Muscle weakness in arms and shoulders

What do the muscles in your arms
and shoulders do?

The shoulder and the upper arm together create one of the most mobile and versatile joints of the human body, enabling full 360˚ movement. The versatility provided by the joint makes it one of the most vulnerable to injury, which can result in muscle weakness. However, there are instances where weakness in these muscle groups may not be attributed to an injury. One possibility, although rare, is muscle weakness caused by a muscle disease.

How does muscle weakness in arms
and shoulders relate to muscle diseases?

Weakness of the proximal muscles (those muscles that are closest to the core of your body), including in the arms and shoulders, can be a symptom in several muscle diseases. For example, in the disease polymyositis, weakness in arms and weak shoulders, as well as weakness in the hips and thighs, can appear over a period of weeks or months. In the instance of polymyositis, muscle weakness may be associated with pain, but this may not always be the case.

Because there can be many reasons for weakness in arms and shoulders, including a variety of muscle diseases, achieving an accurate diagnosis can be difficult and take time. Taking stock of how you are feeling and working out how to effectively communicate your symptoms to a doctor can be an important part of helping them to differentiate between the various potential diagnoses. When diagnosing muscle diseases, seemingly unrelated symptoms can be of high importance.

How would muscle weakness in arms
and shoulders present?

There are a number of ways muscle weakness in the arms could present, for example:

• Difficulty lifting objects
• Struggling to lift arms above head
• Feeling weak while washing hair
• Protruding shoulder blades (scapular winging)

What is scapular winging?

A winged scapular is when the scapula (shoulder blade), can no longer be supported in position and begins to protrude (or wing). Scapular winging is a physical feature that can present itself in a number of muscle diseases where weakness around the shoulder occurs. Although scapular winging can be a symptom of muscle disease there are several more common causes, such as physical injury.

Any concerns you have about potential weakness in your arms and shoulders should be brought up with your doctor. Considering how to describe your symptoms and how to best prepare for an appointment can help. Proximal muscle diseases are rare, but it is always important you discuss any symptom that is concerning you.

SYMPTOM LIST