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الكلية كلية الطب
القسم الجراحة
المرحلة 5
أستاذ المادة اسعد جعفر عبد السادة الطائي
4/18/2011 5:11:46 PM
Orbit;
Anatomy:
The orbit is a bony cage for the eye containing muscles, nerves and vessels essential for proper functioning of the eye. It is pear shaped having an apex, base and 4 walls.
- Apex: annulus of Zinn encircling the optic foramen and the central part of superior orbital fissure (SOF).
- Base: orbital margin, base faces foreward and laterally, closed anteriorly by the orbital septum.
- Roof: frontal bone and lesser wing of sphenoid.
- Medial wall: maxillary, lacrimal, ethmoid and sphenoid bones.
- Floor: zygomatic, maxillary and palatine bones.
- Lateral wall: greater wing of sphenoid and zygomatic bones.
The muscle cone consist of the four recti with their origins (at the annulus of Zinn) forming the apex of the cone and their insertions at the anterior sclera forming the base of the cone and the areas between the muscle courses are traversed by intermuscular membrane as a part of fascia bulbi. It is situated in the center of the orbit harbouring the intraconal orbital space. Orbital fat (intraconal & extraconal) fills in all areas in the orbit not occupied by other intraorbital structures including the eyeball. It is nowhere in direct contact with any of them.
Evaluation of orbital diseases:
1- Proper history:
There are 4 main symptoms in orbital diseases:
a- Proptosis; b- Pain; c- Diplopia and d- Visual impairment.
We should ask about these symptoms in details, e.g.: the progression of proptosis is slow in benign tumours and rapid in malignant. Pain usually indicates inflammation or malignancy. In trauma we always ask if there is CSF rhinorrhoea. Fracture of the medial wall (lamina papyracia) may lead to subcutaneous emphysema (crepitus to palpation) and sometimes there is carotico-cavernous fistula (traumatic) that results in pulsating exophthalmos and a bruit to auscultation. Also ask about diseases of paranasal sinuses because an inflammation or a tumour can spread from them to the orbit. Ask about systemic diseases as well e.g. malignancy or goitre.
2- Clinical examination:
a- Inspection:
* Look for displacement of the eyeball:
1) In the sagittal plane: diagnosed by looking over the head of the patient from behind.
- Anteriorly: called proptosis. Check severity by a transparent ruler or a Hurtle s exophthalmometer, a value > 20 mm is abnormal, up to 23 mild, up to 27 moderate, more than 28 severe. Direction helps to localize the causative pathology. Lid lag & retraction signify thyroid disease. Ocular motility should be noted. Dynamic properties (change in size on straining or dependency) signify vascular element (pulsation signifies direct communication with the dura too).
- Posteriorly: called enophthalmos.
2) In the coronal plane: called dystopia, horizontally or vertically measured by referring to the mid glabellar point.
* VA: if reduced means optic nerve compression or exposure keratopathy.
* Pupillary reactions: relative afferent pupillary defect (RAPD).
b- Palpation:
* Orbital margins: look for a mass or a step.
* Resistance to retropulsion: signifies a tumour or dysthyroid ophthalmopathy.
c- Auscultation: a bruit signifies direct coratico-cavernous fistula.
3- Ophthalmoscopy:
Optic disc (swollen or atrophic), chorodial folds.
4- X-ray:
There are 5 X-ray signs of orbital diseases:
a- Enlargement of the orbit (diffuse or asymmetrical).
b- Changes in bone density: A localized decrease means benign tumour, a diffuse decrease means malignant tumour, an increase means meningioma or Paget s disease.
c- Intra orbital calcification: varix, lacrimal gland carcinoma, optic nerve sheath meningioma and retinoblastoma (in children).
d- Enlargement of SOF: in intracavernous meningioma and posterior extension of orbital tumours.
e- Enlargement of optic canal (foramen) in optic nerve glioma.
5- CT scan
6- Ultrasound
7- MRI
8- Orbital venography: especially if we suspect orbital varices.
Treatment of proptosis:
1- Systemic steroids. 2- Add radiotherapy. 3- Add Azathioprine. 4- Surgery: a) on extraocular muscles to treat restrictive myopathy. b) orbital decompression involving 2, 3 or 4 walls if necessaryCauses of proptosis:
A: In infancy:
1- Capillary haemangioma: It is the most common orbital lesion in infancy, Usually presents in the first month of life as an ill-defined compressible bluish mass usually in the upper nasal quadrant. The mass characteristically increase in size when the infant cries or strains. It grows rapidly in the first 6, months followed by spontaneous regression at 4-5 years.
Treatment: 1- Steroid injection around the tumour is very effective during the early (active) stage. 2- Systemic steroids administered daily over several weeks may reduce the size of the tumour. 3- Local resection using a cutting cautery is usually reserved for the late (inactive) stage, 4- Radiotherapy is seldom used.
2- Encephalocele.
3- Microphthalmia with a cyst.
4- Metastatic neuroblastoma.
5- Orbital retinoblastoma.
B: In childhood:
1- Orbital cellulitis: The most common cause of proptosis in childhood. Secondary to sinusitis. Signs and symptoms are: proptosis, lid swelling, chemosis (severe conjunctival oedema overriding the lid margin), impaired ocular motility and sometimes reduced VA due to pressure on the optic nerve. Complications are orbital abscess or subperiosteal abscess.
Treatment: 1- Hospitalization. 2- Parenteral antibiotics (IV). The condition is life threatening since infection can spread to the cavernous sinus or the brain (brain abscess).
2- Embryonal sarcoma: It is the most common primary malignant tumour of the orbit in children. Presents as rapidly progressive proptosis in a 7-8 years old child. It is highly malignant.
Treatment: Radiotherapy and chemotherapy with relatively good prognosis if treated early.
3- Dermoid cyst. 4- Lymphangioma. 5- Neurofibromatosis.
6- Leukaemia. 7- Glioma of the optic nerve.
8- Hydatid cyst: 20% of orbital mass in Iraq (Alkhalili. A).
C: In adulthood:
1- Thyroid ophthalmopathy: The commonest cause of both uni and bilateral proptosis in adults. Females more than males, most commonly hyper but may be hypo or euthyroid states (ophthalmic Grave s disease).
Signs: Lid lag and retraction because of sympathetic overactivity, proptosis due to increased amount of connective tissue and glycosaminoglycans within the orbit and huge enlargement of extraocular muscles and heavy lymphocytic infilteration and oedema, then inflammation subsides ending in fibrosis causing limitation of ocular movement (restrictive myopathy).
Diagnosis: clinically and CT scan.
Treatment: 1- Localized protective measures: topical lubrication with solutions or ointments and patching the eyes closed at night.2- Systemic corticosteroids or immunosuppressive agents during the acute phase of extraocular muscle myositis. 3- Surgery on an extraocular muscle or orbital decompression. 4- External beam irradiation to the orbital apex.
2- Idiopathic orbital inflammatory disease (Pseudotumour).
3- Cavernous haemangioma.
4- Meningioma.
5- Mucocele.
6- Lymphoproliferative disorders.
7- Tolosa-Hunt syndrome.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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