The effect of left fronto-parietal resections on hand selection: a lesion-tractography study

Strong right-hand preference on the population level is a uniquely human feature, although the neural basis for this is still not clearly defined. Recent behavioural and neuroimaging literature suggests that hand preference may be related to the orchestrated function and size of fronto-parietal white matter tracts bilaterally. Lesions to these tracts induced during tumour resection may provide an opportunity to test this hypothesis. In the present study, a cohort of seventeen neurosurgical patients with left hemisphere brain tumours were recruited to investigate whether resection of certain white matter tracts affects the choice of hand selected for the execution of a goal-directed task (assembly of jigsaw puzzles). Patients performed the puzzles, but also tests for basic motor ability, selective attention and visuo-constructional ability, preoperatively and one month after surgery. Diffusion tractography of fronto-parietal tracts (the superior longitudinal fasciculus) and the corticospinal tract were performed, to evaluate whether resection of tracts was significantly associated with changes in hand selection. A complementary atlas-based disconnectome analysis was also conducted. Results showed a shift in hand selection despite the absence of any motor or cognitive deficits, which was significantly associated with patients with frontal and parietal resections, compared with those with resections in other lobes. In particular, this effect was significantly associated with the resection of dorsal fronto-parietal white matter connections, but not with the ventral fronto-parietal tract. Dorsal white matter pathways contribute bilaterally, with specific lateralised competencies, to control of goaldirected hand movements. We show that unilateral lesions, by unbalancing the cooperation of the two hemispheres, can alter the choice of hand selected to accomplish movements

Effect of mobile unidirectional air flow unit on microbial contamination of air in standard urologic procedures.

BACKGROUND: Infection is one of the most feared complications of surgery. New instrumentation is being developed to reduce deposition of bacteria. METHODS: We investigated 45 major surgical procedures (21 radical nephrectomies [RN] and 24 radical retropubic prostatectomies [RRP]) in our urology department during 2007. In about one-half of the interventions, an ultraclean air flow mobile (UAF) unit was used. Bacterial sedimentation was evaluated by nitrocellulose membranes placed on the instrument tray and by settle plates positioned at four points in the operating room. In 27 operations, an additional membrane was located near the incision. RESULTS: Bacterial counts on the nitrocellulose membranes during RN were 230 colony-forming units (cfu)/m(2)/h with the UAF unit and 2,254 cfu/m(2)/h without the unit (p = 0.001). During RRP, the values were 288 cfu/m(2)/h and 3,126 cfu/m(2)/h respectively (p = 0.001). The membrane placed near the incision during RN showed a microbial count of 1,235 cfu/m(2)/h with the UAF unit and 5,093 cfu/m(2)/h without the unit (p = 0.002); during RRP, the values were 1,845 cfu/m(2)/h and 3,790 cfu/m(2)/h, respectively (difference not significant). Bacterial contamination detected by settle plates during RN showed a mean value of 2,273 cfu/m(2)/h when the UAF unit was used and 2,054 cfu/m(2)/h without the unit; during RRP, the values were 2,332 cfu/m(2)/h and 2,629 cfu/m(2)/h with and without the UAF unit, respectively (NS). No statistically significant differences were detected in the clinical data registered in patients operated on under standard conditions and while the UAF unit was functioning. CONCLUSIONS: The UAF appears able to reduce microbial contamination at the operating table, reaching a bacterial number obtained in ultraclean operating theatres