What is hydrocephalus?
Excessive retention of cerebrospinal fluid in the ventricles or subarachnoid space due to impaired circulation of cerebrospinal fluid, resulting in enlargement of the ventricles and a corresponding decrease in brain parenchyma, is called hydrocephalus and is often clinically associated with increased intracranial pressure.
Causes of hydrocephalus.
The causes of hydrocephalus are 3-fold. ( 1 ) Poor cerebrospinal fluid circulation pathway. ( 2 ) Impaired absorption of cerebrospinal fluid. ( 3) Excessive production of cerebrospinal fluid. The most common causes are poor cerebrospinal fluid circulation pathways, venous sinus thrombosis, and dural arteriovenous fistulas, which cause a significant increase in pressure in the venous sinuses to the point of impaired cerebrospinal fluid absorption. Excessive production of cerebrospinal fluid is caused by choroid plexus papilloma, etc.
Classification of hydrocephalus.
(i) General classification method.
①Fetal hydrocephalus. (ii) Congenital hydrocephalus. (iii) Hydrocephalus in combination with spinal meningioma. (iv) Hydrocephalus after neonatal ventricular hemorrhage. ⑤ hydrocephalus after infection. (6) Hydrocephalus after subarachnoid hemorrhage. (7) Idiopathic adult hydrocephalus. ⑧Post-traumatic hydrocephalus.
(II) The most advanced international classification of hydrocephalus;
Special factors
Type of hydrocephalus
Time of onset
1.Fetal hydrocephalus. 2.Neonatal hydrocephalus. 3.Infant hydrocephalus. 4.Adult hydrocephalus.
A, Intrauterine hydrocephalus. B, Postnatal hydrocephalus.
(1) Congenital hydrocephalus. (2) Acquired hydrocephalus.
A, typical neonatal hydrocephalus. B, early birth hydrocephalus. C, late birth hydrocephalus.
Causes
1.Primary hydrocephalus. 2.Secondary hydrocephalus.
3.Tumor hydrocephalus. 4.Non-tumor hydrocephalus.
5.Developmental hydrocephalus. 6.Brain-damaging or destructive hydrocephalus.
7.Neoplastic hydrocephalus. 8.Traumatic hydrocephalus.
9.Infectious hydrocephalus. 10.Hemorrhagic hydrocephalus.
11.Vascular hydrocephalus. 12.Skeletal hydrocephalus.
Obstruction site
1.Obstructive hydrocephalus. 2.Hypersecretory hydrocephalus.
3.Traffic hydrocephalus. 4.Non-traffic hydrocephalus.
5.Intraventricular obstructive hydrocephalus. 6.External obstructive hydrocephalus.
Location of fluid accumulation
1.Internal hydrocephalus. 2.External hydrocephalus.
3.Intracerebral hydrocephalus. 4.Subarachnoid hydrocephalus.
5.Intracerebral parenchymal hydrocephalus. External parenchymal hydrocephalus.
Mode of onset
1.Acute hydrocephalus.
2.Chronic hydrocephalus.
Mode of progression
1.Rapidly progressive hydrocephalus. 2.Chronic progressive hydrocephalus. 3.Progressive hydrocephalus. 4.Static hydrocephalus.
3.Progressive hydrocephalus. 4.Static hydrocephalus.
5.Surgical resting hydrocephalus. 6.Spontaneous resting hydrocephalus.
Ventricular size
1.Significantly enlarged ventricles. 2.Moderately enlarged ventricles.
3.Mildly enlarged ventricular hydrocephalus. 4.Normal ventricular hydrocephalus.
5.Slit ventricular hydrocephalus.
Intracranial pressure
1.High pressure hydrocephalus.
2.Normal pressure hydrocephalus.
3.Low pressure hydrocephalus.
Relationship with malformation.
1.Simple hydrocephalus. 2.Complex hydrocephalus.
3.Racial degenerative hydrocephalus. 4.Developmental abnormal hydrocephalus.
5.Structurally destructive hydrocephalus.
Prognosis
1.Curable hydrocephalus. 2.Uncurable hydrocephalus.
3.Shunt-responsive hydrocephalus. 4.Shunt-refractory hydrocephalus.
(C) The simplest classification of hydrocephalus usually used in China.
According to the etiology, it is divided into (A) traffic hydrocephalus and (B) obstructive (obstructive) hydrocephalus.
A Traffic hydrocephalus.
A lesion that produces excessive cerebrospinal fluid secretion and impaired absorption is predominant.
Causes.
-
Absorption disorders: often due to intracranial infection, trauma, subarachnoid hemorrhage, etc., which cause arachnoid adhesions and occlusion of the subarachnoid space, arachnoid granules and other superficial vascular spaces and perineural spaces, and obstruction of cerebrospinal fluid absorption.
- Dysplasia of the arachnoid granules, hypoplasia of the brain pool and venous sinus occlusion: congenital hypoplasia of the brain pool, bilateral occlusion and narrowing of the transverse or sigmoid sinuses lead to impaired absorption of cerebrospinal fluid.
- Changes in cerebrospinal fluid composition: such as congenital tumors causing elevated protein content in the cerebrospinal fluid, which affects cerebrospinal fluid absorption.
- Increased cerebrospinal fluid secretion: seen in intracerebroventricular choroid plexus papilloma or carcinoma and in rare choroid plexus hyperplasia.
B Obstructive (obstructive) hydrocephalus.
Causes
1. Congenital malformations.
( 1 ) Narrowing or occlusion of the midbrain aqueduct.
( 2 ) Dandy-Walker syndrome: manifested by hydrocephalus, hypoplasia or lack of cerebellar earthworms, giant arachnoid cyst in the same posterior cranial fossa as the fourth ventricle. Obstruction of the outlet of the fourth ventricle, etc.
( 3 ) Cerebrospinal fluid circulation is obstructed by submicrocephalic tonsillar herniation malformation and skull base depression, producing hydrocephalus.
( 4 ) Familial hereditary hydrocephalus: 7% of male hydrocephalus is caused by chromosomal abnormalities. It is characterized by narrowing of the cerebral aqueduct and moderate mental retardation.
2. Inflammation or hemorrhage.
Can occur at any age. Such as intracranial hemorrhage caused by various meningitis, trauma, surgery, hypertensive cerebral hemorrhage, rupture of cerebral aneurysm and vascular malformation, etc.. Blood clots can rapidly block the interventricular foramen, aqueduct or fourth ventricular outlet and form acute hydrocephalus, or cause subacute or chronic hydrocephalus due to secondary adhesions at the above mentioned sites.
3.Intracranial occupying lesions.
Such as tumors, parasites, cysts, etc., can block cerebrospinal fluid pathways causing hydrocephalus.
Clinical manifestations of different types of hydrocephalus
I. High pressure hydrocephalus (infants, children, adults are different)
(a) Infant hydrocephalus.
1.Large head: for weeks or months after birth, there is a rapid increase in head size, and a few heads are significantly larger than normal at birth.
2, fontanelle enlargement, bulging, high tension, the child is still not sunken when upright, in severe cases, occipital fontanelle and even lateral fontanelle are enlarged.
3.The cranial suture is separated, the head shape becomes garden, the skull becomes thin and soft or even transparent, and the head percussion shows a “broken pot sound.
4, hair thinning, thin and bright scalp, frontal scalp vein anger.
5.The brain cranium is large but the face cranium is small, and in severe cases, the orbital roof is pressed. The eyeballs move down and the sclera is exposed, forming the so-called “sunset sign”.
6. Neurological signs: nystagmus, ataxia, increased muscle tone of the limbs, or mild paralysis, etc.
7.Other signs: blindness, detached strabismus, upward visual impairment, feeding difficulties, and sometimes characteristic high-pitched cries. Mental depression, sluggishness, irritability, difficulty in lifting the head, spastic paralysis, mental retardation, and even convulsions or drowsiness and convulsions. If the disease progresses, brain herniation may occur and death may occur. Death can also occur from complications such as malnutrition, systemic failure, and respiratory infections.
( II ) Hydrocephalus in children.
1.See in toddlers and older children, usually 2 to 10 years old.
2, congenital often from infancy onset, is slowly progressive, acquired secondary to inflammation, intracranial occupying lesions.
3.Because the bone suture is often closed in childhood, the skull enlargement is not obvious.
4.The triad of increased intracranial pressure: headache, vomiting, fundus edema, and retinal hemorrhage in the fundus in severe cases.
5.If there is “broken pot sound” on head percussion, it means the skull suture is separated again.
6. Neurological examination may reveal extraocular muscle paralysis, increased muscle tone of lower limbs, and unstable gait.
7. Mental retardation may appear in the late stage.
8.Endocrine abnormalities, such as precocious puberty or growth retardation.
(iii) Adult hydrocephalus.
According to the urgency of hydrocephalus occurrence, it can be divided into acute hydrocephalus and chronic hydrocephalus. Common causes are spontaneous subarachnoid hemorrhage, cerebral hemorrhage, tumor and meningitis.
1, Acute hydrocephalus: due to sudden blockage of cerebrospinal fluid channels and acute enlargement of the ventricles within a few hours.
Performance.
(1) Acute intracranial pressure increase sign, which is progressively aggravated.
(2) Neck pain: suggests possible herniation of the cerebellar tonsils into the greater occipital foramen.
(3) Transient black clouding, caused by compression of the posterior cerebral artery at the cerebellar rim.
(4) Progressive impairment of consciousness.
(5) Late onset of decerebrate or decorticate tonicity, as well as slow pulse, elevated blood pressure, and deep breathing. If not treated, it can often lead to death.
2.Chronic hydrocephalus: (1) Chronic intracranial hydrocephalus
(1) chronic intracranial pressure increase sign, headache and nausea, vomiting are lighter than acute hydrocephalus, fundus edema is often accompanied by secondary atrophy.
(2) Abduction palsy of both eyes.
(3) Mental and behavioral disturbances or abnormalities, memory loss.
(4) Spastic quadriplegia, characterized by heavy lower extremities and light upper extremities.
(5) Endocrine abnormalities, such as obese reproductive degeneration or precocious puberty.
(6) Rarely, there are bilateral temporal hemianopsia and cerebellar signs.
3. Normal pressure hydrocephalus.
A Normal pressure hydrocephalus in adults is mainly manifested as a triad of signs.
(1) Gait disorder: It is often the first symptom, with the milder ones losing balance and the more serious ones unable to walk or stand. The typical person shows difficulty in starting, walking with feet apart, broken gait, and forward lunge.
(2)
Mental disorders: Mental changes usually appear early and gradually worsen within a few weeks to a few months. At the beginning, there is amnesia of near events, followed by delayed thinking and movement, and in severe cases, there may be significant speech delay, silence, and reduced motor function of the body. Memory and writing functions are significantly impaired.
(3) Urinary incontinence: usually occurs in the later stages. Fecal incontinence is rare.
B. Normal pressure hydrocephalus in children
This disease is often underestimated in children as “compensatory hydrocephalus” or “resting hydrocephalus”. In fact, if these children are treated in time, they can often achieve significant progress. Main manifestations: a large head. b Delayed development, mild to moderate reduction in IQ. c Mild spastic paralysis of limbs.
4 Extracerebral hydrocephalus
The cause is not clear, and most of them develop within 6 months of age, mainly with asymptomatic macrocephaly, mild enlargement of the ventricles and enlargement of the subarachnoid space on the convex side of the brain. In a small number of children, traffic hydrocephalus develops further and gradually becomes symptomatic.
Diagnostic methods for different types of hydrocephalus
Based on the typical clinical manifestations described above, it is not difficult to diagnose this disease. The following tests are helpful to further understand the cause, type, site of blockage and severity of hydrocephalus.
1. Dynamic observation of head circumference. (for children). Normal neonatal head circumference diameter (frontal, occipital) is 33-35 cm, the first 6 months after birth growth is faster, increasing 1.2-1.3 cm per month, the first half of the year can reach 8-10 cm, the second half of the year increased by 2-4 cm, the average head circumference at the age of 1 year is about 46 cm, the second year increased by 2 cm, the third year increased by 2 cm, 5 years of age reached 50 cm, 15 years of age is close to the adult head circumference, about 54-58 cm. At 15 years of age, the head circumference approaches that of an adult, about 54-58 cm. The head circumference of children with hydrocephalus can be two to three times the normal value.
2.Cranial X-ray
In infants, the skull enlarges, the skull bone thins, the plate barrier structure is scarce or even disappears completely, the vascular sulcus becomes shallow or disappears, the cranial suture separates, the fontanelle enlarges and the ratio of craniofacial bone is disproportionate. In children, intracranial hypertension such as enlargement of the pterygoid, absorption of the posterior bed prominence and deepening of the cerebral gyrus pressure traces can be seen, and in some children, frontal foramina can be seen. At present, it is less commonly used.
3.CT and MRI
CT and MRI. It is the main and reliable method to diagnose hydrocephalus. It helps to clarify the etiology, classify and distinguish ventricular enlargement caused by other reasons, and it can observe the ventricular changes after shunt surgery to track the effect of shunt surgery. In particular, Cine-MRI is decisive in differentiating obstructive and traffic hydrocephalus, as well as normal pressure hydrocephalus and ventricular enlargement due to brain atrophy.
4.Ventriculography, brain pool imaging and radionuclide scan. It is mainly used for the diagnosis and treatment of normal pressure hydrocephalus.
Diagnosis of normal pressure hydrocephalus.
Since normal pressure hydrocephalus is easily confused with ventricular enlargement caused by dementia and cerebral atrophy in terms of clinical symptoms and imaging manifestations, and the etiology is different and the treatment methods used are completely different, it is very important to make a correct diagnosis of normal pressure hydrocephalus.
1.CT: It can show the size of the ventricles, the degree of cortical atrophy and the associated lesions. In normal pressure hydrocephalus, the ventricles are significantly enlarged and a deepening of the sulcus occurs, but the two are disproportionate and the enlargement of the ventricles is more pronounced. In some patients, periventricular hypodensity is an important manifestation.
2.MRI: It is possible to distinguish flowing cerebrospinal fluid from resting cerebrospinal fluid, and to differentiate conduit obstruction or traffic, atrophic ventricular enlargement or hydrocephalic ventricular enlargement by measuring the flow rate of cerebrospinal fluid through the conduit.
3.Isotope brain pool scan: Through lumbar puncture, radionuclide is injected into the subarachnoid space and brain scans are performed at 4, 24, 48 and 72 hours. Under normal conditions, the isotope flows on the convex surface of the brain without entering the ventricles, and the isotope disappears completely from the surface of the brain after 48 hours. In patients with primary normal pressure hydrocephalus, isotopes enter the ventricles and remain there for up to 72 hours without accumulation on the convex surface of the brain. Or the isotope enters the ventricle and also accumulates on the convex surface of the brain.
4.Lumbar puncture: The pressure of cerebrospinal fluid is less than 180 mmH 2 O in lateral position, and the patient’s symptoms and signs often improve temporarily after lumbar puncture.
5, continuous intracranial pressure tracing: continuous monitoring of intracranial pressure for 48 to 72 hours can reveal two kinds of pressure changes. One kind of pressure is basically stable with little fluctuation, and the average intracranial pressure is within the normal range; the other kind of intracranial pressure is seen to have a paroxysmal increase in the form of jagged high waves or plateau waves, accounting for about 10% of the pressure measurement time, and the intracranial pressure of the rest of the time is often at the upper boundary of normal or mildly elevated. The latter is clinically effective for surgical treatment.
Lumbar puncture cerebrospinal fluid perfusion test: After successful lumbar puncture, the lumbar puncture needle is connected to a tee tube. The other two ends of the tube are connected to a manometer and syringe, respectively, and saline is injected into the subarachnoid space through the syringe at a rate of approximately 1.5 mL per minute, and the manometer is observed for changes. The rise in pressure does not exceed 20 mmH 2 O per minute when normal, but it is higher than this in normal pressure hydrocephalus.
Differential diagnosis
1. Subdural hematoma or effusion in infants: Although infants with subdural hematoma or effusion also have cranial enlargement and cranial thinning, they are often accompanied by optic nerve papillary edema, but lack the sunset sign. CT scan can be distinguished.
2, rickets: irregular thickening of the skull in rickets, resulting in protrusion of the frontal and occipital bones, square skull, seemingly enlarged skull, but no symptoms of increased intracranial pressure and ventricular enlargement, but there are generalized skeletal abnormalities.
3.Brain dysplasia: Although the ventricles are also enlarged, but the head is not large without intracranial pressure increase, but there are neurological function and intellectual development disorders.
Hydrocephalic anencephaly: In addition to the absence of cerebral cortex in the occipital region, a prominent basal ganglion is also visible on CT films.
5.Megalencephaly: Although the skull is large, there is no symptom of increased intracranial pressure, and the CT shows normal size of the ventricles.
6, brain atrophy: mainly distinguished from normal pressure hydrocephalus. The symptoms of both are similar, but cerebral atrophy usually develops after the age of 50, and the symptoms develop slowly for several years. CT examination is characterized by mild enlargement of the ventricles, but not cumulative fourth ventricle, and significant widening of the sulcus gyrus. MRI shows enlargement of both the ventricles and the subarachnoid space.
MRI is the gold standard for the diagnosis and differential diagnosis of hydrocephalus, as it not only allows precise qualitative and quantitative measurement of the flow rate and flow of cerebrospinal fluid, but also distinguishes the type of hydrocephalus, the site and degree of hydrocephalic obstruction, and the enlarged ventricles caused by cerebral atrophy from normal pressure hydrocephalus.
Treatment of hydrocephalus
Regardless of the cause of hypertensive hydrocephalus, it must be treated promptly. Pharmacological treatment is mainly to reduce cerebrospinal fluid secretion and increase water drainage from the body. It is important to note that pharmacological treatment is mainly used for lighter patients and as temporary preoperative medication. The treatment of hydrocephalus should be mainly surgical. Surgery can be divided into three types: etiologic treatment, reduction of cerebrospinal fluid production, and cerebrospinal fluid shunt. Surgery should be performed as early as possible after hydrocephalus is detected. Surgery is less effective in late stages because of cortical atrophy or severe neurological dysfunction. Before the 1980s, the treatment of hydrocephalus was a very difficult problem, and patients with hydrocephalus had a very high mortality and disability rate, and early shunt surgery, too, had extremely high complications. In recent years, with the development of science and technology, there are many new methods for the treatment of hydrocephalus, the emergence of different mechanisms of shunt valves, and the development of neuroendoscopic technology, many patients have been cured by effective treatment, and return to normal life and work.
(I) Etiological treatment (radical approach)
Etiological treatment should become the preferred method for treating hydrocephalus. For obstructive hydrocephalus, lifting the obstruction is the most ideal method. For example, interventricular foramen perforation, conduit reconstruction, fourth ventricular cyst fistula, intracerebroventricular tumor resection, third ventricular floor fistula, occipital foramen decompression, etc. Using etiologic treatment methods, once the surgery is successful, patients can benefit from it for the rest of their lives. In recent years, neuroendoscopic interventricular foramen perforation, neuroendoscopic conduit reconstruction and neuroendoscopic third ventriculostomy for hydrocephalus treatment have become the most effective and safest minimally invasive methods for hydrocephalus treatment, and the complications of surgery are less than
It is the only unit in China and one of the few units in the world that can perform catheterization and stenting for the treatment of obstructive hydrocephalus.
(II) Reduction of cerebrospinal fluid formation
If choroid plexus resection or electrocautery is used. It is mainly used for traffic hydrocephalus, especially in patients who have failed shunt surgery or are not suitable for shunt. Electrocautery is now performed endoscopically, which can significantly reduce the incidence of surgical complications.
(C) Cerebrospinal fluid shunt
In the early days, various shunt procedures were performed to treat hydrocephalus, including ventricular and ventricular pool shunts, e.g., lateral ventricular and occipital pool shunts. Ventricular body shunt, such as: ventricular (or ventricular pool) ventral shunt, ventriculothoracic shunt, etc. Drainage of cerebrospinal fluid out of the body, e.g., lateral ventricular bulbar shunt. Ventricular and ureteral shunts, etc. Introduction of cerebrospinal fluid onto the cardiovascular system, such as ventriculo-atrial shunt, ventriculo-jugular intraventricular shunt, etc.
Many of the above cerebrospinal fluid shunts have been eliminated due to poor efficacy or the tendency to cause more complications. The most commonly used shunts are ventriculoperitoneal shunts and other shunts. However, the main complications that currently plague the outcome of shunt surgery are complications.
These include.
1, blockage of the shunt system. The most common, generally in the range of 50 to 70%.
2, infection. The incidence is 7-10%, and in children it is more than 30%. Mainly for ventriculitis or peritonitis.
3, excessive or insufficient shunt. ( 1 ) Excessive shunt syndrome is common in children. The patient presents with a typical postural headache, which is aggravated when upright and relieved when lying down. CT examination shows small ventricles. ( 2 ) Chronic subdural hematoma or effusion Most often seen after normal pressure hydrocephalus surgery, mostly due to excessive drainage of cerebrospinal fluid and low intracranial pressure caused by the use of low impedance shunts. ( 3 ) Patients with inadequate cerebrospinal fluid shunts do not improve their symptoms after surgery, and examination reveals that ventricular enlargement still exists or is not significantly changed. The main reason is that the valve pressure of the shunt used is not appropriate.