Fig 4.

GP infarct segments. A, Normal anatomy of the dorsal pallidum, also known as the globus pallidus. The thin line indicates the medial medullary lamina; the thick line, the boundary of the globus pallidus. Surrounding structures include the anterior limb of the internal capsule (IC ant) and the posterior limb of the internal capsule (IC post). The putamen, thalamus, and head of the caudate nucleus are also labeled. The external medullary lamina separates the putamen from the GPe. B, Infarct segments 1–5. Segment 1 seems to be the most sensitive to metabolic infarct in MMA, followed by segment 2, then segment 3; segments 4 and 5 are the least sensitive and usually infarct together. C, An example of a segment 1 infarct (posterior GPe). D, An example of an infarct of segments 1 + 2 (posterior and middle GPe). E, An example of an infarct of segments 1 + 2 + 3 (whole GPe). F, An example of an infarct of segments 1 + 2 +3 + 4 + 5 (complete GP, both externa and interna). Note that the medial medullary lamina (a white matter tract) remains intact and can be seen separating the GPe and GPi.