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Hydrocephalus: Endoscopic approaches and third ventriculostomy

Hydrocephalus: Endoscopic approaches and third ventriculostomy. Ron Levy Dr. Hader May 8 2008. History. 1910 – L’Espinase – attempted fulguration of choroid plexus in 2 infants w/ hydrocephalus with cystoscope – 1 patient died post-op 1922 – Dandy – similar

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Hydrocephalus: Endoscopic approaches and third ventriculostomy

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  1. Hydrocephalus:Endoscopic approaches and third ventriculostomy Ron Levy Dr. Hader May 8 2008

  2. History • 1910 – L’Espinase – attempted fulguration of choroid plexus in 2 infants w/ hydrocephalus with cystoscope – 1 patient died post-op • 1922 – Dandy – similar • 1923 – Fay & Grant – visualized & photographed interior of ventricles of child w/ hydrocephalus w/ cystoscope • 1923 – Mixter – 1st successful 3rd ventriculostomy • 1943 – Putnam – endoscopic choroid plexectomies by cauterization – high failure & peri-op mortality rates • 1970 – Scarff – similar • Decline in neuroendoscopy w/ advent of ventricular shunts & development of microsurgery • Rediscovery of neuroendoscopy w/ advances in technology in 1970’s • 1990 – Jones – 50% shunt-free success rate for endoscopic 3rd ventriculostomy – improved to 60% in subsequent series

  3. Ventricular cannula Endoscope Rod-lens scope (rigid) Higher optical quality Extreme wide angle view (0, 30, 70, 120 degrees) Ease of orientation and guidance Fiberscope (flexible) Camera A digital 3-chip mini video camera is attached to the endoscope via a sterile optical adapter. Video monitor Light source Halogen, mercury vapor, xenon Bright cold light source Color temperature of xenon light resembles that of sunlight (6000 K) Other ports: Various mechanical instruments Scissors Hooks Puncture needles Biopsy and grasping forceps Balloon catheters Electrocautery Bipolar diathermy probes for hemostasis Irrigation RL or NS Solution at 36 to 37C preferable because postoperative increases in body temperature, often seen after abundant irrigation with saline, are rarely encountered. Technology

  4. Hydrocephalus Obstructive hydrocephalus from primary aqueductal stenosis or compressive periaqueductal mass lesions Septum pellucidotomy or septostomy for isolated lateral ventricles Fenestration of loculated ventricles Marsupialization & fenestration of intracranial cysts Aqueductoplasty Neurooncology Biopsy & resection of intraventricular tumors Resection of colloid cysts Endonasal transsphenoidal hypophysectomy Spine surgery Thoracoscopic sympathecotmy Discectomy Lumbar laminotomy Resection of tumors & cysts Craniosynostosis Uses

  5. Pre-operative considerations • MRI scans performed to localize obstruction and for detailed planning • Routine T1- and T2-weighted images in the axial, coronal, and sagittal planes • To demonstrate CSF flow • T2-weighted sagittal inversion recovery turbo spin echo (IRTSE) and cine phase contrast • After identification of the cause of the CSF pathway obstruction, the decision is made whether or not to restore the CSF pathway or to create a bypass into the distal ventricular system or the subarachnoid space • When the ventricles are enlarged and the anatomy is not expected to be distorted, a free-hand approach is performed • In the case of small ventricles (e.g., after shunting) or distorted anatomy (e.g., multiloculated hydrocephalus), neuronavigation is used to determine the ideal entry point • After approaching the ventricle, neuronavigation becomes very inaccurate because of brain shift caused by the release of CSF. When endoscopic orientation is difficult because of the lack of anatomic landmarks, intraoperative imaging such as ultrasound is helpful to remain oriented

  6. Septum Pellucidum Fenestration • Indicated in obstruction of one foramen of Monro leading to dilation of the ipsilateral lateral ventricle (Fig. 1). • The contralateral foramen has to be patent • The perforation is enlarged with the aid of a Fogarty balloon catheter and scissors • Vessels located in the area of the intended fenestration are cauterized with bipolar diathermy and cut • In acute patients with a thick septum pellucidum, the area to be fenestrated is circumferentially coagulated, and the piece of septum is cut out with scissors

  7. Temporal Ventriculostomy • Indicated in isolated temporal or temporo-occipital horns occurring after shunt infections or removal of intraventricular tumors when fenestration into the lateral ventricle is impossible because of anatomic variations or thick scarring in that region • The entry point is selected with the aid of neuronavigation • The burr hole is placed above and behind the ear in the temporo-occipital region to lead in a straight line from the entry point to the tip of the temporal horn • At the tip of the temporal horn, there is usually a thin part of the mesial ventricular wall where the fenestration should be made • The ventricle wall is coagulated and bluntly punctured.

  8. Foraminoplasty • Indicated in obstructions of both foramina of Monro, leading to dilation of both lateral ventricles • Area of the foramen is easily found while following the choroid plexus, which runs from the lateral ventricle into the third ventricle beyond the fornix • The ependyma is coagulated and a scope is bluntly inserted into the third ventricle in front of the plexus away from the fornix • If the foramen are occluded by a membrane, a simple perforation and subsequent dilatation with a Fogarty balloon catheter is sufficient • Foraminoplasty is created within solid brain parenchyma, the risk of closure is expected to be high. Therefore, a stent is inserted from the lateral ventricle to the fourth ventricle. A stent length of about 10 cm minimizes the risk of stent migration.

  9. Endoscopic Third Ventriculostomy • Indicated in any obstruction distal to the floor of the third ventricle • Aqueductal stenosis • Compressive periaqueductal mass lesions (e.g. tectal gliomas) • Intraventricular hemorrhage • Myelomeningocele • Post-infectious hydrocephalous • Intra-cranial cyst • More physiologic treatment of obstructive hydrocephalus by allowing egress of ventricular CSF directly into subarachnoid space, bypassing downstream stenosis • Opening made in the floor of 3rd ventricle • Alternative to VP shunt which is assoc w/ frequent & multiple complications • Opportunity for patient to have shunt-free existence

  10. Technique • Before surgery, computed tomographic or sagittal MRI scans should be inspected to be aware of the individual relation of the basilar artery to the floor of the third ventricle • Performed under general anesthesia • The head is placed in a horseshoe-shaped headrest or, when neuronavigation is used, in three-pin fixation • The entry point is selected to enable a straight approach to the region of interest. With enlarged ventricles, the operating sheath is inserted freehand for third ventriculostomy, aqueductoplasty, and aqueductal stenting. • the entry point should be located opposite of the dominant hemisphere. • After a 3-cm straight scalp incision has been made, a 10-mm burr hole is placed. • Burr hole at or just anterior to coronal suture, 2.5-3 cm lateral to midline • Open dura in cruciate fashion, coagulate edges

  11. No. 14 Fr catheter used to cannulate lateral ventricle • Remove stylet • Pass endoscope thru sheath to visualize lateral ventricle • Identify Foramen of Monro & navigate scope into 3rd ventricle • Identify mamillary bodies & infundibular recess in floor • Sometimes basilar artery visible • Inspection of the ventricle and identification of the main landmarks, i.e., choroid plexus, fornix, posterior commissure, or veins • Continuous irrigation is not performed • In the case of hemorrhage, a 20-ml syringe is used to irrigate the ventricle. Small hemorrhages usually cease spontaneously after a few minutes of irrigation. Rarely, the bipolar diathermy probe is used to achieve hemostasis. • Puncture floor of 3rd ventricle & dilate opening • Perforation of the floor is made just behind the clivus, halfway between the infundibular recess and mamillary bodies in the midline • The floor is bluntly perforated with the aid of rigid instrument, such as a bipolar rod without energy, closed biopsy forceps, or Decq forceps • Perforation with the balloon catheter itself should be avoided because, with firm floors, the catheter may slip to one side or the other, perforating the floor in a less than ideal place and increasing the risk of neurovascular injury • Use of intraoperative Doppler imaging before fenestration to trace the location of vessels underlying the floor of the third ventricle

  12. When the floor is thick or very tough and the attempt at its blunt perforation causes considerable tension to the floor and adjacent hypothalamus, the initial perforation is performed with the aid of the bipolar rod at low energy (10 W). • Thereafter, the opening is enlarged by inflating the balloon of a 3-French Fogarty catheter to achieve an adequate fenestration size of 3 to 6 mm in diameter. The balloon should be prefilled with water instead of air to avoid the pop-up effect and to achieve a continuous inflation • The interpeduncular and pontine cisterns are inspected through the ventriculostomy. When a Liliequist’s membrane is present, it is also fenestrated • On completion, remove scope & sheath the ventricles are inspected with the diagnostic scope to ensure that there is no active hemorrhage. • Look for potential bleeding in the cortical puncture channel. • Gelfoam plug in burr hole • Close galea & skin • Tightly suture the galea to prevent subgaleal CSF accumulation and fistula formation

  13. Anatomy From: Li KW et al. Neurosurg Focus. 2005; 19(6):E1.

  14. From: Jallo GI et al. Neurosurg Focus. 2005; 19(6):E11.

  15. From: Jallo GI et al. Neurosurg Focus. 2005; 19(6):E11.

  16. Patient Selection • Symptoms & signs of hydrocephalus • Features on MRI • Enlarged lateral & 3rd ventricles, w/ N or small 4th ventricle • Midsagittal section demonstrating adequate space between basilar artery & clivus under floor of 3rd ventricle

  17. Post-op Care • Observation in ICU x 1 day • MRI • CINE – CSF flow thru opening in floor of 3rd ventricle • Ax T2WI (“Poor man’s CINE”) – flow void in floor of 3rd ventricle

  18. Outcome • Overall success rate 50~90% • Amini. Endoscopic third ventriculostomy in a series of 36 adult patients. Neurosurg Focus. 2005 Dec 15;19(6):E9. • In cases of obstructive hydrocephalus due to congenital or acquired aqueductal stenosis in adults, the success rate of ETV in avoidance of shunt placement is 72% • Twenty-two percent of the patients in this series in whom ETV was initially successful later experienced closure of the fenestration and recurrent symptoms at a mean interval of 3.75 years • Most failures occur soon after procedure • Reclosure of ventriculostomy ~22% • Longer follow-up studies necessary

  19. Complications • Bleeding • SAH - injury to basilar artery • ICH • IVH - bleeding from choroid plexus • SDH • Injury to surrounding structures • Cranial nerve palsy – CN III, VI • Fornix, caudate, thalamus, thalamostriate venous complex • Hypothalamic / pituitary dysfunction • Typically manifests as DI • Cardiac arrhythmias or resp arrest from manipulation or irritation of hypothalamus • Infection • Mortality ~1% • Specific incidences • CSF leak 3.6% • Meningitis 2.8% • Hemorrhage 1.4% • Hypothalamic injury 1.4% • Cranial nerve injury 1.4% • Seizure 1.4% • Other 1.4% • Total 13.6%

  20. Third ventriculostomy in pediatric patients • Endoscopic third ventriculostomy in pediatric patients: The Canadian experience. Neurosurgery 60:881-886, 2007 • Methods • Failure of procedure was defined as any subsequent operation for CSF diversion or death resulting from hydrocephalus. • Results • 15 year period • 368 patients • Median age 4.8 years (1 day to 20 years) • Follow-up period average of 2 yrs • 57% male • Etiologies • Aqueductal stenosis 34% • Tumors 29% • 22% of patients were previously shunted

  21. Results con’t • 1 year success was 65% • 5 year success was 52% • Only age effected outcomes • Younger patients failed at higher rates • Particularly neonates and infants • Sex, etiology of hydrocephalus, previous surgery, center volume, and surgeon volume had no effect on outcome

  22. Aqueductoplasty • An alternative treatment option in membranous aqueductal stenosis • When the stenosis is located far distally and cannot be visualized with the rigid scope, the 2.5-mm steerable fiberscope is used to inspect the aqueduct • Aqueductoplasty is usually performed with the aid of a 3-French Fogarty balloon catheter, which is gently passed into the stenosis • The aqueduct is not a straight tube, but rather has a curved shape. Advancing a straight catheter into the aqueduct might result in tectal plate injury, causing diplopia

  23. Aqueductal Stenting • Aqueductal stenting is an alternative treatment option to third ventriculostomy in non-neoplastic and neoplastic aqueductal stenosis (Fig. 7) • Aqueductal stenting is the procedure of choice for most cases of trapped fourth ventricle • Stenting is indicated when an increased risk of restenosis is expected • Before inserting the stent, an aqueductoplasty is usually performed and the poststenotic aqueduct is inspected to ensure that the stent will be placed correctly • The stent should be at least 6 cm or longer to prevent stent migration • An alternative fixation option is suturing the stent to the dura at the entry point

  24. Retrograde Aqueductoplasty and Stenting • Indicated in a trapped fourth ventricle (Fig. 8) • Because a trapped fourth ventricle frequently occurs in shunted patients with slit lateral ventricles, an endoscopic standard approach via the frontal horn is often not feasible • Therefore, a direct approach into the dilated fourth ventricle and retrograde aqueduct reconstruction are performed • Neuronavigation is mandatory in finding the ideal entry point, which is usually located 1 to 2 cm apart from the midline • Because the anatomy in the region of the aqueduct is often distorted, neuronavigation is also extremely helpful in selecting the correct position for the aqueductoplasty and stenting • Because the risk of aqueduct closure is considerable, stenting should be performed in most patients

  25. References • Amini. Endoscopic third ventriculostomy in a series of 36 adult patients. Neurosurg Focus. 2005 Dec 15;19(6):E9. • Lwu. Hydrocephalus II: Shunt Dysfunction and Neuroendoscopy. May 18, 2006. • Drake. Endoscopic third ventriculostomy in pediatric patients: the Canadian experience. Neurosurgery. 2007 May;60(5):881-6; discussion 881-6. • Schroeder et al. ENDOSCOPIC TREATMENT OF CEREBROSPINAL FLUID PATHWAY OBSTRUCTIONS. Neurosurgery 60[Suppl 1]:44-52, 2007

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