Differential Diagnosis for Drooling Side of Mouth due to Excess Facial Skin

• Single most likely diagnosis:
  • Facial Hemiparesis or Weakness: This condition, often resulting from a stroke or Bell's palsy, can lead to weakness on one side of the face, including the muscles involved in controlling the mouth. This weakness can cause drooling due to the inability to properly manage saliva and can also result in excess facial skin appearing more pronounced on the affected side due to the lack of muscle tone.
• Other Likely diagnoses:
  • Cerebral Palsy: Individuals with cerebral palsy may have muscle tone abnormalities, including hypotonia (low muscle tone), which can affect the facial muscles and lead to difficulties in managing saliva, resulting in drooling.
  • Parkinson's Disease: Parkinson's disease can cause facial rigidity and bradykinesia (slowness of movement), which may lead to difficulties in swallowing and managing saliva, potentially causing drooling.
• Do Not Miss diagnoses:
  • Stroke or Transient Ischemic Attack (TIA): It is crucial to rule out an acute stroke or TIA, as these conditions require immediate medical attention. Facial weakness and drooling can be symptoms of a stroke affecting the brain's motor control areas.
  • Tumors (e.g., Brainstem or Facial Nerve Tumors): Although less common, tumors affecting the brainstem, facial nerve, or surrounding structures can cause facial weakness and drooling. Early detection is vital for effective treatment.
• Rare diagnoses:
  • Moebius Syndrome: A rare neurological disorder characterized by facial paralysis and impaired eye movement, which can lead to difficulties in managing saliva and result in drooling.
  • Myasthenia Gravis: An autoimmune disease that can cause muscle weakness, including facial muscles, potentially leading to drooling. However, the weakness typically worsens with activity and improves with rest, which might distinguish it from other causes.