Definition:
It's a passive non inflammatory edema ( transudate mostly water) of optic disc. Usually due to increase of ICT.
In passive type there's non inflammatory venous congestion.
In the active type there's arteriolar dilatation and papillitis.
Mechanism
Mechanical theory: intra cranial subarachnoid space is communicating with subarachnoid space around optic nerve. So any increase in ICT will be transmitted to optic nerve pressing on CRV causing transudation.
Recently: papilloedema is due to block of the exoplasmic flow due to increased ICT in the subarachnoid space around the optic nerve. Later, the swollen axons compress the capillaries and veins leading to congestion and transudation.
Etiology:
Intra cranial causes due to increased ICT in:
Neoplasm: 70% , always bilateral unless one nerve is atrophic. In front love tumors, one disc may be directly compressed by the timer leading to primary optic atrophy, while the other disc becomes swollen this is known as Foster Kennedy Syndrome.
Inflammation: brain abscess ,tuberculoma and meningitis.
Vascular: subarachnoid hemorrhage and cavernous sinus thrombosis.
Pseudotumor cerebri:
benign increased ICT with no intracranial lesions or mass.
More in young females due to: hypervitaminosis A and D , oral conceptives and endocrine disorders.
Other causes:
Orbital (rare) due to : retrobulbar mass or inflammation.
Ocular due to : CRVO or hypotony.
Systemic due to : malignant hypertension , toxemia of pregnancy , anemia, polycythemia and renal retinopathy.
Clinical picture:
Symptoms:
Headache, blurring, projectile vomiting (not preceded by nausea) diplopia due to 6th nerve palsy. Amaurosis fugax, gradual loss of vision due to optic atrophy due to pressure and ischemia.
Signs:
Pupil: early normal but late with occurrence of optic atrophy there's dilated interactive pupil and RAPD.
Fundus: like CRVO, retinal hemorrhage and edema, macular exudate (fan) , engorged tortous veins and absent venous pulsations
Disc: (pseudopapillitis) falling of cup, elevation, ill defined edges, hyperaemia.
Field: early enlargement of the blindspot and central scotoma for blue. But late there's contraction of field due to atrophy.
Investigations:
Field of vision.
Central scotoma for blue.
Radiography: X ray, CT scan and MRI.
VEP: early normal but late affected.
Complications:
Post papilledemic secondary optic atrophy.
Prognosis:
Bad in marked edema.
Differential diagnosis:
Papillitis and pseudopapillitis.
Ocular manifestations of brain tumors:
Foster Kennedy Syndrome.
Chiasmal lesions
Orbital Apex Syndrome
Loss of voluntary gaze.
Papilloedema
Formed visual hallucinations
Superior homonymous quad ratanopia.
Saccadic pursuit
Simple visual hallucinations.
Blindness with normal pupils and ERG
Congruent hemianopia with macular sparing .
Treatment:
treatment of the cause , dehydrating agents and decompression of optic nerve sheath.
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