Isolated lateral thalamic infarction: the role of posterior cerebral artery disease.

BACKGROUND AND PURPOSE: Lateral thalamic infarction (LTI) is usually caused by small vessel disease (SVD), i.e., occlusion of the deep perforator. However, focal atherosclerotic posterior cerebral artery disease (PCAD) may produce LTI via thrombotic occlusion of the perforator. We aimed to investigate the prevalence of PCAD in LTI and differences in clinical and imaging findings between LTIs associated with PCAD and SVD. METHODS: We retrospectively evaluated 58 consecutive patients with isolated LTI who underwent diffusion-weighted imaging (DWI) and MR angiography (MRA) within 7 days after stroke onset. Patients were divided into two groups: those with PCAD and those with SVD. Clinical syndromes were divided into pure sensory stroke (PSS) and sensory stroke plus (SS-plus), i.e., the concomitant presence of motor dysfunction or ataxia. Clinical and imaging findings were compared between these two groups. RESULTS: Of the 58 patients, 13 (22.4%) had PCAD. PSS was more frequently associated with SVD than with PCAD (57.8% vs. 23.1%, P=0.032). Initial DWI lesion volume (cm³) was significantly larger in PCAD than in patients with SVD (0.38±0.13 vs. 0.33±0.22, P=0.025). Among the 23 patients (39.7%) who underwent follow-up DWI, patients with PCAD showed a significantly greater increase in subacute lesion volume than those with SVD (P=0.019). Although National Institutes of Health Stroke Scale scores did not differ at admission (P=0.185), they were significantly higher at discharge in PCAD than in patients with SVD (P=0.012). CONCLUSIONS: Our data suggest that PCAD is an important cause of LTI, being related to SS-plus, larger lesion volume, and worse clinical outcomes.

Veneer vs. core failure in adhesively bonded all-ceramic crown layers.

Joining a brittle veneer to a strong ceramic core with an adhesive offers potential benefits over current fabrication methods for all-ceramic crowns. We tested the hypothesis that such joining can withstand subsurface radial cracking in the veneer, from enhanced flexure in occlusal loading, as well as in the core. Critical conditions to initiate fractures were investigated in model crown-like layer structures consisting of glass veneers epoxy-joined onto alumina or zirconia cores, all bonded to a dentin-like polymer base. The results showed a competition between critical loads for radial crack initiation in the veneers and cores. Core radial cracking was relatively independent of adhesive thickness. Zirconia cores were much less susceptible to fracture than alumina, attributable to a relatively high strength and low modulus. Veneer cracking did depend on adhesive thickness. However, no significant differences in critical loads for veneer cracking were observed for specimens containing alumina or zirconia cores.