Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for sudden arm weakness accompanied by facial drooping, speech trouble, confusion, severe dizziness, or leg weakness because these may be stroke symptoms.
Contact the treating clinician promptly if weakness is new or worsening, pain is difficult to control, or the arm is becoming increasingly stiff or swollen.
New symptoms after previous cancer or radiation treatment also deserve timely assessment.
Seek urgent medical care after an injury if the arm becomes pale, blue, cold, very swollen, or pulseless, or if there is uncontrolled bleeding.
These signs can indicate blood vessel damage.
Major trauma with neck pain, breathing difficulty, or near-complete loss of arm movement also requires urgent evaluation.
Follow-up may include repeated strength and sensation examinations, therapy assessments, and EMG or nerve conduction studies.
These visits help show whether nerves are recovering and whether the treatment plan should change.
Routine follow-up remains important even when pain improves.
Pain may settle before strength returns, particularly in neuralgic amyotrophy.
Continuing the agreed rehabilitation and monitoring plan can help protect the arm while recovery develops.
Every sign above is quoted from the sofidex article on Brachial plexopathy. If you are not sure, err upward — it is always reasonable to be checked.