This allows cerebrospinal fluid CSF trapped within the brain's ventricles to escape into its normal pathway. CPC is a procedure that reduces the choroid plexus tissue that produces CSF in two of the four ventricles inside the brain. This decreases the amount of fluid produced and may also reduce the strength of pulses that can cause the ventricles to enlarge.
This makes the ETV procedure more likely to succeed in a child's brain. For Patients. Mean age was 2. Aqueductal stenosis was the most common indication. ETV is associated with lower rates of sepsis and mortality. An early extraction of parasite plus ETV may improve an outcome and reduce shunt failure. Tumor of the posterior third ventricle with hydrocephalus could be managed by complete tumor excision, shunt surgery or external ventricular drainage, followed by tumor excision.
Computer-assisted planning and performing a navigated endoscopic procedure could help in performing both ETV and biopsy in a better way. Hydrocephalus associated with posterior fossa tumor could be managed by ventriculo-peritoneal shunt, tumor excision and ETV. We agree that the best option to treat hydrocephalus due to posterior fossa lesions is total excision. There are public hospitals where patient need to wait for a significant period for their definitive tumor surgery. ETV should be considered as an alternative procedure to VP shunt in controlling severe hydrocephalus, related to posterior fossa tumors while patients await their definite tumor excision.
The use of pre-resectional ETV was found to be an effective and safe procedure with a high success rate. Endoscopic third ventriculostomy is the best option in the treatment of persistent hydrocephalus after posterior cranial fossa tumor removal. Trans-aqueductal removal of an intra-fourth ventricular cyst along with endoscopic third ventriculostomy with a rigid endoscope and angiographic curved tip catheter was found to be an effective treatment, which can obviate the need for posterior cranial fossa exploration.
Hydrocephalus associated with cerebello-pontine angle tumor could be managed by ventriculo-peritoneal shunt, tumor excision and ETV. Total excision of tumor is the best option.
ETV is also an effective method of treatment of hydrocephalus in cerebello-pontine angle tumors. Shunt malfunction is quite common, and some of them could have repeated malfunctions. Such patients with repeated block could be better managed by ETV.
Formerly shunted patients have less favorable results, somewhat greater risk of serious complications; therefore, more experience is essential when offering them an ETV.
On the other hand, looking to the poor results, Woodworth et al [ 39 ] suggested that the ETV combined with concurrent CSF shunting may be an important strategy to prevent catastrophic treatment failure in obstructive hydrocephalus patients, with a history of multiple shunt revisions and complications.
Brainstem compression and obstructive hydrocephalus could be potentially fatal complication of cerebellar infarct, which could be managed by direct surgery or CSF diversion. Obstructive hydrocephalus associated with cerebellar infarction can also be effectively treated with endoscopic third ventriculostomy.
Hydrocephalus is quite common after intraventricular hematoma and is associated with poor prognosis. An effective management of hydrocephalus could improve prognosis in this condition. An external ventricular drainage, thrombolysis do have limitations such as infections and re-bleeding.
An evacuation of hematoma and ETV was found to be safe and effective. Ventriculo-peritoneal shunt and lumber- peritoneal shunts are commonly practiced procedures in communicating hydrocephalus. Role of ETV in communicating hydrocephalus is controversial. ETV was found to be safe and effective in communicating hydrocephalus by various authors. They argue that the endoscopic third ventriculostomy is not an internal shunt alone but improve hydrodynamic in these cases.
The intraoperative finding of mobility of the third ventricle floor after the ventriculostomy suggest that the ETV helps in the restoration of pulsatility of the ventricular walls. Post-operative improvement in these displacements would correlate with the success of ETV. Multiloculated hydrocephalus could develop after ventriculitis and intraventricular hemorrhage. This condition is difficult to treat, which may need multiple shunts and repeated revisions. Endoscope helps in breaking of the multiple loculations, which makes the multiloculated cavities into a single cavity.
Shunt can be performed after communicating all the loculations. Endoscopy reduces shunt revision rate from 2. The slit ventricle syndrome is defined as the triad in shunted patients of intermittent headaches, small ventricles, and a flushing reservoir that slowly refills. This condition is due to transient proximal catheter occlusion, and symptomatic patients typically respond to shunt revision that incorporates an anti siphon device or programmable shunts.
The clinical improvement sometimes fails to occur or occurs only transiently after shunt. ETV can attain a symptom-free and shunt-independent state in these patients.
A flexible neurofiberscope, with a small outer diameter could be inserted along the shunt tube into the collapsed ventricle and ETV, and shunt removal could be performed in some cases. Shunt can also be carefully blocked to allow ventricular dilation, and ETV could be performed in usual manner using rigid scope.
Such patients could undergo distal shunt externalization and occlusion with ICP monitoring. Those patients demonstrating symptomatic hydrocephalus should undergo ETV and shunt removal. Shunt can be removed without need of revision or ETV if patient does not complain of headache after 2 - 3 days of exteriorization and blockage of shunt when the ICP facility is not available.
Although there is increased risk of ETV in slit ventricle syndrome,, there are reports of third ventriculostomy being used in these cases. Pre-operative detailed knowledge of the posterior communicating artery distance from midline is important to provide a safe lateral vascular border. A generous prepontine interval PPI is generally accepted as an anatomical feature that may affect the safety and functionality of ETV. Patients with an obliterated or reduced PPI can safely undergo ETV as surgeon gains sufficient experience in endoscopy.
Complex hydrocephalus is very important cause of failure to improve after ETV. Measurement of lumbar elastance and resistance can predict patency of cranial SAS. Cerebrospinal fluid flow through the interpeduncular and prepontine cisterns is an important determinant in the success of ETV, which can be predicted by the ratio of early CSF stroke volume values of the interpeduncular and prepontine cisterns.
Xiao Di et al found that phase contrast MRI cine flow in basal cistern failed to demonstrate significant differences between successful and failed ETV groups. This indicates that the distal CSF pathways beyond the basal cisterns, around the brain stem and cervicomedullary junction, may play an essential role in achieving ETV success in addition to an adequate fenestration.
ETV is performed in supine position with head flexed so that the burr hole site is at the highest point. This also avoids over drainage of CSF and an entry of air in the ventricles and subdural space, especially in large ventriculomegaly.
Loss of CSF may also be a risk factor for post-operative subdural hematoma. Some authors even prefer semi-sitting position. It is important to note that the size of the lateral ventricles, foramen of Monro and third ventricle should be sufficiently large to allow an introduction of the endoscope and to navigate it into the third ventricle.
Generally, the width of the third ventricle and foramen of Monro should be approximately 7 mm or greater. If a patient has slit ventricles, caused by over shunting of CSF, it will first be necessary to externalize the shunt to control drainage until an adequate working diameter of the ventricles is achieved.
Stereotactic guidance can be used as a surgical adjunct to access ventricle. The optimal trajectory into the third ventricle through foramen of Monro and into the interpeduncular cistern is usually achieved with burr hole, placed at or just anterior to the coronal suture and about 2. Usually, right side burr hole is performed. An exact site of burr hole can be determined by a line, extending from interpeduncular cistern and foramen of Monro on to the skull.
We use brain cannula to puncture ventricle and then introduce endoscope with sheath. Peel-away sheath with a diameter, just slightly larger than the endoscope, can be used. This enables an easy insertion of the endoscope into the ventricle without repeated trauma to cerebral cortex and ependymal vessels. It also allows for convenient egress of irrigation fluid, eliminating any risk of raised pressure. If any significant hemorrhage occurs in the ventricle as a result of the procedure, the peel-away sheath also facilitates copious irrigation until the hemorrhage is cleared.
We use lactate solution irrigation through the endoscope under normal body temperature, using gravity as opposed to any pressure technique to avoid any barotraumas to the brain or ventricles.
Foramen of Monro can be identified by confluence of thalamo-striate vein, septal vein and choroid plexuses. Perforation in the third ventricle floor is made after negotiating endoscope through the foramen of Monro.
Fenestration in the third ventricle floor should be in between mammillary bodies and infundibular recess, at the most transparent site. Location of basilar artery should be identified to avoid an injury and bleeding during procedure, and the fenestration should be made anterior to the artery complex.
Microvascular Doppler probe inserted through the endoscope could be useful to locate artery if basilar artery is not seen. Position of dorsum sellae can be identified by gentle probing by the blunt instrument, such as bipolar forceps if the facility of Doppler is not available. Fenestration should be made just posterior to dorsum sellae. Water jet dissection technique can be used to prevent an injury to vessel and bleeding if the third ventricle floor is thick and opaque. The third ventricular floor should be penetrated bluntly to avoid the risk of vascular injury.
Although we avoid thermal or electric energy for this technique, laser assisted third ventriculostomy was found to be safe and effective by earlier authors. In some cases, an imperforate membrane of Liliequist can be identified, lying beneath the floor of the third ventricle. Such membrane, if present, should be opened under direct endoscopic visualization. An ultrasonic contact probe NECUP-2 can be used to create minimal and controlled lesion in third ventriculostomy.
If any hemorrhaging is encountered during the procedure, copious warm fluid irrigation should be used until all bleeding is visibly stopped and the ventricular CSF is clear. We use careful intermittent closure of outflow channel to create tamponade effect.
This helps in better visualization during bleeding. An external ventricular drain is kept if there was any oozing of blood. Some authors use reservoir routinely, which facilitates management and diagnosis if patients are suspected to have persistent elevation of ICP or block stoma.
Ommaya reservoir in certain high-risk patients may be a useful option for achieving quick ventricular access by medical and non-medical personnel in case of deterioration after ETV. It is difficult, sometimes, to know patency of stoma and cistern after ETV per-operative, especially in hydrocephalus, following an infection and hemorrhage. Mobile C-arm image intensifier system is used for qualitative evaluation of CSF flow across the stoma and in cisternal space.
Intra-operative images in lateral plane are obtained in cine-mode at 6 frames per second. Post-operative ventriculography is performed after advancing the catheter tip to the opening of stoma. Flow of contrast agent across the stoma and it's disappearance from subarachnoid spaces is noted. Images are acquired at 1, 3 and 5 min to trace the radio opaque contrast. Functionality of stoma and subarachnoid space is assessed depending on rate of flow of contrast across the stoma.
We have no experience of this technique, but Dr Mazhar Husain et al used this procedure and found it to be simple and safe technique that helps in confirming the adequacy of endoscopic procedure during surgery, and thereby facilitating intra-operative decision about further management, such as the need for shunt. Rapid transit of contrast from cisternal spaces in less than 1 min was seen.
Fair — Slow flow of contrast across the stoma with slow transit of contrast from cisternal spaces in 1 — 3 min. Poor — Poor flow of contrast across the stoma with retention of contrast in cisternal spaces for more than 3 min. ETV usually fails in poor group, and ventriculo peritoneal shunt is required. Daljeet Singh et al also performed third ventriculography with 3 - 4 cc of omnipaque, injected through the side port of the endoscope in case of doubt of patency of the ETV stoma.
Grotenhuis perforator can be used in ETV, especially in transparent and thin floor. Some additional help is required in tough floor. Such patients may be considered for shunt surgery per-operatively. The clinical potential use of this alternative third ventriculostomy was also pointed out by Spena et al. A decrease in the ventricular size detected soon after endoscopic third ventriculostomy is associated with a satisfactory clinical outcome.
This response continues during the first few months after surgery. The reduction is more prominent in acute forms of hydrocephalus. Reduction of the size of third ventricle width was more than the reduction in lateral ventricle size after successful ETV. CSF flow could be qualitatively described as the flow-void sign that is best appreciated in areas of narrowing. The visualization of this effect on routine T1- weighted or T2-weighted MR images is not consistent. Sagittal T2-weighted turbo inversion-recovery MR images can detect flow-void sign better.
If the stoma is very narrow, the sign may be very weak or even absent. The phase contrast technique is sensitive, even to slow flow, and provides the potential for non-invasive flow quantification. The measurement of stroke volume in ventriculostomy using cine PC MRI provides functional information about the third ventriculostomy.
There are controversies regarding the success of ETV in infants. Some authors found that the ETV success do not depend on an age of the patient. Kulkarni AV et al [ 82 ] reported the relative higher risk of initial failure in ETV, than shunt in children. The relative risk becomes progressively lower for ETV after about 3 months. Patient could experience a long-term treatment survival advantage after an early high-risk period of ETV failure as compared to shunt.
They observed that it might take several years, however, to realize this benefit. However, complications such as fever, bleeding, hemiparesis, gaze palsy, memory disorders, altered consciousness, diabetes insipidus, weight gain and precocious puberty are reported. Intraoperative neural injury, such as thalamic, forniceal, hypothalamic and midbrain injuries are also observed.
Intraoperative bradycardia[ 83 ] and hemorrhages including fatal hemorrhage due to basilar artery rupture are also reported. Attempts to perforate the ventricular floor can lead to bleeding, especially in hydrocephalus following an infection and hemorrhage.
Forniceal injury and other neural injuries could be avoided by proper planning of burr hole, avoiding significant side movements and by selecting proper cases with significantly enlarged foramen of Monro and third ventricle. Per-operative bleeding should be avoided by using water jet dissection in thick and opaque third ventricle, avoiding significant stretching of structure, especially during perforation of tough third ventricle floor. Significant side movement should also be avoided to prevent bleeding due to an injury to structures, like fornix and veins at foramen of Monro.
Rarely, blood might trickle from burr hole site into the ventricle; proper hemostasis must be achieved before entering the ventricle. Proper inspection is must before making perforation in the third ventricle floor; fenestration on the vessel must be avoided. Bradycardia due to raised ICP could be avoided by keeping outflow patent. Bradycardia due to stretching on the brain stem should be avoided, especially during perforation of tough third ventricle floor.
Central nervous system infections, fever, stoma block, CSF leak and post-operative intracranial hematomas were also seen. Post-operative mortality is also reported. However, abnormal prolactin levels were not clinical significant in any of the studied patients. They suggested the longitudinal studies to delineate the effect of ETV on endocrine regulation. Chronic subdural hematoma or subdural hygroma can occur after ETV, especially after Omega reservoir. Post-operative fever could be due to use of electrocautery, which should be avoided.
Post-operative CSF leak could be avoided by plugging cortical and dural opening by gel foam, direct dural closure, especially in large ventriculomegaly in infants,[ 78 ] or by using artificial dural substitute and tissue sealant in at risk patients. Post-operative CSF leak can also be reduced by galeal-pericranial flap. Most of the complications in the ETV patients occur within 4 weeks. However, delayed complications including stoma block can occur, and therefore, a longer follow-up is desirable.
0コメント