The concept of hydrocephalus refers to the excessive accumulation of cerebrospinal fluid in the skull. It is referred to as internal hydrocephalus if the cerebrospinal fluid accumulates in the ventricles, and external hydrocephalus (EH) if the fluid accumulates in the subarachnoid space on the cortical surface.
Etiology of hydrocephalus
The pathological changes of hydrocephalus are the gradual enlargement of the ventricular system, the bulging of the third ventricle downward to compress the pituitary and optic nerve crossings, and the thinning of the brain parenchyma, most obviously in the frontal lobe, which even penetrates the lateral ventricle and connects to the subarachnoid space. The corpus callosum, pyramidal bundle, basal ganglia, tegmentum, choroid plexus and brainstem can be atrophied due to long-term compression. White matter demyelination, neuraxial compression and deformation, gliosis and degenerative neuronal cell degeneration are observed.
Hydrocephalus is a general term for an excess of cerebrospinal fluid and an increase in pressure due to a disorder in the process of cerebrospinal fluid production or circulation and absorption, which expands the space occupied by normal cerebrospinal fluid, resulting in an increase in cranial pressure and enlargement of the ventricles. Most of the causes are due to obstruction of some parts of the cerebrospinal fluid circulation pathway, while excessive births are less common. It occurs mostly in infants within two years of age, and can be divided into two categories: traffic-related, which refers to the obstruction of cerebrospinal fluid absorption on the brain surface; and non-traffic-related, which refers to the obstruction of cerebrospinal fluid circulation within the ventricular system. There are many causes of hydrocephalus, and the common ones are as follows.
1, congenital malformations: such as stenosis of the midbrain aqueduct, diaphragm formation or atresia, interventricular foramen atresia malformation (median foramen of the fourth ventricle or lateral hollow atresia), cerebrovascular malformation, spina bifida, subhypophyseal herniation of the cerebellum, etc.
2, infection: intrauterine infections such as various viruses, protozoa and syphilis spirochete infectious meningitis are not controlled early, and the proliferating fibrous tissue blocks the circulatory orifice of cerebrospinal fluid, or fetal intracranial inflammation may also occlude the cerebral pool, subarachnoid space and arachnoid granules adhesions.
3, hemorrhage: intracranial hemorrhage caused by fibrous hyperplasia, intracranial hemorrhage from birth injury malabsorption, etc.
4, tumor: can block any part of the cerebrospinal fluid circulation, more often seen near the fourth ventricle, or choroid plexus papilloma.
5, other: certain hereditary metabolic diseases, perinatal and neonatal asphyxia, severe vitamin A deficiency, etc.
Clinical manifestations of hydrocephalus
The clinical manifestations are not consistent and are related to the age at which the pathological changes appear, the severity of the pathology, and the duration of the disease. Congenital hydrocephalus in the fetus mostly results in stillbirth. Hydrocephalus may appear at any age after birth, mostly in the first 6 months of life. In younger patients, the cranial sutures are not joined and the head is easily enlarged, so there are fewer symptoms of increased intracranial pressure. Hydrocephalus manifests itself primarily as a rapid, progressive enlargement of the infant’s head weeks or months after birth. In normal infants, the head circumference increases by 1.2-1.3 cm per month in the earliest six months, but in this case, it is 2-3 times larger, with a round skull, frontal protrusion, abnormal enlargement of the fornix, enlarged and bulging fontanelle, separation of the cranial suture, thinning of the skull and even transparency, and the “broken pot” (Maceen) sign on percussion. The temporal frontal area shows angry veins, the eye is downwardly rotated, and the upper sclera is often exposed (sunset sign). The infant is depressed and cannot lift the head. In severe cases, brain dysfunction may be associated with epilepsy, visual and olfactory disturbances, nystagmus, strabismus, limb paralysis, and mental retardation. Since the infant’s head is compensated for enlargement, headache, vomiting and optic nerve papillary edema are not obvious.
Clinical manifestations of hydrocephalus in infants and children.
The clinical manifestations of infantile hydrocephalus are mainly rapid and progressive enlargement of the infant’s skull within weeks or months after birth (normal infant’s head circumference (occipital forehead) grows 1.2-1.3cm per month at the earliest 6 months, but the disease can increase its 2-3 times faster), while the skull bones are rounded, the frontal roof protrudes, the fontanelle expands and bulges, the cranial suture does open, the skull is deformed, the sound of “broken pot” on percussion “The child’s hair is sparse, the temporo-frontal veins are dilated, the eyes are downwardly rotated, and the upper sclera is often exposed in a sunset manner. The child is mentally depressed and cannot lift his head. In severe cases, it may be accompanied by brain dysfunction, manifested as epilepsy, vomiting, convulsions, strabismus, nystagmus, speech disorders, limb paralysis, ataxia, walking difficulties, and mental underdevelopment.
Clinical manifestations of hydrocephalus in older children and adults.
The clinical manifestations of hydrocephalus in older children and adults are different from those of hydrocephalus in infants and children because of the closure of the bony suture in older children and adults.
1.Characteristics of acute hydrocephalus
Clinical manifestations are generally headache, nausea, vomiting, visual impairment, etc.
2.Characteristics of chronic hydrocephalus
The clinical features are chronic intracranial pressure increase, bilateral temporal or whole cranial pain, nausea, vomiting, optic nerve papillary edema or optic nerve atrophy, intellectual development disorder, motor dysfunction, etc.
3.Normal intracranial pressure hydrocephalus features
The main clinical manifestations are: unstable gait, varying degrees of motor disorders, from slow walking, instability, balance disorders to inability to walk, and finally bedridden; mental disorders are one of the early symptoms, initially memory loss, and in severe cases dementia. Individual patients may have urinary and fecal incontinence. In children, the head circumference is within the normal range or slightly above the normal value, psychomotor development is delayed, intelligence is reduced, learning ability is poor, motor disorders, etc.
4.Static hydrocephalus characteristics
Clinical performance is similar to normal intracranial pressure hydrocephalus, the volume of the ventricles remains stable or shrinks, no new neurological impairment occurs, and psychomotor development improves with age.
Dangers of hydrocephalus
The brain is the most important organ of the human body, although the weight of the brain only accounts for 2% of the weight of the whole body, but its blood accounts for 15% of the whole body blood circulation, brain oxygen consumption for adults is 20% of the whole body oxygen consumption, children up to 40%, brain tissue is an abundant liquid organs, water accounts for 80%, once the water, electrolytes in the brain tissue pathological accumulation that causes hydrocephalus, directly endanger the life center, and even cause serious consequences.
Hydrocephalus can be caused by a variety of reasons, and all kinds of clinical involved, common intracranial inflammation, cerebrovascular, traumatic brain injury, various endogenous or exogenous neurotoxins, hypoxic water and electrolyte disorders, acidosis, liver and kidney failure, etc. can be caused by different mechanisms of fluid accumulation in the brain tissue.
(1) It can lead to mental retardation. There may be only mild memory and calculation loss, often accompanied by slowness, indifference and reticence. In severe cases, dementia may be present. A few may have agitation, irritability, laughter, hallucinations, delirium, etc.
②It can lead to mobility disorders. It often starts gradually after the onset of psychiatric symptoms, with difficulty starting and slow and unstable walking. Muscle tone and tendon reflexes are often increased and reflexes are positive. Sometimes there is mild hemiparesis.
(iii) Urinary and bowel disorders. Frequent, incontinent or difficult urination and defecation, sometimes only in the late stage.
In addition, there may be vertigo, transient disorders of consciousness, nystagmus, and Paxinson’s syndrome.
Diagnosis of hydrocephalus
(A) Medical history
1. Congenital hydrocephalus is symptomatic at birth, such as the more common Dandy-Walk anomaly (atresia of the fourth ventricular foramen, dilatation of the fourth ventricle, overgrowth of the skull or cysts formed at the end of the cerebellum blocking the posterior cranial fossa), with a family history.
2. Secondary hydrocephalus may have a history of encephalitis and meningitis, or a postnatal history of intracranial hemorrhage.
3. Most patients have large head, backward intelligence, depression, drowsiness, developmental delay and malnutrition, etc.
(B) Physical examination
1. Head circumference increases, fontanelle bulges, cranial sutures open, skull shape becomes round, percussion has broken pot sound, cranial bones become thin, even translucent. Frontal and temporal veins can be seen in anger. Positive cranial transillumination test.
2. Both eyes are sunset-like, and most patients have nystagmus.
3. Patients often have twitching, or have repeated convulsive episodes. In addition, cranial nerve palsy, limb paralysis, hypertonia or ataxia are also seen as signs.
(C) Auxiliary examinations
1.Cranial radiography or CT examination shows enlargement of cranial cavity, thinning of skull, separation of cranial sutures and enlargement of fontanelle.
Hydrocephalus treatment
Non-surgical treatment
For early stage or mild condition with slow development, the methods are
(1) Application of diuretics or dehydrating agents, such as acetazolamide, dihydrocoumarol, tachyphylaxis, mannitol, etc.
(2) Repeated puncture and release of fluid through the anterior chimney or lumbar spine.
Surgical treatment
Surgical treatment is available for those with progressive hydrocephalus, significantly enlarged skull, and cerebral cortex thickness over 1 cm, which can be divided into the following.
1, surgery to reduce cerebrospinal fluid secretion: choroid plexus resection followed by cautery, which is now used sparingly.
2, surgery to remove the cause of ventricular obstruction: such as cerebral aqueduct formation or dilatation, median foraminotomy and removal of intracranial occupying lesions, etc.
3, cerebrospinal fluid shunt: the purpose of surgery is to establish cerebrospinal fluid circulation pathway, release the accumulation of cerebrospinal fluid, both for traffic or non-traffic hydrocephalus. Commonly used shunts include lateral ventricle-cerebellar medullary pool shunt, third ventriculostomy, lateral ventricle-ventral cavity, superior sagittal sinus, atrium, external jugular vein shunt, etc.
Which patients are not suitable for surgical treatment?
For patients with severe hydrocephalus, low intelligence, blindness, paralysis, and obvious atrophy of brain parenchyma, the thickness of cerebral cortex is less than 1cm, all of them are not suitable for surgery.