Management of intracranial pressure in tuberculous meningitis

Tuberculous meningitis (TBM) remains a common serious neurological emergency especially in the developing world. Elevated intracranial pressure (ICP) is often a feature of severe TBM and is associated with high morbidity and mortality. The pathology associated with TBM, such as cerebral edema, hydrocephalus, tuberculoma(s), and infarcts related to arthritis, contribute to increase in intracranial volume and, therefore, elevated ICP. The three types of edema (vasogenic, cytotoxic, and interstitial) may contribute to cerebral edema. The molecular mechanisms underlying the events that ultimately lead to brain damage and cerebral edema during infection are complex. Similarly to bacterial meningitis, cerebral blood flow autoregulation is probably impaired in TBM, and the mechanisms are unclear. Although no universal guidelines are available to institute ICP monitoring in patients with severe TBM, it is be prudent to monitor patients at risk for increases in ICP. Such an approach helps to detect the secondary brain insults, allowing for a more informed approach to treatment. Treatment of elevated ICP involves a multipronged approach. The first step should be to identify focal brain lesions and hydrocephalus (which require surgical intervention) by brain imaging. Cerebral edema is treated with hyperosmolar agents. Mannitol is currently the most commonly used agent. It appears that use of hypertonic saline as an osmotic agent in infection-related cerebral edema has certain advantages. However, this needs to be established by well-designed trials. Use of steroids reduces not only cerebral edema but also the production of cytokines and other chemicals involved in the immunopathogenesis of TBM. Fever associated with TBM should be aggressively treated, because fever can worsen the impact of elevated ICP. Hyponatremia may complicate TBM and requires appropriate correction because it can aggravate cerebral edema.