Keywords
endoscopic third ventriculostomy - shunt malfunction - hydrocephalus
Introduction
Shunt placement was a standard treatment for patients with hydrocephalus. It is indicated
for both communicating and noncommunicating types of hydrocephalus and for various
etiologies of hydrocephalus, including infection; congenital malformations, such as
aqueductal stenosis, congenital cysts, mega cisterna magna, and Arnold-Chiari malformation;
hemorrhage; and tumor. The risk of shunt malfunction is quite high: 25 to 40% in the
first year after shunt placement, 4 to 5% per year thereafter, and 81% of shunted
patients require revision after 12 years. Therefore, it is considered that shunt failure
is almost inevitable during a patient's life.[1]
[2]
[3]
Endoscopic third ventriculostomy (ETV) for hydrocephalus is an important advancement
for patients with hydrocephalus. The results are different when it is performed after
shunt failure (secondary ETV) than when it is performed as an initial treatment modality
for hydrocephalus (primary ETV). Complications that are reported with ETV include
herniation syndromes and arrhythmia at the time of ETV, injury to the hypothalamic-pituitary
axis and structures adjacent to floor of the third ventricle, including cranial nerves
and major vessels, resulting in subarachnoid hemorrhage or ischemic stroke, with creation
of ventriculostomy, as well as remote intracranial hemorrhage and infection and severe
cognitive and psychiatric sequelae. In this study we assessed the usefulness of ETV
in cases of ventriculoperitoneal shunt malfunction.
Materials and Methods
Ours was a prospective study. We enrolled 21 patients who underwent ETV for shunt
malfunction presenting to our institution's neurosurgical service between January
2011 and December 2012. All patients had a minimum of 9 months of follow-up. In this
study shunt malfunction was diagnosed in all cases with increased ventricular size
in comparison with baseline investigations of computed tomographic (CT) or magnetic
resonance imaging (MRI) findings associated with at least one symptom or sign of increased
intracranial pressure (headache, vomiting, deterioration of conscious level) or shunt
obstruction (shunt chamber not compressible or refilling). Patients who had earlier
undergone shunt surgery and now presented with shunt malfunction were enrolled in
the study. Patients who underwent ETV as a primary procedure were excluded from the
study. Outcome was considered successful if the patient became shunt independent.[4]
The choice to proceed with ETV was based on discussion on the risks and benefits of
the procedure with the patient and attendants. An incision was made over Kocher's
point and burr hole was performed. A ventricular catheter was then used to cannulate
the lateral ventricle. This track was then followed under direct visualization with
a 0-degree scope. The floor of the third ventricle was then perforated and dilated
with a 3F/4F Fogarty catheter. Bipolar cautery and irrigation were used as necessary
for hemostasis. The interpeduncular and pontine cisterns were inspected for the Liliequist
membrane or any other arachnoid adhesions. Liliequist membrane, if present, was punctured.
The scope was then removed, the burr hole was plugged with gel foam, and a layered
closure was subsequently performed. The correlation between the success of ETV and
patient's age at surgery, etiology of hydrocephalus, number of shunt revisions, third
ventricle anatomy, and third ventricle floor were tested with the chi-square test,
with p < 0.05 indicating statistical significance.
Results
Over the study period, 21 patients underwent ETV for the treatment of shunt malfunction.
Of these patients, 17 were males and 4 were females. The age range of patients in
this study was 2 months to 53 years. The causes of hydrocephalus were aqueductal stenosis
in seven patients, tumor in two patients, neurocysticercosis (NCC) in one patient,
tuberculous meningitis (TBM) in six patients, posttraumatic in one patient, and postmeningitic
in four patients. Communicating hydrocephalus occurred in 11 patients and noncommunicating
hydrocephalus 10 patients.
Success and Failure
Total 13 patients (61.90%) underwent successful ETV whereas ETV failure was seen in
8 (38.1%) patients .VP shunt insertion was done in all these patients.
Variables Affecting Endoscopic Third Ventriculostomy Failure
We evaluated different variables for significant effect on ETV failure. We evaluated
success and failure with respect to age, number of shunt revisions, etiology of hydrocephalus,
third ventricle anatomy, and third ventricle floor.
-
Effect of age: ETV was successful in 33.34% of patients aged ≤ 2 years and in 73.33% of patients
aged > 2 years. However, the difference between success rates in both the groups was
not statistically significant (p = 0.088).
-
Effect of shunt revisions: Patients were divided into two groups: (1) patients who underwent one shunt surgery
prior to ETV and (2) patients who underwent two or more shunt surgeries prior to ETV.
In the first group, 50% patients had successful outcome, whereas in the second group
77.78% patients had successful outcome after ETV. The difference between the two groups
was not statistically significant (p = 0.399). [Table 1] shows distribution of patients according to age and number of shunt revisions prior
to ETV.
-
Effect of etiology of hydrocephalus: Total 11 patients were found to have communicating hydrocephalus whereas 10 patients
had noncommunicating hydrocephalus. In communicating hydrocephalus group, 45.45% patients
had successful ETV. In noncommunicating group, the success rate was higher (80%).
However, the difference between success rates in both the groups was not statistically
significant (p = 0.104).
Table 1
Distribution of patients according to age and number of shunt revisions prior to ETV
|
ETV Success
|
ETV Failure
|
|
No. of patients (n = 21)
|
13
|
8
|
|
Age (y)
|
< 2
|
2
|
4
|
|
> 2
|
11
|
4
|
|
Shunt revisions prior
to ETV
|
1
|
6
|
6
|
|
> 1
|
7
|
2
|
Abbreviation: ETV, endoscopic third ventriculostomy.
In communicating hydrocephalus group, 66.67% patients who presented with TBM with
hydrocephalus had successful outcome after ETV. Nearly 25% of patients with pyogenic
meningitis as a cause of hydrocephalus had successful outcome. ETV failed in patient
who developed hydrocephalus following trauma (head injury).
In noncommunicating hydrocephalus group, the causes for hydrocephalus in patients
enrolled in our study were aqueductal stenosis, tumor, and fourth ventricle NCC.
Nearly 71.42% patients with aqueduct stenosis who presented with shunt malfunction
had a successful outcome after ETV. Nearly 100% patients in whom tumor was the cause
of hydrocephalus had successful outcome. One patient presented with fourth ventricle
NCC with shunt malfunction and had a successful outcome after ETV. [Table 2] shows distribution of patients according to etiology of hydrocephalus
Table 2
Distribution of patients according to etiology of hydrocephalus
|
ETV success
|
ETV failure
|
|
Communicating hydrocephalus (11)
|
5
|
6
|
|
TBM
|
4
|
2
|
|
Postpyogenic meningitis
|
1
|
3
|
|
Posttraumatic
|
0
|
1
|
|
Noncommunicating hydrocephalus (10)
|
8
|
2
|
|
Congenital
|
5
|
2
|
|
Tumor
|
2
|
0
|
|
4th ventricle NCC
|
1
|
0
|
Abbreviations: ETV, endoscopic third ventriculostomy; NCC, neurocysticercosis; TBM,
tuberculous meningitis.
Endoscopic Findings
-
Effect of third ventricle anatomy: Endoscopic observations made during the procedure showed normal anatomy of the third
ventricle in 9 patients and indistinct anatomy in 12 patients. Nearly 77.78% patients
who had normal third ventricle anatomy observed during endoscopy had successful outcome
whereas 50% patients who were having indistinct anatomy observed during the procedure
had successful outcome. The difference between the two groups was not statistically
significant (p = 0.195).
-
Effect of third ventricle floor: Thickened third ventricle floor was found in 15 patients while performing ETV. Nearly
53.33% patients with thickened third ventricle floor had successful outcome. Six patients
had normal third ventricle floor. Nearly 83.33% patients in this group had a successful
outcome after the procedure. The difference between the two groups was not statistically
significant (p = 0.201). [Table 3] shows distribution of patients according to endoscopic findings.
Table 3
Distribution of patients according to endoscopic findings
|
ETV success
|
ETV failure
|
|
3rd ventricle anatomy
|
|
Normal
|
7
|
2
|
|
Indistinct
|
6
|
6
|
|
3rd ventricle floor
|
|
Normal
|
5
|
1
|
|
Thickened
|
8
|
7
|
Abbreviation: ETV, endoscopic third ventriculostomy.
Discussion
ETV is a safe and effective procedure for the treatment of appropriately selected
patients. Our overall success rate of 61.90% patients is comparable with other studies.
Buxton et al[5] reported overall success rates of 52%. Cinalli et al[4] reported ETV success in 76% patients whereas Marton et al[6] reported 64% overall ETV success.
In our study the procedure was successful in 80% of noncommunicating hydrocephalus
and 45.45% of communicating hydrocephalus. This result is comparable with the previous
studies. Buxton et al[5] reported success rate of 73% in noncommunicating hydrocephalus and 46% in communicating
hydrocephalus. In our study patients with aqueductal stenosis who presented with shunt
malfunction had high success rate (80%).This is at par with that reported by the previous
studies. In a study by Boschert et al,[7] 82% of their patients remained shunt free after procedure for aqueductal stenosis.
In another study, O'Brien et al[1] reported a success rate of 68% with the patients having aqueductal stenosis. In
our study, a history of pyogenic meningitis was associated with low success rate (25%).
Our results matched those reported by Fukuhara et al[8] who also reported low success rate in these cases. One of the most commonly cited
preoperative factors that predict outcome is the etiology of the hydrocephalus. However,
Lee et al[3] categorized hydrocephalus according to etiology, including neoplasm, infection,
trauma, malformation, and other causes, and found no statistical significance between
hydrocephalus etiology and ETV outcome. In our study we also did not find significant
correlation between etiology and ETV outcome. This can be attributed to fewer number
of patients enrolled in the study.
Patients who had TBM and presented with shunt malfunction had a success rate of 66.67%
in our study. This rate is at par with the rate ranging from 41 to 81% reported by
studies.[9]
[10] Success rates reported for ETV in patients aged ≤ 2 years vary from 0 to 83% with
a mean of 47.8%, which is significantly lower than the success rate in older children.[11]
[12]
[13]
[14] Marton et al[6] reported that age at the time of secondary ETV has no statistically significant
effect. In our series ETV was successful in 33.34% patients aged ≤ 2 years. In our
study age was not found to be significant predictor of outcome of success of ETV in
patients with shunt malfunction. This is in accordance to the aforementioned study.
Defining Success after Endoscopic Third Ventriculostomy
Successful outcome was considered when the patient became shunt independent. In the
existing literature, success of ETV has been most commonly defined as enduring shunt
independence after the procedure.[11]
[13]
[14]
15
Removal of Shunt
We removed ventriculoperitoneal shunt in all patients who underwent ETV. In our study
we encountered shunt tract hematoma in one patient after shunt removal. Removal of
shunt can be decided during ETV as we can look for whether shunt tip is free or is
struck in the choroid plexus. Shunt removal in patients in whom shunt is present for
long time is prone for difficult removal, so shunt can be ligated in such cases.
Complications of Endoscopic Third Ventriculostomy
There were three complications (14.2%) associated with ETV and shunt removal in our
series. Other series have reported complication rates ranging from 6 to 14%.[11]
[13]
[14] Hemorrhage was seen in two patients intraoperatively during ETV, which was managed
with irrigation and cautery. One patient had hemorrhage in shunt tract, which occurred
while removal of shunt. Our complication rate is comparable with that reported by
the previous studies.
Conclusion
In our study the use of ETV in patients with shunt malfunction resulted in shunt independence
in 61.90% patients. Age, etiology, type of hydrocephalus, and number of shunt revisions
did not have a significant impact on the outcome of ETV in our study. Study with more
number of patients will further elucidate the relation of these factors with ETV outcome.
ETV is a good procedure for patients who present with shunt malfunction. It is a technically
demanding procedure and needs expertise. It has got its own complications, but it
relieves a patient from the everlasting complications of shunt surgery.
