Differential Diagnosis for Sharp Stabbing Pains in Right Arm and Right Side Scalp

Single Most Likely Diagnosis

• Trigeminal Neuralgia: This condition is characterized by sudden, severe, sharp stabbing pains typically in the face but can sometimes radiate to the scalp. The pain is usually unilateral and can be triggered by light touch. However, given the simultaneous involvement of the right arm, it might be less likely but still considered due to the nature of the pain described.

Other Likely Diagnoses

• Occipital Neuralgia: Involves the nerves that run from the top of the spinal cord up to the scalp, leading to sharp, stabbing pains. The pain can sometimes radiate to the arm if there's referred pain or involvement of other nerves.
• Cervicogenic Headache: Refers to headaches caused by cervical spine (neck) disorders. These headaches can manifest as sharp pains on one side of the head and can sometimes be accompanied by pain in the arm due to the referral pattern of cervical nerves.
• Migraine: Although migraines are typically described as throbbing headaches, some variants can present with sharp, stabbing pains (ice pick headaches). The simultaneous occurrence in the arm and scalp could be due to the complex neurovascular nature of migraines.

Do Not Miss Diagnoses

• Transient Ischemic Attack (TIA) or Stroke: Although less likely given the description of sharp stabbing pains, any new onset of neurological symptoms, especially those involving sudden pain, should prompt consideration of a TIA or stroke, as these conditions require immediate medical attention.
• Multiple Sclerosis: An autoimmune disease that affects the brain and spinal cord, leading to a wide range of neurological symptoms, including pain. The simultaneous involvement of different body parts could suggest a lesion in the central nervous system.

Rare Diagnoses

• Eagle Syndrome: Involves an elongated styloid process or calcified stylohyoid ligament, which can cause sharp, stabbing pains in the face and head, sometimes radiating to the arm if there's compression or irritation of nearby nerves.
• Raeder’s Syndrome: A rare condition characterized by a combination of symptoms including unilateral facial pain, often described as sharp and stabbing, along with other neurological deficits. It's usually associated with a lesion in the middle cranial fossa.

Each of these diagnoses should be considered and investigated based on a thorough clinical evaluation, including history, physical examination, and appropriate diagnostic tests to determine the underlying cause of the patient's symptoms.