Transcobalamin polymorphism and homocysteine

Traumatic lumbar puncture at diagnosis of childhood acute lymphoblastic leukemiaWe agree with the recommendations of Kebelmann-Betzing et al that initial lumbar puncture should be performed by an experienced clinician and followed immediately by intrathecal therapy.As also stated in our article, 1 we now routinely perform this procedure with patients under short-acting general anesthesia.When the diagnosis of leukemia is uncertain because of the lack of circulating leukemic cells, we postpone lumbar puncture and intrathecal therapy until the diagnosis is established by bone marrow examination.It is difficult to compare the frequency of traumatic lumbar puncture in the series of Kebelmann-Betzing et al with that of ours because the status of their patients was determined retrospectively on the basis of "preserved" cerebrospinal fluid; in contrast, we used fresh samples of cerebrospinal fluid.The integrity of the erythrocytes and the morphology of the leukocytes are expected to be altered in preserved samples.Since we first implemented steps to reduce this iatrogenic complication, we have substantially reduced the frequency of traumatic lumbar punctures with blast cells from 11% to 5% and that of traumatic lumbar punctures without blast cells from 10% to 7%.It should be noted that we stringently define traumatic lumbar puncture as at least 10 erythrocytes per microliter.As shown by Total Therapy Study XIII, 2 early intensive intrathecal and systemic therapy is now more successful in treating and preventing central nervous system (CNS) leukemia, even in patients whose leukemic blast cells are iatrogenically introduced into the cerebrospinal fluid by traumatic lumbar puncture.Therefore, cranial irradiation is seldom necessary in contemporary treatment programs.But others have reported neuropsychologic deficits in children who received CNSdirected therapy consisting solely of approximately 20 intrathecal treatments of methotrexate, hydrocortisone, and cytarabine over 3 years. 3 The challenge now is to optimize intrathecal and systemic therapy to maximize efficacy and minimize toxicity.Developing appropriate measures to avoid traumatic lumbar puncture and hence the need of extra intrathecal therapy is but one step toward this goal.