8. Causes of hyperstosis
vascular disturbances
Irritation of bone without actual invasion
previous trauma
bone production by tumor cells
osteoblastic stimulation of normal bone
bone growth is actually bone invasion by tumor cells.
9. Location of hyperstosis according
to frequency
lesser wing of the sphenoid bone
the greater wing of the sphenoid
The roof of the orbit
the inferior orbital fissure
the infratemporal fossa
the orbital rim
11. Pathophysiology
Head injury
Radiations
Harmonal (estrogen & progestrerone)
Genetic(loss of DNA on 22 chromose)
Androgen receptors(EGF,PDGF)
Viruses(Inoue-melnick virus )
Associated(gliomas,abscess & aneurysms)
12. Epidemiology
Race( Caucasians, Africans, African Americans, and
Asians)
Sex(Caucasians:75%women & 25% men.Africans show
an equal gender ratio).
Age(onset is 50 years increases thereafter)
Mortality(5years:87% & 10 years :58%)
13. Histologic findings
According to the World Health Organization (WHO)
in 1993, :
Benign (grade I) 6.9%: do not invade the brain
parenchyma.
Atypical (grade II) 34.6%: mitosis & increased
nuclear-cytoplasmic ratio.
Malignant (grade III and IV) 72.7%: greater mitosis,
necrosis, and invasion of brain parenchyma.
18. Workup
carotid arteriography
Tumor markers(C-PiB)
F-FDG PET scan
Preoperative visual testing
Intraoperative radiodetection of somatostatin
receptors is feasible, especially in bone-invasive
meningiomas
19. Medical treatment
Indications:
atypical and malignant meningiomas as an adjunct to
surgery
partially resected benign meningiomas
recurrence of meningiomas after a surgical resection.
21. Surgery
Indications:
size of the lesion >2.5cm
presence of signs or symptoms
patient’s condition
changes in the adjacent cerebral tissue (edema) on
imaging studies
surgeon’s experience.
22. Goal of surgery
radical excision of the tumor
resection of the lesion + the dural implant (1-cm
margin) + all hyperostotic bone.
24. Positioning
supine decubitus position
the head fixed in a three-pin head holder
head is slightly extension
rotated toward the contralateral side of the tumor
clinoidal tumors (between 30 and 40)
alar and pterional lesions(between 40 and 50)
25. Skin incision
a frontotemporal(pterional) curvilinear
starting at the root of the zygomatic arch, just 5 mm in
front of the tragus
runs vertically upward
Once it passes the ear, it is curved rostrally and
superiorly toward the ipsilateral frontal region.
26. Variation in skin incision
The midportion of incision can be extended backward,
especially in cases of pterional meningiomas with large
infiltration of the pterion.
If an orbitozygomatic (OZ) approach is required, it is
necessary to extend the incision vertically down to the
level of the ear lobe.
27.
28. Dissection of epicranial planes
superficial temporal artery
a posterior branch has to be coagulated
Dissection continues until the temporal fascia is
identified
Avoid wide separation between the temporal fascia
and the skin to avoid injury to the frontotemporal
branch of the facial nerve
29. Cont..
retrograde direction
two epicranial planes are created
skin and temporal fascia (fasciocutaneous flap)
temporal muscle alone (muscle flap)
30. Craniotomy & tumor resection
anatomic variety of the meningioma
Pterional
Alar
Clinoidal
En-plaque
31. Pterional
If hyperstosis:around the bone infiltration,bone flap of
around 5cm
If hyperstosis is absent:standard craniotomy
Section the tumor to elevate/remove the bone flap
Craneictomy:osseous tumor
33. Alar
frontotemporal craniotomy
extradural resection of the lesser wing of the sphenoid
bone.
Bone removal is continued until complete exposure of
the superior orbital fissure
The dura mater is then opened following a curvilinear
frontotemporal incision, reflecting the dural flap
forward
34.
35. clinoidal
a frontotemporal
resection of the sphenoid ridge
The superior orbital fissure is also completely opened
the posterolateral wall of the orbit is also removed in
case of orbital part of tumor
Anterior clinoidectomy:high speed drill+irrigation
Tumor involving optic nerve:curvillenier incision
37. Cont..
dural implants :coagulated
distal branches of the MCA
distal to proximal direction
initial debulking
Arterial dissection:proximally
The optic nerve
38.
39.
40. En-plaque
it is easier to expose the entire hyperostosis
pterional craniotomy is combined with an OZ
osteotomy,particularly when the lesion extends into
the inferior orbital fissure, infratemporal fossa, or orbit
41.
42.
43. Reconstruction & closure
resect a free dural margin
closure of the dura mater necessarily implies
application of a graft
Local tissue:aponeurotic galea, pericranium,or
temporal fascia
Distant tissues fascia:lata or abdominal fascia
Synthetic & biologic materials, but with a slightly
higher risk of infection.
Watertight closure is mandatory
44. Cont…
reconstruction of the pterional defect:
Autologous materials:split calvarial bone graft or ribs
synthetic materials:methylmethacrylate and titanium
45. Complications
Postoperative EDH:due to wide dural detachment
Csf leak
Seizures:if grow near epileptogenic areas
Cosmetic problems:inadequate reconstruction
Infection:prosthetic material,sinus opened
46. Results
In general, the short- and midterm follow-up results
after SWM resection are excellent
In the majority of cases,gross total resection is
accomplished with minimal morbidity.
However, the critical point is in long-term follow-up
because of the high risk of recurrence, which is
inversely proportional to the degree of tumor resection