Cervical Spondylosis: This condition is a common cause of arm and hand pain in older adults, resulting from wear and tear on the cervical spine. The spasming arm could be due to nerve root irritation or compression, leading to pain radiating down the arm to the hand.

Thoracic Outlet Syndrome: This condition involves compression of the nerves and/or blood vessels that pass through the thoracic outlet (the space between the collarbone and first rib), which can cause pain, numbness, and tingling in the arm and hand, as well as muscle spasms.
Peripheral Neuropathy: Conditions such as diabetes, vitamin deficiencies, or alcohol abuse can cause peripheral neuropathy, leading to nerve damage that may result in pain, numbness, and spasms in the arm and hand.
Tendinitis or Bursitis: Inflammation of the tendons or bursae in the shoulder or elbow can cause pain and spasms in the arm, potentially radiating to the hand.

Acute Coronary Syndrome: Although less common, arm pain can be a presenting symptom of a heart attack, especially in older adults. It's crucial to consider cardiac causes, especially if the pain is accompanied by other symptoms like chest discomfort or shortness of breath.
Stroke or Transient Ischemic Attack (TIA): Sudden onset of arm weakness or spasms could be indicative of a stroke or TIA, requiring immediate medical attention.
Spinal Cord Compression: Conditions like spinal stenosis, herniated discs, or tumors can compress the spinal cord, leading to severe consequences if not promptly addressed. Symptoms can include arm pain, weakness, and spasms.

Complex Regional Pain Syndrome (CRPS): A chronic pain condition characterized by severe, burning pain in the arm or hand, often following an injury. It can also cause spasms and changes in skin temperature and color.
Multiple Sclerosis: An autoimmune disease affecting the central nervous system, which can cause a wide range of symptoms, including muscle spasms, pain, and numbness in the arms and hands, although this would typically be part of a broader clinical picture.
Lyme Disease: In rare cases, Lyme disease can cause neurological symptoms, including pain, numbness, and tingling in the arms and hands, although this would typically be accompanied by other systemic symptoms.