Evaluating Proximal Muscle Weakness
Unexplained proximal muscle weakness in patients can occur in some neurologic conditions and can be easily missed during exams that only focus on distal strength.
When examining patients with sudden limb, neck, or trunk weakness, for proximal muscle strength remember head, shoulders, knees, and toes.
The animations below illustrate some movements that can be useful in proximal muscle weakness assessment and are accompanied by questions that can be used to further evaluate weakness in one or more body area(s).
Muscle group: Shoulder Girdle
Normal movement
Example of weakness in the right shoulder girdle
Patients with weakness on an affected side of the shoulder girdle could have difficulty raising their arm above the head. If both sides are affected, then patients might not be able to raise both arms above the head or hold their head in a neutral position.
Consider asking:
- Are they using one limb less than normal, especially the dominant limb or refusing to use one limb?
- Can they put on a T-shirt?
- Can they give a high-five with each hand?
- Can they feed themselves?
Muscle group: Neck/Shoulder Girdle
Normal movement
Example of weakness on the left side
Patients with weakness in the neck and muscles of the shoulder girdle that control this movement might not be able to shrug their shoulder on the affected side and have difficulty holding up the head. The head might be tilted to the affected side.
Consider asking:
- Is one shoulder higher than the other?
- Can they throw a ball overhead?
- Can they hold up their head?
- Can they tilt the head to each side and return to neutral?
- Can they push with their head against gentle pressure equally on both sides?
Muscle group: Hips
Normal movement
Example of weakness on the right side of the hips
Patients with weakness in the hip muscles might not be able to lift the leg on the affected side, possibly not clearing the toe off the ground. Patients with weakness in both hips might also have trunk weakness and difficulty standing unassisted or unable to attempt this movement.
Consider asking:
- Are they limping or dragging a leg?
- Can they put on pants?
- Can they do a squat and recover?
- Can they lift their leg up if in a seated position?
- Can they get themselves out of the bathtub?
Muscle group: Trunk
Normal movement
Example of weakness in the trunk
Patients with weakness in the trunk might lean on the stronger leg to help themselves to lower down, use their arms for additional support, and widen their stance to assist with balance. Patients may have weakness both in the trunk and hips and might be unable to stand up unassisted or perform this movement.
Consider asking:
- Are they waddling or falling while walking?
- Can they sit up or stand without support?
- Can they get a toy off the ground while standing?
- While on the floor or bed, can they roll themselves side to side?
Keep in mind that young children may not always verbalize their feeling as weakness and may just stop using or refuse to use an affected limb. Trying to assess for proximal weakness through several age-appropriate focused questions and movements can be helpful.
Document Strength, Tone, and Reflexes
Examine both sides for comparison and document both proximal and distal muscle strength, tone, and reflexes.
Disclaimer: This webpage is for informational purposes only to demonstrate areas in which proximal muscle weakness in patients may be observed. Initial clinical presentation of AFM vary widely and often can resemble other neurologic conditions. Proximal muscle weakness can assist clinicians in increasing their suspicion of AFM. However, this information is not intended to be substitute for professional medical advice nor provide a diagnosis based on these demonstrations only. Findings of proximal muscle weakness should be used in conjunction with a thorough history, full physical exam, and other neurodiagnostic studies.