Keywords
endoscopic third ventriculostomy - treatment of adult hydrocephalus - obstructive
hydrocephalus
Currently, the creation of a foramen between the third ventricle and the interpedicular
cistern under the direct guidance of an endoscope is a well-established surgical technique
called endoscopic third ventriculostomy (ETV). The management of obstructive hydrocephalus
using ETV is becoming the treatment of choice, expanding also in cases of communicating
hydrocephalus such as post-traumatic.[1]
It was in 1923 when W. J. Mixter achieved to open the third ventricle into the interpedicular
cistern for the first time in a 9-month-old infant[2] suffering from obstructive hydrocephalus. He did so by using an urethroscope to
visualize the floor of the third ventricle, which he then perforated using sound.
Different attempts have taken place since then, but the technique in its current form
was introduced in the 1990s.[3]
[4] Currently, there are two treatment methods for hydrocephalus patients: cerebrospinal
fluid diversions techniques (shunts) and ETV. In the current project, we present our
experience in managing patients suffering from hydrocephalus performing ETV and we
compare our results and complications with the international literature.
Materials and Methods
During the last 3 years from 2016 to 2019, at 2nd Department of Neurosurgery at ‘Attiko’ University Hospital of Athens, Greece, 20
adult patients underwent ETV due to various causes ([Table 1]).
Table 1
Causes of hydrocephalus
|
Causes
|
Number of patients
|
Preoperative symptoms
|
|
Infection
([Fig. 1])
|
3 (15%)
|
Gait disorder, headache, impaired level of consciousness
|
|
Post-traumatic
|
1 (5%)
|
Vegetative state
|
|
Tumor
|
5 (25%)
|
Impaired level of consciousness
|
|
Aqueduct stenosis
([Fig. 2])
|
2 (10%)
|
Incontinence, dementia, gait disorder
|
|
Normal pressure hydrocephalus ([Fig. 3])
|
5 (25%)
|
Incontinence, dementia, gait disorder
|
|
Intraventricular bleeding
|
2 (10%)
|
Coma
|
|
Cavernoma ([Fig. 4])
|
2 (10%)
|
Impaired level of consciousness
|
|
Total
|
20 (100%)
|
|
Fig. 1 Preoperative CT scan: (A) sagittal plane, (B) axial plane, (C) coronal plane images, (D) intraoperative endoscopic image of the endoscopic third ventriculostomy created
using a light-touch balloon catheter, (E) sagittal postop MRI showing the CSF flow through the ventriculostomy, and (F) MRI-CSF through the ventriculostomy showing sufficient velocity flow). CSF, cerebrospinal
fluid; CT, computed tomography; MRI, magnetic resonance imaging.
Fig. 2 Patient suffering from hydrocephalus caused by stenosis. A: sagittal plane, B: axial plane, C: coronal plane postoperative CT scan, and D: intraoperative image of the creation of the ventriculostomy using the balloon catheter
at the insertion area above the mamillary bodies.
Fig. 3 Patient suffering from normal pressure hydrocephalus. A: sagittal, B: axial, C: coronal postoperative MRI scan, D: intraoperative image of the endoscopic third ventriculostomy stoma at the floor
of the 3rd ventricle, and E: endoscopic image through the ventriculostomy showing the basal artery and it's perforating
branches to the brain stem.
Fig. 4 Patient with hydrocephalus caused by brain stem cavernoma. A: sagittal plane, B: axial plane, and C: coronal plane preoperative CT scan), and D-E: sagittal postoperative MRI-CSF study showing sufficient CSF flow through the ventriculostomy.
Seventeen of these patients underwent brain computed tomography scan and three of
them had magnetic resonance imaging (MRI) brain as part of the preoperative planning.
The diagnoses of the cause of hydrocephalus as well as the identification of the anatomical
landmarks have both reduced the risk of complications.
In operating theater, the patients were positioned supine with head elevated ∼30 degrees
fixed on Mayfield fixation system or lying on a horseshoe and a small area of the
skin of the head was shaved. The incision was done ∼3 cm from the midline, along the
midpupillary line ∼2 cm anteriorly of the coronal suture (Kocher point). The length
of the incision was ∼5 cm and an 8 mm burr hole was performed with the usual technique.
The appropriate use of the anatomical landmarks was of primary importance, as the
procedure was performed without neuronavigation control. The endoscopic system used
for these procedures is the Minop system (B. Braun, Germany) with a rigid endoscope
from Aesculap, United States. The endoscope diameter was 6 mm and the sheath had four
channels. The biggest one was used by the endoscope and the working channel was situated
above the endoscope. Free hand technique was applied to introduce the endoscope into
the lateral ventricle. Irrigation was performed using Ringer's solution and once lateral
ventricle was inspected, then the endoscope was advanced through the Monro's foramen
into the third ventricle, where it was possible to recognize the anatomical landmarks
of the floor of the third ventricle (mammillary bodies and infundibular process).
The fenestration of the roof was performed using bipolar diathermy following dilatation
of the stoma by a balloon to widen further the fenestration of the floor of the third
ventricle. The ETV was considered successful when there was complete resolution of
the symptoms caused by hydrocephalus.
Results
A total number of twenty patients were diagnosed with hydrocephalus and underwent
ETV. Fourteen were male (70%) and six were female (30%). Their mean age was 56.5 years
(median: 60.5 years and range: 19–79). The follow-up period ranged between 3 and 36
months. In two patients, ETV failed and had ventriculoperitoneal shunt done; the first
was done 3 months after the ETV and the second one 12 months after the ETV. In both
cases where the ETV failed, the patients were originally diagnosed with normal pressure
hydrocephalus and underwent urgent shunt insertion after being transferred in acute
and emergency department with low level of consciousness. Five patients presented
with complications postoperatively ([Table 2]).
Table 2
Post-ETV complications
|
Causes
|
Age
|
Complications
|
Outcomes
|
|
1
|
Obstructive tumor—fourth ventricle
|
46
|
Claimed blindness not proven
|
Resolved in 24 h
|
|
2
|
Normal pressure hydrocephalus
|
66
|
III nerve palsy
|
Resolved in 3 mo
|
|
3
|
Obstructive cavernoma
|
62
|
Intraventricular hemorrhage
|
Neurologic deficit
|
|
4
|
Obstructive infection
|
41
|
Intracerebral hemorrhage
|
Neurologic deficit
|
|
5
|
Obstructive tumor—fourth ventricle
|
58
|
Weber syndrome
|
Neurologic deficit
|
Abbreviation: ETV, endoscopic third ventriculostomy.
The intracerebral hemorrhage was of small volume and it did not require surgical management.
All patients after the initial procedure had postoperative MRI with cerebrospinal
fluid flow sequence in 3 and 12 months.
Discussion
The ETV is a minimally invasive reliable technique, which in future might represent
the gold standard method in the management of hydrocephalus. When ETV was first introduced
in neurosurgery, the primary indication was obstructive hydrocephalus. ETV is currently
performed in patients suffering from nonobstructive hydrocephalus such as normal pressure
hydrocephalus and trauma with promising results. Nevertheless, with regard to the
managements of normal pressure hydrocephalus with ETV, there is no global consensus
in the efficiency such method {Balevi:2017hj}{Tudor:2015hd}. As a result, the success
rate of ETV varies from an overall 70[5] to 97% in the first year post-ETV,[6] while the complication rate remains low.[7]
In our center, we had complications in five patients. Three presented with neural
complications such as blindness, which was resolved in 24 hours; Weber syndrome, which
persisted; and third nerve palsy, which was resolved after 4 weeks. Neural complications
are well documented during the ETV procedure and have a low success rate (0.5–1.4%)
especially those with persisting consequences.[8] The principal pathophysiologic mechanisms of these complications are either direct
damage during the insertion of the endoscope or increased intracranial pressure caused
by either an obstruction of the outflow channels or by excessive irrigation volume.
We did not notice any direct injury in our patients nor malfunction of the irrigation
system. Intraoperative hemorrhage was noticed in two patients. In the first case,
the intraventricular bleeding was controlled and managed successfully using continuous
irrigation and compression. The origin of that bleeding was most likely of venous
origin caused by accidental tearing of the vein. The second patient with vascular
injury suffered from intraparenchymal injury caused during the insertion of the endoscope.
The bleeding was minor and no further neurosurgical procedure was required. This kind
of bleeding is relatively frequent occurring in 16.5% of ETV procedures.[9] Major bleeding may also occur, especially in the event of injury of branches of
basilar artery, but such a serious complication was noticed only in 0.49% of the cases.[10]
In our series of cases, the ETV failed in two patients (11%). Failure is defined when
symptoms of hydrocephalus persisted and further management was required with shunt
insertion. Both patients with failed ETV were diagnosed with normal pressure hydrocephalus.
In these cases, while shunt insertion represents the first choice of treatment, ETV
is also performed but without definite benefits. Nevertheless, the perforated floor
of the third ventricle that reduces the systolic intracranial through the stoma[11] as well as the fact that ETV is a minimally invasive technique has made it attractive
in the treatment of nonobstructive hydrocephalus. In three of our patients with normal
pressure hydrocephalus, ETV was successful. The main difference in comparison with
the failed cases is the duration and the severity of the symptoms. Patients with short
duration of symptoms, mild pollakiuria, and gait disturbance have better outcome when
treated with ETV.[12]
In our series of cases, performing ETV leads also to successful management of post-traumatic
hydrocephalus. While there is lack of class I to IV studies regarding the efficacy
of ETV in post-traumatic hydrocephalus, there is no contraindication either.[13] It is not possible to draw any safe conclusion by the mere case of one patient,
but in addition to other cases reported in literature, we believe that ETV in post-traumatic
brain injury should always be taken in consideration, while further trials are necessary
to prove its benefit.
Conclusions
ETV is a surgical technique that is based on bypassing the eventual obstacle of the
cerebral cerebrospinal fluid flow. It is a minimally invasive procedure, relatively
safe with good success rate.
In our center, in the last 3 years we have been performing ETV in patients suffering
from hydrocephalus either obstructive or nonobstructive as part of routine management
of the pathology. While we consider ETV a successful and safe technique for the patients
suffering from hydrocephalus, we strongly believe that further studies are necessary
to establish this procedure as treatment of choice for hydrocephalus.
