Abstract
To clarify the characteristics of patients who suffered from thalamic infarction following occlusion of the posterior communicating artery (PcoA) after clipping surgery, we reviewed the records of 68 patients with IC-PC aneurysm who underwent clipping surgery at our clinic in the past 10 years. Of these, 9 cases were selected for evaluation. Occlusion of the PcoA was confirmed on the postoperative angiograms of 8 of the 9 cases, of which 6 cases had no infarct and 2 cases had thalamic infarction. In the remaining patient (Case 9), occlusion of the PcoA was not seen on the postoperative angiograms, but a thalamic infarction was seen on computed tomography (CT). The diameter of PcoA, degree of back flow from the posterior cerebral artery (PCA), and the result of the Allcock test that was conducted in most cases that did not have back flow from the PCA, and size of the aneurysm were each compared in the 9 cases. Cases 7-9 who developed thalamic infarction, had hemiplegia, impairment of impressibility, and clouding of consciousness. Although these symptoms disappeared in Cases 7 and 9, they persisted in Case 8.
The diameter of the aneurysm was over 11 mm in 2 cases who developed thalamic infarction (Cases 8, 9). Of the 6 cases who did not have thalamic infarction (Cases 1-6), the diameter of the PcoA was over 1mm in 4 cases and below 1mm in 2 cases, and back flow from the PCA was seen in 5 cases. The diameter of the PcoA in the 3 cases who developed thalamic infarction (Cases 7-9) was 1mm or greater (1.0, 2.7 and 2.7mm). Case 7 had back flow from the PCA, Case 8 did not have back flow from the PCA but had a positive Allcock test, and Case 9 did not have back flow from the PCA and the Allcock test was not done.
From these results, we concluded that the occurrence of thalamic infarction associated with PcoA occlusion cannot be predicted from the diameter of the PcoA, the presence or absence of back flow from the PCA, or the result of the Allcock test. We assume that occlusion of the anterior thalamoperforating artery, a branch artery of the PcoA, rather than occlusion of the PcoA itself, causes thalamic infarction.
