Free Web Hosting Provider - Web Hosting - E-commerce - High Speed Internet - Free Web Page
Search the Web

Welcome!

Close

Would you like to make this site your homepage? It's fast and easy...

Yes, Please make this my home page!

No Thanks

  Don't show this to me again.

Close

 CN I: Olfactory Nerve

A deficit in CN I suggests: smoker, trauma, Kallman syndrome, tumor involving the cribriform plate, nasopharyngeal carcinoma, etc.

OPTIC NERVE LESION (begins as central or paracentral scotomata, unilateral blindness, loss of pupil reflex)

Optic Disk Swelling (papilloedema)

1.eye is down and out due to the fact that only lateral rectus VI (out) and superor oblique IV (down) are functioning. Superior oblique intorts. If CN IV intact then the superior oblique intorts when the patient tries to converge and look down.

2. There is also loss of accommodation (fixed ) ciliary muscle

3. Loss of pupillary reflex : eye is dilated. paralysis of constrictor pupillae

4. in diabetes the pupil is spared and reacts normally to light. (parasympathetic fibers undamaged)

5. there is COMPLETE UNILATERAL PTOSIS. levator palpebrae superioris

6. diplopia may not be evident until the eyelid is lifted.

1. aneurysm posterior communicating artery

2. coning of the temporal lobe uncus

3. CN III infarction (diabetes), (atheroma) nb diabetes usu recovers in 3 months

4. hypertension

5. midbrain infarction

6. midbrain tumor

7. Multiple Sclerosis

8. collagen vascular disorders: giant cell (temporal) arteritis

9. syphilis

10. ophthalmoplegic migraine

11. encephalitis

12. parasellar neoplasms

13. meningioma at sphenoid wing

14. basal meningitis

15. carcinoma at skull base

1. myasthenia

2. thyroid eye disease

1. third nerve palsy (complete)

2. Horners (partial)

3. myasthenia

4. congenital/idiopathic

1. myasthenia

2. dystrophica myotonica

3. ocular myopathy/oculopharyngeal dystrophy

4. mitochondrial dystrophy

5. tabes

6. congenital

7. bilateral Horners (syringomyelia)

1. diplopia in all directions except to side of third nerve lesion because lateral rectus intact

2. painful onset eg berry aneurysm or carotid artery aneurysm

3. headache (migraine, cranial arteritis)

4. diabetes

5. hypertension

blood pressure

urinalysis:sugar

ESR in elderly patient for GCA

edrophonium test

TFT, orbital US to exclude thyroid dz.

CT head

arteriography if pupil involved and pain

The pupil reflex arc involves CN II for afferent information, send via the lateral geniculate

without a synapse to the pretectal nucleus on the ispilateral side, synapse and decussation to

both Edinger Westphal nuclei, with afferent limb sent to ciliary ganglion from each EW nucleus

with a synapse in the ciliary ganglion. There are three synapses in the loop.

nb neuroanatomy:

the superior colliculus is in the roof of the midbrain

the most rostral nucleus is the edinger westphal nucleus (superior colliculus)

the pretectal nucleus is caudal (inferior colliculus)

Afferent Pupil Defect

completely blind eye. loss of direct and consensual reflexes (afferent limbs)

affected eye is larger than the other

RAPD: Relative Afferent Pupil Defect, aka Marcus Gunn Pupil.

incomplete damage to afferent limb, eg optic neuritis, retina

not seen with opacities of cornea, lens or with cataracts.

Horner's syndrome (miosis, anhidrosis, ptosis, enophthalmos)

damage to sympathetic pathway

nb.ptosis is usually partial.

nb a third nerve palsy results in a DILATED pupil.

nb the light reflex is intact

if extraocular movements are involved this suggests third nerve palsy or myasthenia)

loss of sweating depends on lesion location.

central lesion: no sweating on entire half head, arm, upper trunk

neck lesion proximal to superior cervical ganglion: decreased facial sweating

lesion distal to superior cervical ganglion: no sweating loss

A lesion distal to superior cervical ganglion: dilates with 1:1000 epinephrine

whereas a normal or proximal lesion does not (due to denervation hypersensitivity of distal lesion)

CAUSES OF HORNERS

hemisphere/brainstem:

1. cerebral infarction (massive)

2. pontine glioma

3. lateral medullary syndrome

4. coning of the temporal lobe (uncus) compressing CN III.

cervical cord

1. syringomyelia

2. cord tumors

sympathetic chain

1. post thyroid/laryngeal surgery

2. carotid artery occlusion/dissection

3. neoplastic infiltrate

4. cervical sympathectomy

T1 root

1. apical bronchial neoplasm

2. apical tuberculosis

3. cervical rib

4. brachial plexus trauma

miscellaneous

1. congenital

2. migrainous neuralgia

3. isolated and unknown cause

the following are not causes of a Horner's

1. diabetes

2. posterior communicating aneurysm

3. increased ICP

4. bells palsy

Arygyll Robertson Pupil (accommodates but does not react, aka light near dissociation)

damage to pretectal nucleus eg due to syphilis.

dorsal midbrain

small irregular pupils

Myotonic Holmes Adie pupil

young adults, female to male 2:1, usually unilateral

enlarged, poorly reactive to light, clow miosis on accommodation

constricts to pilocarpine (supersensitive)

associated with loss of tendon reflexes, eg patellar tendon

Dorsal Midbrain Pupil

1. mydriasis

2. light near dissociation (Argyll Robertson)

3. periaqueductal syndrome (Parinaud): deficient elevation of eyes

CAUSES DORSAL MIDBRAIN PUPIL

a. demyelination

b. pinealoma pressing on tectum

c. infarction of midbrain

d. enlarged 3rd ventricles

Uncal Herniation (herniation of the uncus of the temporal lobe, compressing CN III)

1. ipsilateral hemiparesis

2. fixed and dilated, down and out, ptosis

3. contralateral homonymous hemianopia

CAUSES: usually subdural/extradural hematoma.

Fixed and Dilated Pupil unilateral

1. compression of CN III temporal lobe uncal herniation

2. aneurysm (droopy lid and double vision)

3. eyedrops

4. motion sickness drugs

5. lesion of ciliary ganglion (Adies)

Fixed and dilated pupils (bilateral)

1. brainstem death

2. barbiturate or hypothermic coma

Hutchison Pupil

rapidly rising inracranial pressure

intracerebral hemorrhage

pupil on same side constricts then dilates

opposite pupil then follows same pattern

Bilateral midpoint reactive pupils (normal)

1. metabolic comas, CNS depressants, NOT opiates

Bilateral pinpoint, fixed pupils

1. pontine lesions

2. interruption of sympathetic paths

3. opiates

CN IV Trochlear Nerve

lesion: eye cannot come down and in.

CN VI Abducens Nerve

1. eye cannot abduct.

2. CN VI palsy does not cause nystagmus.