Monomelic amyotrophy is a rare neurological disorder affecting the motor neurons that control voluntary muscles in a specific limb. This condition has several synonyms, including Hirayama disease, juvenile nonprogressive amyotrophy, Benign Focal Amyotrophy, Single Limb Atrophy, and Brachial Monomelic Amyotrophy. Despite the different names and variations, the symptoms and progression of this disorder are typically similar. The affected limb may experience muscle weakness, loss of dexterity, atrophy, and tremors. While there is no cure for monomelic amyotrophy, early diagnosis and treatment can manage symptoms and prevent further progression. Physicians may recommend physical therapy, medication, and assistive devices to improve quality of life.