37.2.1 Endoscopic Third Ventriculostomy

Endoscopic third ventriculostomy (ETV) is certainly the most common neuroendoscopic procedure; therefore, its complications are the best known and best managed. Cerebrospinal fluid (CSF) leak, subcutaneous collection, infection, and neurologic damage from cortical and cerebral hematoma are usually related to the placement of the bur hole and introduction of the endoscope into the lateral ventricle. Contusions of the walls of the lateral ventricle (thalamus, caudate nucleus, fornix), hemorrhage from ependymal or thalamostriate veins, intracranial hypertension from over-irrigation, and pneumocephalus occur during endoscopic navigation within the lateral and the third ventricle. Opening of the third ventricular floor may be associated with complications that include hypothalamic or mesencephalic damage, tearing of the basilar artery or its branches, injury to the oculomotor nerves, and subdural or epidural collections due to the brain collapsing. It is worth mentioning that the incidence of complications is also related to the patient’s characteristics and anatomy rather than the procedure itself. For example, the thin skin of infants can predispose to CSF leak or infection. Similarly, the distortion of anatomy in patients with myelomeningocele or other congenital brain malformations increases the risk of contusions and technical failure. Posthemorrhagic and postinfectious hydrocephalus as well as hyperdense cysts can favor technical failure too. According to a large meta-analysis of 2985 ETVs performed in 2884 patients (age range: 1 day–88 years), the overall rate of complications was 8.5% (range: 0–31.2%).8 Intraoperative bleeding was the most common complication (3.7%), although fatal severe hemorrhage was reported only in 0.6% of cases (basilar artery rupture: 0.21%). Postoperative hemorrhages were rare (0.81%). Intraoperative brain contusions were seen in 0.24%. Infections (mainly meningitis) affected 1.81% of patients while systemic complications (hyponatremia, vein thrombosis, systemic infection) affected 2.34% of them. CSF leak was observed in 1.61% of cases. A technical failure (ETV abandoned) occurred in 4.2% of cases, mainly because of intraoperative bleeding or distorted anatomy. Such complications resulted in a 2.38% overall permanent morbidity, with neurologic morbidity (gaze palsy, hemiparesis, memory disorders, decreased consciousness) in 1.44% of cases, and hormonal morbidity (diabetes insipidus, weight gain, precocious puberty) in 0.94% of cases. It was not possible to estimate the exact rate of transient morbidity. The overall mortality rate was 0.28% (8 patients): 6 patients died in the early postoperative period (2 because of sepsis, 4 because of hemorrhages), while the remaining two in the late postoperative period (sudden death). No differences between pediatric and adult series were detected as well as between series with less or more than 100 cases. (See Chapter 21 for more details.)

37.2.2 Aqueductoplasty and Stenting

Specific complications for acqueductoplasty and stenting are quite rare and mainly transient (10%).9,10 The most frequent is injury of the tectal plate, with following transient or permanent diplopia (dysconjugate eye movement) and/or trochlear nerve palsy.11 Although a stent migration or closure may occur, the stent placement is preferable to the aqueductoplasty alone because of the lower rate of late closure. (See Chapter 22 for more details.)

37.2.3 Septum Pellucidum Fenestration

This is one of the safest neuroendoscopic procedures, usually free from severe complications or permanent morbidity.12 Injuries to the anterior (or posterior) septal vein or to the contralateral ventricle are specific complications of this technique. (See Chapter 23 for more details.)

37.2.4 Foraminopasty of Monro

There are no papers specifically addressing the issue of complications after foraminoplasty of Monro. It is considered feasible and safe when the anatomy is not distorted and an avascular membrane covers the foramen.13 Fornix contusion and bleeding from the thalamostriate and/or anterior septal vein or from the choroid plexus are the main risks. (See Chapter 24 for more details.)

37.2.5 Magendie and Luschka Foraminoplasty

Only sporadic cases done by a transventriculartransaqueductal, or suboccipital-transventricular route are described. In the largest series available, by Torres-Corzo et al (30 patients, transaqueductal transventicular route), transient ocular dysfunction occurred in 3 cases.14 Other possible complications are brainstem injury and intraoperative hemorrhage because of the long surgical route. (See Chapter 28 for more details.)

37.2.6 “Brain Wash”

Neuroendoscopic blood clot aspiration and ventricular irrigation can be used to reduce the risk of requiring a permanent shunt after severe intraventricular hemorrhage.15 Intraoperative and/or postoperative intracranial hypertension, blurry vision, rebleeding, contusions, and electrolytic imbalance (over-irrigation) may occur during and/or immediately after this procedure as well as in case of endoscopic aspiration of intracerebral hematoma.16

37.2.7 Lamina Terminalis Fenestration (Opening)

No major complications were reported by Rangel- Castilla et al in 25 hydrocephalic cases,17 thus showing this technique as a safe alternative to ETV. Potential complications are related to injury to the optic chiasm or to the anterior communicating artery complex. (See Chapter 26 for more details.)

37.2.8 Endoscopic Shunt Management

Neuroendoscopy can be used for shunt placement or revision in selected cases. In these instances, the shunt-related complications, such as malposition, obstruction, and infection, have to be taken into account other than those related to neuroendoscopy (usually, perioperative bleeding but even sudden death).18 (See Chapter 25 for more details.)

37.2.9 Arachnoid or Other Intraventicular or Paraventricular Cyst Fenestration (e.g., Cystic Tumors)

Mortality and morbidity rates ranging around 1 to 5% are reported for arachnoid cysts.19 Bleeding, blurred vision, and brain collapse with postoperative subdural hygroma (decreased size of both cyst and ventricles, if hydrocephalus is associated) are the most common complications. In case of suprasellar arachnoid cysts, where ETV is required, complications may also occur. Chemical meningitis due to the cyst content escape (namely, from craniopharyngioma) seems to be exceptional, probably because of the intraoperative aspiration and irrigation. (See Chapter 17 for more details.)

37.2.10 Colloid Cyst Resection

In spite of the poor vascularization and the soft content, which make the aspiration of colloid cysts easy, the detachment of the capsule from the roof of the third ventricle may be troublesome because of the intimal relation with the internal cerebral veins. Venous bleeding is actually a possible complication other than fornix contusion and aseptic meningitis.5,20 (See Chapter 13 for more details.)

37.2.11 Biopsy/Removal of Intraventricular Tumors

Among neuroendoscopic procedures, tumor resection could be the most challenging. Indeed, the overall complication rate is generally more than 10%, and the early mortality and the permanent morbidity range around 0.2% and 3%, respectively.5,21,22 Intraoperative bleeding from the tumor, seizures, hydro-cephalus, meningitis, and neurologic deficits are the most common and specific complications. Moreover, the risk of inconclusive biopsy (10–15%) and/or tumor dissemination (6–7%) has to be considered. (See Chapter 12 for more details.)

37.2.12 Biopsy of Basal Cistern

Performed to improve the microbiological investigation in patients deteriorating from basal meningitis, this procedure has been recently used with success and with no severe complications by Torres-Corzo et al.23 (See Chapter 31 for more details.)

37.3.1 Intraoperative Complications (Table 37.1)

Bradycardia can arise from over-irrigation (intracranial hypertension), irrigation with hypertonic and/or hypotonic or cold solutions, and during perforation and/or traction of the floor of the third ventricle. Bradycardia is usually reversible by stopping the ongoing action (e.g., by deflating the Fogarty balloon catheter during ETV). If not promptly recognized, bradycardia can lead to asystole. The key points to avoiding this potentially fatal complication are:

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  Always listen to cardiac monitor.

  
  
• 
  

  Check that the outflow channels of the endoscope are open.

  
  
• 
  

  Gently irrigate with isotonic solution (lactated Ringer’s solution) at body temperature (do not utilize saline). The suggested speed of irrigation is < 10 ml/min.24 Alternatively, a pressure monitoring during neuroendoscopy can be done.25

  
  
• 
  

  Avoid the stretching of the third ventricular floor (autonomic nuclei of the hypothalamus).

Sometimes, tachycardia can occur following stretching of the third ventricular floor. Systemic hypertension and/or hypotension can occur, usually related to the same etiologies; the incidence is 10 to 16%.26 Also hypothermia and electrolyte imbalance (hypo- and/or hypernatremia or hyperkalemia) result from hypothalamic damage and inappropriate irrigation (incidence: 1–4%).27 Although, hypothalamic injury can contribute to these phenomena, over-irrigation seems to be the most common cause. Because of the small body surface, hypothermia is typical of small children and is a consequence of the wet drapes resulting from the fluid escape from the endoscope. Intraoperative monitoring of arterial pressure, body temperature, and main electrolytes; proper irrigation; and avoidance of wetting drapes reduce the risk of these complications. Suppression of electrocerebral activity is a further rare or, perhaps, underestimated complication of over-irrigation.28

As mentioned, intraventricular bleeding is one of the most common complications of neuroendoscopy.8 Possible sources of this bleeding include ependymal layer of the ventricles, choroid plexus, floor of the third ventricle, intracerebral vessels or those of the cortical surface, and, less frequently, blood running down from the endoscope trajectory or epidural space, bur hole, or skin. The introduction of the endoscope alone is enough to cause bleeding, especially in patients who suffered for posthemorrhagic or postinfectious hydrocephalus (rigid and fragile ventricular walls) or coagulopathies. Inadequate hemostasis before introducing the endoscope, wrong brain trajectory or wrong entry point into the lateral ventricle, inappropriate or excessive movements of the endoscope during the procedure, repeated introduction of the endoscope without peel-away sheath, the use of sharp sheaths, and the wrong removal of the endoscope (incorrect trajectory, withdrawal of the flexible endoscope in curved position) are the main causes of bleeding. See Table 37.2 for technical important points to remember to avoid perioperative intraventricular bleeding. Intraventricular hemorrhage is often a minor bleeding that can be stopped by simple irrigation at body temperature; most of the times, the blood oozing stops spontaneously. If visible, the source of bleeding can be cauterized (a controlled, forceful irrigation can also be used to better visualize it). The bleeding from the third ventricle floor can be usually blocked by inflating the Fogarty balloon catheter for some minutes (Fig. 37.1). In case of major bleeding with blurring vision, the procedure has to be stopped, and the endoscope has to be promptly moved into the lateral ventricle to start irrigation to remove blood and clear the vision. Since the irrigation may take a long time, the endoscope can be removed leaving the sheath in place to keep on irrigating and to maintain the access to the ventricle. An external drain is usually placed at the end of the procedure. In case of uncontrollable bleeding, neuroendoscopic procedures can be converted into an open surgical procedures to arrest the hemorrhage.24 Intraventricular tumors may represent a further source of hemorrhage during their biopsy or removal. An adequate instrumentarium (namely, high-definition [HD] vision system, laser, and endoscope-compatible ultrasound aspiration system) is mandatory to reduce the risk of tumor bleeding as much as possible.

Although as rare as < 1%, vascular injury is the most feared and severe complication of neuroendoscopy, accounting for almost all cases of intraoperative mortality.8,29 The most frequent site of injury is represented by the abundant vascular content of the interpeduncular cistern that can be damaged during ETV or other procedures inside the third ventricle. The anterior compartment of this cistern contains the basilar artery, the P1 segment of the posterior cerebral arteries, and the posterior choroidal arteries, while the posterior compartment contains the perforating branches of the basilar and the posterior cerebral arteries. Moreover, these vessels, which lie just under the ventricular floor (that can be thick and opaque), can present anatomical variants as to their size and position. On the other hand, the injury to the anterior circle of Willis is rarely reported.30 It results from the damage of the vessels running under the lamina terminalis (proximal A2 tract, Heubner’s artery, fronto-orbital artery, and respective veins) when the lamina is opened because of a distorted anatomy preventing ETV. The bleeding from the circle of Willis’ major branches is often a fatal event and, in case of the patient’s survival, several further problems have to be faced as the neurologic deficits resulting from the vasospasm due to the usually severe subarachnoid hemorrhage, pseudo-aneurysm formation at the site of the vascular injury, a possible cerebral infarction, and the occurrence and/or worsening of hydrocephalus.2 In case of arterial rupture, the operating field is immediately blurred and the blood is quickly and copiously lost. The anesthesiologic management consists in deep sedation of the patient and blood replacement, other than in supporting the vital parameters. The surgical management is the same as illustrated above for the other severe intraventricular bleedings. The early postoperative management is focused on the treatment of the subarachnoid hemorrhage. In case of major venous bleeding (internal cerebral vein, thalamostriate vein, septal veins, big ependymal veins), there is usually enough time to move the endoscope into a safe position and to start the irrigation. The septal veins as well as the ependymal veins can be cauterized. Also small openings on the thalamostriate and/or internal cerebral veins can be cautiously cauterized; on the other hand, a cauterization of a large opening of the wall of these veins should not be performed to avoid its further enlargement. The key points to avoiding vascular injury are:

• 
  

  Knowledge of neuroendoscopic anatomy and its variants.

  
  
• 
  

  Careful preoperative planning based on neuroimaging.

  
  
• 
  

  Choice of a proper point to enter the third ventricle floor (usually, the translucent premammillary recess).

  
  
• 
  

  The use of accessory technology or techniques to make a safer opening of thick and opaque third ventricle floors, such as the water jet dissection31 or the use of intraoperative neuroendoscopic ultrasounds.32

  
  
• 
  

  Avoid sharp instruments or cauterization to open the third ventricle floor.

  
  
• 
  

  Abandon the procedure if the anatomy or the visual field are not clear.

  
  
• 
  

  Intraventricular bleeding and severe (and persistent) bradycardia are also a possible cause of technical failure (procedure abandoned). Other causes are related to:

  
  
  
  
  • 
    

    Visual obscuration as for dense fluid escape from cystic tumors, scope out of focus, fogging of the lenses, or damaged or incorrectly assembled endoscope.

    
    
  • 
    

    Unfavorable intraventricular anatomy, like the presence of intraventricular septa, very small foramina of Monro, very large massa intermedia, partial fusion of the hypothalamic walls, thickening of the third ventricle floor.

    
    
  • 
    

    Distorted anatomy due to large tumors, cysts, brain malformations, scarring due to previous hemorrhage, or infection.

    
    
  • 
    

    Unfavorable position of the target of the procedure that make it hard to be reached (e.g., colloid cysts or pineal tumors) or recognized (e.g., paraventricular tumors covered by ependyma).

A proper (and correctly used) endoscopic armamentarium and meticulous preoperative planning are the best ways to reduce the risk of technical failure. The improvement in neuroendoscopic technology reduced the incidence of this complication in the past 15 years from ~ 25%33 to 3 to 5%.1,27