Clinical characteristics and diagnostic clues to Neurometabolic causes of dystonia

Neurometabolic causes of dystonia are heterogenous and can be challenging to diagnose, yet many of these disorders are potentially treatable. The first step in the workup is to clinically phenotype the underlying condition, followed by ordering selected diagnostic tests based on the clinician's judgement and clinical suspicion. In this review, we highlight the diagnostic clues to various disorders, including lysosomal storage diseases, mitochondrial cytopathies, metal storage disorders, organic acidurias, disorders in carbohydrate metabolism, neurotransmitter diseases and vitamin and cofactor deficiencies. We discuss key diagnostic clues to the presence of these conditions, as well as currently available treatments. We highlight that recognition and characterization of these secondary causes of dystonia facilitate their management, including possible treatment of the underlying neurometabolic disorder.