![]() ![]() Thus, it is essential to understand how brainstem structures are involved in visual pathways. ![]() The neuro-ophthalmologic manifestations of strokes involving the brainstem depend on the location of the ischemic event. Brainstem Stroke Syndromes Pathophysiology ![]() Strokes involving the arteries supplying the brainstem can result in a variety of different ophthalmologic manifestations-such as ocular motor palsies, Collier lid retraction, ptosis, diplopia, gaze palsies, nystagmus, skew deviation, issues with accommodation, and abnormal pupillary constriction/dilation. The brainstem is supplied by the vertebro-basilar system, which includes the following arteries: vertebral arteries, basilar arteries, posterior inferior cerebellar artery (PICA), anterior inferior cerebellar artery (AICA), superior cerebellar artery (SCA), and labyrinthine artery. The risks factors for posterior circulation strokes include the usual vasculopathic risk factors: tobacco smoking, hypertension, hypercholesterolemia, diabetes mellitus, dyslipidemia, migraines with auras, atrial fibrillation, and coronary artery disease. Although dissections of the vertebral artery (especially cervical portions) are common, dissections involving the posterior cerebral arteries, however, are much less common. Atherosclerotic occlusion in the cervical or intracranial vertebral arteries and/or the intracranial basilar and posterior cerebral arteries are also common locations of strokes involving the posterior circulation. Ītherosclerotic occlusive disease in the proximal portion of the vertebral artery of the neck is a common cause of strokes in the posterior circulation. The origin of the arteries supplying the posterior circulation include the aorta and the great vessels in the chest (e.g., innominate, vertebral, subclavian arteries) followed by the cervical and intracranial parts of the vertebral arteries, the basilar arteries and perforating vessels, and the terminal artery the posterior cerebral arteries. The most common causes of strokes involving the posterior circulation include atherosclerosis, embolism, and dissection. The brainstem including the medulla also contains vestibular-otolith pathways and the ocular sympathetic pathway which can produce skew deviation, nystagmus, or Horner syndrome respectively.Īpproximately 20-25% of ischemic stroke involve the posterior circulation. The midbrain-or mesencephalon- and pons have several functions which include involvement in the afferent and efferent pupillary and ocular motor (efferent) pathways. The midbrain, pons, and medulla oblongata are components of the brainstem which control basic body functions such as consciousness, breathing, proprioception, heart rate, and blood pressure. Brainstem stroke syndromes are a subtype of strokes which lead to ischemia of the structures of the brainstem. Posterior circulation strokes involving the brainstem can result in subsequent ophthalmologic manifestations. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |