Factors Predisposing to Clinical Disability in Patients with Cavernous Malformations of the Brain:

Evaluating the Role of Perilesional Tissue in Pathobiology of Epileptogenesis of Vascular Malformations of the Central Nervous System

Background and Purpose

Seizures are common presentation of cerebral vascular malformation (CVM). Topography and haemodynamic alterations are proposed as mechanisms for epileptogenesis, but the role of glial/neuronal alterations in perilesional tissue has not received much attention. Identification of the exact pathophysiologic basis could have therapeutic implications. To evaluate whether angioarchitectural factors of CVM or alterations in neuroglial/stroma of the adjacent cortex contribute to seizures.

Method

The clinical, imaging and histological characteristics of arteriovenous malformation (AVM) and cerebral cavernous malformation (CCM) with and without seizures was evaluated using neuroimaging imaging and digital subtraction angiography parameters and histopathology by morphology and immunohistochemistry.

Results

Fifty-six cases of CVM were diagnosed over a 2-year study period. Of these, 32 had adequate perilesional tissue for evaluation (AVM, 24; CCM, 8). Seizures at presentation was seen in 12/24 (50%) of AVM and 5/8 (62.5%) CCM. In AVM, hemosiderin deposition and gliosis in parenchyma (p=0.01) had significant association with seizure. Siderotic vessels in the adjacent cortex was exclusively seen only in CCM with seizures (p=0.018). Angioarchitectural features of CVM on imaging and neuronal alterations in adjacent cortex on histology failed to show any statistically significant difference between the two groups (p>0.05).

Conclusions

We propose that changes in adjacent cortex appear to be epileptogenic rather than the malformation per se. Reactive gliosis and hemosiderin deposits in perilesional tissue in AVM and siderotic vessels in CCM were associated with seizure. This explains the better outcomes following extended lesionectomy that includes epileptogenic perilesional tissues.

Outcomes studies in cerebrovascular neurosurgery

✓Successfully measuring cerebrovascular neurosurgery outcomes requires an appreciation of the current state-of-the-art epidemiological instruments, their specific relevance to surgical treatments and the underlying pathological entity, and ultimately the right set of questions for the next generation of studies. In this paper the authors address these questions with specific attention to measurement targets, individual modeling scales, and types of studies, all within a conceptual framework for specific disease models in their current state of outcomes modeling in cerebrovascular neurosurgery.

Neurosurgical management of cerebellar cavernous malformations

Object

The aim of this study was to analyze cerebellar cavernous malformations (CMs) with respect to epide-miological, clinical, radiological, and therapeutic aspects.

Methods

Between 1984 and 2004, 100 patients were surgically treated for intracranial CMs at the Division of Neurosurgery of Federal University of São Paulo. The authors reviewed the records of 10 patients whose lesions were located in the cerebellum.

There were four male and six female patients (ratio 1:1.5) whose ages ranged from 14 to 45 years (mean age 33 years). Clinical presentation was sudden or acute in all cases, and neuroimaging examinations performed in all patients demonstrated signs of bleeding. The mean size of the malformations was 4.6 cm, and in all but one patient the lesions were totally removed without complications. After a mean follow-up period of 70 months, all patients were considered to be in good or excellent clinical condition.

Conclusions

Cerebellar CMs should be analyzed separately from other posterior fossa CMs. These lesions can reach large sizes and cause massive hemorrhages, resulting in acute or sudden presentation. Surgery is a safe and effective option that provides a curative treatment when a complete removal is achieved.

Ultrastructural characteristics of hemorrhagic, nonhemorrhagic, and recurrent cavernous malformations

OBJECT

Ultrastructural characteristics of hemorrhagic, nonhemorrhagic, primary, and recurrent central nervous system cavernous malformations (CMs) were examined in an attempt to clarify their pathological mechanisms.

METHODS

Thirteen specimens (nine from samples of CMs and four from healthy control tissue) were processed for ultrastructural study immediately after surgical or postmortem removal, by fixation in glutaraldehyde/formalin and postfixation in OsO4. Transmission electron microscopy was used to examine the vascular walls, endothelium, subendothelium, and cytoplasmic organelles. The vascular walls in CMs demonstrated abnormal ultrastructure with no basement membranes and astrocytic foot processes. Pericytes were rarely seen. Single-layer lining endothelial cells showed fenestrated luminal surfaces. Large gaps were observed at intercellular junctions between endothelial cells, and large vesicles with extremely thin plasma membranes bordering the lumen were common in the lesions that had previously hemorrhaged. Endothelial cells of recurrent CMs had more Weibel-Palade bodies, filopodia, cytoplasmic processes, micropinocytotic vesicles, and filaments than those in primary lesions and normal control tissues.

CONCLUSIONS

The absence of the blood-brain barrier, normal supporting wall structure, and large vesicles bordering the lumen of CM vessels may explain leakage of red blood cells into surrounding brain in the absence of major hemorrhage. Proliferation of residual abnormal endothelial cells may contribute to the recurrence of surgically removed CMs.

Biological activity of adult cavernous malformations: a study of 56 patients

OBJECT

Cerebral cavernous malformations (CCMs) have previously been considered as congenital and biologically static malformations. On the other hand, the potential for growth and de novo generation of CCMs have also been reported. It is therefore important to study the proliferative and neoangiogenetic capacity of these lesions.

METHODS

The authors studied the surgical specimens of 56 CCMs (23 deep and 33 superficial) obtained from adult patients. The proliferative activity of the endothelium and the neoangiogenetic capacity of these lesions were considered through immunohistochemical anaylsis of proliferating cell nuclear antigen (PCNA), MIB-1, Flk-1, vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF)-1alpha, and endoglin antibodies. Positive immunostaining of endothelial cells occurred in 86% of patients for PCNA and in 38% of the cases for MIB 1. The expression of Flk-1 was observed in the endothelium of 71% of the cases, for VEGF in 41%, for HIF-1 alpha in 48.1%, and for endoglin in 63.6% of the cases. The correlation of immunohistochemical and clinical data indicated that VEGF was expressed in significantly less deep-seated lesions when compared with superficial CCMs. Neither the expression of the proliferative markers nor the expression of the angiogenetic antibodies correlated with patient age at surgery, sex, or the number of recent prior hemorrhagic episodes in the patients.

CONCLUSIONS

The CCMs from adult patients are active lesions exhibiting endothelial proliferation and neoangiogenesis. According to the data in this study, neoangiogenesis is more prominent in superficial CCMs than in deep-seated CCMs and is not associated with recent prior hemorrhages.

Gamma knife surgery of brain cavernous hemangiomas

Object.The authors conducted a study to record more detailed information about the natural course and factors predictive of outcome following gamma knife surgery (GKS) for cavernous hemangiomas.

Methods.One hundred twelve patients with brain cavernous hemangiomas underwent GKS between 1993 and 2000. The median prescription dose was 16 Gy. One hundred seven patients were followed for a median of 48 months (range 6–114 months). The rebleeding rate was 1.6%, which is not significantly different with that prior to radiosurgery (2%). An increase in volume was observed in 1.8% of cases and a decrease in 45%. Perilesional edema was detected in 27% of patients, which, together with the rebleeding, caused a transient morbidity rate of 20.5% and permanent morbidity rate of 4.5%. Before radiosurgery 39% of patients suffered from epilepsy and this improved in 45% of them. Two patients with brainstem cavernous hemangiomas died due to rebleeding. Rebleeding was more frequent in female middle-aged patients with a history of bleeding, a larger lesion volume, and a prescription dose below 13 Gy. Edema after GKS occurred more frequently in patients who had surgery, a larger lesion volume, and in those in whom the prescription dose was more than 13 Gy.

Conclusions.Gamma knife surgery of cavernous hemangiomas can produce an acceptable rate of morbidity, which can be reduced by using a lower margin dose. Lesion regression was observed in many patients. Radiosurgery seems to remain a suitable treatment modality in carefully selected patients.

Clinical implications of associated venous drainage in patients with cavernous malformation

Object. The authors reviewed angiograms obtained in patients with cavernous malformations to identify and characterize coexisting venous drainage.

Methods. Fifty-seven patients with cavernous malformations treated at the authors' institutions between 1994 and 2002 were classified into three groups according to the venous system adjacent to the malformation on angiography studies. In Group A patients (23 patients) the malformations had no venous drainage; in Group B patients (14 patients) the lesions were associated with typical venous malformations; and in Group C patients (20 patients) the lesions had atypical venous drainage (AVD). The risk of hemorrhage based on the type of associated venous drainage was analyzed, and the usefulness of magnetic resonance (MR) imaging compared with digital subtraction (DS) angiography in demonstrating associated AVD was determined.

Fifty-seven patients harbored 67 cavernous malformations: Group A patients had 29 cavernous malformations with no associated venous drainage; Group B patients had 17 lesions associated with venous malformations; and Group C patients harbored 21 lesions, 20 of which manifested AVD. Symptomatic hemorrhage was present in 10 (43.5%) of 23 Group A patients and in 28 (82.4%) of 34 Groups B and C patients. Although high-resolution MR imaging revealed the presence of associated venous malformations in 11 (78.6%) of 14 Group B patients, such studies demonstrated AVD in only two (10%) of 20 Group C patients.

Conclusions. Patients harboring cavernous malformations plus venous malformations or AVD are more likely to present with symptomatic hemorrhage than are patients with cavernous malformation alone. The actual incidence of associated venous drainage may be underestimated when MR imaging alone is used rather than combined with DS angiography.

Cerebral cavernous malformations: natural history and prognosis after clinical deterioration with or without hemorrhage

Despite recent studies of the natural history of cavernous malformations, there remains significant uncertainty concerning hemorrhage rates and the importance of lesion location. Controversy arises over varying definitions of "hemorrhage." What is ultimately important to the patient is the occurrence of a neurological event, which may or may not be associated with radiologically documented hemorrhage, as well as the chance of recovery after such an event. The purpose of this study was to determine the rates of occurrence and sequelae of neurological events in 173 patients referred to our vascular malformation clinic with cavernous malformations. All patient data were entered into a database. The mean age at presentation for the 173 patients was 37.5 years. The lesion location was deep (brainstem, cerebellar nuclei, thalamus, or basal ganglia) in 64 patients (37%) and superficial in 109 (63%). Thirty-one patients (18%) had multiple lesions. Disease presentation was due to seizures in 62 patients (36%), hemorrhage in 44 (25%), focal neurological deficit without documented hemorrhage in 35 (20%), headache alone in 11 (6%), and incidental findings in 21 patients (12%). The results obtained in the 110 patients eligible for follow-up review were used to derive information on the rates of hemorrhage and neurological events. An interval event (neurological deterioration) required both symptoms and signs. The total mean follow-up period was 46 months, the majority (65%) of which was prospective. There were 18 interval events in 427 patient-years of follow-up review, for an overall annual event rate of 4.2%. Location was the most important factor for predicting interval event occurrence, with significantly higher rates for deeply located (10.6%/year) compared with superficially located lesions (0%/year) (p = 0.0001). Of patients suffering a neurological event, only 37% had complete resolution of their deficits. This largely prospective study indicates that deep cavernous malformations carry a worse prognosis than superficial lesions with respect to annual rates of neurological deterioration. The alarming rate of adverse clinical events occurring in patients with deep lesions is punctuated by the fact that less than one-half of them recover fully during long-term follow-up review.

A founder mutation as a cause of cerebral cavernous malformation in Hispanic Americans

BACKGROUND

Cerebral cavernous malformation is a vascular disease of the brain causing headaches, seizures, and cerebral hemorrhage. Familial and sporadic cases are recognized, and a gene causing familial disease has been mapped to chromosome 7. Hispanic Americans have a higher prevalence of cavernous malformation than do other ethnic groups, raising the possibility that affected persons in this population have inherited the same mutation from a common ancestor.

METHODS

We compared the segregation of genetic markers and clinical cases of cavernous malformation in Hispanic-American kindreds with familial disease; we also compared the alleles for markers linked to cavernous malformation in patients with familial and sporadic cases.

RESULTS

All kindreds with familial disease showed linkage of cavernous malformation to a short segment of chromosome 7 (odds supporting linkage, 4X10(10).1). Forty-seven affected members of 14 kindreds shared identical alleles for up to 15 markers linked to the cavernous-malformation gene, demonstrating that they had inherited the same mutation from a common ancestor. Ten patients with sporadic cases also shared these same alleles, indicating that they too had inherited the same mutation. Thirty-three asymptomatic carriers of the disease gene were identified, demonstrating the variability and age dependence of the development of symptoms and explaining the appearance of apparently sporadic cases.

CONCLUSIONS

Virtually all cases of familial and sporadic cavernous malformation among Hispanic Americans of Mexican descent are due to the inheritance of the same mutation from a common ancestor.

Seizure outcome after lesionectomy for cavernous malformations

Cavernous malformations that are associated with seizures are often treated by surgical resection consisting of lesion removal, "lesionectomy," alone. Through retrospective analysis the authors have examined some factors that may predict failure to eradicate seizures by such a procedure. A group of 51 patients were examined who had been treated for supratentorial cavernous malformations with preoperative seizures and received postoperative follow up lasting at least 1 year. There was one mortality in the group. Of the remaining 50 patients, 15 (30%) had continued postoperative seizures despite therapeutic levels of antiepileptic medications. Variables that were significantly associated with continued seizures postoperatively included increasing duration of preoperative seizure history (p = 0.03), increasing number of preoperative seizures (p < 0.003), and female sex (p < 0.04). One hundred percent of patients with only one preoperative seizure or a seizure history lasting less than 2 months were seizure free following lesionectomy: approximately 75% to 80% of all patients with two to five seizures, or a seizure history lasting 2 to 12 months, were seizure free; and only 50% to 55% of those with more than five seizures or with preoperative seizure histories lasting more than 1 year were seizure free postoperatively. This investigation indicates that patients with shorter seizure histories and fewer preoperative seizures can be effectively treated by lesionectomy alone, whereas those with longer histories and more seizures are not effectively treated by this procedure and may require more extensive resections.

Natural history of intracranial cavernous malformations

The authors have reviewed the clinical records of 110 patients with intracranial cavernous malformations diagnosed by histological examination and/or magnetic resonance imaging over a mean follow-up period of 4.71 years. These cases were divided, based on their presentation, into a hemorrhage group, a seizure group, and an incidentally diagnosed group. The rate of subsequent symptomatic bleeding was investigated in relation to age at onset, sex, and location of the initial lesion. A high rate of subsequent symptomatic bleeding episodes was found in the hemorrhage group, especially among younger females. The nonhemorrhagic-onset cases had a very low incidence of bleeding. The outcome was generally good, except in patients with lesions in the basal ganglia and brainstem. These findings will be helpful in planning a rational therapeutic strategy for intracranial cavernous malformations.