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| Surgical indications |
Ventriculoperitoneal (VP) shunt insertion is an operation performed to place a catheter into a brain ventricle drain cerebrospinal fluid (CSF) from the ventricular system into the peritoneal space. Usually VP shunts are placed to treat hydrocephalus (hydro = water, cephalus = head) that can result from a number of diseases including: subarachnoid hemorrhage, meningitis, or tumors.
History, physical exam, and diagnostic study [head CT, brain MR (hydrocephalus], consistent with the diagnosis of hydrocephalus. |
| Surgical objectives |
Establishment of a pathway for drainage that by-passes the ventricular drainage system.
Cannulation of the ventricle without causing hemorrhage or other injury.
Catheter tip usually placed at foramen of Monro. |
Considerations
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Size of patient: Ventriculoperitoneal shunts are most often inserted (and revised) in children. The size of the patient is important because of the size of the instruments that must be used, the size of the devices that are implanted, and because of the limited blood volume of the smallest patients (premature infants) who undergo these procedures.
Length of procedure: In patients who have never had a VP shunt inserted before, a shunt can usually be inserted usually in less than an hour. It is important to try to do the procedure as quickly as possible to minimize the risk of infection (the most common complication of VP shunt insertion). The procedure can be done in an hour or less.
Two body cavities must be entered during the procedure: the ventricle and the peritoneum. Some surgical teams find it more efficient to have one surgeon open the head and catheterize the ventricle at the same time that a second surgeon opens the abdomen into the peritoneal space.
Foreign bodies: The ventricular catheter, valve, and peritoneal tubing are all foreign bodies that can harbor bacteria introduced by contamination at the time of surgery or subsequently by seeding of organisms introduced into the blood stream by a variety of surgical and non-surgical mechanisms unrelated to the VP shunt insertion procedure.
External landmarks: The ventricular catheter is usually placed in the anterior horn of the lateral ventricle. The catheter can be placed without direct visualization using external landmarks or, more recently, using an endoscope.
Entry sites and trajectories: The tip of the ventricular catheter is usually placed in the anterior horn of the lateral ventricle as close to the Foramen of Monro as possible. The location of the skin incision determines where the burr hole (skull perforation) will be made and also the trajectory that the ventricular catheter will take for its tip to end up at the Foramen of Monro.
Cortical opening: If the hole in the dura around the ventricular catheter is much larger in diameter than that of the catheter there can be leakage around the catheter of CSF.
Tunneling: The shunt tubing travels through a subcutaneous "tunnel" that runs from the head to the abdomen. This tunnel is created by pushing a hollow metal tube down through the soft tissues under the skin, above the fascia of the neck and chest muscles. |
| Exposure |
shunt insertion requires surgical exposure of the dura and parietal peritoneum
site for the proximal tip of the ventricular catheter is in the lateral ventricle. The intraventricular tip of catheters placed through a
frontal burr hole should end up close to the ipsilateral (same side)
foramen of Monro
. site of entry of the distal (peritoneal) catheter into the peritoneal
cavity
is as high on the abdomen as possible (shortest distance possible from
ventricle to peritoneum), on the belly at a location convenient and
familiar to the surgeon. Subxiphoid or subcostal (usually just over
the liver) are the most commonly used approaches for exposure of the
peritoneum during VP shunt insertion. |
| Approach |
The two approaches: 1. cranial, 2. abdominal required for placement of a VP shunt can be done in sequence or consecutively depending on whether the surgeon is operating alone or with an assistant. |
| Landmarks |
for the cranial portion of VP shunt insertion depend on the site selected for catheter entry through the skull (and trajectory of catheter passage through the brain).
burr hole (catheter tip target: foramen of Monro
1 cm anterior to coronal suture in mid-pupillary line. Posteriorly oriented half moon skin incision 4 cm in diameter drawn with this point at its center
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| Hazards |
Sagittal sinus
Placement of a burr hole too close to midline can result in an opening into the sagittal sinus with potentially massive, difficult to control, hemorrhage.
Cortical / parenchymal vessels
No matter soft and rounded, the metal stylet (rod) running through the ventricular catheter cannot be pushed through the pia and parenchyma of the brain without causing some trauma along the way. Although this trauma is uncommonly clinically significant, large hematomas in the subarachnoid, subdural, intraparenchymal, intraventricular, or a combination of these spaces are all well-described (in the neurosurgical literature) complications VP shunt insertion.
Thalamus
Placement of the ventricular catheter into the thalamus can result in numbness.
Internal capsule
Internal capsule placement can result in contralateral hemiparesis
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| Instruments |
addition to standard dissection tray scalpels, scissors, retractors, needle holders, and perforators, VP shunt placement requires a device for
making a subcutaneous tunnel as well as special tubing, valves, and
sutures to connect and secure the system. |
| Anesthesia |
anesthesia is usually used for ventriculoperitoneal shunt insertion. |
Position |
patient is placed supine with his/her head on a donut with the face turned away from the side on which the ventricular catheter is to be placed. A shoulder bolster is usually placed under the shoulder on the same side as the
ventricular catheter to make it easier to turn the head to the opposite side. |
| Prep and drape |
prepping and draping for ventriculoperitoneal shunt insertion must be particularly meticulous to avoid contamination of the catheter and tubing. |
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Incision
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At
least two incisions are required for VP shunt insertion. A
curved skin incision is made just in front of the coronal suture.
The scalp is flapped forward and a perforator used to make a single burr
hole. The dura is perforated with a pinpoint
cautery The ventricular catheter is placed through the opening in
the dura.
A linear incision is made just below the xiphoid process
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Dissection
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Dissection
for VP shunt insertion:
Cranial
exposure
1.
skin/scalp (full thickness, down to the skull) incision
through
skin and scalp down to the skull. Incision curved. When flapped back
and area of skull 4-5 cm available for placement of a single burr hole.
2.
burr hole
3.
coagulation of dura
Subcutaneous
tunnel
Tunneling
is an essential technique in ventriculoperitoneal shunt insertion.
A
hollow metal cannula (tube) with a blunt (relatively atraumatic) advancing end
is place under the scalp at the coronal flap and pushed forward creating a
tunnel first through the subgaleal space of the head, then through the space
between the subcuticular (deepest layer of skin) and the fascia of the
superficial muscles of first neck, then chest, then abdomen
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Peritoneal exposure
Abdominal
approach: 3 cm incision through skin from just below the xiphoid process (bottom
of breast bone) extending caudally (toward the feet) in the midline.
Midline fibrous connection between the left and right abdominal muscle rectus
abdominus is divided. Just below this is pre-peritoneal
fat. Deep to the fat is the peritoneum.
Identify
and place a stitch in peritoneum.
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Target
manipulation
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Ventricular
catheter placement The
ventricular catheter is placed through the dural hole, through the pia,
through gray and white matter, ependymal lining, and into the ventricle
with reference to external landmarks: The
ventricular catheter is usually positioned "blindly", its tip guided
to its final location at the Foramen
of Monro with reference to external
landmarks.
coronal burr hole and cortical entry: The glabella
is marked with a rubber stopper that can be palpated with the drapes over the
face. The catheter is aimed simultaneously for the glabella
and the external
auditory meatus (outer opening of the ear canal). Peritoneal
catheter placement: A
small hole is made in the peritoneum and the distal end of the shunt
drainage catheter is fed through it into the peritoneal space
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Problems
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Problems that can arise during surgery include:
Tunneling device tip through skin
Pneumothorax
Intestinal injury
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Hemostasis
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The
only sites where the surgeon can obtain hemostasis during VP shunt insertion are
along the cranial and abdominal incisions, around wall of the burr hole, on the
surface of the dura. Unfortunately, any clinically significant
bleeding secondary to VP shunt insertion is most likely to occur deep within the
brain where the surgeon can neither see nor operate.
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Closure
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Closure of the scalp wound is with interrupted 00
(2-"0") Vicryl sutures. The skin is approximated with Steristrips.
The abdomen is closed by tying together the 0000 (4-"0") Neurilon
sutures tagging the peritoneum together, then with interrupted 00
(2-"0") Vicryl for the linea alba, and finally 000
(3-"0") Vicryl for the subcuticular layer. Steristrips
are used to approximate the skin.
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Duration
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Duration
Insertion of a
ventriculoperitoneal shunt takes approximately 1 1/2 hours:
anesthesia: placement of lines, induction, intubation:
30 minutes
positioning: 10 minutes
prep: 10 minutes
exposure (peritoneum): 10 minutes
exposure (dura) 10 minutes
connections: 10 minutes
extubation: 10 minutes
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Post
Op
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After
VP shunt insertion the patient is usually taken to Recovery.
Immediately post-operatively the patient is monitored for signs of neurologic
deficit for a duration of approximately an hour.
Once recovered, in the absence of any apparent complication, taken to a regular
hospital ward.
A
follow up CT (or MR) is
sometimes obtained to verify that the ventricular catheter tip is located at the
desired location in the anterior horn of the lateral ventricle close to the
foramen of Monro.
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Recovery
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Most
patients are discharged the morning after an uncomplicated VP shunt
insertion.
The
abdominal and scalp incisions usually heal within 7 days after which time it is
O.K. for the patient to get them wet. Patients can usually return to work
within two weeks of VP shunt insertion.
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Rehabilitation
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Rehabilitation
may be required for patients with serious long term disability resulting
from their hydrocephalus -- the disability in most of these patients will
neither worsen nor improve with shunting.
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Follow
up
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Most
patients with uncomplicated VP shunt insertion are sent home the day after
surgery with a prescription for pain medication and possibly for an oral
antibiotic to be taken for 7 to 10 days.
After discharge from the post surgical unit the patient following VP shunt
insertion should be seen in the Outpatient/Ambulatory
Clinic (Office) 7 to 10 days post-operatively for suture or staple
removal and wound check.
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Reoperation
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Revision
(re-operation for removal or adjustment or one or all components of) a
ventriculoperitoneal shunt system is one of the most common procedures done by
neurosurgeons (particularly those who operate on large numbers of
children). |
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Risks
& complications |
Tunneling device tip through skin
Pneumothorax
Intestinal injury
Parenchymal placement
Hemorrhage
Infection
Obstruction
Disconnection
Subdural hematoma
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Prognosis |
The
prognosis depends on the condition for which the patient was shunted and their
neurologic status at the time of operation. |
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Procedure
Position
The patient is placed supine with his/her head on a donut with the face turned away from the side on which the ventricular catheter is to be placed. A shoulder bolster is usually placed under the shoulder on the same side as the ventricular catheter to make it easier to turn the head to the opposite side.
Prep and drape
The prepping and draping for ventriculoperitoneal shunt insertion must be particularly meticulous to avoid contamination of the catheter and tubing.
Incision
Opening
The techniques for opening the head and abdomen differ:
Cranial
A curved skin incision is made just in front of the coronal suture. The scalp is flapped forward and a perforator used to make a single burr hole. The dura is perforated with a pinpoint cautery The ventricular catheter is placed through the opening in the dura.
Abdomen
A linear incision is made just below the xiphoid process
Tunneling
Tunneling is an essential technique in ventriculoperitoneal shunt insertion.
Ventricular catheterization
The ventricular catheter is usually positioned "blindly", its tip guided to its final location at the Foramen of Monro with reference to external landmarks. The glabella is marked with a rubber stopper that can be palpated with the drapes over the face. The catheter is aimed simultaneously for the glabella and the external auditory meatus.
Hazards
Problems that can arise during surgery include:
Bleeding in the neck
Pneumothorax
Intestinal injury
Closure
Closure of the scalp wound is with interrupted 00 (2-"0") Vicryl sutures. The skin is approximated with Steristrips. The abdomen is closed by tying together the 0000 (4-"0") Neurilon sutures tagging the peritoneum together, then with interrupted 00 (2-"0") Vicryl for the linea alba, and finally 000 (3-"0") Vicryl for the subcuticular layer. Steristrips are used to approximate the skin.
Duration
Insertion of a ventriculoperitoneal shunt takes approximately 1 1/2 hours:
anesthesia: placement of lines, induction, intubation: 30 minutes
positioning: 10 minutes
prep: 10 minutes
exposure (peritoneum): 10 minutes
exposure (dura) 10 minutes
connections: 10 minutes
extubation: 10 minutes
Post op
After VP shunt insertion the patient is usually taken to Recovery. Immediately post-operatively the patient is monitored for... for a duration of ...
Once recovered, in the absence of any apparent complication, taken to a regular hospital ward.
Most patients with uncomplicated VP shunt insertion are sent home the day after surgery with a prescription for pain medication and possibly for an oral antibiotic to be taken for 7 to 10 days.
Follow up
Post op CT
A follow up CT (or MR) is sometimes obtained to verify that the ventricular catheter tip is located at the desired location in the anterior horn of the lateral ventricle close to the foramen of Monro.
Wound check
After discharge from the post surgical unit the patient following VP shunt insertion should be seen in the Outpatient/Ambulatory Clinic (Office) 7 to 10 days post-operatively for suture or staple removal and wound check.
Reoperation
Revision (re-operation for removal or adjustment or one or all components of) a ventriculoperitoneal shunt system is one of the most common procedures done by neurosurgeons (particularly those who operate on large numbers of children). Revision of ventriculoperitoneal shunt
Recovery
The abdominal and scalp incisions usually heal within 7 days after which time it is O.K. for the patient to get them wet. Patients can usually return to work within two weeks of VP shunt insertion.
Prognosis
The prognosis depends on the condition for which the patient was shunted and their neurologic status at the time of operation.
