SPHENOID WING MENINGIOMA

SPHENOID WING MENINGIOMADR.MUMTAZ ALI NEUROSURGERY RESIDENTJPMC,KARACHI

outlinesBackgroundDefinationClassificationCauses & location of hyperstosisPathophysiologyEpidemiologyPresentationD/DWorkupTreatment(medical & surgical)Complicationsconclusion

Background

In 1614, Felix Plater In 1864,John cleland : cribriform plate & right frontal sinus In 1915,Cushing & weed : arachnoid

Defination

Meningiomas :arachnoid cap cells SWM : bony crest formed by wings (lesser and greater) the sphenoid bone. sphenoid ridge(lesser wing : internal 2/3 & greater wing its external 1/3)

Cont

Classification

En-plaque/spheno-orbital/hyperostoticGloboid meningiomas:deep, inner, or clinoidal middle or alar lateral, outer, or pterional

Enplaque/spheno-orbital/hyperostotic

carpet-like dural growthreactive hyperostosisextends :posteriorly :cavernous sinus anteriorly :orbital apex

Causes of hyperstosis vascular disturbancesIrritation of bone without actual invasionprevious traumabone production by tumor cellsosteoblastic stimulation of normal bonebone growth is actually bone invasion by tumor cells.

Location of hyperstosis according to frequencylesser wing of the sphenoid bonethe greater wing of the sphenoidThe roof of the orbitthe inferior orbital fissurethe infratemporal fossathe orbital rim

GLOBOID MENINGIOMASdeep, inner, or clinoidal middle or alar lateral, outer, or pterional

PathophysiologyHead injuryRadiationsHarmonal (estrogen & progestrerone)Genetic(loss of DNA on 22 chromose)Androgen receptors(EGF,PDGF)Viruses(Inoue-melnick virus )Associated(gliomas,abscess & aneurysms)

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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%)

Histologic findingsAccording 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.

PresentationHeadacheorbital painvisual deficitPtosisdiplopiaEctropionConjunctivitis

Presentationcorneal ulceration, scleral hemorrhagesOculomotor deficitFacial hypoesthesia.Memory impairmentolfactory hallucinationshemiparesis.

Differenetial diagnosis

Fibrous dysplasiaOsteomaosteoblastic metastasisPagets disease,hyperostosis frontalis internaerythroid hyperplasiasarcoidosis

Workup

Endocrine(TSH),FSH &LH)CT scan and MRIauscultation of the skullplain skull filmsbone scans

Workupcarotid arteriographyTumor markers(C-PiB)F-FDG PET scanPreoperative visual testingIntraoperative radiodetection of somatostatin receptors is feasible, especially in bone-invasive meningiomas

Medical treatmentIndications:atypical and malignant meningiomas as an adjunct to surgerypartially resected benign meningiomasrecurrence of meningiomas after a surgical resection.

Medical treatmentDrugs:Antiestrogen(tamoxifen:nolvadex)Antiprogestrone(gastrinone)Mifepristone, RU-486 (Mifeprex)Antineoplastic(hydo-oxyurea & interferon alpha 2B)Anti-PDGF(trapidil)Dopamine antagonist(bromocriptine)

Surgery

Indications:size of the lesion >2.5cmpresence of signs or symptomspatients conditionchanges in the adjacent cerebral tissue (edema) on imaging studiessurgeons experience.

Goal of surgeryradical excision of the tumor resection of the lesion + the dural implant (1-cm margin) + all hyperostotic bone.

Preparation intravenous general anesthesia.Antiepileptic drugsbroad-spectrum antibioticsGlucocorticoidsNeurophysiologic monitoring

Positioning supine decubitus positionthe head fixed in a three-pin head holderhead is slightly extensionrotated toward the contralateral side of the tumorclinoidal tumors (between 30 and 40) alar and pterional lesions(between 40 and 50)

Skin incisiona frontotemporal(pterional) curvilinearstarting at the root of the zygomatic arch, just 5 mm in front of the tragusruns vertically upwardOnce it passes the ear, it is curved rostrally and superiorly toward the ipsilateral frontal region.

Variation in skin incisionThe 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.

Dissection of epicranial planessuperficial temporal arterya posterior branch has to be coagulatedDissection continues until the temporal fascia is identifiedAvoid wide separation between the temporal fascia and the skin to avoid injury to the frontotemporal branch of the facial nerve

Cont.. retrograde direction two epicranial planes are createdskin and temporal fascia (fasciocutaneous flap)temporal muscle alone (muscle flap)

Craniotomy & tumor resectionanatomic variety of the meningiomaPterionalAlarClinoidalEn-plaque

PterionalIf hyperstosis:around the bone infiltration,bone flap of around 5cmIf hyperstosis is absent:standard craniotomySection the tumor to elevate/remove the bone flapCraneictomy:osseous tumor

Pterional craniotomy

Alarfrontotemporal craniotomy extradural resection of the lesser wing of the sphenoid bone.Bone removal is continued until complete exposure of the superior orbital fissureThe dura mater is then opened following a curvilinear frontotemporal incision, reflecting the dural flap forward

clinoidala frontotemporal resection of the sphenoid ridge The superior orbital fissure is also completely openedthe posterolateral wall of the orbit is also removed in case of orbital part of tumorAnterior clinoidectomy:high speed drill+irrigationTumor involving optic nerve:curvillenier incision

Cont.. wide splitting the sylvian fissure Retractors are placed on the frontal and temporal lobes

Cont..

dural implants :coagulateddistal branches of the MCA distal to proximal direction initial debulkingArterial dissection:proximallyThe optic nerve

En-plaqueit is easier to expose the entire hyperostosispterional craniotomy is combined with an OZ osteotomy,particularly when the lesion extends into the inferior orbital fissure, infratemporal fossa, or orbit

Reconstruction & closureresect a free dural marginclosure of the dura mater necessarily implies application of a graftLocal tissue:aponeurotic galea, pericranium,or temporal fasciaDistant tissues fascia:lata or abdominal fasciaSynthetic & biologic materials, but with a slightly higher risk of infection.Watertight closure is mandatory

Contreconstruction of the pterional defect:Autologous materials:split calvarial bone graft or ribs synthetic materials:methylmethacrylate and titanium

ComplicationsPostoperative EDH:due to wide dural detachmentCsf leakSeizures:if grow near epileptogenic areasCosmetic problems:inadequate reconstructionInfection:prosthetic material,sinus opened

ResultsIn general, the short- and midterm follow-up results after SWM resection are excellentIn 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

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