2024 Volume 11 Pages 353-356
A 74-year-old woman had a lacunar infarction in the brainstem and was admitted to Takeda General Hospital for treatment. She had significant sequelae and was discharged with a Modified Rankin Scale 0. Imaging follow-up was conducted every year after discharge on an outpatient basis. Seven years later, MRI of the head revealed a previous cerebral hemorrhage in the right basal ganglia. The imaging findings reveal that the patient was diagnosed with cerebral hemorrhage due to a cavernous malformation. The patient was asymptomatic, so imaging follow-up was continued, but the cavernous malformation grew in size over the next 8 years and caused three more hemorrhages. The last hemorrhage caused damage to the right extrapyramidal tract, which resulted in rapid cognitive decline and tremors of the left upper limb. To remove the cavernous malformation, a transsylvian-anterior transinsular approach was employed. Involuntary movements of the left upper limb disappeared postoperatively. A de novo cavernous malformation rarely grows to such a large size as it did in this case. A cavernous malformation in the basal ganglia must be carefully removed, ensuring that the perforating branches of the middle cerebral artery, which includes the lenticulostriate arteries, that may run along the borders of the mass are not damaged.
Reportedly, the prevalence of cerebral cavernous malformation is approximately 0.2%-0.9%.1) Its rate of detection has increased because of advances in imaging equipment such as magnetic resonance imaging. A cavernous malformation is familiar in some cases2) but sporadic in others.3,4) Moreover, a cavernous malformation may be congenital in some cases, but a few acquired cases have been reported.3) A developmental venous anomaly (DVA),5,6) genetic abnormalities,4) irradiation,7) and hormone therapy8) have been reported to cause a de novo cavernous malformation, but numerous aspects of the mechanism of its development are unclear. In this report, we present a very rare case of a cavernous malformation that suddenly appeared in the right basal ganglia. It subsequently grew in size because of repeated hemorrhaging within the mass, which resulted in cognitive decline and tremors of the left upper limb.
A 74-year-old woman who was suffering from a lacunar infarction in the brainstem was urgently admitted to Takeda General Hospital. She was treated with an intravenous infusion and discharged without notable sequelae. An MRI scan of the head was conducted every year on an outpatient basis. An MRI scan carried out 7 years later suddenly revealed a previous cerebral hemorrhage in the right basal ganglia (Fig. 1A and B). The imaging findings show that the patient was diagnosed with a hemorrhage due to a cavernous malformation. The patient was asymptomatic; hence, imaging follow-up was continued. The lesion regressed for a time, but the cavernous malformation hemorrhaged again three times over the next 8 years and grew large in size (Fig. 1C and D). The last hemorrhage caused tremors in the left upper limb, and the patient's unsteadiness when walking worsened. Additionally, her cognitive function rapidly declined. The appearance of aprosexia and memory impairment were observed. There was no family history or history of radiation therapy. On imaging, the cavernous malformation was loculated and occupied the insular gyri and anterior putamen from the right caudate nucleus. Cerebral angiography did not present any dilated vessels suggestive of a DVA (Fig. 2A). The right lenticulostriate arteries have shifted posteriorly by the tumor. The malformation was removed under general anesthesia. Surgery was carried out using a transsylvian-anterior transinsular approach. The central aspect of the right sylvian fissure was dissected to expose the M1-2 segments of the right middle cerebral artery. The perforating branches of the middle cerebral artery were determined, and navigation confirmed the localization of the malformation from the surface of the insular cortex. A cortical incision was performed from the limen insula to the short gyrus, and the malformation was confirmed. The malformation was cauterized and shrunk as it was decompressed piece by piece. The malformation was clearly demarcated from the brain. The lenticulostriate arteries, which branch from the middle cerebral artery, ran along the posterior caudal surface of the malformation. The lenticulostriate arteries were carefully dissected from the malformation (Fig. 2C). A DVA was not noted intraoperatively. The malformation was completely removed under a microscope (Figs. 2B, 1E). The lenticulostriate artery was preserved, and the postoperative diffusion-weighted image revealed that there was no ischemic lesion in the basal ganglia (Fig. 1F). The histological diagnosis was consistent with a cavernous malformation (Fig. 2D). Tremors in the left upper limb tremor disappeared postoperatively. The patient was still unsteady when walking, so she was transferred to convalescent rehabilitation.
Course of imaging of a cavernous malformation in the right basal ganglia.
A. MRI reveals no malformation beforehand.
B-D. Minor bleeding occurred repeatedly from 2015 to 2023, causing a malformation to grow.
E. Postoperative CT showing that the cavernous malformation was excised.
F. Postoperative DWI shows no ischemic lesion after removal of the malformation.
A. Cerebral angiography demonstrates that the right lenticulostriate arteries have shifted posteriorly (arrowhead). There is no staining of the mass.
B. The cavernous malformation that was removed.
C. Lenticulostriate arteries spared after malformation removal.
D. Histologically, thrombus formation and organization are evident along with cavernous vascular structures.
A cerebral cavernous malformation is included in the classification of cerebral vascular malformations proposed by Russell et al. in 1977,9) and it was considered a congenital condition. However, improvements in diagnostic imaging techniques have enabled the detection of smaller lesions, and now, the generally accepted view is that a cavernous malformation is a condition that can also be acquired.3) A DVA,5,6) genetic abnormalities,4) irradiation,7) and abnormal hormone secretion8) have been suggested to be the causes of a de novo cavernous malformation. However, various aspects of the mechanism of its development are unclear. The following has been reported as a possible mechanism for the development of a de novo cerebral cavernous malformation.10) Blood flow in the medullary veins is disrupted for some reason and venous pressure increases, which causes thrombosis of the venous vessels and leakage of red blood cells, resulting in the formation of a hematoma. Angiogenesis occurs in the surrounding area and intimal proliferation progresses, causing the main part of the cavernous malformation to develop. This process repeats at the same site, which causes the cavernous malformation to grow (cascade of hemorrhagic angiogenic event). In a reported case, a DVA was so fully developed that it was confirmed via an MRI scan preoperatively.10) In the current case, preoperative cerebral angiography presented no vessels suggestive of a DVA. Nevertheless, there are no reported cases of a de novo cerebral cavernous malformation that is as large as the one in the current case.
Conservative treatment is typically selected for an asymptomatic cavernous malformation, but excision is often carried out in cases of repeated bleeding.2) In the current case, bleeding had recurred, but the patient was asymptomatic. There were concerns regarding surgical complications, so the patient was treated conservatively. However, the malformation grew large enough to occupy the right basal ganglia, which caused tremors in the left upper limb and cognitive decline. Tremor is due to extrapyramidal disorders. Cognitive dysfunction is caused by damage to the cortico-basal ganglia loop. The basal ganglia form various communication pathways with the cerebral cortex. Among them, the dorsolateral prefrontal cortex and basal ganglia loops are mainly involved in decision making and working memory and executive functions. The disorder results in the appearance of executive dysfunction and memory impairment.11) Surgical removal was selected as treatment. Surgery to treat a cavernous malformation in the basal ganglia is usually conducted using a transsylvian transinsular approach.12-14) If the malformation is localized to the anterior limb of the internal capsule from the lateral caudate nucleus, the anterior transinsular approach is generally selected, in which the short gyrus is incised through the limen insulae in the anterior portion of the insular gyri. If, however, the malformation is localized to the putamen, thalamus, or globus pallidus, the posterior transinsular approach is selected, in which the long gyrus is incised posteriorly through the circular sulcus.12) The lenticulostriate arteries displaced by the mass run along the borders of the mass and must be spared during surgery. In the current case, we were able to follow the lenticulostriate artery branching from the M1-M2 junction of the middle cerebral artery. Dissection was possible because gliotic tissue was present between the malformation and the lenticulostriate arteries. In cases of a giant malformation including the current case, however, sparing the perforating branches of the middle cerebral artery is not always possible. If the posterior limb of the internal capsule is damaged by dissection of the malformation, hemiplegia is inevitable. Therefore, the indications for surgery should be carefully determined.
In this report, a case of a de novo cerebral cavernous malformation with repeated hemorrhaging into the right basal ganglia is presented. Preoperative imaging and intraoperative findings revealed no evidence of a DVA and an unknown origin. When removing a cavernous malformation, careful attention should be paid to the perforating branches of the middle cerebral artery running along the borders of that malformation.
The patient involved in the study provided informed consent.
The authors have no conflicts of interest to declare.
