KEY POINTS• Normal-pressure hydrocephalus (NPH) is a syndrome that predominantly occurs during the sixth to seventh decade of life and is characterized by a clinical triad of gait difficulty, urinary incontinence, and dementia.
• The primary treatment for NPH is surgical shunting of CSF from the ventricular system. The most accepted technique is surgical diversion of CSF into the peritoneal cavity. Ventriculoperitoneal (VP) shunt surgery may produce a remarkable resolution of symptoms and improvement in quality of life. The challenge is to select patients for surgery who are likely to have a favorable outcome.
• As with any surgical procedure, the risks associated with VP shunt surgery must be weighed against the likelihood of a beneficial outcome. Patient factors to consider are the presence of comorbid conditions, immune status, functional status, and age.
• Failure to experience symptom improvement within 6 months after VP shunt insertion requires a thorough evaluation. Possible causes are misdiagnosis, shunt malfunction, and underdrainage.
Mr. A., a 76-year-old male, presents with a 2-year history of progressive gait unsteadiness. His gait has become slow, and he has started using a walker because he feels unstable. He has also had several falls in the past year. According to his wife, Mr. A. has become more forgetful lately. He is no longer able to manage their checkbook, and last week he was unable to remember how to get to the bank. He has lost interest in playing golf, his favorite pastime. On further questioning, Mr. A. admitted to having urinary urgency and losing bladder control on a few occasions. Physical examination findings indicate that he has decreased attention and concentration as well as difficulty with short-term recall. His long-term memory is intact. His gait is wide and unsteady without tremor or rigidity. What is the most likely diagnosis?
This case is a classic presentation of normal-pressure hydrocephalus (NPH), a syndrome that predominantly occurs in the sixth to seventh decade of life and is characterized by a clinical triad of gait difficulty, urinary incontinence, and dementia. The cardinal signs and symptoms that characterize NPH are independently common in the geriatric population, making this diagnosis difficult. The exact incidence of NPH is unknown, but a meta-analysis of 39 studies on dementia estimates that 1% of patients with dementia have NPH.1 As the population ages, the number of patients with NPH is expected to increase. Thus, primary care PAs should be familiar with the diagnosis and treatment of this disease.
NPH occurs secondary to a reduction of CSF absorption into the venous circulation through the arachnoid granulations. NPH may develop secondarily from disease processes that cause inflammation of the meninges (subarachnoid hemorrhage, meningitis, head injury); however, the majority of cases are primary or idiopathic.2 Reduced absorption leads to accumulation of CSF in the ventricular system, resulting in enlargement of the ventricles. The intracranial pressure (ICP) is temporarily elevated during active ventricular enlargement, but the ICP normalizes as the ventricular surface area increases. The pressure of the enlarged, fluid-filled lateral ventricles impinges on adjacent white matter tracts and produces symptoms that progressively worsen.