Keywords traditional technique - capsule modification technique - hydrocephalus
Capsule Modification Technique
The capsule modification technique (CMT) has been developed for the placement of ventriculoperitoneal
shunt after evaluating the inherent difficulties encountered with the traditional
technique (TT). It is basically a capsule-like attachment [[Fig. 1A ]] that connects at the distal end of the traditional tunneller [[Fig. 1B ]], resulting in a modified tunneller [[Fig. 1C ]]. The CMT is started similar to TT with openings made at cranial and abdominal ends
[[Fig. 2A ]]; however, once the distal end of the tunneller (cranial end) is out of the subcutaneous
plane, a capsule-shaped attachment is attached to it [[Fig. 2B ]]. It fits into the tunneller like a cap of a pen. Once attached, the tunneller is
partially withdrawn from the abdominal end gradually [[Fig. 2C ]] for 8 cm beyond the cranial opening of the subcutaneous plane (10 cm in neonates
where the length of the peritoneal end is shortened to provide additional widened
space for the connector). Once the capsule has reached the destined site, the tunneller
is pushed out again, and the attachment along with stylet is removed [[Fig. 2D ]]. The peritoneal end of the catheter is passed and the tunneller is removed [[Fig. 2E ]]. Finally, the ventricular end is connected to the peritoneal end and skin is closed
in layers [[Fig. 2F ]). The CMT is extremely simple and basic and its benefits are considerable.
Fig. 1 Parts of tunneller system.
Fig. 2 Schematic representation of modified capsule tunneling for the placement of the ventriculoperitoneal
shunt system. (A ) Subcutaneous placement of the tunneller after making openings at the cranial and
abdominal ends. (B ) Attachment of the distal (capsule attachment) at the cranial end of the tunneller.
(C ) Retraction (pulling down) of the entire assembly caudally until capsule reaches
the mastoid area, where the chamber of catheter needs to be placed. (D ) Pushing up the entire assembly from the cranial opening with the removal of capsule
attachment and style. (E ) Passing of the peritoneal end of the catheter and the removal of the tunneller.
(F ) Placement of the ventricular end of the catheter and connecting entire system followed
by closure in layers.
The space so created ensures the chamber fits snugly and perfectly, thereby eliminating
any dead space, which is usual and common in cases where dilatation is done using
instruments such as artery forceps or Penfield dissector. The space for proper placement
of chamber is made at the exact place so that there is no need for manipulation while
placing the catheter and any kinking is avoided. It further eliminates the need to
re-position the chamber as well as avoid contact of blood with the opening in the
chamber, thus minimizing the risk of blockage. Excessive dilatation of the subcutaneous
plane is avoided, thereby decreasing the chances of peri-catheter collection of cerebrospinal
fluid and subsequent risk of infection.
Discussion
Ventriculoperitoneal shunting is one of the most common neurosurgical procedures performed.
However, not much attention has been given to the technique involved in the procedure.
It tends to play a crucial role in ensuring proper placement of the tubing in the
subcutaneous plane free of any kinking. Several techniques and modifications have
been suggested;[1 ]
[2 ]
[3 ]
[4 ]
[5 ] however, no modification has been done or proposed in performing this procedure
keeping in mind the position of the chamber of the shunt tubing. There are several
studies on the management of shunt failure due to migration and infection.[6 ]
[7 ] Skin of pediatric patients, especially post tubercular, is very fragile; hence,
transient redness of the skin is seen in many cases, suggesting the need for careful
and gentle tunneling. The space created by various instruments such as artery forceps
results in a lot of dead space where CSF gets collected and is prone to infection.
There is adequate evidence that duration of surgery, minimizing contact of shunt tubing
with gloves, and decreased need of manipulation of tubing are associated with less
risk of infection and shunt failure.[8 ]
[9 ]
[10 ]
[11 ] The duration of surgery has a direct impact on the outcome and complications. Revisions
are associated with increased morbidity. Our CMT showed reduced overall duration of
surgery with not a single case of kinking in the chamber/tubing and absence of entry
of any amount of blood through the opening of the chamber as no manipulation was required
at the time of fixing the ventricular to peritoneal end of the shunt. There was no
need to revise the position of the chamber with a reduced need for shunt revision.
Conclusion
This new technique appears to be superior to the traditional one. It was found to
reduce operative time with no kinking of the catheter and no contact of the catheter
with the skin and other tissue. This technique has been suggested to simplify the
procedure and minimize other shunt-related risks and complications. However, a dedicated
study incorporating the role of etiology and associated factors on the outcome is
needed for effective statistical analysis.
