Right Aortic Arch Associated with Left Internal Carotid Artery Agenesis

Anatomical variations of origin of the internal carotid artery: Report of two cases and systematic review of the literature

BACKGROUND

Anatomical variations of origin of the internal carotid artery (ICA) are very uncommon and may pose a diagnostic and therapeutic challenge.

OBJECTIVE

We report a case of direct origin of the right ICA from the innominate artery (aplasia of common carotid artery) and a case of duplication of right ICA in healthy patients who performed duplex ultrasound (DUS) for primary cardiovascular prevention screening.

METHODS

In both cases, the ultrasound scan was performed both in a transverse plane and on the longitudinal axis, and in one of the two cases, a computed tomography angiography was performed to confirm the diagnosis. A review of the current literature about anatomical variations of origin of carotid arteries was also performed.

RESULTS

The most frequent congenital anomaly is represented by the aplasia of the CCA, followed by the agenesis and by the duplication of the ICA. In most cases, the anomaly is discovered occasionally and symptoms are aspecific. Diagnosis is usually confirmed through a multimodality imaging approach, including DUS of extracranial carotid arteries, magnetic resonance imaging (MRI), and computed tomographic angiography. In most cases, treatment was conservative, with pharmacological therapy aimed at the symptoms.

CONCLUSION

The recognition of such variations is mandatory, particularly when the patient needs a surgical treatment that may involve the vessel with the anatomical variations.

Treatment of a posterior cerebral artery aneurysm in the context of complex cardio-cerebrovascular variations using the Tubridge flow diverter

We present a case of intracranial aneurysm located in the P1 segment of left posterior cerebral artery in the context of tetralogy of Fallot. Complex variations included right aortic arch with abnormal branching. Also, the bilateral vertebral arteries were absent, with a type I persistent proatlantal intersegmental artery of the left side. The aneurysm was treated with endovascular intervention with a Tubridge flow diverter and was noted to be completely cured on 6-month follow-up. We discuss the many considerations in this patient including developmental and modern-era treatment.

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.

Multiple Variations at the Base of an Adult Skull: Implications in Radiology and Skull Base Surgery

Knowledge of variations at the base of the skull may be important for academic, anthropological, forensic, and clinical purposes, especially in computed tomography and magnetic resonance imaging and while performing safe radical surgery. This report presents multiple variations at the base of an adult Indian skull. The variations noted include the presence of foramen of Civinini bilaterally, absence of carotid canal on the left side, reduced size of foramen lacerum on the left side, presence of petro-occipital foramen bilaterally, asymmetry between the jugular fossae, and asymmetrical occipital condyles. The rare, multiple variations reported here might be useful for neurosurgeons, orthopedic surgeons, and radiologists.