Differential Diagnosis for NPH (Normal Pressure Hydrocephalus)

• Single most likely diagnosis:

  • Idiopathic Normal Pressure Hydrocephalus (iNPH): This is the most likely diagnosis given the context of NPH, as it is the primary condition associated with the term. iNPH is characterized by the enlargement of the cerebral ventricles with subsequent increase in cerebrospinal fluid (CSF) pressure, but with normal CSF pressure measurements during lumbar puncture. Symptoms include gait disturbance, dementia, and urinary incontinence.

• Other Likely diagnoses:

  • Secondary Normal Pressure Hydrocephalus: This condition occurs after a known cause such as head trauma, subarachnoid hemorrhage, or meningitis, leading to hydrocephalus. The clinical presentation is similar to iNPH but with a clear precipitating event.
  • Chronic Subdural Hematoma: Although not a form of hydrocephalus, it can present with similar symptoms such as gait disturbance and cognitive decline, especially in the elderly, and is an important differential due to its potential for treatment.

• Do Not Miss diagnoses:

  • Brain Tumor: Although less common, a brain tumor could cause obstructive hydrocephalus or increased intracranial pressure, presenting with symptoms that might mimic NPH. Missing this diagnosis could be catastrophic.
  • Subarachnoid Hemorrhage: Acute or chronic bleeding into the subarachnoid space can lead to hydrocephalus and symptoms overlapping with NPH. Early detection is crucial for management.
  • Cerebral Vasculitis: Inflammation of the blood vessels in the brain can lead to a variety of symptoms including those that mimic NPH. It is a critical diagnosis not to miss due to its potential for severe outcomes if untreated.

• Rare diagnoses:

  • Aqueductal Stenosis: A rare condition where the aqueduct of Sylvius is narrowed, obstructing the flow of CSF and leading to hydrocephalus. It can present at any age, including adulthood, with symptoms similar to NPH.
  • Dandy-Walker Syndrome: A congenital condition characterized by hydrocephalus, agenesis of the cerebellar vermis, and cystic dilation of the fourth ventricle. Although typically diagnosed in infancy, rare cases might present later in life with symptoms that could be confused with NPH.