2. Benign tumors of the neuroectodermal origin
constituting 0.5% to 1% of all intracranial neoplasms
They arise from the anterior aspect of velum
interpositum or the choroid plexus of the third
ventricle, in close proximity with the foramen of
monro
Slow growing
13. PATHOGENESIS
Origin: Unknown
Implicated structures include:
Paraphysis
Diencephalic ependyma in the recess of postvelar arch
Ventricular neuroepithelium
Comprised of fibrous epithelial-lined wall filled with
either mucoid or dense hyaloid substance
14.
15. Can occur in any age with peak between the 2nd and 4th
decades of life with no sex predilection.
Cyst wall is lined with simple or pseudostratified
cuboidal or low columnar ciliated epithelial cells
Stain positive for PAS & S100 and negative for GFAP,
vimentin and neurofilament.
16. SYMPTOMS
In 75% of the patients, the initial symptom is headache
with variable intensity.
Other symptoms include nausea, vomiting, gait
disturbance and blurred vision.
A sudden increase in ICP from rapid onset
hydrocephalus can lead to sudden death
17. By compression of the surrounding anatomic
structures, the patient can experience thermal
dysregulation, electrolyte and hormonal imbalances,
endocrine dysfunction , altered personality, memory
loss or visual changes.
18.
19.
20. Most cysts <1cm donot produce hydrocephalus and are
asymptomatic.
Colloid cysts may cause chronic, acute or intermittent
hydrocephalus .
Intermittent symptoms are attributed to the movement
on the cyst on its pedicle causing intermittent
obstruction to CSF flow.
21. EVALUATION
Imaging usually demonstrates the tumor located in the
anterior third ventricle.
If there is obstruction to CSF flow due to the cyst, it
manifests as pathognomonic hydrocephalus involving
only the lateral ventricles.
MRI is usually the imaging modality of choice.
22. CT SCAN:
Most are hyperdense
Density may correlate with
viscosity of the contents
Typically homogenous, with
presence of calcifications being
an exception.
23. MRI :
Appearance variable
T1WI: Hyperintense
T2WI: Hypointense
No or minimal contrast enhancement, sometimes only
involving the capsule
Symptomatic patients are more likely to display T2
hyperintense cysts
30. DIVERSION PROCEDURES:
Bilateral ventriculoperitoneal shunts
Unilateral shunt with septum pellucidotomy
However, direct surgical treatment is usually
recommended due to:
To prevent shunt dependency
To reduce the possibility of tumor progression
Risk of cardiovascular instability
31. SURGICAL MANAGEMENT:
Transcallosal approach : Not dependent on
ventriculomegaly
Transcortical approach: In patients with HCP
Stereotactic drainage
Ventriculoscopic removal
32. STEREOTACTIC DRAINAGE:
Maybe useful in patients with normal ventricles
High recurrence rate
Short hospital stay and early recovery time
Viscous contents and tough capsule lead to failure of
procedure
33. Two features correlating with unsuccesful aspiration:
High viscosity: Correlates with hyperdensity on CT
Deflection of the cyst from tip of the aspiration needle
due to small size
35. Start with sharp-tipped 1.8mm probe, and advance to
3–5mm beyond target site (to accommodate for
displacement of cyst wall
36. Use a 10ml syringe and apply 6–8ml of negative
aspiration pressure
37. If this does not yield any material, repeat with a
2.1mm probe.
Although complete cyst evacuation is desirable, if this
cannot be accomplished an acceptable goal of
aspiration is re-establishment of patency of the
ventricular pathways (may be verified by injecting 1–2
cc of iohexol)
38. ENDOSCOPIC Vs. MICROSURGICAL
ENDOSCOPIC MICROSURGICAL
Lesser extent of resection Greater extent of resection
Higher rates of recurrence (3.91%) Lower rates of recurrence (1.48%)
Higher rates of reoperation (3.0%) Lower rates of reoperation (0.38%)
Lower complication rate (10.5%) Higher complication rate (16.3%)
Similar mortality rate Similar mortality rate
39. ENDOSCOPIC APPROACH:
Planning:
Preop MRI for frameless stereotactic guidance
Place patient’s head in three point fixation, flexed at 45
degrees
Incision should be behind the hairline
Place a burrhole 8cm from the nasion, 5 -7 cm lateral to
the midline
40. PROCEDURE:
Create a burrhole large enough for easy maneuvering
of the endoscope (usually 11mm)
Tap into the lateral ventricle
Use a 0 degree scope to identify the landmarks of the
colloid cyst and foramen on monro.
41.
42.
43. Change to a 30 degree scope
Colloid cyst can be identified by its greenish grey
membrane
Resection technique for the cyst depends on it’s size
and consistency
If the contents are liquid, cyst can be punctured and
contents aspirated through an appropriate suction tube.
Sometimes, cyst has to be opened with microscissors
and contents removed in a piecemeal fashion
44.
45. TRANSCALLOSAL APPROACH:
Interhemispheric approach to the third ventricle via a
parietal craniotomy
Position: Supine with neck flexed. Thorax elevated at
20 degrees. Keep the head vertical
Skin Incision:
Inverted U with the top just left of midline, 6cm anterior
to the coronal suture, to 2 cm behind the coronal suture,
taking the sides for 7-8cm
Souttar skin incision
46.
47. Craniotomy:
The bone flap is either trapezoid or triangular
For adequate exposure, it is critical to go all the way to
the superior sagittal sinus
To stay away from the motor strip and to keep sagittal
sinus exposure as anterior as possible:
2/3rd of the craniotomy anterior to the coronal suture
1/3rd posterior to the coronal suture
48. Total craniotomy size should be 6cm
4cm anterior to the coronal suture
2 cm posterior to the coronal suture
4cm to the right of midline
The dural flap is based towards the sagittal sinus
49.
50.
51.
52.
53.
54. COMPLICATIONS:
Venous infarction
Sacrifice of critical cortical draining veins
SSS thrombosis
Transient Mutism due to rough retraction of cingulate gyrus
Decrease in spontaneous speech due to resection of anterior
portion of CC
Damage to fornix resulting in temporary or persistent
amnestic syndromes
Intraventricular bleeding
CSF leak
55. TRANSCORTICAL APPROACH:
Patient supine with three pin fixation, head flexed at
30 degrees, 10 to 50 degree rotation to the contralateral
side
3x4 cm bone flap placed over the location of the
middle frontal gyrus
Medial border should just cross the midline and the
anterior border 2cm anterior to the coronal suture and
posterior border 2 cm behind.
Notas do Editor
Paraphysis : Evagination of the roof of the third ventricle