Normal intracranial pressure hydrocephalus

Introduction to normal intracranial pressure hydrocephalus Normal intracranial pressure hydrocephalus refers to normal intraventricular pressure and enlarged ventricles. The clinical manifestations of gait instability, unresponsiveness and urinary incontinence are the main symptoms, and have a certain effect on gait instability and mental retardation after shunt treatment. When the intracerebral pressure gradient is formed in the arachnoid granule blockage, it does not produce hydrocephalus, but a benign intracranial pressure increases. When the cerebrospinal fluid increases in the ventricular system and the subarachnoid space, the ventricular enlargement occurs - hydrocephalus Therefore, the formation of pressure gradients on the ventricles and cerebral cortex surface is the cause of ventricular enlargement. This model of pressure gradient formation has been proved by the artificial model of cat hydrocephalus induced by kaolin. basic knowledge Sickness ratio: 0.05% Susceptible people: no specific population Mode of infection: non-infectious Complications: brain subarachnoid hemorrhage meningitis brain tumor

The cause of normal intracranial pressure hydrocephalus

(1) Causes of the disease

The cause can be divided into two categories, one is a clear cause, such as subarachnoid hemorrhage and meningitis, the other is sporadic and no obvious cause, the main pathological change of the disease is the expansion of the ventricular system, the convex surface Or the subarachnoid adhesion and occlusion of the brain, the most common cause is subarachnoid hemorrhage, followed by intracranial tumors, but also familial normal cranial hydrocephalus. Paget disease sometimes produces subarachnoid Extensive cavity obstruction, meningeal infections, such as tuberculous meningitis, arachnoid adhesions occur in the late stage of the lesion; traumatic subarachnoid hemorrhage and intracranial hemorrhage into the subarachnoid space can produce hydrocephalus, recently It is believed that the narrowing of the midbrain aqueduct is also a common cause.

(two) pathogenesis

In the case of normal intracranial pressure, the mechanism of ventricular enlargement is still not fully understood. At present, it is mainly the cerebrospinal fluid dynamics theory.

1. When the pressure gradient in the brain is formed in the arachnoid granule, it does not produce hydrocephalus, but the benign intracranial pressure increases. When the cerebrospinal fluid increases the flow resistance in the ventricular system and the subarachnoid space, the ventricle enlarges. The accumulation of water, thus the formation of pressure gradients on the ventricle and cerebral cortex surface, is the cause of ventricular enlargement. This model of pressure gradient formation has been proved by the artificial model of cat hydrocephale induced by kaolin.

2. Increased pulsatile pressure of cerebrospinal fluid. The average cerebrospinal fluid pressure in normal intracranial hydrocephalus is not increased, but the pulsatile pressure of the cerebrospinal fluid may increase, and the ventricle may be enlarged. Under normal circumstances, venules, intercellular proteins and lipids in the brain parenchyma are proposed. It has a sponge-like elastic substance, in which the liquid component can be squeezed out when the intracranial pressure is raised, and the brain parenchyma can be compressed under a certain degree of pressure. This pressure is called the brain tissue bioelastic value below this value. The intracerebral pressure only acts on the brain tissue without any liquid extrusion in the brain parenchyma, but the pressure around the ventricles is greater than the pressure in the brain parenchyma, which produces ventricular dilatation. Figure 1 shows the pressure in the ventricles. Relationship with brain parenchyma.

3. Principle of closed elastic container It has been suggested that the initial intracranial pressure of patients with normal intracranial hydrocephalus is increased, resulting in ventricular enlargement, according to the Lapace principle, that is, the product of the liquid pressure (P) of the closed elastic container and the area of the container wall (A). It is equal to the wall bearing capacity (F, F=PA). Thus, once the ventricle is enlarged, although the brain pressure returns to normal, the pressure on the brain wall is still increased. It is also suggested that normal intracranial pressure hydrocephalus is due to brain tissue compliance. To change the manifestation of ventricular enlargement, Welch et al reported that hypertensive arteriosclerotic cerebrovascular disease is more than three times higher than that of patients of the same age group. It is speculated that changes in the elasticity of cerebrovascular wall increase brain tissue compliance, and pressure gradients on the brain surface may occur. Significant change.

At present, the pathophysiological changes of brain tissue in the study of normal intracranial pressure hydrocephalus are mainly:

1 The cerebral blood flow produced by the compression of brain tissue is reduced.

2 abnormalities in neurobiochemical substances in brain tissue, such as an increase in glial fibrin and a decrease in vascular intestinal peptides.

3 secondary neuronal damage.

Normal intracranial pressure hydrocephalus prevention

Strengthening the prevention and treatment of subarachnoid hemorrhage, meningitis and brain trauma can help prevent the occurrence of normal intracranial pressure hydrocephalus.

1. Maintain an optimistic and happy mood. Long-term mental stress, anxiety, irritability, pessimism and other emotions will make the balance of the cerebral cortex excitatory and inhibition process imbalance, so you need to maintain a happy mood.

Normal intracranial pressure hydrocephalus complications Complications Brain subarachnoid hemorrhagic meningitis brain tumor

Normal intracranial pressure hydrocephalus may be associated with spontaneous subarachnoid hemorrhage, head trauma, meningitis, and brain tumor surgery.

Symptoms of normal intracranial pressure hydrocephalus common symptoms memory disorder anxiety gait instability strong grip reflexes sluggish ataxia response dull will loss personality hydrocephalus

Normal intracranial pressure hydrocephalus is mainly characterized by progressive intellectual changes, gait abnormalities and urinary incontinence.

1. Intelligence changes are more common, usually appear first, but sometimes see gait abnormalities. The main changes in intelligence are slow response, near memory loss, dullness, fatigue, apathy, etc., further impaired thinking ability, decreased computing power, personality changes, similar to Alzheimer's disease.

2. Mild gait abnormalities are characterized by slow and unstable walking and widening of the step base, but no obvious cerebellar signs. It is difficult for heavy people to walk, stand, and stand up, and bedridden in the late stage. The dyskinesia of the lower limbs is heavier than the upper limbs, which is characterized by incomplete pyramidal tract damage, often with hyperreflexia and pathological signs.

3. Urinary incontinence appears relatively late, varying degrees.

4. Head CT or MRI can show bilateral ventricular symmetry expansion, third ventricle and fourth ventricle are also enlarged, brain atrophy. Continuous intracranial pressure monitoring can detect the increase of intracranial pressure during the eye movement period after the patient is asleep, which can be distinguished from senile dementia caused by brain atrophy. Lumbar puncture showed normal cerebrospinal fluid pressure and normal CSF examination.

Examination of normal intracranial pressure hydrocephalus

Lumbar puncture, when the patient is in the lateral position, the cerebrospinal fluid pressure is usually not higher than 24kPa (180mmH2O). In the absence of other intracranial lesions, the cerebrospinal fluid sugar, protein and cells are calculated within the normal range. If the symptoms improve, the shunt can be indicated to be effective.

1. Imaging examination

Head CT examination is an important means of normal intracranial pressure hydrocephalus examination. It can determine the extent of ventricular enlargement and cortical atrophy and the cause of hydrocephalus. It is also a means of observing postoperative shunting effect and complications. Typical CT scan The manifestation is that the ventricle is enlarged and the cortical atrophy is not obvious. MRI images can observe small intracranial lesions from the sagittal, crown, and horizontal levels and are superior to CT. At the same time, the dynamic changes of cerebrospinal fluid can be observed by MRI, and the hydrocephalus can be evaluated. A low signal change in the T1-weighted image around the ventricle may indicate a progression of hydrocephalus.

2. Radionuclide cerebral angiography

Radionuclide lumbar injection into the subarachnoid space, photographic observation when entering the brain and ventricles, the most commonly used is iodine 131I labeled human serum protein (RISA), recently used indium - diethylamine pentaacetic acid (DTPA) The marker, about 500 UC, was injected into the subarachnoid space and scanned at 4h, 24h, 48h and 72h, respectively. Three cases were seen in the scan:

(1) Normal type: The radionuclide is convex in the brain and does not flow into the ventricle.

(2) Normal intracranial pressure hydrocephalus: radionuclide enters the ventricle and stays, and the convex surface of the brain cannot be displayed within 72 hours.

(3) Hybrid type: Most patients have this type, that is, the ventricle and cerebral convex surface can be displayed in the staging scan. Since the radionuclide scanning has no positive relationship with the judgment of the shunting effect, this test does not evaluate the normal intracranial pressure hydrocephalus. Too much help is not commonly used in clinical practice.

3. Other examinations of the skull plain film generally have no signs of chronic intracranial hypertension; EEG can be seen as a continuous wide slow wave; 131I in patients with normal intracranial hydrocephalus can show a decrease in cerebral blood flow, cerebral angiography lateral image can be seen in the brain The anterior artery is extraordinarily straight, and the middle cerebral artery lateral lobes are displaced outward. When there is brain atrophy, the distance between the small blood vessels and the inner plate of the skull is widened during the capillary period. The cerebral ventricles are seen in all ventricles and varying degrees. The brain pool is enlarged, and these are not commonly used in clinical examination of hydrocephalus.

Diagnosis and identification of normal intracranial pressure hydrocephalus

Based on medical history, clinical manifestations, and imaging-assisted examinations, a clear diagnosis can generally be made.

Differential diagnosis

Normal intracranial pressure hydrocephalus is mainly differentiated from brain atrophy. The symptoms are similar. The former may have a history of spontaneous subarachnoid hemorrhage (such as sudden severe headache, nausea, vomiting, neck stiffness), head trauma, meningitis and brain. After a tumor, the patient's symptoms often appear within a few weeks to a few months after the onset of the disease, most of which are less than 1 year. The latter age is about 50 years old, and the symptoms develop slowly. Some are seen in lacunar infarction or cerebral hemorrhage. After the patient, most of them have no obvious cause. Sometimes both diseases can occur at the same time. Brain biopsy has differential diagnosis value for Aezheimer's disease and other encephalopathy.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.