Orthostatic Hypotension: This condition, characterized by a significant drop in blood pressure upon standing, can lead to frequent falls due to decreased blood flow to the brain, causing dizziness or fainting. Normal MRI scans would not rule out this diagnosis since it is related to blood pressure regulation rather than structural brain abnormalities.

Vestibular Disorders: Problems with the inner ear's balance system can cause dizziness and increase the risk of falls. Conditions like benign paroxysmal positional vertigo (BPPV), labyrinthitis, or vestibular migraines could be responsible.
Musculoskeletal Issues: Weakness or instability in the muscles and bones, particularly in the elderly, can significantly increase the risk of falls. Conditions such as osteoporosis, muscle dystrophy, or severe arthritis might not show up on an MRI of the head but could still cause frequent falls.
Neurodegenerative Diseases: Early stages of diseases like Parkinson's disease or multiple system atrophy can present with balance issues and increased fall risk before significant structural changes are visible on an MRI.

Cardiac Arrhythmias: Certain heart rhythm abnormalities can lead to reduced blood flow to the brain, resulting in dizziness or fainting and subsequent falls. Although not directly related to head MRI findings, these conditions are critical to identify due to their potential for severe consequences.
Seizure Disorders: Some types of seizures, especially those without overt convulsions (e.g., complex partial seizures), can cause falls. An MRI of the head might appear normal if the seizure focus is not in a structurally abnormal area or if the condition does not cause noticeable changes on the MRI.
Medication Side Effects: Various medications, including sedatives, antihypertensives, and certain antidepressants, can increase the risk of falls due to side effects like dizziness, orthostatic hypotension, or impaired balance.

Autoimmune Disorders: Conditions like multiple sclerosis or autoimmune encephalopathies can sometimes present with balance issues or dizziness leading to falls, even if the initial head MRI appears normal.
Metabolic Disorders: Certain metabolic conditions, such as hypoglycemia or hyperglycemia, can cause dizziness and falls. These would not be visible on an MRI of the head but are important to consider in the differential diagnosis.