In conclusion, LC-MS arises as a complementary tool to H-NMRS for metabolic profiling of the CSF. This technique appears promising for the identification of novel IEM involving the nervous system. (n=4), dopa-responsive dystonia (n=3), serine biosynthesis defect (n=1), cerebral folate deficiency (n=1), glycine encephalopathy (n=2), and pyridoxal phosphate dependent seizures (n=1). There was consanguinity in all, except one. Positive yield of a diagnostic LP for the diagnosis of inherited neurotransmitter metabolism disorder was overall 25.8%. Oculogyric crisis (50%) and diurnal variation (81.8%) were the only statistically significant variables, in patients with and without a specific diagnosis.