**Main topics**

i.e. Shunt failure Shunt revision Shunt dependency/independency Overdrainage Shunt surviva

In 1937 Walter Dandy published a series of 22 patients treated surgically for intracranial hyper-tension without a tumor [1]. Among his cases treated with subtemporal decompression during a period of 10 years, there were 3 children. Later on, this condition with papilledema, headache and visual disturbances was called benign intracranial hypertension, and many of them could be managed favorably by medical treatment [2]. In more severe cases, it soon became clear that this obscure disease is not always that benign [3]. In severe cases the term malignant pseudotumor was introduced [4]. Later on the term Idiopathic Intracranial Hypertension (IIH) was introduced [5].

Neurosurgical treatment with CSF diversion has been performed in severe cases where the response to medical treatment has been unsatisfactory, or as primary treatment in patients with severe visual affection [6, 7]. Unlike the situation for

hydrocephalic children treated with CSF shunts who for the most become shunt dependent, clinical results on long term shunt dependency in IIH are unavailable.

Modified Dandy criteria: *Symptoms and signs of raised intracranial pressure (headache or papilledema). No localizing signs in neurological examination (except abducent nerve palsy). Normal neuroimaging. Increased intracranial pressure as measured by lumbar puncture. Normal CSF composition. Alert and awake patient. No other cause of raised intracranial pressure.*

#### **1.1 Diagnostic work-up**

Idiopathic intracranial hypertension is a diagnosis where other causes I leading to increased intracranial pressure have been excluded by CT or MRI, including unobstructed venous outflow. Normal CSF composition rules out infection. The diagnosic procedure of intracranial hypertension itself is usually performed by a simple lumbar puncture. This gives CSF for analysis, and fluid may spurt out in cases of severe IIH. When the Intracranial pressure (ICP) is measured via the lumbar route, the patient is posisioned flat with the puncture site in equal hight as the IIIrd ventricle. The needle seize should not be very thin (G19), to obtain a presice manometric pressure reading. Loss of fluid should be avoided, since the pressure falls rapidly unless ICP is very high. Pathological elevated ICP is above 25 cm H2O (15–20 in children). ICP is,however, influenced by a number of factors that may give misleading results when ICP is evaluated by the lumbar route.

Firstly, the patient should be cooperative and relaxed. Furthermore ICP is highly influenced by changes in PaCO2. If the patient is anxious and hyperventilate, ICP will fall rapidly. The pressure recording can also be performed by the use of standard fluid pressure transduces and may be combined by other diagnostic work-up, such as lumbar infusion tests. In children, these diagnostic procedures must be undertaken during general anesthesia and normocapnia.

When patients with severe headache but without papilledema or visual affection, are given a IIH diagnosis, correct evaluation of the CSF hydrodynamic situation is pertinent. If CSF pressure is observed under unstable conditions or is influenced rapid changes in the central venous pressure, misinterpretations may take place. Queckensteds test (venous compression in the neck) demonstrates this effect on the CSF pressure, and was previously used to exclude a spinal block. Lumbar infusion tests can be used to explore the need for therapeutic CSF diversion, and of course demonstrate that an indwelling shunt is patent (LP-shunt or VP-shunt). A simple lumbar puncture will of course also be helpful to exclude severe shunt failure, as well as shunt infection.

It should be pointed out that the lumbar puncture itself will give an opportunity to explore the possibilities for a good result in IHH patients. After puncture with a 19G cannula, CSF will leak during the following three weeks, especially in true IIH patients with increased CSF pressure. This is why some individuals without IIH, will experience post-puncture headache due to intracranial hypotension. The beneficial effect of LP and CSF removal on severe headache and visual affection, is often temporary and repeated punctures or shunt implantation will be needed.

### **2. Methods**

All children (0–19 years old) who underwent a shunt implantation for IIH during the years 1980–2000 in our institution were identified from the surgical *Will CSF Diversion in Patients with Idiopathic Intracranial Hypertension (IIH) Lead… DOI: http://dx.doi.org/10.5772/intechopen.96291*

protocols. Ethical approval was obtained from the medical ethics committee of Norway, the Regional Committee of Medicine and Heath.

We present our experience with these pediatric patients shunted for IIH during the years 1984 to 2000; and therefore have long-term follow-up.
