.Intracranial Aneurysms

1. .Intracranial Aneurysms • Etiology: • Congenital – miliary aneurysms • Arteriosclerosis • Inflammation • Sub-acute bacterial endocarditis produces mycotic aneurysms • Syphilis 4. Ttauma – caroticocavernous fistula

2. Clinical features : • Those of ophthalmological interest affect the circle of Willis. • They give rise to symptoms in 3 ways. • By mechanical pressure on neighbouring structures causing symptoms characteristic of a tumour in the chiasmal region.

3. By sudden increase of size and periodic leakage. • Acute unilateral severe headache. • Partial 3rd nerve paralysis – ptosis, diplopia • Sudden rupture – subarachnoid haemorrhage. • Severe headache, vomiting, coma • Ophthalmoplegia • Fundus examination shows – papilloedema, retinal heamorrhages, subhyaloid heamorrage.

4. Hydrocephalus: • 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.

5. Meningitis 1)Cerebro spinal meningitis (due to meningo-coccus) produces : a) Papillitis b) Paralysis of 3rd ,4th or 6th cranial nerves. 2) Tuberculous meningitis in children. There may be • Papillitis or papilloedema • Miliary tubercles in the choroid; they are seen at the posterior pole of the fundus. • Paralysis of 3rd,4th or 6th cranial nerves.

6. Encephalitis : • Ocular palsies – ptosis is common • The disease is often followed by Parkinsonian tremor, spasmodic conjugate deviation of the eyeball.

7. Neurosyphalitis : • Basal gummatous meningitis • Papillitis or papilloedema • 3rd or 5th cranial nerve palsies • Tabes dorsalis • Primary optic atrophy • Argyll –Robertson pupil • 3rd or 5th cranial nerve palsy

8. G.P.I. general paralysis of insane a) Primary optic atrophy • Argyll –Robertson pupil • Ocular palsies are rare

9. Intracranial tumours : • These include • In children – glioblastoma multiforme • In adults – astrocytoma, meduloblastoma, meningioma of the sphenoidal ridge, adenoma of pituitary body. They produce 2 sets of symptoms.

10. 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.

11. B) Focal sings are due to involvement of the structures in the neighbourhood of the tumour. • Prefrontal tumour of the olfactory groove Foster Kennedy syndrome (refer). • Pituitary – bitemporal hemianopia • Temporal lobe – visual hallucination • Tumour of midbrain – 3rd nerve palsy with contralateral hemiplegia, facial palsy of the upper motor neurone type (Weber's syndrome).

12. 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.

13. Ocular symptoms and signs These are less in the morning and after rest. They are worse in the evening when the patient is tired. • Ptosis : is the first sign. It is initially unilateral but later is always bilateral. • External opthalmoplegia : usually bilateral. May be asymmetric. Internal opthalmoplegia is not seen. The diagnosis can be confirmed by injection neostigmine or injection tensilon (edrophonium).

14. Treatment • Medical : a) Oral anticholinesterases – neostigmine b) Systemic cortico-steroids. 2) Surgical : Thymectomy