Benign Paroxysmal Positional Vertigo (BPPV): This condition is characterized by brief, intense episodes of vertigo triggered by specific head movements. It's a common cause of severe dizziness and is often related to the movement of otolith crystals in the inner ear.

Vestibular Migraine: A type of migraine that can cause severe dizziness or vertigo, often accompanied by headache, sensitivity to light and sound, and nausea.
Labyrinthitis: An inner ear disorder that involves inflammation of the labyrinth, leading to severe dizziness, vertigo, and sometimes hearing loss.
Medication Side Effects: Certain medications, such as sedatives, antidepressants, and blood pressure medications, can cause dizziness as a side effect.

Stroke or Transient Ischemic Attack (TIA): Although less common, a stroke or TIA can present with sudden onset of severe dizziness or vertigo, and it's crucial to rule out these conditions due to their high morbidity and mortality.
Meniere's Disease: A disorder of the inner ear that can cause episodes of severe dizziness, vertigo, hearing loss, and tinnitus. While not immediately life-threatening, it significantly impacts quality of life.
Cardiac Arrhythmias: Abnormal heart rhythms can lead to reduced blood flow to the brain, causing dizziness. Identifying and treating arrhythmias is critical to prevent serious complications.

Acoustic Neuroma: A rare, non-cancerous tumor on the nerve connecting the inner ear to the brain, which can cause dizziness, vertigo, and hearing loss.
Multiple Sclerosis: An autoimmune disease that can affect the brain and spinal cord, leading to a wide range of symptoms, including severe dizziness and vertigo.
Mal de Debarquement Syndrome: A rare condition that occurs after a period of exposure to motion, such as being on a boat, and is characterized by persistent dizziness and imbalance.