Twig-like Middle Cerebral Artery: a Seldom Vessel Anomaly of Important Relevance

Angioarchitecture of Twig-like Middle Cerebral Artery: the Looping Lenticulostriate Artery Anastomoses as an Angiographic Landmark for Hemorrhagic Presentation

PURPOSE

The twig-like middle cerebral artery (TL-MCA) is a vascular anomaly reconstituting the MCA-M1 segment through a plexiform arterial network. Most patients with TL-MCA have a high risk of hemorrhage, but the associated vascular anatomical risk factors are poorly understood. To investigate the angioarchitecture of TL-MCA in detail to distinguish the radiological differences between hemorrhagic and non-hemorrhagic onset.

METHODS

3214 cerebral digital subtraction angiography procedures were performed, and patients with TL-MCA were included and their clinical and anatomical characteristics were retrospectively reviewed.

RESULTS

12 patients (median age 47 years, and 9 women) with TL-MCA were included (incidence rate, 0.37%). Among them, four had hemorrhagic stroke, five had ischemic stroke, and three had no symptoms. Perforator anastomoses were identified in five patients (41.6%). Among the four patients with intraparenchymal hemorrhage (IPH), three had looping lenticulostriate artery (LSA) anastomoses and one had non-looping LSA anastomosis. One looping LSA anastomosis was discovered fortuitously in a patient explored for headaches. The recurrent artery of Heubner, which is responsible for the plexiform arterial network, was identified in 10 patients (83.3%). Angiographic evolutions (de novo TL-MCA) were observed in three patients, and one patient experienced a clinical evolution of a TL-MCA with non-looping LSA anastomosis, progressing from no symptoms to IPH.

CONCLUSIONS

In this small series, looping LSA anastomoses were mainly observed in TL-MCA with IPH. This anatomical disposition could represent a potential risk factor. The TL-MCA always affects the subpallial segment of the MCA-M1, and may be a subpallium-related pathology.

Current state and confusion of twig-like middle cerebral artery

A twig-like middle cerebral artery (MCA) is an uncommon lesion in which a plexiform network of small vessels replaces the M1 segment of the MCA. Currently, we have insufficient information for twig-like MCAs. Therefore, a review of the literature using PubMed was conducted. In this review of twig-like MCAs, the following were discussed: the definition, pathogenesis, hemodynamics, associated aneurysm, clinical manifestations, imaging examinations, therapeutic strategies, therapeutic complications and prognosis. In addition, we proposed a reasonable grading system for twig-like MCAs, which is significant. For a twig-like MCA, the pathogenesis is unclear, and congenital and acquired factors can be involved. A twig-like MCA disturbed cerebral hemodynamics. An associated aneurysm can occur in patients with twig-like MCAs. Twig-like MCAs can present subclinically and without clinical symptoms, hemorrhage, or ischemic strokes. Of all the available imaging examinations, digital subtracted angiography is the gold standard. When treating a twig-like MCA, it is feasible to target the associated aneurysm, and extracranial-intracranial bypass can be effective in reducing the risk of strokes, but more evidence is needed. Now, the decision to perform surgery for twig-like MCAs should be made on a case-by-case basis.

De novo formation of twig-like middle cerebral artery: An illustrative case

Background

Twig-like middle cerebral artery (T-MCA) is a rare vascular abnormality characterized by the replacement of the M1 segment of the middle cerebral artery (MCA) with a plexiform arterial network of small vessels. T-MCA is generally regarded as an embryological persistence. Conversely, T-MCA may also be a secondary sequela but no reports of cases of de novo formation exist. Here, we report the first case describing possible de novo T-MCA formation.

Case Description

A 41-year-old woman was referred to our hospital from a nearby clinic because of transient left hemiparesis. Magnetic resonance (MR) imaging revealed mild stenosis of the bilateral MCAs. The patient then underwent MR imaging follow-ups once a year. MR imaging at the age of 53 showed a right M1 occlusion. Cerebral angiography revealed a right M1 occlusion and formation of a plexiform network consistent with the occlusion site, leading to the diagnosis of de novo T-MCA.

Conclusion

This is the first case report describing possible de novo T-MCA formation. Although a detailed laboratory examination did not confirm the etiology, autoimmune disease was suspected to have precipitated this vascular lesion.

Anterior cerebral artery dissection for a patient with ipsilateral aplastic or twig-like middle cerebral artery: An illustrative case report

Background

An aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a rare anomaly, which sometimes causes ischemic infarction. Collateral flow from the ipsilateral anterior cerebral artery (ACA) is important for patients with Ap/T-MCA. If ipsilateral ACA stenosis or occlusion occurs, a large infarction with a wider field than the ACA territory could happen. First, mechanical thrombectomy was performed for the right ACA near occlusion caused by arterial dissection with ipsilateral Ap/T-MCA in this case. Second, Wingspan stenting was performed for the right ACA restenosis.

Case Description

A 77-year-old female presented to the hospital with the left hemiparesis. We diagnosed a right ACA infarction caused by right ACA occlusion. Digital subtraction angiography showed right Ap/T-MCA and ipsilateral ACA near occlusion. Thrombectomy was performed, and recanalization was achieved with mild ACA stenosis. The lesion was the dissection due to angiographical finding. Two months after treatment, transient left hemiparesis occurred and right ACA stenosis progressed. Computed tomography perfusion showed hypoperfusion of the right hemisphere. Wingspan stenting was performed from the left internal carotid artery through the anterior communicating artery with an intermediate catheter. The patient was discharged without any neurological deficit.

Conclusion

We reported the first case of a patient who underwent Wingspan stenting for the right ACA dissection with Ap/T-MCA. Short-term follow-up and aggressive intervention should be considered for collateral pathway dissection with Ap/T-MCA because the symptoms can become serious. The patients with Ap/T-MCA should be cautious about the collateral pathway arterial changes in particular ipsilateral ACA due to the increasing hemodynamic stress.

Radiological and clinical features of twig-like middle cerebral artery in comparison with moyamoya angiopathy: a multicenter retrospective study

OBJECTIVE

Twig-like middle cerebral artery (T-MCA) is a rare congenital anomaly that is difficult to distinguish from moyamoya angiopathy (MMA), given the similarity of the angioarchitectures. The aim of this study was to gain insights into the radiological and clinical features of T-MCA and to distinguish this condition from MMA.

METHODS

A multicenter retrospective study was conducted in 29 patients with T-MCA and 57 patients with MMA. Demographic, radiological, and clinical data were compared between the patients with T-MCA and those with MMA.

RESULTS

The T-MCA group tended to be older than the MMA group (mean age 47 ± 18 vs 39 ± 22 years). Twenty patients with T-MCA (69%) were initially diagnosed with MMA. All T-MCA cases had twig-like networks and steno-occlusive changes involving the MCA. The T-MCA group had a higher incidence of intracranial aneurysms (35% vs 11%) and coexisting arterial anomalies (48% vs 12%). T-MCA and MMA cases had significant differences in involvement of the internal carotid artery terminus (0% vs 100%) and posterior cerebral artery (0% vs 23%), and in transdural anastomosis (0% vs 51%). T-MCA cases were less likely to present with stroke (59% vs 86%) and more likely to be asymptomatic (28% vs 12%). Of the patients with stroke, those with T-MCA had more hemorrhagic strokes (41% vs 29%) and fewer ischemic strokes (59% vs 71%) compared to those with MMA.

CONCLUSIONS

This study suggests that T-MCA is a different disease entity from MMA based on significant differences in the radiological and clinical features. Neurosurgeons should recognize this anomaly and understand the key features that differentiate T-MCA from MMA.

Aplastic or twiglike middle cerebral artery with contralateral middle cerebral artery stenosis showing transient ischemic attack: illustrative case

BACKGROUND

Aplastic or twiglike middle cerebral artery (Ap/T-MCA) is a rare anomaly characterized by a unilateral MCA occlusion with plexiform vessels that causes hemorrhagic and (less commonly) ischemic strokes. The reasons for this are rarely discussed, and thus optimal treatment for ischemic Ap/T-MCA remains controversial. Here, the authors report a case of Ap/T-MCA with transient ischemic attacks treated by bypass surgery and discuss the mechanism of ischemic development and treatment methods.

OBSERVATIONS

A 62-year-old hypertensive man with transient, recurrent left hemiparesis visited the authors’ hospital. Magnetic resonance angiography showed proximal occlusion of the right MCA and stenosis in the left MCA. Digital subtraction angiography revealed occlusion of the right MCA and abnormal vascular networks, leading to a diagnosis of Ap/T-MCA with contralateral MCA stenosis. Antiplatelet therapy with aspirin was insufficient, and a superficial temporal artery–MCA bypass was performed. There were no ischemic or hemorrhagic events postoperatively.

LESSONS

Atherosclerosis seems to have a significant impact on the development of ischemic stroke in patients with Ap/T-MCA, and the presence of coexisting atherosclerotic stenotic vascular lesions outside the Ap/T-MCA site is substantial in its development. Bypass surgery is a promising treatment option for ischemic Ap/T-MCA.

Western Moyamoya Phenotype: A Scoping Review

Moyamoya, a rare angiographic finding, is characterized by chronic and progressive stenosis at the terminal end of the internal carotid artery, followed by collateralization of the cerebral vasculature at the base of the skull. Coined by Suzuki and Takaku in 1969, the term "moyamoya" means a "puff of smoke" in Japanese, a reference to the angiographic appearance of moyamoya collateralization. Moyamoya is most commonly found in East Asian countries, where much governmental and civilian effort has been expended to characterize this unique disease process. However, despite its rarity, the occurrence of moyamoya in Western countries is associated with significant divergence regarding incidence, gender, sex, age at diagnosis, clinical presentation, and outcomes. Here, we attempted to review the Western literature on moyamoya presentation using the PubMed database to characterize the Western phenotype of moyamoya. We were guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR). We reviewed papers generated from a search with keywords "moyamoya case report," those reported from a Western institution, and those reported on a relevant association. Our scoping review demonstrated various clinical associations with moyamoya. Moreover, we summarized the demographic profile and clinical symptomatology, as well as reported disease associations to better elucidate the Western phenotype of moyamoya.

Aplastic or twig-like middle cerebral artery harboring unruptured cerebral aneurysms treated by clipping and bypass surgery: illustrative case

BACKGROUND

Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a congenital MCA anomaly. It may present with symptoms of both hemorrhage and ischemia, similar to moyamoya disease, and hemodynamic stress may play an essential role in the development of symptoms in both clinical entities. The optimal treatment remains controversial in symptomatic patients with Ap/T-MCA. This report discussed the treatment method for a patient with Ap/T-MCA with unruptured aneurysms who presented with intraventricular hemorrhage (IVH) treated by aneurysm clipping and bypass surgery.

OBSERVATIONS

In a 46-year-old woman with a sudden headache, computed tomography showed left IVH. Magnetic resonance angiography showed a left MCA aneurysm and MCA trunk stenosis. Three-dimensional angiography demonstrated a plexiform arterial network and multiple aneurysms arising from the MCA and in the plexiform network, leading to the diagnosis of Ap/T-MCA harboring unruptured aneurysms. The patient was successfully treated by craniotomy with aneurysm clipping and bypass surgery to prevent further intracranial hemorrhages and/or aneurysm rupture.

LESSONS

Especially in cases such as Ap/T-MCA, in which hemodynamic stress has a significant effect, the optimal treatment method should be based on vascular morphology and the impact of hemodynamic stress.

Twig-like middle cerebral arteries: Clinical and radiological findings

BACKGROUND AND PURPOSE

Aplastic or twig-like middle cerebral artery (MCA) is a rare vascular anomaly characterized by replacement of the M1 segment by a plexiform network of small vessels. Though rare, familiarity with this entity and ability to differentiate it from radiological mimics such as moyamoya changes and steno-occlusive diseases are important. We review the clinical and radiological manifestations of patients diagnosed with twig-like MCA on cerebral angiograms over a five-year period.

MATERIALS AND METHODS

Retrospective review of all patients diagnosed with twig-like MCA on cerebral angiograms was performed from January 2015 to January 2020. This was the inclusion criterion for this retrospective study. For each patient, demographic data, clinical presentation, imaging findings and management strategies were reviewed.

RESULTS AND CONCLUSIONS

Between January 2015 and January 2020, three patients with twig-like MCA were identified from 657 patients who underwent four-vessel diagnostic cerebral angiograms (0.45%). In all three cases, the involvement was unilateral (two left-sided and one right- sided). Two patients were male, and one was female. Patients ages were 25, 26 and 46 years. Two of the three patients presented with headache and the third patient with pulsatile tinnitus. There were otherwise no ischemic or hemorrhagic changes. No other vascular anomaly was identified. Twig-like MCA is a rare anatomical variant in which a plexiform network of small vessels replaces the M1 segment of the MCA. Accurate diagnosis and distinguishing this entity from radiological mimics such as moyamoya and steno-occlusive diseases are important for appropriate management and to prevent unnecessary investigations.

Subarachnoid Hemorrhage Attributable to Bilateral Aplastic or Twiglike Middle Cerebral Artery

BACKGROUND

Aplastic or twiglike middle cerebral artery (MCA), a congenital anomaly related to the abnormal development of the MCA, is rare. It is usually unilateral; bilateral lesions are extremely rare. An aplastic or twiglike MCA may lead to cerebral ischemic stroke, intracranial hemorrhage, and subarachnoid hemorrhage (SAH). In patients with ischemic stroke due to hemodynamic stress, extracranial-intracranial (EC-IC) bypass surgery is indicated. As hemodynamic stress may also elicit SAH, it is important to select the appropriate treatment. EC-IC bypass surgery was successful in a patient with bilateral aplastic or twiglike MCA who suffered SAH due to hemodynamic stress.

CASE DESCRIPTION

A 64-year-old female with a history of surgery for tetralogy of Fallot experienced SAH in the left sylvian fissure. As angiography showed a bilateral aplastic or twiglike MCA and single photon emission computed tomography revealed a decrease in the cerebral blood flow in the left MCA territory, we attributed her SAH to hemodynamic stress due to the decreased blood flow in the MCA territory and to the vulnerability of abnormal vessels as are seen in moyamoya disease. We performed EC-IC bypass surgery to reduce hemodynamic stress. A cerebral angiogram obtained 2 weeks postoperatively revealed sufficient blood flow in the MCA territory from the superficial temporal artery used for bypass. In the course of 2-year follow-up she remained stroke free.

CONCLUSIONS

The presence of aplastic or twiglike MCA may lead to stroke due to hemodynamic stress. EC-IC bypass surgery may help to prevent stroke recurrence and SAH.

Aplastic or Twig-Like Middle Cerebral Artery Presenting with Intracerebral Hemorrhage During Pregnancy: Report of Two Cases

Background

An aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a rare congenital anomaly that can present with both ischemic and hemorrhagic stroke. The etiology of this pathology has remained unclear. Here, we report 2 cases of intracerebral hemorrhage (ICH) owing to an Ap/T-MCA in pregnant patients.

Case Description

In both patients, cerebral angiography revealed a steno-occlusive lesion and an abnormal arterial network on the unilateral middle cerebral artery. One patient was treated conservatively for a putaminal hemorrhage, and a cesarean section was performed uneventfully 6 months after onset of the ICH. The other patient underwent a craniotomy for evacuation of the lobar hemorrhage. Subsequently, a cesarean section was performed uneventfully. Both patients gradually recovered without significant disabilities.

Conclusions

An Ap/T-MCA is a rare congenital anomaly and is a potential cause of ICH for pregnant patients. A cesarean section is a useful option for pregnant patients with this condition.