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In vitro Nuclear Magnetic Resonance (NMR) spectroscopy is a validated biochemical tool for metabolic analyses of human body fluids and diagnosis of inborn errors of metabolism in children and adults. The technique is of special interest because it requires minimal sample preparation, it can detect simultaneously compounds of different nature and it offers structural information on the metabolites present in body fluids. In the last decade, in vitro NMR spectroscopy contributed to the identification of new inborn errors of metabolism, some of which are amenable to therapeutic intervention. Standardized analyses of body fluids, especially cerebrospinal fluid, are therefore indicated in patients affected with neurodegenerative disorders of unknown etiologies, for which extensive metabolic and genetic screening failed to identify the primary defect. In addition, the use of multivariate statistical analyses allows the comparison of the whole metabolic profile between patients with a given neurodegenerative disorder and controls. This so-called metabonomic approach yields promises for the discovery of biomarkers that can help detecting disease onset and progression, as well as evaluating therapeutic efficacy. Finally, the combination of in vitro NMR spectroscopy with genetic analytical tools may constitute a successful pathophysiological approach to investigate neurological disorders of unknown etiology.

The diagnosis of certain metabolic diseases is problematic because it cannot be achieved with conventional blood and urine analyses but requires cerebrospinal fluid (CSF) study. CSF analysis is essential for the diagnosis of neurotransmitter metabolic disorders (synthesis defects of biogenic monoamines, non ketotic hyperglycinemia and homocarsinosis), defects of specific transporters (glucose cerebral transporter (Glut1) deficiency and cerebral folate deficiency) and is of help for the diagnosis of disorders of cerebral energy metabolism (respiratory chain disorders and pyruvate dehydrogenase deficiency). Our goal is to give an outline of hereditary metabolic diseases whose diagnosis is based on CSF analysis. We will detail late onset clinical forms which may be first seen in an adult neurology department.