sure or, on occasion, it is necessary to insert an additional (unvalved) sub-dural shunt; this is sometimes plumbed into the existing shunt below the valve.
In the infant, the lowered intracranial tension following shunt insertion may lead to premature closure of the cranial sutures, producing a secondary craniosynostosis with cranial deformity.
Asymmetrical drainage of the ventricles may also be seen to cause trapping or isolation of part of the ventricular system. It may be difficult to distinguish whether this is a true consequence of the shunt or related to com-partmentalization of the ventricles as a result of the original pathology, for example post-menin-gitic hydrocephalus. Trapping of the fourth ventricle is an example of this process and can be seen after apparently successful treatment of hydrocephalus with a shunt. Isolation of the fourth ventricle may be discovered incidentally or may result in symptoms of raised intracra-nial pressure or cerebellar disturbance. In symptomatic cases, the fourth ventricle can be drained either by inserting an additional shunt system or by placing a catheter into the fourth ventricle and plumbing this into the existing supratentorial shunt via a T or Y connector. It is important that the connection is made above the valve to ensure that the ventricles are drained at the same pressure.
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The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.