ACQUIRED BRAIN INJURY

AN OPTOMETRIC APPROACH

Acquired Brain Injuries

 

 

Acquired Brain Injuries

Closed/Open head injury
&endash; Open head injury: direct invasion through skull

&endash; Closed Head injury: blow to head

indirect damage to nervous tissue

tearing/shearing of nerves

&endash; "whiplash" injuries

&endash; ischemic neuropathies

&endash; Accelerating injury: coup brain injury

&endash; Decelerating injury: contre-coup brain injury

 

Visual Signs/Symptoms Common to Acquired Brain Injuries

Cranial nerve lesion
&endash; Oculomotor dysfunction

Muscle palsy

Head tilt/turn

Strabismus

Diplopia

Asthenopia

 

Cranial nerve lesion
&endash; Accommodative defect

Difficulty reading

Blurred vision

Asthenopia

 

Cortical injury
&endash; Visual field defect

&endash; Nystagmus

&endash; Agnosia

&endash; Aphasia

&endash; Imperception (Neglect)

 

Cortical injury
&endash; Perceptual defect

Poor balance

Decreased attention

Visual hypersensitivity

 

CRANIAL NERVE INJURIES

Cranial Nerves

Most common infranuclear lesions in acquired brain injury are:
&endash; Abducens Nerve

&endash; Trochlear Nerve

&endash; Oculomotor Nerve

Tests to identify infranuclear problems

&endash; Ductions/versions

&endash; Parks three step test

&endash; Hess-Lancaster test

&endash; Accommodative Tests

&endash; Eyelid Evaluation

&endash; Facial expression/facial sensitivity

Cranial Nerves

Common sites of injury
&endash; Orbit

&endash; Cavernous sinus

&endash; Along intracranial course of CN IV and CN VI

 

CORTICAL INJURY

INTRODUCTION

Hemispheric Asymmetries

Left hemisphere
Speech and language comprehension
&endash; Verbal behavior and processing

&endash; Learning/remembering verbal information

Processing analytical and/or sequential information

Motor control of right side of the body

 

Left hemisphere
Sensory processing for the right side of the body

Visual processing for the right hemifield

&endash; Processing visual information

words

numbers

common objects

 

Right hemisphere
Spatial relations
&endash; Math

&endash; Music

Processing simultaneous information

&endash; Shape/color

&endash; Depth

 

Right hemisphere
&endash; Auditory processing of non-language sounds
Noises

Melodies

&endash; Motor control of left side of the body

Sensory processing for the left side of the body

Visual processing for the left hemifield

 

Cortical Localization Of Specific Functions

Frontal lobe
Primary motor cortex

Pre-motor cortex

Broca's motor area

Supplemental motor cortex

 

Frontal lobe
Frontal eye fields

Prefrontal association cortex

&endash; Superior and inferior prefontal convexities

&endash; Orbitofrontal cortex

 

Parietal lobe
Responsible for integration and analysis of sensory information
&endash; Posterior parietal lobe
Integration of object orientation and localization

Conducts spatial information to the frontal lobe

Relation to neglect syndrome

&endash; Parietal-temporal-occipital association area (angular gyrus)

Integration of different sensory modalities
&endash; Visual

&endash; Auditory

&endash; Tactile

 

Temporal lobe
Responsible for audition, recognition and identification of objects

Complex learning and recall

&endash; Primary auditory cortex

&endash; Wernicke's area

&endash; Language perception takes place

&endash; Integrates audition and visual cues

&endash; Matches with memory of word as seen or heard

&endash; Relation to aphasias

&endash; Inferior temporal lobe

- object recognition

 

Occipital lobe
Responsible for processing of vision
&endash; Primary visual cortex (17, V1)

&endash; Visual association areas (18,19, V2, V3)

&endash; Occipital eye fields

 

Primary visual cortex
Direct geniculocortical projections
&endash; Retinotopic order

Reduced VA's

Visual field loss

 

Visual association areas:
Interacts with
&endash; Language centers in left hemisphere

&endash; Spatial relations (post parietal) in right hemisphere

Decodes, codes, integrates and stores visual information

 

Occipital eye fields
Involved with smooth pursuits

Involved with optokinetic nystagmus

oInvolved with visual fixation

 

CORTICAL INJURIES

OPTOMETRIC EVALUATION

Visual Signs/Symptoms Common to Cortical Acquired Brain Injuries

Cortical injury

&endash; Visual field defect

&endash; Nystagmus

&endash; Agnosia

&endash; Aphasia

&endash; Imperception (Neglect)

&endash; Visual perceptual defects

 

Visual Field Defects

May occur with cortical injury to virtually any lobe

Temporal lobe - superior temporal quadranopsia

Parietal lobe - inferior temporal quadranopsia

Occipital lobe - homonymous field defects with/without macular sparing

Definitions:

Aphasia: inability to recognize, comprehend or express written or spoken words

&endash; Receptive aphasia

&endash; Conductive aphasia

&endash; Expressive aphasia

Ataxia: loss of smooth execution of movement

Visual agnosia: inability to understand or interpret what is seen (small)

 

Alexia: inability to recognize and comprehend written words

Visual imperception (neglect): Most commonly associated with posterior parietal lobe injury and affects the contralateral hemifield

o Results in decreased abilities in; localization, scanning, saccadic movements,

o fixation and orientation responses

Sensorimotor Evaluation

Right hemisphere injury patients have decreased performance on;

&endash; Spatial orientation tasks

&endash; Visual motor integration activities

&endash; Figure ground tests

 

Left hemisphere injury patients have decreased performance on;

&endash; Visual memory tests

&endash; Language intensive activities

 

Motor free tests

Visual motor integrative tests

Accommodative amplitude/facility

Binocular ranges/facility

Oculomotor control and fixation stability