Aetiology of neurogenic palsies

Question 1

What can interrupt neural supply?

Answer 1

Interruption of blood supply
Intracranial vascular abnormality
Space occupying lesion
Ophthalmoplegic migraine
Trauma
Changes in intracranial pressure
Diseases (e.g diabetes, multiple sclerosis)
Inflammatory conditions (e.g meningitis)
Infections
AIDS
Migraines- changes in blood flow in vessels in the head

Question 2

Prognosis of neurogenic palsies

Answer 2

Recovery more likely:
When treatment of underlying cause successful (Park et al, 2008)

Regression:
Notably in tumours
Spontaneous remission

Question 3

Interruption of blood supply to nerve

Answer 3

Ischaemic attacks (small vascular accidents – due to blockage or bleed)
Isolated palsies in the elderly frequently due to these
Recovery rate - high (e.g 90% of 3rd n palsy by 6/12, Akagi et al, 2008)

Question 4

Conditions causing neurogenic palsies

Answer 4

Diabetes
Arteriosclerosis
Hypertension

Question 5

Stroke

Answer 5

when blood supply to a part of the brain is cut off

Question 6

Ischaemic stroke

Answer 6

decreased blood supply caused by a blockage (most strokes)

Question 7

Haemorrhagic stroke

Answer 7

bleeding in or around the brain (more rare)

Question 8

Transient ischamic attack (TIA)

Answer 8

Acute vascular disturbance where the disability lasts less than 24 hours

Question 9

Infarction

Answer 9

Development of an area of localised tissue death (necrosis) as a result of lack of oxygen (anoxia) caused by an interruption in blood supply e.g. occlusion of an artery.

Question 10

Thrombosis

Answer 10

Aggregation of platelets, fibrin, clotting factors and cellular elements of blood which become attached to the interior wall of a vein or artery

Question 11

Risk factors

Answer 11

Patel et al (2005) 6th nerve palsies
Confirmed diabetes as a risk factor – 6 fold increase for diabetes, 8 fold increase for diabetes and hypertension
Hypertension alone – no increase
Jacobson et al (1994) Ocular motor nerve palsies
Diabetes - 5.75 increase
Left ventricular hypertrophy – 5.5 increase NOT hypertension alone

Question 12

Progression in ischaemic palsies

Answer 12

Pain and sudden diplopia typical initial symptoms in ischaemic or compressive disorders

11/16 patients examined within 1 week of onset showed progression (3 to 23 days)

No group differences found, but non-progressive recovered quicker (mean 7.2 weeks c/w mean 11.2 weeks)

Mechanism: ?intraneural compression and further microvascular ischaemia from oedema after initial insult(Jacobson et al, 1995)

Question 13

Myasthenia and cocaine abuse- 3rd NP

Answer 13

Cocaine abuse especially in young people (Nemeth et al, 1993)
Also consider in cases with Myasthenia – may precipitate or exacerbate symptoms

Question 14

Giant cell (temporal) arteritis

Answer 14

Inflammatory disease of blood vessels
Affects artery walls, predominantly extracranial vessels - particularly superficial temporal arteries
6% - 70% irreversible visual loss
Occult giant cell arteritis - where there are no systemic symptoms (ocular only)
Median age of onset: 75 years. Rare under 50 years

(Kawasaki and Purvin, 2009)

Question 15

Erythrocyte sedimentation rate (ESR) in GCA

Answer 15

Normal: 0-30 mm/hr

Age difference - lower in the young

96% of GCA patients had ESR>50mm/h – hallmark of GCA
(Martinez-Taboada et al, 2000)

Question 16

GCA symptoms

Answer 16

Jaw claudication, headache, weight loss, malaise, anorexia, scalp tenderness, abnormal temporal artery(tender, nodular, or nonpulsating temporal artery), myalgia, fever, anaemia, neck pain

Question 17

Ocular findings in GCA

Answer 17

Symptoms
Amaurosis fugax (painless, transient, monocular or binoc visual loss)
Visual loss
Diplopia
Eye pain

Ocular ischaemic lesions
Anterior ischaemic optic neuropathy (lack of blood supply to ON)
Central retinal vein occlusion
Cilioretinal artery occlusion
Posterior ischaemic optic neuropathy (lack of blood supply to retrobulbar ON)

Question 18

Intracranial vascular abnormalities

Answer 18

Aneursyms, arteriovenous malformations, fistulas

Question 19

Aneursyms symptoms

Answer 19

Persistent localised dilations of a blood vessel wall which may result from a developmental defect or be acquired from:e.g. acquired degenerative change, infection, inflammation, trauma

Symptoms occur from pressure, bleeding or rupture

Question 20

Percentage of ruptured aneurysms

Answer 20

90% asymptomatic until rupture

10% present with mass effect

Interval warning to rupture - 1 day to 4 months (median 14 days) (Barrow and Reisner, 1996)

Rupture: 12% die before receiving medical attention
(Biousse et al 1998)

Question 21

Ruptured aneurysms cause

Answer 21

Patients describe as ‘the worst headache of their life’

Medical emergency – aim is to repair the artery and stop bleeding with immediate surgery

Any patient presenting with diplopia & terrible headache needs to be seen as a medical emergency

Aneurysms make leak before they rupture

Question 22

Ocular movements in neurogenic palsies

Answer 22

Internal carotid and posterior communicating artery- 3rd nerve palsy

Intracranial portion of internal carotid- Compression anterior visual pathway

Cavernous sinus- 3rd and 6th nerve Isolated 6th nerve palsy (frequently with ipsilateral Horner syndrome)

Question 23

Arteriovenous malformations causes

Answer 23

Congenital, anomalous communications between arterial & venous circulations

Blood is shunted from arteries to veins without an intervening capillary bed

Usually become symptomatic during 2nd & 3rd decades of life

Presence of objective bruit valuable diagnostic sign

Headache - often misdiagnosed as migraine

Signs and symptoms occur due to compression, haemorrhage, ischaemia or vascular steal

Question 24

Carotid-cavernous fistulas findings

Answer 24

Abnormal connection between carotid artery and cavernous sinus
Classified as:
Traumatic or spontaneous
Velocity of flow: High or low
Direct or dural
Internal carotid or external carotid

Question 25

Carotid-cavernous fistulas- two types

Answer 25

High flow- direct
Low flow- indirect/ dural

Question 26

High flow carotid cavernous fistulas findings

Answer 26

Often after head injury
Pulsating exophthalmos
Conjunctival chemosis
Cranial Bruit
Diplopia in 60-70%

Question 27

Low flow carotid cavernous fistulas findings

Answer 27

Minor signs and symptoms
Onset of redness one or both eyes
Mild proptosis, minimal eyelid swelling, conjunctival chemosis
May or may not be cranial bruit
Diplopia - most often 6th nerve palsy
20-30% result in visual loss

Question 28

Cavernous sinus syndrome: Characteristics

Answer 28

3rd, 4th 6th nerve palsy, alone or in combination (usually ipsilateral)
Oculosympathetic paralysis
Proptosis
Ophthalmic and maxillary division of 5th nerve may be affected
Periorbital or hemicranial pain
Trigeminl neuralgia

Question 29

Aetiology of cavernous sinus syndrome

Answer 29

Trauma
Vascular (CC fistula, aneurysm, thrombosis)
Tumour (e.g cavernous sinus meningioma)

Question 30

Aetiology of space occupying lesion

Answer 30

Aneurysms
Subdural haematoma
Tumours (Neoplasms)

Question 31

Which nerves are mostly affected by tumours

Answer 31

4th and sixth nerves most commonly affected
3rd nerve affected in pituitary tumours
-its suspected where palsy is progressive or does not recover

Question 32

Tumours findings

Answer 32

Remitting sixth nerve palsy in skull base tumour
(Volpe and Lessell 1993)

7 cases reported - recovery 1 week to 18 months

“All patients recovered completely at least once and did so without surgical intervention, radiotherapy, or chemotherapy”
Possible mechanisms for recovery: remyelination, axonal regeneraton, relief of transient compression, restoration of impaired blood flow, slippage of a nerve previously stretched over tumour, immune responses to tumour.

Question 33

Ophthalmoplegic Migraine findings

Answer 33

Rare condition – sometimes called intracranial neuralgia
Unilateral headache
Followed by 3rd nerve palsy - partial or complete, pupil often affected
6th nerve may be affected and a suggested cause of recurrent 6th nerve palsy in children - in absence of any pathology

Question 34

Trauma in 4th nerve

Answer 34

4th nerve particularly susceptible to closed head trauma

Question 35

Trauma in 6th nerve

Answer 35

6th nerve may be affected if downward displacement of brain stem

Question 36

Trauma in 3rd nerve

Answer 36

3rd nerve least frequently affected by trauma, frontal blow to accelerating head

Question 37

Shaken baby syndrome

Answer 37

isolated or bilateral palsies may occur

Question 38

Idiopathic intracranial hypertension IIH occurence

Answer 38

Occurs rarely in children
In adults higher incidence in females and in the obese

Question 39

IIH symptoms

Answer 39

Headache
Nausea and vomiting
Papilloedema (swelling of optic disc)
Pulsatile tinnitus
6th nerve palsy commonest – 3rd & 4th also reported
Unilateral or bilateral

(NB Also concomitant strabismus or decompensation has been reported)

Question 40

Treatment for IIH

Answer 40

Can respond to Diamox or gain relief following lumbar puncture

Question 41

IIH following a dural puncture

Answer 41

Following dural puncture (e.g diagnostic lumbar puncture; accidentally during epidual anaesthesia)

Headache (and nausea), worse when upright, may occur after puncture

Question 42

Rare IIH complications

Answer 42

Extraocular muscle palsy is a rare complication
6th nerve palsy commonest – 3rd & 4th also reported
Unilateral or bilateral
Onset 1 – 3 days after puncture

(Nishio et al, 2004)

Question 43

Which nerves are affected in diabetes

Answer 43

3rd nerve or 6th nerve most frequently affected
Pupil generally spared

Question 44

Why does diabetes cause nerve palsies

Answer 44

Interruption of blood supplyInflammation of nerveFocal demyelination