Lenticulostriate artery aneurysm
Charcot-Bouchard aneurysms are minute aneurysms (microaneurysms) in the brain that occur in small penetrating blood vessels with a diameter that is less than 300 micrometers. The most common vessels involved are the lenticulostriate branches (LSA) of the middle cerebral artery (MCA). LSAs originate from the MCA just before its bifurcation, and they can vary between 2 to 12 in number (average 8.1). Most branches arise medially (99.2%), close to the internal carotid artery. They supply the basal ganglia, and more specifically, the putamen and caudate, followed by the thalamus, pons, and cerebellum.
Charcot-Bouchard aneurysms are named after the French physician Jean-Martin Charcot and his student Charles Joseph Bouchard. In the 19th century, Bouchard discovered these aneurysms during his research under Charcot. Cole and Yates strengthened Charcot and Bouchard’s work by demonstrating that aneurysms truly exist using microangiographic techniques in the 1960s. However, it has been a topic of lively debate if it is, in fact, the rupture of these aneurysms that are responsible for the intracerebral bleeds.
Individuals with chronic systemic hypertension are at high risk of developing atrophy of the outer muscular layer. With the loss of integrity of the vessel wall, microaneurysms develop in LSA, which are at high risk of rupture. Bleeding of aneurysms into the deep structures of the brain parenchyma is also referred to as intraparenchymal hemorrhage or, more broadly, as intracerebral hemorrhage. Clinically the deficits that present can point towards the location of the bleed. The first-line diagnostic modality for these patients is a non-contrast computed tomography (CT) of the head to visualize the bleed. Depending on the severity and location of the hemorrhage, the treatment options vary from observation to neurosurgical intervention 1)
Epidemiology
Aneurysms of lenticulostriate artery (LSA) perforators are uncommon. There are few data on their natural history, and opinions differ on the treatment strategies.
Classification
Aneurysms of the lenticulostriate artery (LSA) are rare lesions that are categorized into either proximal (at the junction of the middle cerebral artery trunk) or distal (within the basal ganglia).
Vargas et al, report a case series and summarize the most recent literature with current treatment recommendations, and propose an anatomical classification for these entities.
A retrospective review of all patients who were diagnosed with an LSA aneurysm on cerebral angiogram was performed. An extensive online literature search was performed to identify other studies reporting on the diagnosis and management of ruptured and unruptured lenticulostriate aneurysms.
48 cases were identified in the literature and reviewed: 27 patients were treated surgically; five cases were treated with endovascular therapy; two cases underwent gamma knife radiosurgery; and 13 cases were managed conservatively.
They classified these aneurysms into three types: type 1 describes aneurysms arising from the middle cerebral artery next to a perforating LSA; type 2 is an LSA aneurysm from which the perforating artery or arteries arise-the type 2A subtype is one in which the aneurysm neck incorporates the origin of the perforating arteries and the type 2B describes perforating arteries arising from the dome of the aneurysm; and type 3 describes a fusiform aneurysm beyond the first loop or turn of an LSA.
LSA aneurysms are rare entities that present several treatment challenges 2).
These lesions have been reported against the background of a diverse array of pathologies including hypertension, vascular malformations, moyamoya disease, substance abuse, systemic lupus erythematosus, ventricular neurocytoma, and Sneddon syndrome; however, most cases are idiopathic.
The ruptured aneurysm has a high risk of re-bleeding with a consequent marked decreased risk of patient survival and functional independence, for proximal LSA aneurysm, neurosurgery has been the mainstay of treatment, but its efficacy remains controversial.
Development of devices and improved operator experience have rendered endovascular coiling an alternative and acceptable option for such patients 3).
Systematic Reviews
2021
Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a literature search was conducted in the PubMed, Cochrane, EBSCOhost, Scopus, Web of Science, and ProQuest search engines to identify reported studies of LSA aneurysms until July 1, 2020. A descriptive analysis was performed.
Results: A total of 71 studies with 112 cases of LSA aneurysms were included. Patient age ranged from 2 months to 83 years (median, 44.5 years). Male and female patients were affected similarly (49% and 51%, respectively). The most common presentation was aneurysmal rupture (78%), and headache was the most frequently reported symptom (36%). Overall, 48% of the patients had undergone underwent surgical treatment, 30% conservative management, 21% endovascular treatment, and 1% radiosurgery. Four patients died, all of whom had presented with aneurysmal rupture.
Hinojosa-Gonzalez et al. summarized the reported cases of LSA aneurysms, with their clinical presentation, management, and outcomes, for physicians who may be confronted with this diagnosis. Future studies that use available classification systems and include as much detail as possible should be encouraged to fully elucidate the optimal management strategy for these patients 4).
Case reports
An 81-year-old woman developed consciousness disturbance. Computed tomography revealed hemorrhage in the right caudate nucleus and lateral ventricles. Three-dimensional computed tomographic angiography demonstrated only an aneurysm at the basilar artery. On angiography, on the sixth day, an aneurysm at the right lenticulostriate artery was demonstrated. Then, the aneurysm disappeared on three-dimensional computed tomographic angiography on the 15th day. Subsequent radiological examinations revealed no vascular anomaly in the right lenticulostriate artery.
An aneurysm at this location can show dynamic changes based on radiological findings. Close radiological observation is necessary 5).
Lenticulostriate artery aneurysm in moyamoya disease
Case series
Patients with moyamoya disease and LSA aneurysm rupture admitted to Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medicine School from October 2012 to March 2015 were analyzed retrospectively. They were followed up for 1 year. The modified Rankin Scale (mRS) was used to evaluate the outcomes, and 0-2 was defined as good outcome. The demographic characteristics, image anatomical features, treatment schemes, and outcomes of the patients were summarized. The Pubmed database was used to retrieve other similar studies, which combined with this group of cases for analysis. Results A total of 10 patients were enrolled, 2 males and 8 females, aged 29-72 years, with an average of 43. 6 years. All cases were intracranial hemorrhage, including 3 cases of cerebral hemorrhage, 6 cases of ventricular hemorrhage, and 1 case of subarachnoid hemorrhage. At the time of admission, 7 patients had disturbance of consciousness, and 3 patients underwent emergency extraventricular drainage. Among them, 5 patients received endovascular embolization, 4 had good outcome, 1 had mild neurological deficit (mRS score 3); 2 received surgical treatment, all had good outcome; 3 received conservative treatment, all had re-bleeding, 2 died, and 1 had severe disability (mRS score 4). Fourteen eligible articles were included, and a total of 18 patients were included in the analysis: surgical treatment in 7 cases, endovascular treatment in 6 cases, and conservative treatment in 5 cases (self-healing in 1 case). According to the data of this group of patients and literature reports, the good outcome rate of the patients with early interventional embolization or craniotomy clipping treatment was significantly higher than that of conservative treatment (70. 6％vs. 22. 2％; P = 0. 038). Conclusion There is a certain risk of conservative treatment of Moyamoya disease complicated with LSA aneurysm rupture and requires active treatment. Interventional embolization of the parent artery or surgically clipping of aneurysm can effectively improve the clinical outcome of such patients. Interventional embolization of the parent artery and aneurysm can be selected simultaneously if the condition of the parent artery is allowed. Surgery can be selected when the condition of parent artery is poor and the aneurysm is located in the superficial part 6).
Case reports
A case report of a child with a ruptured distal lenticulostriate artery aneurysm that required careful decision-making and preparation before microsurgical excision. MR angiography was performed in the planning phase and neuronavigation was used during surgery. The surgery was a success, with the patient suffering minimal postoperative focal deficit, which later turned out to be transient 7).
A 42-year-old woman presented with a sudden onset of dysarthria and right hemiparesis. Putaminal hemorrhage from a ruptured aneurysm in the left LSA was detected. Angiographically, moyamoya vessels were revealed. The aneurysm in the left LSA was saccular type and seemed to be related to Moyamoya disease. As the aneurysm was successfully approached with a microcatheter, coil embolization without parent artery occlusion was performed. Rebleeding from the embolized aneurysm in the LSA did not occur. This is the first report of a ruptured LSA aneurysm embolized using coils through a flow-guiding microcatheter without parent artery occlusion in a case of Moyamoya disease 8).
One case of ruptured LSA aneurysm is related to Moyamoya disease (MMD). Surgical treatment of this aneurysm is challenging because of its deep location and complex neural structures around the LSA. They report one case treated with endovascular Onyx embolization, successfully and review the LSA aneurysm associated with MMDÂ 9)
A 49-year-old man who presented with a hemorrhage in the basal ganglia. An angiogram revealed a distal LSA aneurysm in the setting of moyamoya disease. The patient’s aneurysm was successfully embolized by the use of Onyx 18. In this report, we present the first case of onyx embolization of a LSA aneurysm and review all the previous cases that were managed with endovascular techniques.
Conclusion: Treatment of these lesions with either surgery or endovascular therapy is challenging and requires specialized expertise. Given the risks of surgery, we believe that LSA aneurysms are best treated by endovascular means, especially in the setting of moyamoya disease 10).