This article includes discussion of hydrocephalus, acquired hydrocephalus, noncommunicating hydrocephalus, and communicating hydrocephalus. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Acute hydrocephalus is a life-threatening condition that is usually treatable with prompt surgical intervention. Various alterations in the normal cerebrospinal fluid (CSF) dynamics, which result in elevated intracranial pressure, are together termed hydrocephalus. There are many causes of hydrocephalus, including aqueductal stenosis, congenital anomalies, tumors, infection, hemorrhage, and inflammatory diseases. Hydrocephalus may present acutely or in a more chronic fashion, depending on the severity of the CSF alterations. Treatment is surgical and may include resection of causative lesions, shunt placement, or third ventriculostomy. Patients who require shunt placement are at a life-long risk of shunt failure and acute neurologic decline. The author reviews the basic characteristics of this condition and its management, including updates about endoscopic third ventriculostomy as an alternative surgical procedure to shunt placement.
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• Hydrocephalus is an abnormal elevation of intracranial pressure due to altered cerebrospinal fluid dynamics.
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• Various etiologies are associated with hydrocephalus and are classically grouped into communicating and non-communicating categories.
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• Treatment may be limited to removing an obstructive lesion or placing a temporary CSF diversion system but often requires either a shunt or a third ventriculostomy for long-term management.
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• Shunt failure is a complication that often requires prompt recognition due to the high morbidity associated with delayed treatment.
Historical note and terminology
In the early 1700s Vesalius was the first to accurately recognize hydrocephalus as an accumulation of fluid within the cerebral ventricles. During the remainder of the 18th century, Morgagni and others described the neuroanatomic and pathologic causes of hydrocephalus. In the next century, the physiology of CSF circulation began to be elucidated. Magendie is credited with developing the concept of an active bulk flow of CSF.
The first half of the 20th century was a time of rapid increases in our understanding of the clinical and radiographic aspects of hydrocephalus. Of particular importance is the contribution of Dandy with the introduction of pneumoencephalography in 1918 and pioneering work in neuroendoscopy (13). The work of D.S. Russell is important with regards to the addition of systematic pathological studies of the causes of hydrocephalus.
The last 3 decades have provided us with better, less invasive techniques for the diagnosis of hydrocephalus with the developments of computed tomography, cranial sonography, and magnetic resonance imaging. MRI has been particularly important because of its ability to accurately image hindbrain structures and obstructive lesions, as well as its ability to identify areas of CSF flow.
The history of hydrocephalus treatment can be divided into premodern and modern eras. The premodern era has been reviewed by Pudenz (26). Harvey Cushing introduced CSF diversionary procedures in the early 1900s (32). The modern era began with the development of the valve-regulated shunt system by Nulsen and Spitz in the 1950s. Since that time, valve-regulated shunts have become the standard of care. A few studies have reported effective medical treatments of certain forms of infantile hydrocephalus using isosorbide or furosemide and acetazolamide. However, study results have not been consistent, and these treatments have not received widespread acceptance. Recently, there has been a resurgence in endoscopic third ventriculostomy as a method of treatment.