The basilar artery (Latin: arteria basilaris) contributes the posterior component of the circle of Willis and supply contents of the posterior cranial fossa. It arises from the confluence of two vertebral arteries at the medullo pontine junction, to ascend through the basilar sulcus on the ventral aspect of the pons. It provides arterial supply to the brainstem, cerebellum, and contributes the posterior part of the circle of Willis through the posterior cerebral arteries. Clinical manifestations of basilar artery pathology range from the impaired level of consciousness, cranial nerve deficits, cerebellar dysfunctions, and motor and sensory dysfunctions. A cerebrovascular accident involving the basilar artery may result in characterized clinical syndromes, notable among them are the “locked-in syndrome” and the “top-of-the-basilar syndrome.”
The basilar artery branches into the following arteries:
At around day 28 of embryonic life the brain receives arterial supply from the primitive carotid artery via the carotid-vertebrobasilar anastomosis, formed by three longitudinal neural arteries (named after the accompanying nerves):
This primitive anastomosis begins to disintegrate sequentially to pave the way for the definitive arterial circulation of the central nervous system (CNS).
At day 29:
Days 30 to 35:
As the basilar artery courses through the basilar sulcus on the ventral aspect of the pons, it travels adjacent to the abducens nerve at the lower pontine border and the oculomotor nerve as it ascends more cranially.
Some commonly documented variations in basilar artery distribution include:
Surgical recanalization using stent-assisted angioplasty or traditional angioplasty is an option in the management of high-grade basilar artery stenosis with poor response to medical thrombolysis. However, varying mortality and morbidity rates following surgery remains a disincentive.
Basilar Artery Aneurysms
These accounts for about 5% of intracranial aneurysms, but the most common of the aneurysm of the posterior circulation. Symptoms vary as the size of an aneurysm; these include headaches, visual disturbances, nausea, vomiting and loss of consciousness. Aneurysms of less than 15 mm may be asymptomatic. A basilar artery aneurysm may rupture causing a subarachnoid hemorrhage; this may be heralded by a sudden and severe headache described as "thunderclap." Patient may describe it as "worse headache of my life".
Basilar Artery Thrombosis
This refers to a cerebrovascular accident or stroke due to occlusion of the basilar artery by a thrombus. The risk factors are like in any other cerebrovascular accident. Implicated risks include atherosclerosis promoting factors like hypertension, hyperlipidemia, cigarette smoking, obesity, diabetes, coronary artery disease, among others. Clinical manifestation often corresponds to level and degree of occlusion ranging from hemiparesis, quadriparesis, ataxia, dysphonia, dysarthria, oculomotor palsy, and abducens palsy. These may present as groups of signs and symptoms recognized as distinct clinical syndromes:
Transient occlusion of the vertebrobasilar system resulting in reversible ischemia manifesting as temporary cerebellar or brainstem dysfunctions commonly as follows: vertigo, diplopia, dysarthria, ataxia, confusion, and sudden fall due to knee weakness called a “drop attack." It also is called the beauty parlor syndrome after the early 1990s incidence of stroke in victims noticed to have hyperextended their necks at the wash basin for a prolonged time at the salon. The underlying pathology is chiefly an atherosclerotic pathology of the vertebrobasilar system, made only worse by the associated triggers most notorious of them is sudden change in position, especially from prolonged sitting to an errect position, this should however not be confused with positional change associated with Benign Paroxsymal positional vertigo (BPPV)
MRI with Angiography : This is the preferred imaging study, as it afford a more sensitive delineation of areas of ischemia as well as areas of stenosis within the vertebrobasilar circulation.