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Posthemorrhagic hydrocephalus
Posthemorrhagic hydrocephalus results from obstruction of the cerebrospinal fluid flow at the posterior fossa cisterns. The cerebrospinal fluid exits the ventricular systems through the orifices of Luschka and Magendie. These orifices are in the region of the medulla oblongata. The fluid from this area must flow from the base of the cranium (posterior fossa) to the convexity to drain through the Pachioni corpuscles. The obstruction at the posterior fossa is due to obliterative arachnoiditis.
The clinical manifestations of progressive posthemorrhagic hydrocephalus usually include an abnormal increase in head circumference and a full fontanelle. Clinical manifestations may not be present despite significant ventriculomegaly.
The diagnosis of
posthemorrhagic hydrocephalus is based on the presence of large ventricles and no signs of cerebral atrophy. The distinction between ventricular distension due to hydrocephalus and ventricular enlargement due to cerebral atrophy can often be made based brain ultrasound (Figure 253.1). Computed tomography or MRI may be needed to demonstrate atrophy or hydrocephalus.

 

Figure 253.1. Characteristic ultrasonographic findings in brain atrophy [A] and hydrocephalus [B]. The two ultrasounds on top [A] demonstrate typical atrophic changes: large subarachoid spaces (green arrows), prominent sulci (pink arrows), angular frontal horn of the lateral ventricles (blue arrows), moderate to mild lateral ventricular enlargement of the frontal horns (tan arrows), no enlargement of the temporal horn of the lateral ventricle or third or fourth ventricle. The two ultrasounds on the botton [B] demonstrate typical findings of posthemorrhagic hydrocephalus: no subarachnoid space, thin sulci (pink arrows), round frontal horns of the lateral ventricles (blue arrows), large ventricles (tan arrows), periventricular echogenicity (yellow arrows), large third and temporal horns of the lateral ventricles (red arrows).

Treatment of posthemorrhagic hydrocephalus

Posthemorrhagic hydeocephalus has no treatment. Intraventricular fibrinolytic agents such as urokinase, streptokinase, and tissue plasminogen activator are not currently recommended. Posthemorrhagic hydrocephalus may require shunting depending on its evolution.

Evolution of posthemorrhagic hydrocephalus

Posthemorrhagic hydrocephalus can arrest or become progressive. An arrested hydrocephalus implies that the size of the ventricle remained the same from one ultrasound to the next. Progressive hydrocephalus implies that the ventricle increased in size from one ultrasound to the next. An arrested hydrocephalus may become progressive and a progressive hydrocephalus may arrest.

When to conclude that arrested hydrocephalus will not progress?
There is no data supporting an answer to this question. Two ultrasounds one week apart that demonstrate no increase in ventricular size probably implies that no further ventricular size increase will occur.

When to conclude that progressive hydrocephalus will not spontaneously arrest before producing brain damage?
There is no data supporting an answer to this question. Probably, clinically silent, slowly progressive hydrocephalus for one month or rapidly progressive hydrocephalus for one week may produce brain damage. Hydrocephalus producing clinical manifestation is also likely to produce brain damage. Human studies using near-infrared-spectroscopy and Doppler ultrasound have shown that even relatively small and slowly progressive increases in ventricular size negatively affect brain metabolism in the periventricular area. In animals, it has been documented that ventricular distension results in periventricular damage (hypoperfusion, anaerobic metabolism, and loss of high-energy phosphates).

 

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periventricular hyperechogenicity periventricular hyperechogenicity large subarachnoid space angular frontal horn of the lateral ventricle large sulcus moderate size lateral ventricle moderate size lateral ventricle angular frontal horn of the lateral ventricle large sulcus large subarachnoid space large temporal horn of the lateral ventricle large lateral ventricle round frontal horn of the lateral ventricle thin sulcus large temporal horn of the lateral ventricle large third ventricle large ventricles round frontal horns of the lateral ventricles thin sulcus Pause pointer on arrows for labels. Figure must be centered. du Plessis, 1998