Shunt Surgery

SR Neurosurgery SGPGIMS LUCKNOW

1. SHUNT SURGERY Dr. Yashveer Singh SR( MCh ) Department of Neurosurgery SGPGI

2. HISTORY They believed that this disease was caused by an extra-cerebral accumulation of water.

3. In Early 20th-century, closed ventricular drainage like gold, glass, silver, and rubber tubes, catgut, linen thread (Passed from Ventricle to Subdural Space). Same techniques were used to connect lumbar thecal sac to peritoneum or renal pelvis. Torkildsen shunts: Dandy, shunts from lateral ventricle to cisterna magna (Also shunts from the lumbar spine to the ureter)

4. Revolution (1952): Nulsen and Spitz successful perform Ventriculo -jugular shunt using a spring and stainless-steel ball valves (Occlusion of catheter by Hematoma frequent ). Holter first designed a multislit valve shunt for use in his son because of hydrocephalous (First use Silicon). Pudenz concluded that silicone is best material & designed two valves to use as ventriculo -atrial (VA) shunts.

5. INDICATIONS

6. CONTRAINDICATIONS

7. GOALS OF SURGERY To acquire normal Intracranial pressure. To acquire optimum neurological function. G ood cosmetic result . Normal sized ventricles are not the goal of therapy (some children have a paucity of brain tissue).

8. SHUNT SURGERY Shunt surgery is one of the most unforgiving types of surgery in neurosurgery Majority of shunt complications are due to either blockage or infection (There are largely related to the factors that the surgeon can influence). Meticulous attention to detail and thorough planning prior to surgery reduce shunt-related complications.

9. S hunt consist of ventricular catheter, valve & distal catheter (to divert CSF from the ventricle to the another site capable of absorbing the extra fluid load) The most common locations for distal catheter insertion are peritoneum, pleura & right atrium (M.C. Peritoneum).

10. PRINCIPLES 1- Informed consent Rationale for the procedure Potential complications Potential outcome 2- S hunt hardware

11. I mportant factors need to be considered when planning a shunt. 1-Most appropriate site for insertion of the ventricular catheter. Inspect scan to determine most appropriate site. Generally most catheters are inserted by P arieto -occipital ( Keen’s Point ) or Frontal bur hole ( Kocher’s Point ) either left or right. The most appropriate sites is often related to the underlying pathology driving the hydrocephalus (would not be appropriate to insert a VP shunt into the contralateral side of a tumor causing mass effect and midline shift, because this may exacerbate the midline shift). For patients who have had a recent shunt infection, it is optimal to use an uninfected bur hole site.

12. Keen’s Point Most commonly used. B urr hole should be placed 2.5 to 3 cm superior and posterior to the pinna of the ear on the left of right side depending upon the intracranial pathology. The catheter should be aimed in a slight cephalic direction and positioned perpendicular to the temporal lobe cortex. P assed to a depth of 4 to 5 cm or until reaching the trigone of ipsilateral lateral ventricle.

13. Kocher’s Point It lies along the mid-pupillary line and is 1 to 2 cm anterior to the coronal suture. Catheter should be directed at an angle that is perpendicular to the intersection of lines drawn from the ipsilateral medial canthus and the ipsilateral external auditory meatus. Catheter should be passed to a depth of approximately 6 cm below the skin surface or until the frontal horn of the ipsilateral lateral ventricle is penetrated.(For maximal drainage of CSF, the tip of the catheter should be placed near the foramen of Monro ). This point is lateral to the SSS and anterior to the primary motor cortex, 2 critical areas that should be avoided .

14. Dandy’s Point At this point, the tip of the catheter should be positioned within the body of the ipsilateral lateral ventricle In this the catheter’s trajectory is near or through the optic radiations, damage to the visual fields is a theoretic concern when completing this technique.

15. Frazier’s Point( Dandy's point  ) The catheter is aimed medially and superiorly to a point that lies 4 cm above the contralateral medial canthus and passed to an initial depth of 5 cm. After CSF is encountered, the catheter stylet is removed, and the catheter is soft-passed an additional 5 cm (total 10 cm), positioning the catheter entirely within the body of the ipsilateral lateral ventricle.

16. Kaufman’s Point

17. Paine’s Point This technique should be employed when there is concern for severe brain edema after completing a frontotemporal craniotomy

18. Menovsky’s Point It is indicated in the setting of brain edema, allowing for CSF drainage and brain relaxation prior to complete bone removal.

19. Tubbs’ Point No burr hole made so more time efficient . increases the risk of a globe injury and requires blind puncture of the orbital roof .

20. Sanchez’s Point It is used to catheterize the temporal horn and can be employed to divert CSF in the setting of a trapped ventricle or to endoscopically access mesial temporal structures.

21. 2-The most appropriate site for insertion of the distal catheter. Most appropriate site for insertion of distal catheter: peritoneum > pleura > right atrium Pleura and Right atrium should only be used when there is clear evidence that use of the peritoneum is highly likely to result in malabsorption, infection, or abdominal content damage.

22. 3-The most appropriate valve to implant . Maintain one-way flow and prevent reflux. Avoiding over drainage of CSF and gravity-dependent swings in ICP( Low-pressure headache and SDH). The most appropriate valve depends on a number of factors age of the patient, what valve was used previously, the symptoms the patient exhibits, the number of previous shunt revisions, and whether having flexibility in the opening pressure is important. In general, patients should have the same valve reinserted if there were no clinical or radiologic problems before shunt dysfunction.

23. For new shunts, the age of the patient is important. Neonates and young infants with open fontanelles have relatively low intracranial pressure compared to patients with a closed fontanelle (valve inserted should allow drainage at lower pressures) Medium-pressure valves is recommended in older children. Variable pressure valves are reserved for patients with complex shunt problems in whom the likely optimal intraventricular pressure based on history, examination, and investigations remains unclear.

24. 4-Inspection of the site of the insertion of the ventricular ,peritoneal catheter and proposed peritoneal catheter trajectory. Specific issues to consider site of previous incisions (avoid tunneling under scar tissue), the quality of skin (patients with multiple shunt revisions with large amounts of scar tissue and patients who have undergone radiotherapy are likely to be at higher risk of wound complications) The skin thickness and the presence of other devices such as central venous catheters, gastrostomies, pacemakers, and other implanted devices may impede safe tunneling. The underlying pathology may also affect the bur hole site.

25. 5-Evidence of concurrent illness . It is preferable to avoid inserting a VP shunt in the presence of infection. In critically ill patients, even if their illness has been attributed to shunt malfunction, it may be more appropriate to insert an EVD. (ICP measurement, ICP modulation by CSF drainage, and eliminates uncertainty whether the newly inserted shunt has failed if the patient fails to improve neurologically).

26. 6-Past shunt history in patients who require a VP shunt revision. W hat difficulties were faced intraoperatively in previous surgery. The last operation note, previous scans, and discharge summaries are invaluable pieces of information . 8- Need for assistance.

27. VP SHUNTS General anesthesia A ntibiotics on induction H orseshoe headrest with a bolster placed under the shoulder ipsilateral to the ventricular catheter insertion site for positioning . Head tilted by rotation and lateral flexion of the neck to contralateral side

28. Urinary bladder must be empty in a h/o previous laparoscopic peritoneal trochar insertion Hair is clipped (not shaved) in the operating room . Cleaning of operative site. S ite of the bur hole and abdominal incisions selected and marked before draping . Appropriate location for bur hole - Surface landmarks - Preoperative imaging (More appropriate ) - Use of neuronavigation

29. For frontal bur hole placement: Just anterior to the coronal suture 2 to 3 cm from midline (mid pupillary line). Preparation of small intervening incision just posterior to ear ( U sually required to tunnel through the subcutaneous tissue plane from the frontal region to the abdomen. ) Skin meticulously prepared with antiseptic solution : povidine –iodine or chlorhexidine Drapes except for a small band of skin from bur hole site to abdomen

30. Time out: C orrect patient, correct side, scans and equipment available Horseshoe incision: pedicle based on the direction shunt For frontal bur holes: obliquely oriented pedicle Size of the bur hole should be adequate to insert the ventricular catheter

31. Small dural incision just large enough to allow passage of the ventricular catheter In infants, particularly if premature, an opening between the splayed sutures at either frontal or occipital sites can be used for dural access. Brain pia cauterized. Abdominal incision simultaneously opened (by second operator). Avoid umbilical incisions. Peritoneum approached by dissection in layers V ital to confirm that peritoneum has been entered(Intraperitoneal flooding the field and watching fluid drain into the peritoneum, or by passing a blunt dissector into the abdominal cavity ) The use of abdominal trocars is safe and acceptable technique.

32. Tunneling is potentially dangerous maneuver( subcutaneous throughout its course) Direction Cranial or Caudal (No effect on complications) Potential entries while tunneling : skin , peritoneum, pleural space, lung, heart, great vessels of the neck and skull base including foramen magnum. As a rule: the tip of the trocar should be palpable below skin at all times and the tip should pass superficial to ribs and clavicle. Common site of resistance to tunneling is deep cervical fascia of the neck If excessive force required to pass the tunneler , separate incision can be given

33. The anesthetist should be made aware during tunneling specially at chest (especially in neonates, there is potential to affect ventilation). The peritoneal tubing with the attached valve passed along the tube, attaching suction to the distal end & irrigating. Subcutaneous pocket to seat the valve. Ventricular catheter trajectory is then determined. Frontal bur hole, landmarks for foramen of Monro are intersection of the planes through the midline and just anterior to the external auditory meatus (perpendicular to the skull ). If head is tilted - palpable electrocardiogram electrodes placed at these points prior to draping

34. From the occipital location, target at midpoint of forehead just at the normal hairline: catheter proceeds into frontal horn instead of temporal horn. For frontal bur holes: optimal position of ventricular catheter tip is just anterior to the foramen of Monro For occipital bur holes : optimal position is the atrium of the lateral ventricle Tip of the catheter away from the ventricular walls or choroid plexus. The ventricular catheter can be felt to ‘pop’ once the ependyma is breached with concomitant gush of CSF. Gently irrigating the catheter may show pulsatile CSF flow into and out of catheter Withdrawing vigorously may draw brain tissue into the catheter and plug the shunt

35. N o evidence that multiple catheter passes affect outcome M aking fewer passes likely to result in fewer complications Ultrasound guidance in real time may reduce number of passes required. Iatrogenic intraventricular hemorrhage: uncommon complication that occurs as a result of choroid plexus hemorrhage If CSF is quite blood stained: convert the operation to an EVD and obtain an urgent CT scan Ventricular catheter connected to the valve and ties are placed along connections

36. The valve system positioned into the subcutaneous pocket Peritoneal catheter checked for spontaneous CSF flow S hould not close until confirmed that shunt is working If doubtful, system should be disconnected to verify that both ends are patent. The distal catheter inserted into the peritoneum (making sure it enters easily and enough length to account for patient growth) If catheter keeps backing out of abdomen : Coiling up in pre-peritoneal space or abdominal adhesions Closure of the peritoneum does not prevent hernia Wound closure in layers

37. Attach the shunt valve to the catheter and pump in prime system

38. Secure the valve using suture of choice

39. Abdominal incision site

40. Skin closure critical: CSF leak predisposes to wound breakdown/infection. Rate of shunt infection as high as 57.1% in presence of perioperative CSF leakage Positioning in postoperative period is important Premature infants may be particularly prone to skin ulceration if positioned with the full weight of the head on the valve hardware. In patients with large ventricles, early ambulation may predispose subdural hemorrhage. Patients to eat on completion of surgery and clearance of anesthesia .

41. The postoperative hospital stay - 2 to 3 days Intravenous prophylactic antibiotics postoperatively for two doses only Shunted patients typically have rapid resolution of acute symptoms. In infants, a sunken fontanelle is typical Low-pressure headache can occur in older patients: bed rest, hydration & simple analgesia A postoperative scan is important to obtain as a baseline Evidence shows the ventricles do not reach their final size on average until 1 year of age

42. VENTRICULOPLEURAL SHUNTS A dditional option for distal catheter placement. Contraindications : previous chest surgery & adhesion, active pulmonary disease & borderline pulmonary function ( P leural effusion might push them into respiratory failure). Infants more likely to develop significant effusion temporarily. Recommendation: Preoperative chest x-ray & PFT. Most common route to enter pleural space is along the anterior axillary line, in 4 th to 6th intercostal space on right.

43. A muscle-splitting approach along the upper border of the rib reveals translucent pleura & lung moving with ventilation (to avoid the neurovascular bundle ). P leura opened sharply N o need to collapse the lung : it moves away being at sub atmospheric pressure during inspiration and retracts slightly from chest wall. Distal catheter introduced gently and carefully guided along the chest wall and away from lung parenchyma Catheter need to be cut to avoid putting excess tubing A Valsalva maneuver by the anesthetist to inflates the lung adequately

44. Wound should be closed in three layers. Rapidly closing the muscles with few sutures avoids further air entry into the chest Small pneumothorax usually seen postoperatively resolves over the next few days Monitored for any evidence of respiratory distress with serial chest films and continuous oxygen saturation monitoring. In patients in whom the pleural fluid progressively accumulates leading to respiratory distress : percutaneous drainage of the fluid and accessing another site for tubing.

45. VENTRICULOATRIAL SHUNTS The right atrium is another alternative to the peritoneum for distal catheter placement. A im is to place the distal catheter just above the right atrium. Atrial catheters have a slit valve to prevent reflux of blood up the tubing. Patient placed in supine position with head slightly down to avoid air embolus. The anesthetist involved throughout the procedure because ventricular ectopic beats are common Catheter tunneled to the neck area in the proximity of the site of insertion of the atrial catheter.

46. T wo methods: Open or percutaneous Open procedure : Right sided neck incision made to expose the common facial vein, which is tied proximally & held with a stay suture distal to the venotomy site. The catheter is then advanced down the jugular vein into the superior vena cava Fluoroscopy is used to identify the final position of the tip of the catheter

47. Percutaneous method : C annulating subclavian vein under color flow Doppler ultrasound guidance Seldinger wire passed into the vein and progressed to the entrance to the right atrium Dilator expands the entrance to the subclavian vein V entricular catheter inserted. Under fluoroscopic guidance, tip of the catheter positioned just above right atrium Atrial catheter then connected with straight connector to the distal catheter Incisions closed in two layers.

48. OTHER SITES OF INSERTION Intracranial sites: Superior sagittal sinus retrograde to the direction of flow, SAS, SDS. Extra-cranial sites: Sub- galeal space, Mastoid antrum. Cervical region:Duct of salivary gland, Common facial vein. Thorax: SVC, Thoracic duct, Spinal epidural space, Bone marrow. I nsertion into another peripheral vein (help of vascular surgeons). Gallbladder, Omental bursa, Stomach, Gallbladder, Urinary bladder, Ureter, Ileum, Uterine tube.

49. COMPLICATIONS

50. COMPLICATIONS THAT MAY OCCUR WITH ANY SHUNT 1-Obstruction: Most common cause of shunt malfunction( most common site ventricular catheter. 2-Disconnection at a junction, or break at any point. 3-Infection 4-Hardware erosion through skin.

51. 5-Seizures: 5.5% risk >1 year, 1.1% after the 3 years (Higher with frontal catheters than with parieto -occipital catheter). 6-Act as a conduit for extra-neural metastases of certain tumors ( Medulloblastoma ). 7-CSF collection around reservoir. 8-CSF leak around the distal end of ventricular catheter 9- -Silicone allergy: Rare

52. COMPLICATIONS WITH VP SHUNT 1 -Obstruction of peritoneal catheter (Distal slit openings or slit valves, due to occlusion by omentum or trapping debris, peritoneal cyst, severe peritoneal adhesions, malposition of catheter tip, over-distended bladders that have ruptured . Fluid can be aspirated percutaneously and analyzed for BUN and creatinine (which should be absent in CSF ). 2 -Peritonitis from shunt infection 3 -Hydrocele 4 -Inguinal hernia 5-CSF ascites

53. 6-Tip migration A- into scrotum. b -Into Rectum C-Perforation of a viscus: stomach, bladder, diaphragm. 7- I ntestinal obstruction. 8-Volvulus. 9- O vershunting

54. COMPLICATIONS WITH VA SHUNT 1-Requires repeated lengthening in growing child 2-Higher risk of infection , septicemia 3-Possible retrograde flow of blood into ventricles if valve malfunctions (rare ). 4-Right-sided heart failure, intraoperative air embolus& cardiac arrhythmias 4-Shunt embolus 5-Vascular complications: perforation, thrombophlebitis, venous thrombosis, pulmonary micro-emboli may cause pulmonary hypertension.

55. EVIDENCE-BASED APPROACH TO COMPLICATION PREDICTION AND AVOIDANCE DURING SHUNT SURGERY R ate of shunt complications : 1 month - 15% : 1 year -25% : 5 year-34% Failure rates in pediatric studies are even higher: 38% shunt failure rate at 1 year, going up to 48% at 2 years Most common complications are shunt blockage and infection.

56. FACTORS AFFECTING SHUNT COMPLICATION RATE 1-Hardware issues 2-Patient factors 3-Surgical environment and surgical technique

57. 1-Hardware issues A-Valve Selection: either pressure- or flow-regulated systems. Pressure-regulated valves are either open or closed to CSF flow, depending on the pressure across them. Pressure-regulated valves 1-Slit valves( slits within tubing open when the pressure is high enough). 2-Miter valves(Two opposing leaflets are in the closed or open position depending on the pressure differential). 3-Diaphragm valves( mobile flexible membrane moves in response to pressure changes) 4-Metallic spring ball valves( spring moves up and down depending on the pressure ).

58. Opening pressure: At which valves open is fixed. There are low, medium, and high pressure valve at 5 , 10, and 15 cm H2O pressure, respectively. Flow-regulated valves : Reducing the caliber of the tube through which CSF flows when pressure increases but some flow is maintained at all times Programmable valves allow the opening pressure to be altered using an externally applied device. Many of these systems rely on a magnet to alter the setting, so the setting may need to be checked following an MRI. The newer valves are MRI compatible .

59. Does the Chosen Valve Affect Patient Outcome? Valveless shunt : can cause siphoning, intracranial hypotension with risk of subdural hematomas Kan et al- suggested incidence of slit ventricle syndrome is lower in patients with flow-controlled valve No compelling evidence related to shunt obstruction rate

60. B-Ventricular and Distal Catheter Material The majority of shunt catheters are made from silicone rubber Antibiotic-impregnated catheters( C lindamycin and Rifimpin ): P revent a bacterial biofilm from developing on the shunt tubing preventing shunt infection. Silver-impregnated polyurethane catheters: S ilver prevents formation of bacterial colonies on the tubing .

61. 2-Patient factors Strong predictor of shunt-related complications. A-Age: S ignificant factor in shunt failure (children 48%, adult 27%) B-Underlying etiology of hydrocephalus Incidence of shunt failure greater if multiple shunt revisions. Shunts are also more likely to fail within 6 months of implantation. The majority of patient risk factors for shunt failure are not alterable .

62. 3-Surgical environment and surgical technique A-Surgeon and Surgical Experience High-volume institutions had a lower in-hospital mortality rate compared to low-volume institutions surgeon’s experience significantly correlates to the survival of a VP shunt July effect: Kestle et al showed a small detrimental effect in terms of shunt-related complications when new residents arrive to service

63. B-Preoperative Prophylactic Antibiotics Haines and Walters: A meta-analysis demonstrating a 50% reduction in shunt infection when antibiotic prophylaxis was used N o evidence on which antibiotic is most appropriate , under local policy.

64. C-Skin Preparation No evidence that any particular skin preparation results in a lower shunt infection rate Darouiche et al published a multicenter prospective, randomized, controlled study demonstrating reduced infection rates in clean, uncontaminated surgery (not including shunt surgery) when using chlorhexidine–alcohol compared to povidine –iodine. D- No Hair Shave: Clipping. E-Double Gloving : Not been proved to reduce shunt infection Reduce the incidence of glove perforations

65. F-Length and Position of the Ventricular Catheter Tuli et al- ventricular catheter surrounded by CSF on a postoperative image had significantly lower risk of blockage compared to a catheter tip touching the brain or embedded in parenchyma The optimal length of the ventricular catheter for frontally placed shunts - 5 to 5.5 cm, for occipitally placed shunts is 5.5 to 6 cm. However, ventricular anatomy based on preoperative imaging should dictate the length of the catheter No difference in incidence of shunt blockage depending on site

66. G-Placement of Distal Catheter Borgberg et al- shunt revision rate 51 % for VA shunts, 38.5 % for VP shunts Mortality rate of VA shunts – approx 3%

67. REFERENCES 1-SCHMIDEK & SWEET, OPERATIVE NEUROSURGICAL TECHNIQUES (INDICATIONS, METHODS, AND RESULTS , SIXTH EDITION VOLUME 1). 2-CRANIOMETRICS AND VENTRICULAR ACCESS: A REVIEW OF KOCHER’S, KAUFMAN’S, PAINE’S, MENOVKSY’S, TUBBS’, KEEN’S, FRAZIER’S, DANDY’S, AND SANCHEZ’S. 3-UPDATING TECHNOLOGY OF SHUNT VALVES MATHEUS FERNANDES DE OLIVEIRA,I RENAN MURALHO PEREIRA,II FERNANDO GOMES PINTO III,IV