Basilar artery stroke

1. How does occlusion of the basilar artery usually occur?
2. What symptoms usually occur when a branch of the basilar artery is occluded?
3. What is locked-in syndrome?
4. What sort of lesion results in clumsy hand syndrome?

Answers:
1. Occlusion results from atherosclerotic plaque in the basilar artery, occlusion of both vertebral arteries, or occlusion of one vertebral artery when the other is inadequate size.
2. Internuclear ophthalmoplegia, conjugate horizontal gaze palsy, ocular bobbing.
3. Tetraparesis with only vertical eye movement intact, but patient is fully conscious due to sparing of reticular activating system. Caused by bilateral lesions of ventral pons.
4. Basis pontis, internal capsule (anterior limb).