Peri-operative neurological complications.

Brain injury from cardiac surgery is an important source of patient morbidity and mortality. The relationship between risk of brain injury and advanced age portends a rising frequency of these complications due to an increasing proportion of elderly patients undergoing cardiac surgery. This review will explore the aetiology and risk factors for peri-operative stroke, postoperative cognitive dysfunction and postoperative delirium. The prevention of each of these conditions will also be discussed, with a focus on brain protection strategies and the avoidance of cerebral embolism and hypoperfusion.

Cerebrovascular hemodynamics, gait, and falls in an elderly population: MOBILIZE Boston Study.

OBJECTIVE: To determine whether alterations in cerebral blood flow regulation are associated with slow gait speed and falls in community-dwelling elderly individuals. METHODS: The study sample consisted of 419 individuals from the MOBILIZE Boston Study (MBS) who had transcranial Doppler ultrasound measures of cerebral blood flow velocity. The MBS is a prospective cohort study of a unique set of risk factors for falls in seniors in the Boston area. We measured beat-to-beat blood flow velocity in the middle cerebral artery in response to 1) changes in end-tidal CO(2) (cerebral vasoreactivity) and 2) blood pressure changes during a sit-to-stand protocol (cerebral autoregulation). Gait speed was measured during a 4-meter walk. Falls were tracked by monthly calendars, and demographic and clinical characteristics were assessed at baseline. RESULTS: A multivariate linear regression analysis showed that cerebral vasoreactivity was cross-sectionally related to gait speed (p = 0.039). Individuals in the lowest quintile of vasoreactivity had lower gait speeds as compared to those in the highest quintile (p = 0.047). In a negative binomial regression analysis adjusted for relevant covariates, the relationship between cerebral vasoreactivity and fall rate did not reach significance. However, when comparing individuals in the lowest to highest quintile of cerebral vasoreactivity, those in the lowest quintile had a higher fall rate (p = 0.029). CONCLUSIONS: Impaired cerebral blood flow regulation, as measured by cerebral vasoreactivity to CO(2), is associated with slow gait speed and may lead to the development of falls in elderly people.

Ironing-out mechanisms of neuronal injury under hypoxic-ischemic conditions and potential role of iron chelators as neuroprotective agents.

Iron is the most abundant transition metal in the brain, where it functions as an important cofactor in a host of vital metabolic processes and plays an absolutely essential role in cell viability. Free iron is also very toxic when present in high concentrations, thus placing this essential metal at the core of neurotoxic injury in a number of neurological disorders. The pivotal role of iron in cellular homeostasis, including its latent toxicity, necessitates a tight regulation of iron metabolism. Oxygen and iron appear to play an important role in iron homeostasis. They appear to exert their homeostatic role by modulating the proteins involved in a complex interplay between iron sensing, transport, and storage. These key regulatory proteins include ferritin (intracellular storage), transferrin (extracellular transport), transferrin receptor, and iron regulatory protein (sensor of intracellular iron concentration). The interplay of iron and oxygen is most intriguing in the setting of stroke, where hypoxia and free iron appear to interact in causing the subsequent neuronal death.