<prompt> In traumatic brain injury, changes in brain metabolism are seen. All are true EXCEPTThere is a decrease of pyruvate dehydrogenase activityThere is accumulation of lactate in brainThere is lactate uptake from circulationCSF lactate is associated with good prognosis  <response>: In Traumatic brain injury anaerobic condition prevails. So brain cells switch to anerobic metabolism producing increasing amount of lactate Option B is correct. Now if this lactate is getting utilized as energy source within brain cells through TCA it is associated with good prognosis means tissue is recovering from injury, However, if the lactate is not getting utilized in brain cells and it will be expoed out from cell in to CSF. This outcome means severe damage to brain cells so that they are not able to utilize lactate. Hence increased lactate levels in CSFare associated with poor prognosis. but D is wrong Pyruvate dehydrogenase activity is decreased due to hypoxic conditions. Option A is correct Now if this lactate is getting utilized as energy source within brain cells through TCA it is associated with good prognosis means tissue is recovering from injury. However, if the lactate is not getting utilized in brain cells and it will be expoed out from cell in to CSF. This outcome means severe damage to brain cells so that they are not able to utilize lactate. Hence increased lactate levels in CSF are associated with poor prognosis. but D is wrong Also, increase lactate uptake from the circulation into brain cells is seen as the injured brain uses lactate as fuel. Option C is correct 