Normal Pressure Hydrocephalus (NPH): This condition is characterized by the triad of urinary incontinence, gait disturbance (loss of balance), and dementia (forgetfulness), which matches the patient's symptoms. The enlarged ventricles on MRI further support this diagnosis, as NPH involves an accumulation of cerebrospinal fluid (CSF) in the brain's ventricles, leading to their enlargement.

Alzheimer's Disease: While Alzheimer's primarily presents with memory loss, advanced stages can include balance issues and incontinence. However, the significant enlargement of ventricles is less typical for Alzheimer's.
Vascular Dementia: This condition, resulting from reduced blood flow to the brain, can cause memory loss, balance issues, and incontinence. MRI findings might include white matter changes and lacunar infarcts, in addition to ventricular enlargement.
Frontotemporal Dementia: A group of diseases characterized by the progressive damage to the frontal and/or temporal lobes of the brain, leading to significant changes in personality, behavior, and language, but can also include motor symptoms and incontinence.

Brain Tumor: Although less common, a brain tumor (such as a meningioma) could cause increased intracranial pressure, leading to ventricular enlargement, and symptoms depending on its location, such as incontinence, balance issues, and cognitive decline.
Subarachnoid Hemorrhage or Chronic Subdural Hematoma: These conditions can lead to increased pressure within the skull, potentially causing ventricular enlargement and the patient's symptoms. They are critical to identify due to their potential for severe outcomes if not promptly treated.
Infectious or Inflammatory Conditions (e.g., Neurosyphilis, Lyme Disease): Certain infections can cause cognitive decline, balance issues, and incontinence, along with changes on MRI, including ventricular enlargement.

Idiopathic Intracranial Hypertension (IIH): Characterized by increased pressure within the skull without a detectable cause, IIH can lead to symptoms like headache, vision changes, and potentially cognitive issues, but ventricular enlargement is not a hallmark.
Aqueductal Stenosis: A rare condition where the flow of CSF is blocked, leading to hydrocephalus. It's more commonly diagnosed in infancy but can occur in adults, presenting with symptoms similar to NPH.
Dandy-Walker Syndrome: A congenital condition involving the cerebellum and the fluid-filled areas around it, which could lead to hydrocephalus and symptoms like those described, though it's typically diagnosed much earlier in life.