Clinical characteristics & investigation of neurogenic palsies Flashcards
Concomitant is…
The angle of deviation is the same fixing either eye and in all positions of gaze
Incomitant is..
The angle of deviation varies depending on the eye used for fixation and direction of gaze. Caused by:
Neurogenic palsy
Mechanical limitation
Anisometropia
Neurological palsies
Nerve supply to muscle affected
May affect one individual muscle or group of muscles
Consider observations and determine further investigations required
Recording of clinical picture to show evidence of recovery, regression, stability
Visual acuity
Normal Acuity - usually
Reduced acuity
Previously present e.g old amblyope
Traumatic mydriasis
Related to neurogenic condition e.g retrobulbar neuritis in MS
If recent, can contribute to decompensation of longstanding palsy
Co-incidental pathological cause
Position of vertical action
RE LE
SR IO IO SR
IR SO SO IR
Muscle actions- SR
Elevation
Intorsion
Adduction
Muscle actions - IR
Depression
Extorsion
Adduction
Muscle actions- SO
Depression
Intorsion
Abduction
Muscle actions- IO
Elevation
Extorsion
Abduction
Rad Sin
Recti- adduct
Superior- intort
Four considerations when testing
Deviation in the primary position
Fixing with unaffected eye (primary deviation)
Fixing with affected eye (secondary deviation)
Abnormal head posture (compensatory head posture) to avoid deviation
Observe AHP for
Head turn
Head tilt
Head elevation / depression
Observe during visual task
Put head straight and observe return to AHP
Look for facial asymmetry – suggests longstanding
AHP use
Head turn to place eyes away from action of affected muscle
Head elevation or depression - ditto
Head tilt for:
Vertical – As head tilts e.g. to right – right eye moves up and left eye moves downThus tilt to lower eye to use this
Torsion – As head tilts e.g. to right –right eye intorts and left eye extortsThus if left extorsion is present, tilt right to match fellow eye to that eye position
Cover test recording
Record AHP
N.B. Single cover removes reason for AHP Record first with AHP N&D then without AHP
Record Size and Type of deviation
Note-
Degree of incomitance fixing either eye
Difference in vertical deviation between N & D
obliques larger at near
recti larger at distance
Q- LSR u/a
Action LSR?
Resultant deviation in p.p?
Position where SR elevates eye – largest u/a here…
Where do eyes want to be to avoid this?……
What’s the AHP?
What to observe during OMs
Smoothness of movement during pursuit
Head movements in child may indicate avoidance of affected movement
Pupils
Lid position, changes
Globe position, changes
Nystagmus
Underaction
Reduced ocular rotation which improves on testing duction
-BIOS
Restriction
Abnormal ocular rotation where the movement does not improve fully when testing ductions
-BIOS
Limitation
Abnormal ocular rotation
-BIOS
In ocular movements testing assess
versions and ductions and interpret muscle sequelae development
Eye movement systems
Smooth pursuit
Saccades
OKN
VOR
Do all nerve palsies have BSV
Most commonly normal BSV, or potential for. BUT DO NOT ASSUME
May have previous deviation with suppression or AC, diplopia may occur with change in angle
Traumatic loss of fusion
Measurement of binocular function
With / without AHP – latter more repeatable former only possible if longstanding
With /without refractive correction - if indicated
Near / distance
Nine positions of gaze
PCT
Synoptophore
Torsion
Synoptophore
Torsionometer
Double Maddox Rod
Maddox Rod
Subjective where small vertical deviations
N.B. Expected deviation not always found due to a pre-existing deviation
Lees screen testing
Measurement of deviation in nine positions of gaze (up to 30°)
Compares one eye to fellow eye
Aids identification of affected eye and muscle
Aids differential diagnosis of neurogenic and mechanical limitations
Illustrates degree of concomitance
Used for monitoring patient
N.B Torsion can only be measured with a special adaptation
Can Lees screen be used for bilateral conditions
Not good for bilateral conditions
Uses of field of uniocular fixation
Excellent to record the eye movements when ductions are affected
A good representation of eye movements in bilateral conditions and mechanical limitations such as Graves’ orbitopathy
Use of measuring field of BSV
Records area in which BSV is maintained
Excellent record of patients symptoms
Investigating neurogenic palsies determines
Nerve(s) affected (unilateral or bilateral)
Possible causes
Longstanding or recently acquired
Presence of A or V patterns
Recovery, regression, stability
Need for referral
Management plan
