Differential Diagnosis

The patient's complaint of vibrations in the forearm, particularly in the non-dominant hand and only during activity, suggests a neurological or musculoskeletal issue. Here's a categorized differential diagnosis:

• Single most likely diagnosis
  • Benign Fasciculations: This condition is characterized by small, localized, involuntary muscle contractions that can feel like vibrations or twitching under the skin. The fact that the symptoms are only noticeable during activity and not at rest, and have been gradually becoming more apparent over several years, aligns with benign fasciculations, which are often more noticeable in certain positions or during muscle activity.
• Other Likely diagnoses
  • Carpal Tunnel Syndrome: Although more commonly associated with pain, numbness, and tingling, some patients with carpal tunnel syndrome may experience vibrations or a similar sensation in the forearm or hand, especially if the median nerve is compressed.
  • Radial Neuropathy: Damage to the radial nerve can cause a variety of symptoms, including weakness, numbness, and potentially abnormal sensations like vibrations, especially in the back of the hand or forearm.
  • Muscle Strain or Overuse: Repeated strain or overuse of the forearm muscles could lead to sensations of vibration or fatigue, particularly if the patient has recently increased activity levels or changed their routine.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Amyotrophic Lateral Sclerosis (ALS): While rare, ALS can initially present with fasciculations (muscle twitching) and should be considered, especially if there are other symptoms such as muscle weakness, atrophy, or difficulty with speech or swallowing.
  • Multiple Sclerosis: This condition can cause a wide range of neurological symptoms, including abnormal sensations. Although less common, it's crucial to rule out multiple sclerosis due to its potential for significant morbidity.
• Rare diagnoses
  • Peripheral Nerve Tumors: Rarely, tumors affecting the nerves of the forearm could cause abnormal sensations, including vibrations.
  • Neuromuscular Junction Disorders (e.g., Myasthenia Gravis): These conditions can cause muscle weakness and potentially abnormal sensations, though they are less likely to present with the specific symptom of vibrations in one forearm.