LANGE USMLE ROAD MAP NEUROSCIENCE Second Edition Ebook PDF download
LANGE USMLE ROAD MAP NEUROSCIENCE Second Edition Ebook PDF download BERRY ANEURYSMS AND SUBARACHNOID HEMORRHAGE
• Blood released from an aneurysm accumulates in the subarachnoid space and irritates the meninges.
The meningeal irritation causes headaches as well as increased intracranial pressure, vomiting, and
an altered level of consciousness.
• The optic and oculomotor nerves (CNs II and III) are the nerves most commonly compressed by a berry
B. An ischemic stroke results from a vascular occlusion without hemorrhage;
80% of strokes are ischemic strokes.
C. Most ischemic strokes involve large superficial branches of the anterior or
posterior circulations and are commonly caused by a thrombus or embolus or
result from systemic hypoperfusion.
1. A thrombus is a clot that forms in a wall of an artery, usually at the site of an
atherosclerotic plaque that occludes a vessel at that site.
a. Outside the skull, common sites for the development of a thrombus are at
the origin of a vertebral artery from the subclavian or at the origin of an
internal carotid from the common carotid.
b. In the anterior circulation, common sites for the development of a throm-
bus are in the internal carotid artery proximal to the origins of the MCA
c. In the posterior circulation, common sites for the development of a
thrombus are at the site where the vertebral arteries join to form the basi-
lar or at the branch points of the basilar into the PCAs.
• A thrombus in the anterior circulation may result in a weakness or sensory loss in the contralateral
upper limb, lower limb, or face, which may be combined with aphasia, apraxia, or agnosia.
• A thrombus in the posterior circulation may result in a weakness or sensory loss in the contralateral
upper limb, lower limb, or face, which may be combined with cranial nerve signs, gait ataxia, or hemi-
2. An embolus is a clot that may form at a site of thrombus but dislodges and
travels through the bloodstream to occlude a cerebral vessel distal to the
a. Emboli most commonly arise from atheromatous plaques in the extracra-
nial parts of the vertebral or internal carotid arteries.
b. Cardiac anomalies such as valvular heart disease also commonly give rise
to emboli. Air, fat, cholesterol, and protein may also form an embolus.
c. In the anterior circulation, the superficial branches of the MCA are most
commonly occluded by an embolus.
d. In the posterior circulation, a cerebellar artery or a PCA is most com-
monly occluded by an embolus.
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