Quantitative proton magnetic resonance spectroscopy of children with adrenoleukodystrophy before and after hematopoietic stem cell transplantation

Abstract

About 35-40% of boys with X-linked adrenoleukodystrophy (ALD) develop a rapidly progressive cerebral form which leads to severe neurologic disability and death within 3 - 5 years after onset of clinical symptoms. Because previous proton magnetic resonance spectroscopy (MRS) studies of ALD identified metabolite patterns characteristic of demyelination, gliosis, and neuro-axonal loss, this work tested the hypothesis that MRS - apart from indicating disease progression - provides criteria for the outcome after hematopoietic stem cell transplantation (HSCT) which has been promising at an early stage of the active disease. Follow-up quantitative proton MRS was performed in frontal and occipital white matter of ALD patients (n = 12) before and up to 5 years after HSCT. The observed metabolite alterations were retrospectively correlated with the clinical outcome representing either a stable condition (n = 5), a further deterioration (n = 5), or death (n = 2). While disease progression of patients before HSCT was mainly characterized by a further increase of elevated choline-containing compounds (Cho) as an indicator of active demyelination, a positive outcome after HSCT was correlated with high N-acetylaspartate (tNAA) levels in affected white matter before HSCT yielding positive and negative predictive values for tNAA of 80%. Although to be confirmed in a larger cohort of patients, the present findings suggest the preservation of neuroaxonal integrity as a prerequisite for an arrested course. Conversely, the combination of increased Cho with markedly reduced tNAA before HSCT apparently reflects a degree of tissue degeneration which precludes a successful therapeutic intervention.