ASK DIS: Corticosteroid in Brain Tumour

Corticosteroids decrease brain edema
reduce peritumoral and vasogenic brain edema, reduce increased intracranial pressure and frequency of plateau waves, decrease cerebral spinal fluid production, and decrease tumor cerebral blood flow
Reduction of intracranial pressure and improvement in neurologic symptoms usually begins within hours
A decrease in capillary permeability can be identified within six hours and changes of diffusion-weighted MRI indicating decreased edema are identifiable within 48 to 72 hours
However, adequate reduction in elevated ICP resulting from peritumoral edema may take several days with glucocorticoid therapy alone

Choice

Dexamethasone has been the corticosteroid of choice in this patient population because of its high potency relative to other agents, its low mineralocorticoid (sodium retaining) effect, and its long biologic half-life (i.e., 48 hours).
Other steroids at equivalent doses probably also work, but given the clinical ease of use and comfort, dexamethasone is used.

Dosing

vary greatly from patient to patient and depend on the diseases being treated
After surgery, a maximum dose of 16 mg daily, administered in 4 equal doses, is recommended for symptomatic patients. This protocol should ideally be started by the neurosurgeon.

Dexamethasone Tapering

Most patients begin to improve symptomatically within hours of dexamethasone administration, achieving maximum benefit within 24–72 hours
A high rate of side effects is associated with prolonged dexamethasone use, as is a risk of suppression of the hypothalamic–pituitary–adrenocortical axis.
Dexamethasone should therefore be tapered once symptoms begin to improve
Published evidence and recommendations about the optimal tapering schedule are varied
In general, the tapering schedules most commonly reported involve a gradual decrease in the dose or dosing interval over a period of 2–4 weeks to prevent rebound symptoms, with longer periods for symptomatic patients
A gradual decrease in dose and/or dosing interval of dexaxamethasone every 3-7 days, in an attempt to reach a physiologic dose equivalent to 20 mg of cortisol per day (i.e., approximately 0.75 mg of dexamethasone per day), should be attempted (Szabo & Winkler, 1995).
In clinical practice, dexamethasone tapering schedules are often prescribed for short-term therapy, and usually consists of an empiric reduction in dose of 2-4 mg every 1-3 days, by either reducing the dose and/or the interval. Other tapering schedules have been reported in this patient population and include a "slow taper" of lowering the dose by 4 mg every week
Patients who have high-grade tumours, are symptomatic, or have a poor life expectancy, can be maintained on a 0.5-1.0 mg daily dose of dexamethasone

Examples of Recommendations

Tapering		Duration of each dosing
4 mg BD > then 2 mg BD > then 1 mg BD > then 1 mg OD		every week
4 mg BD than stop		For 3 days
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4059813/
empiric reduction in dose of 2-4 mg	every 1-3 days
lowering the dose by 4 mg	every week
http://www.medscape.com/viewarticle/498465_5
4 QID > 4 TDS > 4 BD > 4 OD > 2 OD	Every 3-5 days
4 QID > 2 TDS > 3 OD > 1 OD	Every 3-5 days
*Suggested local practices*

References:

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