Walter Dandy, in collaboration with Kenneth Blackfan , Department of Pediatrics, conducted experimental studies in dogs , which led him to conclude that the obstruction at the foramen of Monro, aqueduct of Sylvius, or around the brainstem, produce hydrocephalus and cause decreased absorption of cerebrospinal fluid (CSF).
Blackfan’s research with Dandy involved an experimental model to produce hydrocephalus in dogs that helped establish the basis of our current understanding of cerebrospinal fluid physiology. This work was published in two classical papers in the American Journal of Diseases in Children, one in 1913 and the other in 1917 1).
The second paper was later reprinted in the Annals of Surgery 2).
Blackfan’s collaborative work with Dandy also expanded to the description of internal hydrocephalus in infants, the early recognition of hydrocephalus in children, the signs of cerebral venous thrombosis, and a landmark paper on the treatment of meningococcal meningitis.
It is more common in infants, although it can occur in older adults.
The most common type of hydrocephalus in developing countries is postinfectious hydrocephalus.
There is no international consensus on the classification of hydrocephalus, and there are various systems based on the age of onset, CSF dynamics and anatomical area of accumulation, the levels of CSF pressure and the presence of symptoms.
The most accepted classification is based on the etiology.
Hydrocephalus has many causes.
Congenital hydrocephalus, most commonly involving aqueduct stenosis, has been linked to genes that regulate brain growth and development.
Newborn infants with germinal matrix hemorrhage.
Hydrocephalus can also be acquired, mostly from pathological processes that affect ventricular outflow, subarachnoid space function, or cerebral venous compliance.
Hydrocephalus after decompressive craniectomy…
The classic understanding of hydrocephalus as the result of obstruction to bulk flow of CSF is evolving to models that incorporate dysfunctional cerebral pulsations, brain compliance, and newly characterised water-transport mechanisms.
Aquaporin 4 channels are implicated in the pathophysiology of hydrocephalus, a disease of water imbalance that leads to CSF accumulation in the ventricular system. Many molecular aspects of fluid exchange during hydrocephalus have yet to be firmly elucidated, but review of the literature suggests that modulation of AQP4 channel activity is a potentially attractive future pharmaceutical therapy. Drug therapy targeting aquaporin channels may enable control over water exchange to remove excess CSF through a molecular intervention instead of by mechanical shunting 3).
Hydrocephalus can also cause death.
Infants commonly present with progressive macrocephaly whereas children older than 2 years generally present with signs and symptoms of intracranial hypertension.
One children with headaches, diagnosed with hydrocephalus, who played wind instruments. The patient manifested that their headaches worsened with the efforts made during playing their musical instruments. Martínez-Lage et al. hypothesize that the headaches might be influenced by increases in their intracranial pressure related to Valsalva maneuvers and had serious doubts on if we should advise our young patients about giving up playing their music instruments 4).
Imaging plays a central role in the diagnosis of hydrocephalus. While magnetic resonance (MR) imaging is the first-line imaging modality, computed tomography (CT) is often the first-line imaging test in emergency patients.
The MR imaging protocol should always include sagittal high-resolution T2-weighted images.
When an inflammatory etiology is suspected, imaging with contrast agent administration is necessary. 5).
Hydrocephalus causes transependymal resorption of spinal fluid that in turn produces periventricular interstitial transependymal edema.
The features of reelin expression in the brain of fetuses and newborns at 22-40 weeks' gestation with internal hydrocephalus should be considered as morphological differential and diagnostic criteria for the disease in relation to its etiology 6)
Intracerebral hemorrhage with intraventricular extension and hydrocephalus may increase mortality or severe disability 7).
The evaluation of hydrocephalus remains focused on ventricular size, yet the goal of treatment is to allow for healthy brain development. It is likely that brain volume is more related to cognitive development than is fluid volume in children with hydrocephalus.
Hydrocephalus is treated by normalizing CSF, but normal brain development depends on brain growth. A combination of brain and CSF volumes appears to be significantly more powerful at predicting good versus poor neurocognitive outcomes in patients with hydrocephalus than either volume alone 8).
In infants with hydrocephalus, a greater 1-year CSF diversion failure rate may occur after endoscopic third ventriculostomy (ETV) compared with shunt placement. This risk is most significant for procedures performed within the first 90 days of life. Further investigation of the need for multiple reoperations, cost, and impact of surgeon and hospital experience is necessary to distinguish which treatment is more effective in the long term 9).
Kaestner et al., conducted a retrospective survey of the OR-database during a 10 year period. All newly inserted shunt systems and subsequent shunt revisions are recorded according to quantity and time point. All patients were subdivided according their aetiology of HC.
260 patients were eligible with a follow-up of 4.5 years. Subgroups were: 90 patients with NPH, 76 patients with posthaemorrhagic and 16 patients had posttraumatic HC. 22 received a shunt as a consequence of a tumour, 41 were children and 15 for other causes. Overall revision rate was 39.5%. During the first 6 months 55.6%, 57.9% and 75% of patients with NPH, posthaemorrhagic and posttraumatic HC had revisions. In contrast only 38.1% of children and 20% of tumour cases required early revision.
Two different patterns of revision are evident: mainly early revisions in morphologically stable diseases such as posthaemorrhagic, posttraumatic and NPH and predominantly late revisions in changing organisms such as children and tumour patients. The conception HC may be transient because of a lack of late revisions cannot be supported by this data 10).