Review Note
Last Update: 04/01/2024 02:31 AM
Current Deck: Neurology::Stroke
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What are the complications of PComm aneurysms? {{c1::Oculomotor nerve}} palsy with possible {{c2::motor}} sparing
Notes
The complications of PComm aneurysms indeed include Oculomotor nerve palsy with possible motor sparing. When a PComm aneurysm expands or ruptures, it can compress the nearby oculomotor nerve (cranial nerve III). This compression can lead to classic symptoms including ptosis (drooping of the upper eyelid), diplopia (double vision), and an outward and downward deviation of the eye due to unopposed action of the lateral rectus and superior oblique muscles, respectively. The reason motor function may be spared in some cases is due to the anatomical arrangement of the nerve fibers within the oculomotor nerve; the fibers controlling pupillary constriction are superficial and more susceptible to compression, whereas the motor fibers are located centrally and may be spared, especially in the early stages of compression.
PComm Aneurysm Pathophysiology Outline:
- Etiology: PComm aneurysms arise at the junction where the posterior communicating artery branches from the internal carotid artery. They are a subtype of saccular (or berry) aneurysms, which are the most common type of cerebral aneurysm.
- Mechanism: The wall of the aneurysm may press against adjacent structures, including the oculomotor nerve. Alternatively, rupture of the aneurysm can lead to subarachnoid hemorrhage, causing direct damage or secondary effects due to increased intracranial pressure or vasospasm.
- Progression: The aneurysm may grow slowly and asymptomatically until it reaches a size that causes symptoms by compression or suddenly presents with rupture, leading to potentially life-threatening complications.
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