Vestibular Disorder: This is a common cause of falls, especially in the elderly. Vestibular disorders, such as benign paroxysmal positional vertigo (BPPV), can lead to balance problems and falls. Negative MRI and X-ray results do not rule out vestibular issues, as these tests are not designed to diagnose problems with the inner ear or balance system.

Orthostatic Hypotension: A drop in blood pressure upon standing can cause dizziness and falls. This condition is common in the elderly and can be due to various factors, including dehydration, medication side effects, or autonomic nervous system dysfunction.
Neurodegenerative Diseases (e.g., Parkinson's Disease, Multiple System Atrophy): These conditions can cause balance problems, gait disturbances, and falls. Early stages might not show significant findings on MRI or X-rays.
Medication Side Effects: Certain medications, such as sedatives, antihypertensives, and antidepressants, can increase the risk of falls due to their effects on blood pressure, balance, or cognitive function.

Subdural Hematoma: Although MRI and X-ray results are negative, a subdural hematoma could be missed, especially if it is small or if the scans were not specifically looking for this. This condition can be life-threatening and requires immediate medical attention.
Spinal Cord Compression: This is another critical condition that might not be evident on routine MRI or X-ray scans, especially if they were not focused on the spine. Spinal cord compression can lead to significant neurological deficits and requires prompt intervention.
Cardiac Arrhythmias: Conditions like atrial fibrillation or other arrhythmias can cause falls due to transient loss of consciousness. These would not be visible on MRI or X-ray but are crucial to diagnose due to their potential to cause severe outcomes.

Ehlers-Danlos Syndrome: A genetic disorder that can affect the body's connective tissue, leading to joint hypermobility and potentially increasing the risk of falls.
Mal de Debarquement Syndrome: A rare condition characterized by a persistent feeling of swaying or imbalance after exposure to motion (like being on a boat), which can lead to falls.
Autoimmune Disorders (e.g., Multiple Sclerosis): Although less common, autoimmune disorders affecting the central nervous system can cause balance problems and falls. Negative initial imaging does not rule out these conditions, as lesions might be small or located in areas not well visualized by standard MRI or X-ray techniques.