I. .Intracranial Aneurysms

• Etiology:

1. Congenital – miliary aneurysms

2. Arteriosclerosis

3. Inflammation

a) Sub-acute bacterial endocarditis produces mycotic aneurysms

b) Syphilis

4. Ttauma – caroticocavernous fistula

Clinical features:

• Those of ophthalmological interest affect the circle of Willis.

• They give rise to symptoms in 3 ways.

1. By mechanical pressure on neighbouring structures causing symptoms characteristic of a tumour in the chiasmal region.

2. By sudden increase of size and periodic leakage.

a) Acute unilateral severe headache.

b) Partial 3rd nerve paralysis – ptosis, diplopia

3. Sudden rupture – subarachnoid haemorrhage.

a) Severe headache, vomiting, coma

b) Ophthalmoplegia

c) Fundus examination shows – papilloedema, retinal heamorrhages, subhyaloid heamorrage.

II. Hydrocephalus:

1) Congenital : Fundus examination shows optic atrophy.

Papilloedema does not occur inspite of increased intracranial pressure. This is due to enlargement of the skull since sutures have not fused.

2) Aquired : cardinal signs of increased intracranial pressure are seen – headache, vomiting and papilloedema.

III. Meningitis

1)Cerebro spinal meningitis (due to meningo-coccus) produces :

a) Papillitisb) Paralysis of 3rd ,4th or 6th cranial nerves.2) Tuberculous meningitis in children. There may be a) Papillitis or papilloedemab) Miliary tubercles in the choroid; they are seen at

the posterior pole of the fundus.c) Paralysis of 3rd,4th or 6th cranial nerves.

IV. Encephalitis :

1) Ocular palsies – ptosis is common

2) The disease is often followed by Parkinsonian tremor, spasmodic conjugate deviation of the eyeball.

V. Neurosyphalitis :

1) Basal gummatous meningitis

a) Papillitis or papilloedema

b) 3rd or 5th cranial nerve palsies

2) Tabes dorsalis

a) Primary optic atrophy

b) Argyll –Robertson pupil

c) 3rd or 5th cranial nerve palsy

3) G.P.I. general paralysis of insane

a) Primary optic atrophy

b) Argyll –Robertson pupil

c) Ocular palsies are rare

VI. Intracranial tumours :

• These include

1) In children – glioblastoma multiforme

2) In adults – astrocytoma, meduloblastoma, meningioma of the sphenoidal ridge, adenoma of pituitary body.

They produce 2 sets of symptoms.

A) Generalised symptoms of increased intracranial pressure, head-ache, vomiting, convulsion, bradycardia. Those tumours which tends to produce internal hydrocephalus – midbrain, parieto-occipital region and cerebellum are most certain to cause papilloedema. Tumours of pituitary tend to produce primary optic atrophy. Ocular palsies due to increased intracranial pressure are relatively rare ; 6th nerve palsy dose not have any localising value.

B) Focal sings are due to involvement of the structures in the neighbourhood of the tumour.

1) Prefrontal tumour of the olfactory groove Foster Kennedy syndrome (refer).

2) Pituitary – bitemporal hemianopia

3) Temporal lobe – visual hallucination

4) Tumour of midbrain – 3rd nerve palsy with contralateral hemiplegia, facial palsy of the upper motor neurone type (Weber's syndrome).

VII. Myasthenia hravis :

• Is characterised by fatigue and weakness of striated muscles within the body. It is an auto-immune disorder where post-synaptic acetylcholine receptors are damaged. Associated abnormalities of thymus may be seen. It is most commonly seen in the age group of 20-40 years.

Ocular symptoms and signs

These are less in the morning and after rest. They are worse in the evening when the patient is tired.

1) Ptosis : is the first sign. It is initially unilateral but later is always bilateral.

2) External opthalmoplegia : usually bilateral. May be asymmetric. Internal opthalmoplegia is not seen.

The diagnosis can be confirmed by injection neostigmine or injection tensilon (edrophonium).

Treatment

1) Medical :

a) Oral anticholinesterases – neostigmine

b) Systemic cortico-steroids.

2) Surgical :

Thymectomy