Late Decrease in Cerebral Blood Flow in Bacterial Meningitis: More than a Simple Normalization of Acute Inflammatory Vessel Wall Architecture?

Acute bacterial meningitis is a disease with an overwhelmingly high mortality rate and high incidence of adverse neurological sequelae and poor neurological recovery amongst survivors. Amongst the numerous complications of bacterial meningitis, the presence of cerebrovascular disease represents a severe disease form. Vascular involvement during bacterial meningitis has long been established by numerous pathological and angiographic studies. Cerebrovascular changes known to occur in bacterial meningitis ranging from narrowing of large arteries by vasospasm to critical stenosis/obliteration of small to medium sized arteries/arterioles by vasculitis. Not surprisingly, alterations in CBF velocities have commonly been described during the inflammatory process and may represent an important component of brain injury during meningitis. In accordance with previous studies observing a biphasic cerebral flow pattern characterized by an early but transient increase in flow velocity, mostly due to reflexive vasospasm, and later by a sustained decrease in flow velocity, likely attributable to stenotic vasculitis, cerebral ischemia is a notable complication of bacterial meningitis during the advanced disease phase. Impaired cerebral perfusion during the late stages of disease may result from a variety of factors that contribute to a vital component of cerebral injury in bacterial meningitis. The pathogenesis of cerebral ischemia with progression of disease course is less clearly understood but may involve a complex interaction between inflammatory processes, systemic dysfunction, energy impairment, neuronal damage and intracranial pressure, factors of which we aim to more precisely understand and assign a more definite contributory role in the development of cerebrovascular ischemic consequences with advanced stages of bacterial meningitis.