Neurosurgery

has not been generally adopted, even in specialist departments. There are strongly held views regarding the relative safety or otherwise of different instruments and methods for perforating the floor.

The argument against using laser or diathermy is the perceived risk of vascular damage, but no study has demonstrated an advantage in terms of either efficacy or safety for any particular method. The absence of any reporting system for adverse events, beyond individual personal or institutional systems, makes any such opinion difficult to confirm, but it is probably wise to keep any use of diathermy to a minimum, and to ensure that it is always used under direct vision. Similar strictures relate to the methods used for enlarging the opening. The most widely used is probably the balloon catheter, and as long as care is taken, it may well be safer than diathermy. Blunt hooks, as can be used through a disposable Channel™ neuroendoscope, appear to be safe and are most intuitive to the neurosurgeon, especially in the subarachnoid space. A sensible precaution would seem to be the practice of starting with a small, centrally placed opening and then looking through it into the space below the floor to check on position and the presence or absence of second membrane, adhesions, vessels or tumor. This will be easier to accomplish with a flexible neuroendoscope or a Channel™ neuroendoscope than with most rigid neuroendoscopes. The only safe rule is to abandon the procedure if the anatomy is not clear.

Throughout, the surgeon must be mindful regarding the irrigation, ensuring that there is easy egress of irrigate; with flexible and disposable Channel™ neuroendoscopes, the route of escape of the irrigate is between the endoscope and the inner wall of the plastic cannula. It is not difficult to allow the cannula to slip out of the ventricle, under which circumstance there will be no way for irrigate to escape.

At moments of high tension the surgeon may inadvertently pinch the plastic cannula, occluding it, allowing irrigate to accumulate in the ventricles with resultant rise in intracranial pressure. This will be particularly dangerous if the neuroendoscope is within the narrow confines of the third ventricle. Such circumstances can cause cardiac dysrhythmias, especially if the ventricular walls are stiff.

Whereas it is always tempting to take a wander through the ventricular system, especially with a flexible neuroendoscope, the surgeon should avoid the enticement of 'ventricular tourism' (with acknowledgement to Professor Christian Sainte-Rose) and withdraw from the operative scene. The cerebral ventricles should be left full so as to encourage flow through the NTV. Attention to the wound and its closure is worthwhile: in babies and infants with thinner, less well developed scalp tissues, the author now uses a small scalp flap of the size that would be used for insertion of a ven-triculostomy reservoir, thus avoiding having a scalp incision directly over the dural incision. Formal closure of the dura is said to help eliminate cerebrospinal fluid leakage (G. Cinalli, personal communication), and the scalp is closed in layers.

The anesthetist must concentrate on the monitoring, and must be alert to the possibility of cardiovascular changes and the need to report them immediately to the surgeon.

A pilot study employing sophisticated statistical analysis failed to show any increased risk of epilepsy in children undergoing NTV [28].

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