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Intracranial hypotension syndrome

Introduction
Cause
Examine
Diagnosis

Introduction

Introduction Low intracranial pressure syndrome is a clinical syndrome characterized by orthostatic headache caused by various causes of cerebrospinal fluid pressure in the lateral subarachnoid space of the lumbar subarachnoid space below 0.59 kPa (60 mmH2O). Low intracranial pressure syndrome is generally caused by a decrease in brain volume, a decrease in cerebrospinal fluid, or a decrease in blood volume in the brain, resulting in a decrease in total intracranial volume, resulting in a decrease in intracranial pressure and a series of clinical manifestations. Its unique clinical manifestations have recently Gradually attracted attention, but there are many problems that have not yet been elucidated. Clinically, this syndrome is not uncommon. It is often misunderstood if it is not recognized. It is often divided into symptomatic low intracranial pressure and primary low intracranial pressure.

Cause

Cause

(1) Reduced brain volume

Loss of water or cachexia state such as loss of brain parenchyma, brain volume reduction; cerebrospinal fluid production decreased; blood concentration, increased blood osmotic pressure, brain atrophy.

(two) cerebrospinal fluid reduction

1, cerebrospinal fluid leakage: lumbar puncture or meningeal surgery can be due to leakage of cerebrospinal fluid from the pinhole and local choroid plexus reflex sputum and control of spinal fluid disorder in the hypothalamus. In the case of craniocerebral trauma or craniocerebral surgery, surgery or trauma leads to a decrease in cerebral circulation or a skull base fracture, resulting in leakage of cerebrospinal fluid and reflex spasm of local cerebral plexus vessels. Patients with meningocele with cerebrospinal fluid leakage.

2, other: allergic chronic soft meningitis and choroidal ependymitis after infection or infection; shock state; it has been reported that barbiturate chronic poisoning may have low intracranial pressure syndrome.

mechanism

Because of the many causes of low intracranial pressure syndrome, the mechanism is complex, and it is believed that intracranial hypotension is often caused by the following three reasons.

(1) Volume reduction

1. Dehydration or cachexia state At this time, intracranial hypotension is formed by the following three factors:

1) Loss of brain parenchyma and shrinking brain volume. 2) Cerebrospinal fluid production is reduced. 3) Concentration of blood, increased blood osmotic pressure, and thus increased absorption of cerebrospinal fluid.

2, brain atrophy: generally does not cause intracranial hypotension. Because brain atrophy is a chronic process, its reduced volume is gradually replaced by an increase in cerebrospinal fluid.

(two) cerebrospinal fluid reduction

1. Cerebrospinal fluid leakage: After lumbar puncture, low intracranial pressure can be produced due to the continuous leakage of cerebrospinal fluid from the pinhole and the local venous choroid plexus reflex sputum and the control of the hypothalamic central nervous system caused by cerebrospinal fluid.

2, craniocerebral trauma or craniocerebral surgery: due to surgery or trauma caused by decreased brain circulation and local choroid plexus reflex sputum, causing intracranial hypotension, often accompanied by conscious disturbance. In addition, traumatic brain injury can cause choroid plexus villus matrix hemorrhage, followed by intracranial hypotension in the stage of villus stromal fibrosis. Therefore, low intracranial pressure syndrome after traumatic brain injury is often one of the main symptoms in the late stage of brain trauma.

3, infection or infection - allergic anti-celebral chronic meningitis and choroidal ependymitis: due to fibrosis of the choroid plexus matrix of the patient's ventricle, the upper choroid plexus often atrophy, collagen fibers and argyrophilic fibers in the villus matrix The collagen fibers and the small arteries of the hiring hair are transparent, and therefore, the lumen of the villus arteries is often narrow or occluded. In addition to the villus, a fibrous film is formed. Due to the above pathological changes, the production of cerebrospinal fluid is reduced, resulting in intracranial hypotension.

4, poisoning: It has been reported that chronic barbiturate poisoning has a low intracranial pressure syndrome, and its pathogenesis is unknown.

5, primary intracranial hypotension: the cause and pathogenesis of primary low intracranial pressure is not clear, according to the literature may be related to the following factors: 1 choroid plexus cerebrospinal fluid production decreased or overabsorbed; 2 nerve root anatomy abnormalities; 3 Choroid plexus vasospasm; 4 hypothalamic dysfunction; 5 meningeal swelling and meninges, arachnoid palsy.

6, shock state: any cause of shock state, can reduce cerebral blood flow, resulting in lower pressure of cerebrospinal fluid.

When the partial pressure of carbon dioxide in the blood is lowered, the volume of the cerebral vascular bed is reduced, and the intracranial pressure is significantly lowered. Patients often have mental retardation, which is caused by a rapid suppression of cerebral blood circulation or insufficient blood supply. After the patient inhaled carbon dioxide, the partial pressure of carbon dioxide in the blood increased, and the cerebral blood vessels dilated, the intracranial pressure increased, and the condition improved significantly.

Examine

an examination

(1) medical history

There are many causes of low intracranial pressure syndrome. It should be noted whether there is dehydration or cachexia state. After lumbar puncture or craniocerebral trauma or cranial brain surgery, cerebrospinal fluid leaks continuously from pinhole or injury and local choroid plexus reflex And control the cerebrospinal fluid produced by the hypothalamic center of the disorder, infection or infection - allergic chronic soft meningitis and cerebral periventricular inflammation, chronic barbiturate poisoning, shock state.

(2) Physical examination

For patients with low intracranial pressure syndrome, careful examination can often confirm the diagnosis, should pay attention to the relationship between some headache and body position, headache and cough, increase the relationship between abdominal pressure, lying position and erect pulse, blood pressure, pupil size, both sides Whether it is equal and responds to light; eyeball activity; whether there are blurring of the fundus or edema of the papillary sac, bleeding and exudation; the movement, sensation and reflex of the cranial nerve and spinal nerve, especially the bilateral abductor nerve; meningeal spur Call for neck muscle tenderness. Making timely judgments on the condition and choosing the most appropriate auxiliary examination will be of great help to diagnosis and treatment.

(3) Auxiliary inspection

In addition to routine blood, urine, stool, electrocardiogram, chest X-ray and other examinations, patients with increased intracranial pressure should also choose an auxiliary examination according to the medical history and physical examination.

1, lumbar wear: lateral position of the lumbar spinal fluid pressure below 0.59kPa (60mmH2O) or can not be measured, negative pressure without cerebrospinal fluid outflow, no bleeding cerebrospinal fluid outflow, with a small needle pumping only a small amount of cerebrospinal fluid. The cerebrospinal fluid pressure is lower than 3.432 kPa when sitting. The protein content of cerebrospinal fluid can be slightly increased, and the number of red blood cells is slightly increased. This is because the low pressure of cerebrospinal fluid leads to high edema of the meninges. Then the slight increase of red blood cells may be an inflammatory reaction or a response to extravasation of red blood cells.

2, skull CT or MRI can show that the ventricles, cerebral cisterns become smaller, sulci narrowing and extensive, diffuse meningeal thickening, and can exclude cerebellar tonsil obstruction leading to lowering cerebrospinal fluid pressure during lumbar puncture.

Diagnosis

Differential diagnosis

The diagnosis should be differentiated from the following symptoms:

1. Increased intracranial pressure: normal adult intracranial pressure is 0.8 ~ 1.8kPa, children are 0.5 ~ 1kPa. Increased intracranial pressure means that the pressure generated by the contents of the cranial cavity on the cranial wall exceeds the normal range, that is, the patient's lateral position is used for lumbar puncture, and the cerebrospinal fluid hydrostatic pressure exceeds 2 kPa. Cranial hypertension is not only a very common syndrome in neurosurgery, but is also common in other subjects.

2. Hydrocephalus: Hydrocephalus is a general term for cerebrospinal fluid production or circulatory absorption process, resulting in excessive cerebrospinal fluid volume, increased pressure, and enlarged space occupied by normal cerebrospinal fluid, which in turn increases intracranial pressure and ventricular enlargement.

3. Intracranial space-occupying lesions: There are mainly brain tissue, cerebrospinal fluid, cerebral blood vessels and blood flowing in the lumen of the normal human cranial cavity. Under normal circumstances, the cranial cavity is completely closed, the volume of the cranial cavity and the volume of the contents contained therein are constant, and the intracranial pressure is maintained (about 0.686-1.96 kPa, or 70-180 mm water column). The so-called intracranial space-occupying lesion refers to a certain space in the cranial cavity occupied by focal lesions, causing clinical focal neurological symptoms, signs and increased intracranial pressure. This lesion is called intracranial space-occupying lesion.