Hydrocephalus is a condition in which there is an increase in the amount of cerebrospinal fluid in the skull and an enlargement of the ventricular system or subarachnoid space due to cranio-cerebral disorders that cause excessive secretion or absorption of cerebrospinal fluid, usually due to obstruction of the cerebrospinal fluid circulation and malabsorption, but less frequently due to excessive secretion.
Disease classification
Classification according to pathology
(1) Obstructive hydrocephalus: Obstructive hydrocephalus, also known as non-traffic hydrocephalus or intraventricular type obstructive hydrocephalus, is formed when a lesion is located in or near the ventricular system and obstructs the cerebrospinal fluid circulation in the ventricular system. It is the most common type of hydrocephalus, which is caused by obstruction above the fourth ventricular outlet. It is common in arachnoid cyst, atresia or stenosis of the aqueduct, hypoplasia of the median foramen or interventricular foramen, Chiari malformation, craniopharyngioma, etc.
(2) Traffic hydrocephalus: Traffic hydrocephalus is hydrocephalus due to obstruction of extraventricular cerebrospinal fluid circulation pathways or impaired absorption, and also hydrocephalus due to excessive production of cerebrospinal fluid (papilloma)
According to the level of intracranial pressure.
(1) High cranial pressure hydrocephalus;
(2) Normal intracranial pressure hydrocephalus;
(3) low cranial pressure or negative pressure hydrocephalus;
Causes of disease
Hydrocephalus can be caused by a variety of reasons, including intracranial inflammation, cerebrovascular malformation, traumatic brain injury, various endogenous or exogenous neurotoxins, hypoxia, water and electrolyte disorders, acidosis, liver and kidney failure, etc. All of them can cause fluid accumulation in brain tissue through different mechanisms.
Clinical manifestations
Typical symptoms are headache, vomiting, blurred vision, optic nerve papillary edema, occasional diplopia, vertigo and seizures.
Patients with chronic hydrocephalus are clinically characterized by chronic intracranial pressure increase, and may present with bilateral temporal or whole cranial pain, nausea, vomiting, optic nerve papillary edema or optic nerve atrophy, intellectual developmental impairment, and motor dysfunction.
Normal pressure hydrocephalus is a special type of traffic hydrocephalus, mostly occurring at the base of chronic traffic hydrocephalus, where compensatory regulation results in reduced secretion and accelerated compensatory absorption of partially intact arachnoid granules, resulting in a new equilibrium. Although the ventricular system is enlarged, the cerebrospinal fluid pressure is normal or close to normal, so it is called normal pressure hydrocephalus. CT manifestations: general enlargement of the ventricular system and deepening of the cerebral sulcus, but the two are disproportionate, with more significant enlargement of the ventricles. The clinical manifestations are mostly dementia, ataxia, and urinary incontinence (triad of signs), which should be differentiated from cerebral atrophy
Indications for surgery
Surgery was originally considered to be indicated for cases with high intracerebroventricular pressure (more than 250 mm water column) or in cases where non-surgical treatment has failed. Nowadays, patients with normal pressure hydrocephalus who have undergone lumbar puncture for external drainage should undergo VP surgery if their symptoms are relieved and their ambulation is significantly improved. At present, the understanding of hydrocephalus is further deepened, and a part of patients with enlarged ventricles and low intracranial pressure, even negative pressure, are found to have the same symptoms as normal pressure hydrocephalus, with high compliance of brain tissue, and the symptoms are obviously improved after negative pressure external drainage.
Surgical modalities.
(1) Decongestion surgery (etiologic treatment): etiologic treatment should be the method of choice for hydrocephalus. For obstructive hydrocephalus, removal of obstruction is the most desirable method.
(3) Cerebrospinal fluid shunts
Ventriculoperitoneal shunt;
Lumbar pool ventriculoperitoneal shunt
Postoperative complications
1, blockage of the shunt system: the most common.
2. Infection: the incidence is 7% to 10%, and in children, it is more than 30%. It is mainly ventriculitis or peritonitis.
Excessive or inadequate shunting: ( 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 ) Inadequate cerebrospinal fluid shunts The patient’s symptoms do not improve after surgery, and examination reveals that the enlarged ventricles are still present or not significantly changed. The main reason is the improper pressure of the shunt valve used, resulting in poor drainage of cerebrospinal fluid.
4. Slit ventricle syndrome: It usually refers to the symptoms of increased intracranial pressure such as headache, nausea, vomiting and ataxia, unresponsiveness and lethargy several years after shunt surgery. However, CT scans reveal a less-than-normal ventricular morphology, and the examination valve is usually pressed and then slowly reflows, suggesting obstruction at the ventricular end of the shunt. The pathogenesis is due to prolonged excessive drainage of cerebrospinal fluid.
The most effective way to prevent these complications is to shunt with an adjustable pressure shunt system.