Keywords
idiopathic - fourth ventricle outlet obstruction - hydrocephalus - Luschka - Magendie
- endoscopic third ventriculostomy - foramina
Introduction
Hydrocephalus is caused due to the accumulation of excess cerebrospinal fluid (CSF)
in the ventricular system of the brain. In the event of obstruction of the fourth
ventricle outlet (foramina of Luschka and Magendie), dilatation of all four ventricles
occurs (tetraventricular hydrocephalus). Etiology includes intracranial bleed, intracranial
infection (bacterial, tubercular, cysticercal meningitis) Dandy–Walker malformation,
Arnold–Chiari malformation, Basilar invagination and other craniovertebral junction
abnormalities, and tuberous sclerosis.[1] In rare cases, no causative factor can be identified that is causing fourth ventricle
outlet obstruction (FVOO). Such a condition is called idiopathic fourth ventricle
outlet obstruction (IFVOO). Congenital occlusion of the foramina of Luschka and Magendie
is known to occur; however, the etiology is unknown.[2]
[3] As such cases are rare, only a handful of them are described in the literature.
In this paper, the author presents his own experience with IFVOO and reviews the relevant
literature.
Case Details
Clinical Presentation
A 50-year-old female presented to our hospital with the chief complaints of headache,
difficulty in walking, imbalance while standing and walking, diplopia, vertigo, and
three to four episodes of loss of consciousness for the past 6 months. Initially,
the patient had taken medications from a local physician for the same, but no symptomatic
relief occurred. On examination, the patient had bilateral modified Friesen grade
III papilledema, positive bilateral cerebellar signs. A brain MRI ([Fig. 1]) was done, which was suggestive of tetraventricular hydrocephalus with obstruction
of the foramina of Luschka and Magendie. The preoperative radiological diagnosis was
IFVOO. Laboratory findings were normal.
Fig. 1 Brain MRI (A-D) showing tetraventricular hydrocephalus with obstruction of foramina of Luschka (yellow
arrow) and Magendie (blue arrow).
Surgery
The patient underwent a right-sided medium-pressure ventriculoperitoneal shunt at
the Keen's point. CSF came under high pressure, in a jet-like fashion, at the rate
of 80 to 90 drops/minute.
Postoperative Course and Follow-Up
On postoperative day 1, the patient reported significant improvement in gait ataxia,
vertigo, and diplopia. The rest of the postoperative course in the hospital was uneventful.
At the 3-month follow-up, the patient had complete resolution of the presenting complaints.
Literature Review
A comprehensive review of the literature was undertaken to examine the management
of IFVOO. We searched on the PubMed database using the terms “FVOO,” “tetraventriculomegaly,”
and “hydrocephalus.” Inclusion criteria: Cases of tetraventricular hydrocephalus that
did not have any associated congenital malformation or any other secondary cause,
such as intracranial bleed, intracranial infection, or tuberous sclerosis. Excluding
criteria: Cases of communicating hydrocephalus; secondary causes such as congenital
malformation, intracranial bleed, intracranial infection, tuberous sclerosis; case
reports that provided incomplete information regarding clinical presentation, radiological
findings, management protocols, and functional outcomes. About 24 articles (a total
of 63 cases of IFVOO) fulfilled our criteria and were included in this study, besides
my own case ([Table 1]).
Table 1
Literature review of Idiopathic fourth ventricle obstruction cases
|
S.No
|
Study, year
|
Age/Sex (M/F)
|
Number of patients
|
Clinical presentation
|
Surgery
|
Outcome
|
Resurgery
|
Mean follow-up
|
|
1
|
Coleman and Troland, 1948[2]
|
17 y/M
|
1
|
Headache
|
Craniotomy
|
Improved
|
N/A
|
N/A
|
|
2
|
Holland and Graham, 1958[17]
|
31 y/F
|
1
|
Blurred vision
Nausea
Headache
Weakness of right leg
|
Craniotomy
|
Dead
|
N/A
|
N/A
|
|
3
|
Amacher and Page, 1971[24]
|
21 y/F
|
1
|
Headache Vomiting
Nausea
|
Craniotomy + VC shunt
|
Improved
|
N/A
|
1 year
|
|
4
|
Yoshioka et al, 1985[25]
|
Mean age = 35.3 y/M = 3
|
3
|
Gait disturbance
Cerebellar ataxia
|
Craniotomy + shunt
|
Improved
|
N/A
|
1 year
|
|
5
|
Rifkinson-Mann et al, 1987[18]
|
Mean age = 47 y/M = 2
|
2
|
Hemiparesis
Hemianopsia
Headache
Vomiting
Blurred vision
|
Craniotomy
|
Improved
|
N/A
|
1 year
|
|
6
|
Aesch et al, 1991[16]
|
35 y/M
|
1
|
Ataxia
Headache
Nausea
|
VP shunt
|
Improved
|
N/A
|
2 months
|
|
7
|
Osaka et al, 1995[19]
|
20 y/F
|
1
|
Headache
Nausea
Papilledema
|
Craniotomy
|
Improved
|
N/A
|
N/A
|
|
8
|
Hashish et al, 1999[26]
|
Mean age = 51.5 y
F = 2
|
2
|
Headache
Gait disturbance
Nausea
Memory disturbance
|
Craniotomy + VC shunt
|
Improved
|
N/A
|
6 years
|
|
9
|
Suehiro et al, 2000[29]
|
27 y/F
|
1
|
Dizziness
Headache
Nausea
|
ETV
|
Improved
|
N/A
|
N/A
|
|
10
|
Huang et al, 2001[20]
|
15 y/F
|
1
|
Headache
Nausea
Vomiting
Amenorrhea
|
Craniotomy
|
Improved
|
N/A
|
14 months
|
|
11
|
Carpentier et al, 2001[10]
|
58 y/F
|
1
|
Visual impairment
Dizziness
Headache
Nausea
Vomiting
Gait disturbance
|
ETV
|
Improved
|
N/A
|
3 years
|
|
12
|
Inamura et al, 2001
|
9 months/M
|
1
|
Macrocephaly
Arrest of mental development
|
VP shunt
|
Improved
|
N/A
|
3 months
|
|
13
|
Karachi et al, 2003[11]
|
Mean age = 47.3 y/M = 1, F = 2
|
3
|
Headache
Vomiting
Papilledema
Vertigo
Nausea
Gait disturbance
Sphincteric disorders Impairment of higher functions
|
ETV
|
Improved
|
N/A
|
36 months
|
|
14
|
Mohanty et al, 2008[1]
|
>2 years
|
12
|
N/A
(not specified in respect to PFVOO cases)
|
ETV
|
N/A (in respect to PFVOO cases)
|
Failed to describe (not specified in respect to PFVOO cases)
|
4.2 years
|
|
15
|
Longatti et al, 2009[4]
|
60.6 years
|
10
|
Ideomotor slow down
Gait disturbance
Depression
Dizziness
Memory impairment
Incontinence
Visual impairment
Headache
Vomiting
|
ETV = 8
ETV + aqueductoplasty = 1
Endoscopic magendieplasty = 1
|
Improved = 9
Lost to follow-up = 1
|
N/A = 7
1. Recurrence after 12 years, re-ETV done
2. Recurrence after 3 years/ VP shunt done
3. Recurrence after 2 months, re-ETV done
|
47.7 months
|
|
16
|
Hashimoto et al, 2014
|
20 months/M
|
1
|
Syndrome of inappropriate antidiuretic hormone secretion
|
ETV
|
Improved
|
N/A
|
N/A
|
|
17
|
Torres-Corzo et al, 2014[6]
|
18.5 years/M = 2, F = 5
|
7
|
Lethargy
Bulging fontanel
Headache
Gait disturbance
Seizures
Blurring of vision
Nausea
Vomiting
|
ETV + magendieplasty = 5
ETV + magendieplasty + aqueductoplasty = 1
Endoscopic magendieplasty = 1
|
Improved
|
N/A
|
26.5 months
|
|
18
|
Ishi et al, 2015[15]
|
3 y/M
|
1
|
Headache
Vomiting
|
ETV
|
Improved
|
Recurrence after 1 year, re-ETV done
|
32 months
|
|
19
|
Kasapas et al, 2015[21]
|
37 y/F
|
1
|
Headache
Blurred vision
Vomiting
Phonophobia
Recent memory loss
Bilateral papilledema
|
Craniotomy
|
Improved
|
N/A
|
2 weeks
|
|
20
|
Duran et al, 2017[22]
|
19 y/F
|
1
|
Headache
Diplopia
Intracranial hypertension
|
Craniotomy
|
Improved
|
N/A
|
N/A
|
|
21
|
Pérez et al, 2019
|
41 y/F
|
1
|
Headache
Imbalance
Nausea
Vomiting
|
ETV
|
Improved
|
N/A
|
6 months
|
|
22
|
Bai et al, 2019[23]
|
15 y
|
1
|
Headache
Vomiting
|
Craniotomy
|
Improved
|
N/A
|
1 year
|
|
23
|
Rosa et al., 2021[14]
|
7 y/M
|
1
|
Abdominal pain
Vomiting
Sixth and seventh cranial nerve palsy
|
VP Shunt twice
VA Shunt once
|
Deteriorated
|
ETV after 10 months
|
6 years
|
|
24
|
Krejčí et al, 2021[7]
|
Mean age = 40.9 y/M = 3, F = 5
|
8
|
Headache
Vertigo
Gait disturbance
Diplopia
Vomiting
Papilledema
|
ETV = 5
Craniotomy = 2
Acute ventricular drainage = 1
|
Improved = 7
Death = 1
|
1. VP shunt in 1 patient
2. Recurrence after 6 weeks, re-ETV done
|
75.4 months
|
|
25
|
This study
|
50 y/F
|
1
|
Headache
Difficulty in walking
Imbalance while standing and walking
Diplopia
Vertigo
Papilledema
Three to four episodes of loss of consciousness
|
VP shunt
|
Improved
|
Not done
|
3 months
|
|
26
|
Summary
|
Mean age = 28 years/M = 17,
F = 24
Sex N/A = 23
|
Total = 64 patients
|
Headache 50% (n = 32)
Vomiting 31.3% (n = 20)
Gait abnormalities 31.3% (n = 20)
Diplopia 6.25% (n = 4)
Vertigo 9.38% (n = 6)
Papilledema 12.5% (n = 8)
Cranial nerve palsy 1.6% (n = 1)
Raised intracranial pressure 3.1% (n = 2)
Memory loss = 6.25% (n = 4)
Seizure = 1.5% (n = 1)
Phonophobia = 1.5% (n = 1)
Loss of consciousness = 1.5% (n = 1)
Lethargy = 1.5% (n = 1)
Bulging fontanel = 1.5% (n = 1)
Vision abnormalities = 9.4% (n = 6)
Syndrome of inappropriate antidiuretic hormone secretion = 1.5% (n = 1)
Amenorrhea = 1.5% (n = 1)
Incontinence = 3.1% (n = 2)
Abdominal pain = 1.5% (n = 1)
Depression = 1.5% (n = 1)
|
Craniotomy = 10
Shunt = 7
ETV = 23
Endoscopic magendieplasty = 8
Endoscopic aqueductoplasty = 2
|
Improved = 48 (75%)
Deteriorated = 1 (1.5%)
Death = 2 (3%)
Lost to follow-up = 1 (1.5%)
N/A = 12 (19%)
|
ETV = 5 (7.8%)
Shunt = 2 (3.1%)
|
Mean follow-up = 20.9 months
|
Abbreviations: ETV, endoscopic third ventriculostomy; F, female; M, male; PFVOO, Primary
fourth ventricle outlet obstruction; Ventriculo-cisternal shunt; VP, ventriculoperitoneal
shunt; y, years.
Discussion
Etiopathogenesis and Demography
Tetraventricular hydrocephalus resulting from FVOO is caused due to multiple conditions.
Hydrocephalus due to intracranial hemorrhage or intracranial infection is more common,
occurring due to CSF malresorption, leading to lower endoscopic third ventriculostomy
(ETV) success rates in these cases.[1] In IFVOO, hydrocephalus is principally obstructive in nature owing to the membranous
occlusion of the foramina of Luschka and Magendie. The underlying mechanism leading
to this occlusion is unknown. It may be congenital or acquired.[4] Congenital occlusion of the foramina of Luschka and Magendie is well-documented.[2]
[3]
[5]
[6] However, it fails to explain the exact pathogenesis leading to congenital cases
of IFVOO becoming symptomatic. In acquired causes, the mechanism that has been suggested
is underlying inflammation leading to scarring of the arachnoid layers in the cisterns
and ventricles. This was supported by the findings of anomalous membranous proliferation
in the interpeduncular cistern and thickening of the floor of the third ventricle.[7] In cases of ETV failure, signs of scarring in the interpeduncular cistern were found.[8]
[9] Multiple studies have shown an increased number and toughness of the membranes in
the interpeduncular cistern, abnormal third ventricle floor rigidity, and changes
in the choroidal plexus in the ventricle, leading to a higher risk of ETV failure
in such cases.[1]
[4]
[6] The other explanation is that the increased intracranial pressure leads to a dilated
fourth ventricle, which causes the membranes of foramina of Luschka and Magendie to
come into contact with the dura mater, interrupting the CSF flow.[10] This might be the underlying mechanism in patients with acute hydrocephalus. However,
there seems to be a lack of consensus regarding the primary cause. IFVOO is typically
seen in adults, with no gender predilection.[7] The authors propose the fact that since the majority of the affected patients are
adults, there appears to be an ongoing subclinical inflammatory process in the patients
of IFVOO over a prolonged time period. This might lead to IFVOO with the congenital
anomaly being present in the background.
Clinical Presentation
Headache and gait difficulties are the most commonly encountered symptoms in IFVOO.
Krejčí et al reported that primary surgery was successful in patients who had headaches
in the preoperative period.[7] Symptoms of normal-pressure hydrocephalus were described in patients with obstructive
tetraventricular hydrocephalus in the literature.[11] It becomes difficult to distinguish patients with normal pressure hydrocephalus
(NPH) from IFVOO, as NPH is a more common entity.
Radiologic Findings
Both IFVOO and communicating tetraventricular hydrocephalus present with Hakim's triad—progressive
gait impairment, cognitive deficits, and urinary urgency and/or incontinence. It is
difficult to distinguish them on clinical grounds. Brain MRI is the imaging modality
of choice in such cases. Krejčí et al reported that the presence of ballooning of
the fourth ventricle, decreased prepontine cistern volume, decreased retrocerebellar
space, and concomitant anterior displacement of the brainstem were found to be specific
for IFVOO.[7] However, these radiological features appear to be diagnostic of FVOO rather than
IFVOO. As IFVOO leads to an obstructive type of hydrocephalus, preoperative MRI findings
such as third ventricle bowing and concomitant fourth ventricle ballooning appear
to indicate the diagnosis of IFVOO. Resolution of third ventricle bowing and fourth
ventricle ballooning was associated with successful management of IFVOO.[7]
[12]
[13] The presence of a widely dilated aqueduct of Sylvius differentiates IFVOO from a
trapped fourth ventricle.[4]
Treatment and Outcome
Treatment modalities for IFVOO include ETV,[13]
[14]
[15] shunt surgery,[3]
[16] open fenestration via suboccipital craniotomy,[2]
[17]
[18]
[19]
[20]
[21]
[22]
[23] or a combination of the two.[24]
[25]
[26]
Suboccipital craniotomy and wide opening of the membrane were performed based on the
fact that by removing the obstruction of the fourth ventricular outlets, CSF flow
could be normalized.[17]
[24] Frequent recurrences of the hydrocephalus were seen, although the patients showed
initial clinical improvement with ventricle sizes becoming near normal.[27]
[28]
The use of ETV in FVOO was first described by Mohanty et al, where they reported an
overall success rate of 65%, with favorable outcomes (91% success) in patients of
age more than 2 years, with failure in all patients younger than 6 months of age.[1]
[15] Other studies have also reported successful outcomes using ETV for IFVOO, although
in one study, redo ETV was done following recurrence of hydrocephalus.[15]
[29]
In the literature, the majority of patients with IFVOO underwent endoscopic intervention.
In patients with IFVOO, ETV failure can occur at any time, in comparison to the other
types of hydrocephalus, in which failure typically occurs in the first few weeks.[4]
[30] Literature review has found that in cases of IFVOO, ETV has a higher failure rate
compared with the rest of the treatment options.[7]
Some cases of IFVOO present with a substantial increase in the volume of the fourth
ventricle, which may lead to small prepontine and suprasellar cisterns due to the
brainstem being pushed anteriorly. This may lead to the basilar artery being pushed
closer to the third ventricle floor, making ETV an unsafe procedure. In such cases,
Endoscopic fourth ventriculostomy as described by Giannetti et al can be performed.
ETV has its own advantages as it is safer to perform. In endoscopic fourth ventriculostomy,
there may occur extra manipulation of the third ventricle, cerebral aqueduct, and
fourth ventricle with the increased risk of damage to the surrounding neurovascular
structures. Hence, it should be considered a surgical option only in cases when ETV
is not possible.[31]
Ventriculoperitoneal shunts have been utilized for the management of IFVOO, although
long-term follow-up is not available in such cases.[3]
[16] Hence, it is difficult to assess the efficacy of ventriculoperitoneal shunts in
such cases.
Conclusion
The precise mechanism by which IFVOO develops and causes tetraventricular hydrocephalus
is still unknown. Obstructive hydrocephalus results from IFVOO; hence, ETV is considered
to be the treatment of choice in such cases. But in such cases, the risk of ETV failure
remains higher. Literature review suggests long-term follow-up in patients undergoing
ETV, as the failure can occur at any time. The initial treatment procedures, such
as open fenestration via craniotomy and shunt surgery, remain still relevant and effective
procedures for IFVOO. An alternate line of treatment for it would be endoscopic fenestration
of the fourth ventricle outlets. Larger studies involving multiple hospitals are required
to confirm these findings.
