Metabolic neuropathies and myopathies.

Area of Science:

• Neurology
• Metabolic Disorders
• Genetics

Background:

• Inborn errors of metabolism (IEMs) can manifest with neuromuscular dysfunction.
• These disorders often involve cellular organelles such as mitochondria, peroxisomes, and lysosomes.
• IEMs can lead to progressive neuropathy, recurrent episodes of neurological deficits, or acute motor deficits.

Purpose of the Study:

• To review the impact of inborn errors of metabolism on muscle and peripheral nerve.
• To discuss the pathophysiology, clinical manifestations, and associated systemic involvement of metabolic myopathies.
• To highlight treatable causes and common metabolic myopathies.

Main Methods:

• Literature review of inborn errors of metabolism affecting the neuromuscular system.
• Analysis of pathophysiology related to energy production and reactive oxygen species (ROS).
• Categorization of IEMs based on affected organelles and clinical presentation.

Main Results:

• Treatable IEMs include β-oxidation defects, pyruvate dehydrogenase deficiency, porphyria, and vitamin B12 deficiency.
• Multisystemic disorders like lysosomal, mitochondriopathic, and peroxisomal diseases affect multiple organs.
• Common symptoms include exercise intolerance, myalgias, cramps, myoglobinuria, limb weakness, and elevated creatine kinase.
• Carnitine palmitoyl transferase deficiency, acid maltase deficiency, and lipin deficiency are frequent causes of rhabdomyolysis.

Conclusions:

• Metabolic myopathies are often associated with extra-neuromuscular disorders affecting the heart, liver, brain, retina, skin, and kidney.
• Understanding IEMs is crucial for diagnosing and managing neuromuscular and systemic manifestations.
• Early diagnosis and intervention can improve outcomes for treatable metabolic myopathies.