Twig-like middle cerebral artery: Embryological persistence or secondary consequences?

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.

Twig-like MCA: A rare cause of intracranial bleeding

Twig-like or unfused middle cerebral artery (MCA) is a rare congenital vascular anomaly defined by the absence of the M1 segment. It can be found incidentally or can be revealed by cerebral ischemia or hemorrhage. Although rare, neuroradiologists should be familiar with such findings in order to differentiate them from differential diagnoses such as Moyamoya disease and steno-occlusive disorders of the MCA. We report a case of a twig-like MCA revealed by intracranial bleeding in an 84-year-old woman.

Rare neurovascular variants that you probably have not seen before

BACKGROUND

Recognition of neurovascular variants is crucial for safe endovascular and neurosurgical interventions. We aim to review and highlight various uncommon neurovascular variants and anomalies with a discussion of their relevant embryology and pathology.

METHODS

A retrospective review of a prospectively maintained neurovascular database was performed to identify uncommon neurovascular variants and anomalies. A pictorial review of these neurovascular findings is provided along with relevant embryological development, clinical significance, and potential pathological associations.

RESULTS

A pictorial review of selected neurovascular variants and anomalies is presented. These entities, divided between intra- and extra-cranial findings, include infra-optic origin of the anterior cerebral artery, meningo-ophtalmic artery, duplicated posterior cerebral artery, duplicate middle cerebral artery (MCA), MCA fenestration, twig-like MCA, pure arterial malformation, corkscrew basilar artery, persistent hypoglossal artery, persistent trigeminal artery and its variants, direct branches from the common carotid and cervical internal carotid arteries (ICA) (ascending pharyngeal artery from the ICA, thyroidal arteries from the CCA/brachiocephalic, arteria thyroidea ima), and extra-cranial carotid fenestration. The angiographic findings of these entities are presented with relevant 3D reconstruction and multimodal cross-sectional imaging correlation when available.

CONCLUSIONS

This pictorial review highlights uncommon neurovascular variants and anomalies that neuroradiologists, interventionalists, and neurosurgeons should be aware of for accurate diagnosis and safe interventions.

Combined duplicate origin and early bifurcated middle cerebral artery diagnosed by magnetic resonance angiography

PURPOSE

To describe a case of combined duplicate origin and early bifurcated middle cerebral artery (MCA) incidentally diagnosed using magnetic resonance (MR) angiography.

METHODS

A 51-year-old woman with an unruptured left MCA aneurysm underwent cranial MR angiography with a 3-Tesla scanner for presurgical evaluation. MR angiography was performed using a standard 3-dimensional time-of-flight technique.

RESULTS

An unruptured left MCA aneurysm at the M1-M2 junction was identified. The maximum aneurysm diameter was 9 mm. Two almost equally sized right MCAs arose from the terminal segment of the right internal carotid artery. These two channels soon anastomosed, and the temporal branch arose from the inferior channel. The aneurysm was successfully treated with coil embolization.

CONCLUSION

We herein report a case of a combined duplicate origin and early bifurcated MCA. This variation can also be regarded as anastomosis between the main MCA and the duplicated MCA. This variation has been previously reported as segmental duplication of the MCA. This is the third case of this rare MCA variation reported in the relevant English-language literature. The term "segmental duplication" may be confused with duplicate origin of the MCA, in which only one artery is located distal to the fusion.

Triplicated middle cerebral arteries (duplicated and ipsilateral accessory) associated with triplicated anterior cerebral arteries (accessory) diagnosed by magnetic resonance angiography

PURPOSE

To describe a case of duplicated middle cerebral artery (MCA) combined with ipsilateral accessory MCA, forming a triplicated MCA, associated with the accessory anterior cerebral artery (ACA), forming a triplicated A2 segment of the ACA detected incidentally on magnetic resonance (MR) angiography.

METHODS

A 70-year-old woman with internal carotid artery (ICA) stenosis at the origin, which was detected by ultrasound, underwent cranial MR imaging and MR angiography of the intracranial region for an evaluation of brain and cerebral arterial lesions. The MR machine was a 3-Tesla scanner. MR angiography was performed using a standard 3-dimensional time-of-flight technique.

RESULTS

Multiple ischemic white matter lesions are observed. No significant stenotic lesions were observed in intracranial arteries. The right duplicated MCA was originated from right distal ICA. And main MCA was originated from right ICA bifurcation. Right accessory MCA was arisen from the A2 segment of the right ACA. Thus, the right MCA was triplicated. There was also an accessory ACA forming a triplicated ACA at its A2 segment. These findings were clearly identified on partial volume-rendering (VR) images.

CONCLUSION

We herein report a case of triplicated MCA associated with triplicated ACA. MCA variations are relatively rare, and this is the third case of triplicated MCA reported in relevant English-language literature. To identify multiple cerebral arterial variations, creating partial VR images using MR angiographic source images is useful.

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.

Coiling an aneurysm in the twig-like MCA via a Marathon microcatheter: A case report

INTRODUCTION AND IMPORTANCE

The twig-like middle cerebral artery (MCA) is rare and has a plexiform network of small vessels that replaces the MCA trunk, with a prevalence ranging from 0.11 %-1.17 %. It can be associated with an aneurysm. A Marathon microcatheter may be an alternative for coiling procedures. However, this technique has rarely been reported.

PRESENTATION OF CASE

A 63-year-old man suffered from headaches. The neurological examination results were unremarkable. Angiography revealed a twig-like MCA with an unruptured aneurysm. Due to stenosis of the aneurysm neck, a Marathon microcatheter was used to successfully reach the aneurysm, and coiling was completed with Chinese Visee coils. Postoperatively, the patient recovered uneventfully. Due to the lack of ischemic changes in the right hemisphere, the patient was kept under follow-up observation. At the 8-month follow-up by telephone, the patient was healthy.

CLINICAL DISCUSSION

Aneurysms in the twig-like MCA may have stenosis of the aneurysm neck, and routine microcatheters used to deliver coils are often too thick to catheterize the aneurysm neck. The Marathon microcatheter has a distal inner diameter (ID) of 0.013, and as an alternative for coiling procedures, it may be soft enough to thin enough to go into the aneurysm. However, it can be used in the delivery of certain coils.

CONCLUSION

Aneurysms in the twig-like MCA are difficult to catheterize with the routine microcatheters used to deliver coils. A Marathon microcatheter may be used to perform the coiling procedure. However, only certain coils that match the Marathon microcatheter can be chosen.

Twig-like Middle Cerebral Artery: Case Series in a European Population

OBJECTIVES

Twig-like middle cerebral artery (MCA) is a rare anomaly where the M1 MCA is partially or completely replaced by a plexiform network. It has been described in angiographic series from Asian and South-American cohorts, but has not yet been reported in a European population.

METHODS

The digital subtraction angiograms (DSAs) of adult patients referred to a single neurovascular center for a diagnostic hypothesis of moyamoya arteriopathy (MMA) from 2018 to 2023 were prospectively and retrospectively checked by experienced neuroradiologists for identifying patients with twig-like MCA. The angioarchitecture of twig-like MCA was systematically evaluated and described.

RESULTS

Five of 30 (16.7%) male patients (mean age 55.8 + 14.7 years) of European ancestry were identified as having twig-like MCA. The clinical presentations were ischemic stroke (2 of 5), hemorrhagic stroke (1 of 5), and headache (2 of 5). All patients showed a unilateral involvement on DSA and in 1 of 5 (20%) an intracranial aneurysm was found. DSA was used to confirm the diagnosis of twig-like MCA and define the angioarchitecture and associated anomalies. An accessory MCA and recurrent artery of Heubner were found in 3 of 5 (60%) cases, feeding the network together with the anterior choroidal artery (4 of 5, 80%).

CONCLUSIONS

Twig-like MCA is a rare vascular anomaly, but it seems to be less rare than expected among adult European patients with suspected MMA on noninvasive neuroimaging studies. DSA is fundamental for a reliable differential diagnosis and should not be omitted in these patients.

Twig-like middle cerebral artery as a variety of isolated middle cerebral artery disease with new vessel formation: illustrative case

BACKGROUND

Twig-like middle cerebral artery (T-MCA) is reported as a rare vascular anomaly characterized by reconstitution of the M1 segment of the middle cerebral artery (MCA) by a plexiform network of small vessels. Although it is generally believed that the etiology of T-MCA is an embryological persistence, some investigators have suggested that T-MCA may be a secondary consequence. Here, the authors report a second case of de novo T-MCA formation and reconsider the concept of T-MCA in connection with isolated MCA disease.

OBSERVATIONS

A 40-year-old man's brain magnetic resonance imaging (MRI) checkup showed moderate stenosis of the M1 segment of the left MCA. Annual MRI follow-up was planned, and when performed 1 year later, it showed occlusion of the M1 segment of the left MCA. Cerebral angiography revealed occlusion of that M1 segment with abnormal arterial networks. This case was diagnosed as de novo T-MCA. The patient has remained asymptomatic for 2 years.

LESSONS

The reports of de novo T-MCA indicate that acquired factors may be involved in the pathogenesis of T-MCA. We suggest that T-MCA should be defined as a variety of isolated MCA disease with new vessel formation.

Revised concept of rete-like collateral formation: Rete mirabile does not exist in humans

The carotid rete is a physiological network between the external and internal carotid arteries (ICA) in lower vertebrates. However, true carotid rete does not exist in humans. This review aimed to contrast the physiological function of human "rete-like collaterals" with that of lower vertebrate "rete mirabile". An explanation for the development of rete-like collaterals in human intracranial arteries was also discussed. The rete mirabile (carotid, vertebral, spinal, and thoracic) in lower vertebrates has a specific physiological role and does not form vasculature for the same purpose in humans. Therefore, the term "rete mirabile" should not be used for cases reported in humans. Instead, "rete-like collaterals" is preferred. In the literature, rete-like or arterial anastomosis was observed in the ICA cavernous portion and the intradural arteries. Based on the hypothesis of the segmental concept, it applies to the ICA and intracranial arteries. Whether in the ICA, middle cerebral artery, posterior cerebral artery, or posterior inferior cerebellar artery, the segmental concept is the same and should be considered to have formed secondary collaterals after segmental regress or dysgenesis of affected arteries. Summarily, the significance of this review lies in its reevaluation of vascular structures previously described as "carotid rete" in humans to a true and preferred term, "rete-like collaterals". It also provides insights into the historical context and potential genetic factors associated with the formation of arteries in humans, contributing to a better understanding of human vascular anatomy.

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.

Aplastic or twig-like middle cerebral artery and cardiogenic cerebral embolism mimicking moyamoya disease with RNF213 polymorphism: A case report

Progressive stenosis and occlusion of the bilateral internal carotid artery terminals and circle of Willis are typical features of Moyamoya disease. However, aplastic or twig-like middle cerebral artery (Ap/T-MCA)-wherein the unilateral main trunk of the middle cerebral artery (MCA) is not depicted, and a plexiform arterial network is formed-is similar to the findings of Moyamoya disease. Here, we describe a 78-year-old man who presented with mild right paralysis and aphasia. Magnetic resonance angiography (MRA) at admission did not show the bilateral MCAs. The findings were similar to those of Moyamoya disease, and his symptoms worsened after hospitalization. Endovascular treatment was performed, and the left MCA was completely recanalized. Later, paroxysmal atrial fibrillation was detected, and we finally determined that left MCA occlusion had occurred due to embolism. The right MCA was completely occluded at its origin, indicating an Ap/T-MCA. Embolic occlusion of the unilateral MCA and contralateral Ap/T-MCA made this case resemble Moyamoya disease in the acute stage. Even when chronic occlusion is suspected on MRA in acute cerebral infarction, endovascular treatment should be considered. Additionally, a heterotypic R4810K polymorphism was later found in the RNF213 gene. To our knowledge, this is the second report of Ap/T-MCA with the RNF213 gene polymorphism; however, their association remains unclear and requires further analyses.

A case of cerebral infarction due to aplastic or twig-like middle cerebral artery after lung cancer surgery

Aplastic/twig-like middle cerebral artery is a rare vascular abnormality. We report a case of postoperative cerebral infarction caused by this disease. The patient is a male in his 40s. A 9-cm tumour was revealed to have invaded the superior vena cava from his right lung. He underwent right upper and middle bilobectomy. Due to the vascular invasion, the intraoperative bleeding exceeded 2 litres. Mechanical ventilation was required for postoperative pneumonia. After extubation, he was unable to write and was found to have cerebral infiltration in the left middle cerebral artery region. The cause of the cerebral infarction was investigated, but no thrombus in the left atrium or arteriosclerosis was found. No atrial fibrillation was observed during or after the surgery. Magnetic resonance angiography of the brain revealed an aplastic/twig-like middle cerebral artery.

A Case of Aneurysmal Subarachnoid Hemorrhage with Middle Cerebral Artery Aplasia at 30 Weeks of Pregnancy

Objective

We report a case of subarachnoid hemorrhage (SAH) that occurred at 30 weeks of pregnancy and was treated by coil embolization in a woman with middle cerebral artery (MCA) aplasia.

Case Presentation

A 40-year-old woman who was 30 weeks pregnant presented to the emergency department with a half-day history of headache and nausea. She had sudden onset headache and her symptom did not improve. There was no neurological deficit. Head CT at the referring hospital revealed SAH. The fetal state was stable. There was no sign of threatened premature delivery. Head MRA revealed aplasia of the left MCA and aneurysm with a daughter sac at the A1 segment of the anterior cerebral artery (ACA). Head DSA revealed that the A1 aneurysm with a daughter sac arose from the anomalous collateral artery leading to a plexiform network. The diagnosis was SAH due to rupture of an A1 aneurysm. Performance of less invasive coil embolization seemed to be possible and was carried out under general anesthesia. The operation was completed after placing one coil and confirming that most of the aneurysmal dome was embolized, including the daughter sac. There was no cerebral vasospasm and no obvious neurological deficit. Antiplatelet drugs were only required for 10 days after the operation. Pregnancy was stable and the patient delivered a baby by cesarean section at 38 weeks of pregnancy.

Conclusion

A rare case of aneurysmal SAH in a pregnant woman with MCA aplasia was successfully treated by endovascular surgery.