Dementia is reversible? Come and see if it is caused by this disease

Author: Yang Yunna, Department of Neurosurgery, Beijing Chaoyang Hospital, Capital Medical University

With the deepening of the aging of the population and the extension of life expectancy in my country, the incidence of cognitive impairment has continued to increase, and it has also attracted more and more widespread attention from the public. Cognitive function usually includes five major cognitive domains, namely memory, attention, language ability, executive ability and visual-spatial ability. Cognitive impairment may occur if one or more of these cognitive domains is damaged. Cognitive impairment can be divided into mild cognitive impairment and dementia according to the severity. Mild cognitive impairment has little impact on the ability to live and social activities and is often overlooked. What is commonly known as "dementia" by the general public is the severe stage of cognitive impairment. Common manifestations of dementia include a series of symptoms such as slow thinking, memory loss, decreased time and space discrimination ability, inattention and decreased problem-solving ability, which seriously affect the patient's daily life and social function, bring great pressure to patients and their families, and also bring a heavy burden to the healthcare system.

Clinically, cognitive impairment is caused by a variety of reasons, including Alzheimer's disease, vascular dementia, Parkinson's disease dementia, Lewy body dementia, etc. The cognitive impairment caused by these diseases often gradually worsens and is difficult to improve. However, there is a relatively rare disease that can be treated with surgery to improve cognitive levels, that is Normal Pressure Hydrocephalus (NPH). Since this type of cognitive impairment may recover after treatment, it is also called "reversible dementia."

What is normal pressure hydrocephalus?

People often joke about "water in the brain". In medicine, there is indeed a disease with increased cerebrospinal fluid in the brain, which is called hydrocephalus. Hydrocephalus is a disease caused by excessive accumulation of cerebrospinal fluid in the ventricles. It can be divided into high-pressure hydrocephalus and normal-pressure hydrocephalus according to the size of intracranial pressure. Normal-pressure hydrocephalus, as the name suggests, means that the cerebrospinal fluid pressure measured by lumbar puncture is normal. It has gradually become an important culprit affecting the physical and mental health of the elderly. The main clinical "triad" of normal-pressure hydrocephalus is cognitive impairment, gait disorder and bladder dysfunction. The patient's condition may progressively worsen without treatment. Imaging examinations usually show enlarged ventricles. After early diagnosis, shunt surgery can reverse the condition and improve clinical symptoms. However, some patients with normal-pressure hydrocephalus are often misdiagnosed as Parkinson's disease because of their abnormal gait.

Why does normal pressure hydrocephalus occur?

Normal pressure hydrocephalus is clinically divided into two categories: one is secondary normal pressure hydrocephalus, which can occur at any age and is often secondary to some clear craniocerebral diseases, such as craniocerebral trauma, subarachnoid hemorrhage, cerebral hemorrhage, intracranial infection, etc.; the other is idiopathic normal pressure hydrocephalus, which often occurs in the elderly and has a more insidious onset, making it difficult to identify the cause and risk factors. Although the pathological mechanism of normal pressure hydrocephalus is not fully understood, it may be related to cerebrospinal fluid absorption disorders, which can lead to ventricular enlargement, paraventricular tissue compression edema, decreased cerebral blood flow and metabolic disorders, causing clinical discomfort symptoms.

What are the symptoms of this disease?

The most common manifestation of normal pressure hydrocephalus is the triad of cognitive impairment, gait disorder and bladder dysfunction, and the proportion of all three occurring simultaneously is approximately 60%.

Cognitive impairment: The incidence rate is over 80%, manifested as slow thinking, emotional indifference, memory, attention, calculation, executive ability and other functional disorders, similar to the symptoms of other types of cognitive impairment such as Alzheimer's disease and vascular dementia. The early symptoms are generally mild, mainly with decreased attention, memory, word fluency and executive ability. In the later stages, when the disease is severe, comprehensive cognitive impairment occurs, affecting the patient's daily life and work. This type of cognitive impairment may recover after treatment, so it is called "reversible dementia."

Gait and balance disorders: The incidence rate is over 90%. The main manifestations of gait abnormalities are slow walking, unstable swaying, small stride, wider distance between the feet, reduced height of the feet, difficulty starting and turning, but normal arm swing function when walking. In the early stages of the disease, the symptoms of gait disorders are mild and difficult to detect, often with dizziness. As the disease progresses, typical gait disorders will gradually manifest themselves. In the late stages of the disease, patients need assistance to walk, or even cannot walk at all. Balance disorders often occur early, causing patients to fall easily.

Bladder dysfunction: The incidence rate is over 60%, and the main manifestations are frequent urination and urgency. In severe cases, urinary incontinence or even fecal incontinence may occur, and a small number of cases may experience urinary retention.

In addition to the above triad, some patients may also experience headaches, dizziness, Parkinsonian tremors, increased sleep, etc., but these symptoms are not specific and require careful identification.

How to determine if you have normal pressure hydrocephalus?

The diagnosis of normal pressure hydrocephalus requires a comprehensive judgment by a professional neurosurgeon or neurologist based on medical history, symptoms, physical examination, and imaging examinations. When the elderly have cognitive impairment and it gradually worsens, the neuropsychological scale can be used to assess the cognitive function status, and then the medical history and physical examination can be combined to determine whether gait abnormalities and urinary incontinence are present at the same time. The discovery of ventricular enlargement in cranial CT or MRI examinations is strong evidence to support the diagnosis of this disease, and it also helps to exclude other organic brain diseases. It should be noted that the clinical "triad" can also be seen in other geriatric diseases, and ventricular dilatation on imaging is also difficult to distinguish from brain atrophy. Therefore, it is easy to miss or misdiagnose clinically. For normal pressure hydrocephalus that is difficult to determine, lumbar puncture and fluid drainage is an important diagnostic technique that can not only measure intracranial pressure, but also make a diagnosis by observing whether the patient's symptoms improve after drainage.

How do I get medical attention? What treatments are available?

In principle, patients with cognitive impairment should first consider visiting a neurology clinic. Most cognitive impairments caused by etiologies are difficult to cure or improve with current medical treatments, and can only delay the progression of the disease. However, if it is confirmed that the cognitive impairment is caused by normal pressure hydrocephalus, early surgery can improve the patient's condition and prognosis. Therefore, once diagnosed, surgical treatment should be performed as soon as possible if there are no obvious contraindications to surgery.

The most commonly used surgical treatments are ventriculoperitoneal shunt and lumbar peritoneal shunt. 1. Ventriculoperitoneal shunt is suitable for the vast majority of patients. The proximal end of the shunt is placed in the ventricle, and the distal end is placed subcutaneously into the peritoneal cavity. Excess cerebrospinal fluid flows through the catheter and the one-way valve into the peritoneal cavity to treat hydrocephalus. This surgical technique is mature, simple to operate, and less traumatic. 2. Lumbar peritoneal shunt is to place the proximal end of the shunt into the lumbar cistern in the lumbar sacral region through lumbar puncture, and the distal end is still placed in the peritoneal cavity. This surgical method does not require puncturing the ventricle, avoids direct damage to the brain tissue, and has less surgical trauma. Currently, most shunts used in clinical practice are equipped with adjustable pressure shunt valves. Physicians can adjust the flow of the one-way valve according to the patient's symptoms through an external adjustment device to help the patient further improve the symptoms.

The effect of surgical treatment varies from patient to patient, but most patients can significantly improve their gait, cognitive ability, urinary incontinence and other symptoms after surgery. Some patients may need several months to see significant improvement. The success rate of surgery is very high, so it is hoped that patients can be discovered, diagnosed and treated early to obtain the greatest clinical benefits and improve their quality of life.