Carpal Tunnel Syndrome: This condition is a common cause of intermittent tingling and numbness in the thumb, index, and middle fingers, which are innervated by the median nerve. The symptoms described, including the distribution of the tingling sensation and the absence of motor deficits, are consistent with carpal tunnel syndrome.

Cervical Radiculopathy: Compression or irritation of the C6 or C7 nerve roots in the cervical spine can cause similar symptoms, including tingling and numbness in the thumb, index, and middle fingers. The intermittent nature and short duration of the symptoms could be related to positional changes or activities that exacerbate cervical nerve root compression.
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). It can cause tingling, numbness, and other symptoms in the arm and hand, including the thumb, index, and middle fingers, especially if the compression affects the lower trunk of the brachial plexus.

Transient Ischemic Attack (TIA) or Stroke: Although less likely given the specific distribution of symptoms and the absence of motor deficits, it's crucial to consider vascular causes, especially in a patient with hypertension. TIAs or strokes can present with transient neurological symptoms, and missing these diagnoses could have severe consequences.
Multiple Sclerosis: This autoimmune disease can cause a wide range of neurological symptoms, including numbness, tingling, and sensory deficits. While the pattern of symptoms might not be as typical for multiple sclerosis, the disease's variability means it should be considered, especially if other explanations are not found.

Vitamin B12 Deficiency: This condition can cause neurological symptoms, including numbness and tingling in the hands and feet. However, the specific distribution of symptoms to the thumb, index, and middle fingers would be unusual for a vitamin B12 deficiency.
Peripheral Neuropathy: Certain types of peripheral neuropathy, such as those associated with diabetes or alcohol abuse, can cause tingling and numbness. However, these conditions typically have a more widespread distribution of symptoms and are often accompanied by other systemic signs or symptoms.
Tumors or Cysts Compressing Nerves: Rarely, tumors or cysts can compress nerves, leading to focal neurological symptoms. Examples include ganglion cysts compressing the median nerve or schwannomas affecting the brachial plexus. These diagnoses are less likely but should be considered if more common explanations are ruled out.