From the Guidelines
Communicating hydrocephalus is most commonly caused by conditions such as subarachnoid hemorrhage, meningitis, and other factors that impair cerebrospinal fluid absorption, excluding Arnold Chiari malformation. The causes of communicating hydrocephalus can be understood by examining the factors that lead to impaired cerebrospinal fluid (CSF) absorption. According to a recent systematic review and meta-analysis published in The Lancet Global Health 1, the pooled proportion of postinfectious hydrocephalus, which can be a cause of communicating hydrocephalus, was found to be 28% (95% CI 22–36) with high heterogeneity. Some key causes of communicating hydrocephalus include:
- Subarachnoid hemorrhage, which can lead to blood products obstructing arachnoid granulations, thus impairing CSF absorption
- Meningitis, where inflammatory debris blocks CSF reabsorption, as seen in bacterial, viral, or fungal infections
- Prior neurosurgical procedures that disrupt normal CSF flow dynamics
- Traumatic brain injury resulting in subarachnoid scarring
- Certain brain tumors, particularly those near the fourth ventricle or basal cisterns, which can alter CSF dynamics The underlying pathophysiology involves impaired CSF absorption at the arachnoid granulations or altered CSF dynamics, leading to ventricular enlargement despite open communication between ventricles, as supported by the findings of the study 1. Treatment typically involves CSF diversion procedures such as ventriculoperitoneal shunting or endoscopic third ventriculostomy, depending on the specific cause and patient factors. In the context of the provided evidence, it is essential to consider the methodological quality of the studies, as well as the income level of the countries, when interpreting the results, as seen in the stratified pooled estimates provided in the study 1.
From the Research
Causes of Communicating Hydrocephalus
- Subarachnoid hemorrhage (SAH) is a possible cause of communicating hydrocephalus, as it can lead to fibrosis of the arachnoid villi, obstructing cerebrospinal fluid (CSF) flow 2
- Meningitis is not explicitly mentioned as a cause in the provided studies, but brain trauma, infection, and intracranial hemorrhage (ICH) are listed as potential triggers for communicating hydrocephalus 3
- Tumor surgery and other neurological diseases can also damage the CSF system and lead to communicating hydrocephalus 3
- The absorbing ability of CSF can compensate for damage to the CSF system within a certain range, but if the damage exceeds this range, hydrocephalus can occur 3, 4
Other Factors
- Proliferation of arachnoidal cells, triggered by inflammatory reactions or blood clotting products, may also contribute to the development of communicating hydrocephalus 2
- Disturbances in CSF flow dynamics, including pulsatile flow and pressure changes, can lead to hydrocephalus, but the exact mechanisms are not fully understood 5
- The size of the ventricles does not necessarily correlate with the absorptive capacity or resting pressure of CSF, suggesting that other factors are involved in the development of communicating hydrocephalus 4