investigation of nerve palsies Flashcards
define concomitant and incomitant
The angle of deviation is the same fixing either eye and in all positions of gaze
The angle of deviation varies depending on the eye used for fixation and direction of gaze. Caused by:
Neurogenic palsy
Mechanical limitation
Anisometropia
what are neurogenic 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
what is the va in pts with neurological palsies usually like
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
what are the primary secondary and teritiary actions of the eom
remember rad sin
recti adduct and superiors intort
SR Elevation Intorsion Adduction
IR Depression Extorsion Adduction
SO Depression Intorsion Abduction
IO Elevation Extorsion Abduction
what things need to be considered in patients with neurological deviations
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
what are abnormal head postures
Observe 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
what to record on cover test
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 Also note:
Degree of incomitance fixing either eye
Difference in vertical deviation between N & D
obliques larger at near
recti larger at distance
where is the head turned for people with abnormal head postures
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
what general observations are made during om
Smoothness of movement during pursuit
Head movements in child may indicate avoidance of affected movement
Pupils
Lid position, changes
Globe position, changes
Nystagmus
what is an underaction
Underaction
Reduced ocular rotation which improves on testing duction
what is a restriction
Restriction
Abnormal ocular rotation where the movement does not improve fully when testing ductions
what is a limitation
Limitation
Abnormal ocular rotation
what needs to be checked on ocular movements
Check versions and ductions
Interpret development of muscle sequelae
Include the different eye movement systems:
Smooth pursuit
Saccades
OKN
VOR
how to assess binocular functions
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
what measurements need to be taken for people with neurological palsies
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
