Characteristics of neurological palsies Flashcards
what is a third nerve palsie
Commonly known as the oculomotor nerve.
The impairment of the nerve is commonly associated with a down and out appearance of the ipsilateral eye, enlarged pupils and often sluggish reactions.
This reflects the presence of some depression and full abduction action of the globe, controlled by the superior oblique and lateral rectus which are innervated by the fourth cranial nerve and sixth cranial nerve respectively.
how to localise an isolated third nerve palsie
It is straightforward to localise an isolated third nerve palsy when complete ptosis is apparent as it involves the LPS.
Other factors involve complete paralysis of innervated extraocular muscles and pupil mydriasis. However, third cranial nerve palsies are often subtle and overlooked as they result from partial defects. The only reason for this is that third cranial nerve palsies are often incomplete
describe the course of a third nerve palsie
This nerve is in the brainstem within the midbrain and originates from the oculomotor nucleus. The point at which the nerve leaves the cranial cavity via the superior orbital fissure the nerve divides into two branches:
The superior branch innervates the superior rectus which elevates the eyeball and the Levator palpebrae superioris which raises the upper eyelid. The superior branch of the oculomotor nerve also travels with sympathetic fibres which innervate the superior tarsal muscle which keeps the eyelid elevated after the LPS.
The inferior branch provides innervation to the inferior rectus which depresses the eyeball, the medial rectus which is an adductor of the eyeball and inferior oblique which is responsible for elevation, abduction, and lateral rotation of the eyeball. This branch also innervates the sphincter pupillae and ciliary muscle.
what are the common aetiologies of a third nerve plasy
Most common cause of third nerve palsy:
Pressure on the nerve
Inadequate blood flow to the nerve (Low, 2020)
Third nerve palsy can be acquired or congenital. All acquired third nerve palsies should be investigated thoroughly to ensure there are no space occupying lesions.
Causes of third nerve palsy include:
Congenital: 43%
Local inflammation: 13%
Trauma: 20%
Aneurysm: 7%
Myasthenia Gravis
Migraines
what are the causes of a congenital third nerve palsieCauses of congenital third nerve palsy are following:
Causes of congenital third nerve palsy are following:
Oculomotor nucleus development aplasia or hypoplasia
Birth trauma during labour because of force on skull
Infection such as meningitis (eyewiki.aao.org, n.d.)
CN III palsy can also be either complete/ incomplete.
Incomplete palsies are most commonly associated with compressive aetiologies (tumours and aneurysms).
Incomplete → Abnormal pupil reaction, as well as lids not being fully involved.
Complete → Complete or near complete ptosis & involvement from all EOM innervated by CN III.
what are the actions of the muscles
Action of muscle(s):
· Controls the movement of 4 muscles
· Inferior rectus which depresses the eyeball
· Medial rectus which is an adductor of the eyeball
· Superior rectus which is responsible for elevation, adduction, and lateral rotation of the eyeball
· The Lavator palpabrae superioris which raises the upper eyelid.
what are the possible ahps for people with third nerve palsies
Patients with third nerve palsies may develop characteristic head postures. Usually when the palsy is mild or during recovery.
These head postures serve to avoid diplopia or, when fixation is with the paretic eye, to allow fixation of a target directly in front of the patient.
Temporary management of the abnormal head posture can be accomplished by patching one eye with a Fresnel prism or with Botulinum toxin. When spontaneous resolution of the paresis does not occur, surgical treatment is usually needed for permanent correction of the face turn. Surgical outcomes are usually satisfactory except in cases of complete or nearly complete third nerve palsy (Archer, 1995).
Significant abnormal head posture could cause permanent tightening of neck muscles that can lead to chronic neck ache or headache. An abnormal head posture may also cause the facial bones to grow abnormally leading to facial asymmetry.
what cover test findings are found with someone with a third nerve palsie
Complete 3rd nerve palsy
XT, HoT, incyclotropia
Divisional palsy
Superior division (SR, levator palpebrae superioris) = HoT
Inferior division (IR, MR, IO) = XT, HT
Single muscle palsy
SR = HoT
IR = HT
MR = XT
IO = HoT, ET, incyclotropia
what are the divisions of third nerve palsies
Divisions of 3rd nerve palsies:
Complete 3rd nerve palsy = ‘down and out’
Total paralysis
Partial paralysis (paresis)
A complete 3rd nerve palsy means that the SR (which elevates), the IR (which depresses), the MR (which adducts), and the IO (which elevates, abducts, and extorts) will be affected. This will cause the affected eye to have an exotropia, hypotropia, as well as an incyclotropia.
Incomplete 3rd nerve palsy
Divisional palsy
The superior division supplies the SR (which elevates) and the levator palpebrae superioris (elevates eyelids) and therefore if it is affected, the eye will have a hypotropia. The hypotropia may cause a pseudoptosis where the coexisting ptosis can be assessed with the eyes fixing in the primary position.
The inferior division supplies the IR (depresses), the MR (which adducts), and the IO (which elevates, abducts, and extorts) therefore if it is affected, the eye will present with an exotropia and a hypertropia
Single muscle palsy
SR elevates the eye therefore SR palsy will cause a hypotropia
IR depresses the eye therefore IR palsy will cause a hypertropia
MR adducts the eye therefore MR palsy will cause an exotropia
IO elevates, abducts and extorts the eye therefore IO palsy will cause an hypotropia, esotropia, and incyclotropia
what ocular movement findings are found in people with third nerve palsies
The superior branch supplies the levator muscle and superior rectus muscle. The inferior branch supplies the medial rectus, inferior rectus and inferior oblique muscles and carries the pupil reflex fibres”
On ocular motility testing of a third nerve palsy elevation, depression and adduction will all be limited and these limitations can be either partial or complete dependent on the seriousness of the palsy.
It is also likely that a ptosis will be present in the patient, in which case either the orthoptist performing ocular movements or a helper will need to elevate the eyelid
what is an example of a hess chart found in a patient with a third nerve palsy
Hess charts of patients suffering from a third nerve palsy will show a small squashed field on the chart of the afflicted eye and the other eye will demonstrate a hess chart showing overaction
what effect on bsv does a third nerve palsie have
A large aim of treatment is the restoration of BSV and steropsis - when the ptosis and deviation are corrected both usually can .
what tests need to be conducted for a third nerve palsie
Diplopia: People have double vision when they look in a certain direction(Rubin, 2022)Diplopia: People have double vision when they look in a certain direction(Rubin, 2022)
Pupil Reflex: Pupils may not narrow (constrict) in response to light.
Measure size of ptosis: measure distance between the
upper and lower lid margin whilst patient is in primary gaze.
( normal: 7-12mm) (Eyes On Eyecare, 2022)
Test presence of torsion on depression to check SO action
Look for Aberrant regeneration
The affected eye turns slightly outward and downward when the unaffected eye looks straight ahead, causing double vision.
Pupil reflex test - Pupils may not narrow (constrict) in response to light so will be widened (dilated)
The 3rd nerve allows movement of the upper eyelid so with a 3rd nerve palsy the affected eye will have ptosis which can be measured.
where does the fourth nerve originate from
It originates from the trochlear nuclei within the medial midbrain at the level of the inferior colliculus.
The nerve fibers decussate (cross-over) to the other side of the brain stem, before leaving the brain-stem at the junction of the midbrain and pons
*Only brainstem which leaves from the posterior surface of the brainstem
It runs anteriorly and inferiorly within the subarachnoid space before piercing the dura mater
The nerve then moves along the lateral wall of the cavernous sinus
Then enters the orbit of the eye via the superior orbital fissure.
what are the common aetiologies of a 4th nerve palsie
may have other health problems along with congenital fourth nerve palsy and may compensate for diplopia with variable head positioning at later stages in life.
TRAUMA - CN IV has the longest intracranial course and is vulnerable to damage, even with relatively mild trauma, patients typically report symptoms immediately after the injury.
Vascular disease e.g. diabetes (reduces blood supply to nerve), aneurysm (bulging area of an artery that can press onto nerve or burst subsequently decreasing blood supply to nerve)
Increased intracranial pressure -(pressure in skull can press on nerve)
Injury - The most common cause of fourth nerve palsy in adults. Most common causes of injury are whiplash or concussions. Another common cause is from poor blood flow which is related to diabetes. Fourth nerve palsies that are caused by injury may not go away.
Idiopathic- cause is unclear and not caused by injury. Idiopathic cases may improve or completely resolve over a matter of weeks on their own.
what are the muscle actions of superior oblique
depression
intorsion
abduction
what are symptoms and signs of a 4th nerve palsy
There are 2 types of 4th nerve palsy:
Isolated - this is the most common type of nerve palsy, and is congenital. (1)
Non isolated - this type of palsy is normally caused by trauma, infection and inflammation. (2)
Signs and symptoms.
Diplopia - different types can be present in a 4th nerve palsy, the most common are: Binocular, torsional and vertical diplopia.
Vision - problems can accrue when someone has been suffering with a 4th nerve palsy for a long period of time, things like: blurred vision, focussing problems and dizziness. In the end these vision can cause a person’s daily life to become very difficult.
Head posture - people can develop a head tilts in the opposite direction to the affected eye, this head posture occurs due to the 4th nerves affect on the superior oblique (intorsion and depression).
(3), (4)
what are fetatures are present in a congen trial 4th nerve palsy
unilateral
Facial asymmetry common - shallowing between lateral canthus & edge of mouth
Abnormal Head Position - Head depression with head tilt or turn to the unaffected side
First symptom of the palsy decompensating is intermittent diplopia
A large hyperphoria (usually exceeding 20 diopters) with AHP
Potential manifest vertical deviation without AHP
bilateral palsy
Abnormal Head Position - Chin depression with no head tilt or turn unless one side is affected more than the other
Non fixing eye may have V pattern esotropia and hypertropia
Associated inferior oblique overaction
No symptomatic torsion but can be seen objectively in fundus test.
how is a congenital 4th nerve palsy managed
Correct refractive error and treat any amblyopia if present.
Potential surgery for: Marked AHP, moderate/large angle deviations of decompensating cases, strabismus
If the patient has an abnormal superior oblique tendon a superior oblique tuck procedure may correct the palsy.
Also could have other surgeries to weaken the overacting muscles.
what ahp do people in 4th nerve palsies have
Abnormal head posture is where a patient will tilt their head at an angle that is away from the normal primary position, due to misalignment of the eyes. This is so the patient can avoid deviation, diplopia or relieve strain.
Someone with a 4th nerve palsy, with the superior oblique affected/weakened, will tilt their head away from the affected eye, so their eyes can become more straight or where the eyes are best aligned.
Because their superior oblique is affected, the affected eye will therefore not be able to turn ‘in and down’, as the action of the superior oblique is to abduct, depress and intort the eye. The patient will move their head, chin down to compensate diplopia.
For example, if it’s the right eye that’s affected, the patient would tilt their head to the left and with chin depressed (away from the affected eye), to avoid diplopia. If that patient tilts their head towards the affected eye, there would be an increase in hypertropia, and therefore vertical diplopia.
We can test if a patient has AHP by:
Observing them during a visual task, such as reading off a board
Put their head straight and observe if they return back to AHP repeatedly.
Look for facial asymmetry, where the ipsilateral side of face can look less developed
what cover test findings are found in a unilateral 4th nerve palsy
Unilateral 4th Nerve Palsy
Hypertropia in primary gaze (as SO depresses the eye)
Excyclotorsion (as SO intorts the eye)
Sometimes esotropia (as SO abducts the eye)
what cover test findings are found in someone with a bilateral 4th nerve palsie
Bilateral 4th Nerve Palsy
Alternating hyperdeviation - right HT on right head tilt and left HT on left head tilt
This is due to compensatory activation of the ipsilateral SR (while compensating for the intorsion, it also elevates the eye as that is the primary action)
Crossed HT (right HT on left gaze and left HT on right gaze as SO cannot depress the eye)
Excyclotorsion > 10º
Large V pattern ET > 25º
Tertiary action of SO is abduction thus on downgaze it will not be able to abduct the eyes, causing the eyes to be closer together compared to upgaze
what ocular movement findings are found in someone in a fourth nerve palsy
Ipsilateral hypertropia and excyclotorsion are frequently seen due to the superior oblique’s function of intorsion and depression the eye. Patients can also develop a compensatory head tilt in the direction away from the affected muscle. They can present with vertical diplopia, torsional diplopia, head tilt, and ipsilateral hypertropia.It can be rather difficult to diagnose. But looking at the patient’s ocular movements can help us to identify it. (12)
what muscle sequelae would develop in someone with a 4th nerve palsy
As the IV nerve palsy restricts the superior Oblique muscle, there is an underaction shown on the RE of this muscle.
Overaction of the right Inferior Oblique
Underaction of the Left Superior rectus
Overaction of the Left Inferior Rectus
what tests are done for a 4th nerve palsy
The trochlear nerve is tested by requesting the patient to adduct and depress the eye. This motion of movement is mainly controlled by the superior oblique, and failure to depress the eye indicates a problem with 4th nerve or right superior oblique muscle.
To compensate for a 4th nerve palsy, the patient will usually present with a head tilt towards the opposite side and tucking in of the chin.
During clinical examination, the eyes will display hypertropia with the affected eye being slightly elevated relative to the other normal eye. A critical sign of a 4th nerve palsy on performing these tests is the patient reporting diplopia. The diplopia presented may either be vertical or diagonal, and is usually worse on downward gaze.
Another way to test the 4th nerve is via ‘Bielchowsky head tilt test’. This test can be used when a 4th nerve palsy is suspected, and can reduce or stop diplopia by tilting the head toward the shoulder of the unaffected side.
Assess torsion
what is a 6th nerve palsy
Generally diagnosed in adults above the age of 70
From birth/trauma/medical condition
Common causes include:
Diabetes
Hypertension
Skull fracture
Stroke
Multiple sclerosis
Meningitis
what is a 6th nerve palsy
Generally diagnosed in adults above the age of 70
From birth/trauma/medical condition
Common causes include:
Diabetes
Hypertension
Skull fracture
Stroke
Multiple sclerosis
Meningitis
what are features of a 6th nerve palsy (unilateral)
An eso deviation in primary gaze that increases for distance
A head turn for to minimise diplopia often larger for distance fixation
Diplopia worse on attempted lateral gaze
Those with mild degree of palsy can sometimes maintain BSV by using the physiological V pattern and head depression
Secondary changes in other horizontal rectus EOM if the muscle sequelae has fully developed
what are features of a 6th nerve palsy (bilateral)
Usually a marked Esotropia, often bigger for distance but can be equal for long standing palsies
A head turn to fixing eye to allow foveal fixation if large deviation
In long-standing palsies contracture of the medial rectus muscles, often preventing abduction to the midline in total palsy
describe the structure and function of abducens nerve
The abducens nerve is purely a motor nerve and has no sensory functions as opposed to the oculomotor and trochlear nerves.
Innervates the LR - abducts the eye on ipsilateral side
Rotates the eye laterally - abduction
A palsy will give an esodeviation
Secondarily plays a role in the innervation of the contralateral MR
(Hering’s law - yoke muscle innervation is equal) (Nguyen, 2021).
Due to its location, it is more prone to damage as its not supported by the dural wall of the sinuses
what is the course of the 6th nerve
Leaves anterior midbrain at junction between pons and medulla and runs within subarachnoid space
Travels up, forwards, and laterally.
Pierces dura and bends sharply against the clivus bone
Travels forward to lie within the cavernous sinus (covered only by its endothelium); related inferolaterally to the internal carotid artery
Carries on towards lateral rectus
what is the ateiology of a 6th nerve palsy
Lesions can affect any part of the nerve’s pathway. Localisation is based on the presence of other neurological signs.
Fascicular damage - demyelination, vascular disease and tumours
Peripheral damage - e.g. closed head injury, bacterial infection of middle ear and subarachnoid haemorrhage secondary to ruptured aneurysms.
The false localizing sign- sixth nerve is vulnerable to damage caused by raised intracranial pressure
High intracranial pressure: structural pathology which leads to downwards pressure on the brain stem (e.g. space-occupying lesion) and stretch the abducens nerve along the clivus bone.
Diabetic neuropathy and thrombophlebitis of the cavernous sinus.
what ahp would be seen in someone with a 6th nerve palsy
The abducens nerve abducts the eye
Sixth nerve palsy will cause an eso deviation (eye turns in)
Adopting head turn reduces diplopia by moving the eye away from the affected muscle
if a right et Right head turn
if left et- left head turn
what cover test findings would be present for someone with a 6th nerve palsy
In a patient with a 6th nerve palsy there would most likely be an esotropia which would usually be larger in the distance than at near.
This would be due to muscle sequelae which would be:
Primary underaction of the lateral rectus
Overaction of the contralateral medial rectus
Overaction of ipsilateral medial rectus
Secondary inhibition of contralateral lateral rectus
If there is any abnormal head posture it will usually be a head turn towards the affected side to help the patient to see in that direction.
This should be assessed for near and distance as it may vary significantly from one distance to the other and they may even only turn their head for distance fixation.
You should also correct any head posture when doing the cover test
what ocular movement findings would be found with someone
The primary underaction of the affected lateral rectus results in limited abduction.
There is overaction of both contralateral and ipsilateral medial recti.
There is also secondary underaction of the contralateral lateral rectus.
what specific tests are there for a 6th nerve palsy
Moving a pen laterally for the patient to follow with their eyes only allows the eye to abduct using the sixth nerve
Failure to follow the pen fully suggests an issue with the 6th nerve
6th nerve palsies can be mimicked by multiple other diseases meaning other brain scans may need to be done to cancel these out (thyroid eye disease, congenital esotropia)
what specific tests are there for a 6th nerve palsy
Moving a pen laterally for the patient to follow with their eyes only allows the eye to abduct using the sixth nerve
Failure to follow the pen fully suggests an issue with the 6th nerve
6th nerve palsies can be mimicked by multiple other diseases meaning other brain scans may need to be done to cancel these out (thyroid eye disease, congenital esotropia)
what is the prognosis for 6th nerve palsies
King et al. (1995) found that 78.4% of the patients tested had spontaneous recovery of their CN VI nerve palsies.
36.6% of which recovered within 8 weeks and 73.7% by 24 weeks.
16.4% did not recover however, over one third of the failed recovery group had “serious underlying pathology accounting for their palsy” (King et al, 1995)
what are the actions of the superior oblique muscle
depression
intorsion
abduction
what does a 4th nerve palsie result in
results in the underaction of the superior oblique
will result in hypertropia , abduction and excylotorsion
patients may report vertical and or torsional diplopia that is worse in downgaze
what are the common aetiologies of a 4th nerve palsy
There are known and unknown causes of a number of fourth nerve palsies. These can be due to
idiopathic lesions- mostly congenital
Trauma - due to the proximity of the decussation of the nerves at the medullary velum
Microvascular lesions
Aneurysms and tumours - (very rare)
what are known causes of acquired palsies
Most acquired bilateral palsies are caused by closed head injury. So are many unilateral palsies.
Diabetes
Intracranial tumours
Myasthenia gravis
In a study conducted by Dosunmu and Hatt (2018) they found that the majority of isolated 4th nerve palsies were thought to be congenital despite them being presented throughout childhood, other aetiologies such as trauma were less frequent.
what are congenital palsies caused by
Anatomical anomaly of the SO tendon, which causes an abnormal or absent insertion of the muscle or it may cause a loose tendon
A autosomal (autosome= a chromosome that is not a sex chromosome) dominat form of inheritance.
what are common features of a 4th nerve palsy
excyclotorsion (> 7 degrees)
Absent or small hypertropia in primary gaze
Positive Bielschowsky head tilt test - this means that when head is tilted towards affected side the vertical deviation will increase and when head is tilted towards the unaffected side there will be a decrease. But in bilateral cases head tilt is only common if one side is more affected than other.
Underaction of both superior obliques on duction testing
V-pattern is common
Important in differential diagnosis
what cover test findings are found in 4th nerve palsies
If there is a head posture the test is carried with and without head tilt.
The main deviation tends to be a small angle horizontal deviation.
There may be a slight hyper deviation in primary position.
Patients often exhibit a reversal of height in lateral positions of gaze.
Hypertropia is often smaller than expected due to counter balancing.
Hess Chart shows “tipping” of the fields outwards in typical bilateral fourth palsies.
In bilateral cases, a V pattern is often present and often significantly so; greater than 25 PD .
In the presence of this, one should always suspect a bilateral case, especially where there is an excyclotorsion of greater than 7◦ and a tendency towards reversal of any hyper-deviation or diplopic images on lateral gaze (Hermann 1981).
what ahp may be present in 4th nerve palsies
Chin depression which is marked and difficult to maintain
SO depresses the eye so we depress the chin so eyes go up
In asymmetrical cases: head tilt and face turn to the less affected side, usually with some chin depression.
describe acquired cases of 4th nerve palsies
Acquired cases
Acquired palsies often cause vertical or oblique torsional diplopia which worsens in contralateral and downgaze. Therefore patient would experience difficulty walking down stairs and reading
Torsional diplopia is often the main symptom in symmetrical cases, invariably preventing fusion. The typical head posture in these cases is a marked and obvious head depression, which is the only means of avoiding diplopia.
When torsional symptoms are prominent, particularly in downgaze there will also be a large esotropia.
Congenital cases
Asymmetry of the face may be observed in cases over time.
Children will present with a chin down and head tilt to the less affected eye. Often to avoid diplopia
what are specific tests for a bilateral 4th nerve palsy
Convergence
May be reduced due to vertical deviation, or convergence insufficiency. To differentiate, measure again after correcting deviation.
BSV
BSV often not present in these patients. Test repeated with and without AHP
Hess’s
Can demonstrate effects of palsy on the other muscles.
Field of vision
Diplopia on near testing when looking down, usually vertical, uncrossed diplopia. If exo deviation present, horizontal element will be crossed.
what are specific tests for a bilateral 4th nerve palsy
Convergence
May be reduced due to vertical deviation, or convergence insufficiency. To differentiate, measure again after correcting deviation.
BSV
BSV often not present in these patients. Test repeated with and without AHP
Hess’s
Can demonstrate effects of palsy on the other muscles.
Field of vision
Diplopia on near testing when looking down, usually vertical, uncrossed diplopia. If exo deviation present, horizontal element will be crossed.
what are the steps of the parks bielschowsky three step test
determine which eye is hypertrophic in pp
determine weather the hypertropia increases on right or left gaze
determine weather the hypertropia increases on right or left tilt
what would you see on a hess chart for bilateral cases of strabismus
The first hess chart is of a patient with asymmetrical bilateral superior oblique palsy. It is asymmetrical as the superior oblique underaction is greater in the right eye than the left eye so the right eye is affected more than the left eye.
In primary position, the right eye is higher and the left eye is lower so there’s a right hyper deviation.
V pattern esotropia on down-gaze
Primary underaction is most likely the left superior oblique underaction.
The second hess chart is of a patient with symmetrical bilateral superior oblique palsy. It is symmetrical as the superior oblique underaction is the same size in both eyes.
There is a V-pattern esotropia on downward gaze with bilateral superior oblique underaction.
There is a V-pattern exotropia on upward gaze with bilateral inferior oblique overaction.
how to measure torsion
Torsional diplopia often is common therefore prevents fusion
Can be measured subjectively or objectively using tests such as double maddox rod, torsionometer or synoptophore. Objective Fundus photography
It was found that the Maddox Rod was most effective as it helped to ‘determine the ocular cyclotorsion’ (Khanam et al, 2022)
Patients use a abnormal Head posture used to eliminate diplopia
how to measure bsv
Patients do have BSV
The deviation makes it difficult to demonstrate this BSV
The torsion makes it even more difficult to navigate this BSV
Putting patient on the synoptophore may be the only way to demonstrate the BSV
