemangioblastomas (HB) are rare, histologically benign, highly vascularized tumors often associated with von Hippel-Lindau (VHL) disease. The aim of the current study is to demonstrate the benefit of early surgical resection of large spinal HBs in selected asymptomatic patients with VHL. METHODS: Seventeen patients underwent microsurgical resection of 20 spinal HBs at the Department of Neurosurgery at Helsinki University Central Hospital (HUCH). Thirteen tumors were in the cervical spine, five in thoracic and one patient had two lumbar lesions. MRI tumor showed an associated syrinx in 16 patients (94%). Tumor volume ranged from 27 to 2730 mm(3). Out of 17 patients, 11 (65%) tested positive for VHL in mutation analysis. Five of these patients with tumors ranging from 55 to 720 mm(3) were treated prophylactically. RESULTS: Complete tumor resection was performed in 16 patients (94%) who were followed up for a median of 57 months (range 2-165 months). No patient had neurological decline on long-term follow-up. Among the patients with VHL, five patients with preoperative sensorimotor deficits showed improvement of their symptoms but never regained full function. One patient who presented with tetraplegia remained the same. Otherwise, all five patients with prophylactic surgery remained neurologically intact. CONCLUSION: Although documented growth on serial MRIs and the need for pathological diagnosis have been suggested as indications for surgery in otherwise asymptomatic patients, our series showed that a potentially larger group of asymptomatic patients with spinal HB associated with VHL would benefit from microsurgical resection. Long-term results of the surgical management of spinal HB are generally favorable. Our results suggest staging and early treatment for spinal HB larger than 55 mm(3), especially in patients with VHL. Small spinal HBs may be followed up.

Solitary Hemangioblastoma at the Filum Terminale: A Case Report and Review of Literature

Spinal hemangioblastomas at the filum terminale are rare. Only a few reports present immunohistopathological features of spinal hemangioblastomas. A 55-year-old woman presented with sustained low back pain and intermittent numbness in both lower extremities. She already had a decompressive surgery for a left L5-S1 extraforaminal lesion 7 months ago. Her incidental mass lesion had been slightly enlarged for 7 months and concordant symptoms had also been prolonged. Her tumor was removed en bloc with a unilateral hemilaminotomy and bilateral decompression technique. The patient's symptoms improved immediately after the surgery. In immunohistochemical stains, the stromal cells were positive for inhibin-alpha, neuron specific enolase (NSE), and the endothelial cells were positive for CD31, CD34, and factor VIII related antigen in confirming the diagnosis of hemangioblastoma. We report a rare case of intradural extramedullary spinal hemangioblastoma at the filum terminale. Complete en bloc resection was achieved with no morbidity. The immunohistopathological staining include inhibin-alpha confirmed an accurate diagnosis of the hemangioblastoma distinguishing from other vascular tumors.

Intramedullary Spinal Hemangioblastoma Associated with Syringomyelia

Intrameduallary spinal hemangioblastoma is frequently associated with syringomyelia. It grows slowly and can be removed totally. Syringomyelia can be subcided by total removal of tumor and opening of syringomyelia. Two cases of intramedullary spinal hemangioblastomas associated with syringomyelia are reported. Intramedullary tumor and syrinx was easily diagnosed by magnetic resonance imaging(MRI). They are successfully managed by total removal of tumor and opening of syrinx. Patients showed improved neurological status after operations.