Brain GABA and glutamate levels across pain conditions: A systematic literature review and meta-analysis of 1H-MRS studies using the MRS-Q quality assessment tool

•Meta-analysis of excitatory and inhibitory neurometabolites across pain conditions.•Introduces the new Magnetic Resonance Spectroscopy quality assessment tool (MRS-Q).•GABA, Glutamate, Glutamine and Glx concentrations appear unique to pain conditions.•Provides key knowledge to inform biomarker research in headaches and pain.•Findings highlight need to improve reporting in spectroscopy literature.