What is the Difference Between Polymyositis and Polymyalgia Rheumatica?

Polymyositis and polymyalgia rheumatica are both inflammatory muscle diseases, but they have distinct differences in their symptoms, characteristics, and treatment. The main differences between polymyositis and polymyalgia rheumatica include:

Symptoms: Polymyositis causes weakness in muscles without pain, while polymyalgia rheumatica causes symmetrical painful muscles and stiffness without weakness.
Age of Onset: Polymyositis typically affects people over 18 years of age, while polymyalgia rheumatica usually occurs in people in their 50s.
Muscle Involvement: Polymyositis affects proximal muscles, which are closer to the center of the body, while polymyalgia rheumatica affects distal muscles, which are farther from the center of the body.
Prognosis: Polymyositis is a destructive inflammatory muscle disease, meaning it can cause permanent damage to muscle tissue, while polymyalgia rheumatica is not considered a destructive inflammatory muscle disease.
Laboratory Findings: In polymyositis, creatine kinase levels are typically elevated, while in polymyalgia rheumatica, they are usually normal.
Treatment: The distinction between polymyalgia rheumatica and polymyositis is crucial for determining the appropriate treatment and prognosis. Treatment for polymyalgia rheumatica often involves corticosteroids, while treatment for polymyositis may involve other medications, physical therapy, or, in some cases, intravenous immunoglobulin therapy.

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Comparative Table: Polymyositis vs Polymyalgia Rheumatica

Here is a table highlighting the differences between polymyositis and polymyalgia rheumatica:

Aspect	Polymyositis	Polymyalgia Rheumatica
Age of Onset	Affects people older than 18 years	Affects people over the age of 50, with prevalence increasing with age
Symptoms	Proximal muscle weakness without pain	Symmetrical painful muscles and stiffness without weakness
Inflammatory Status	Destructive inflammatory muscle disease	Not a destructive inflammatory muscle disease
Conditions to Differentiate	Polymyalgia rheumatica must be differentiated from conditions like Fibromyalgia, Late Onset Rheumatoid Arthritis, Polymyositis, Dermatomyositis, and Remitting Seronegative Symmetrical Synovitis with Pitting Edema	Polymyositis must be differentiated from conditions like Polymyalgia Rheumatica, Dermatomyositis, Fibromyalgia, and Remitting Seronegative Symmetrical Synovitis with Pitting Edema
Treatment	Treatment for Polymyalgia Rheumatica often includes corticosteroids	Treatment for Polymyositis often involves immunosuppressive medications and corticosteroids

In summary, polymyositis causes weakness in muscles without pain, while polymyalgia rheumatica causes symmetrical painful muscles and stiffness without weakness. The age of onset also differs, with polymyositis affecting people older than 18 years and polymyalgia rheumatica affecting people over the age of 50.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.