Week 1 - PT 711

Primary vs Secondary Effects

Primary: affect motor (neuromuscular), sensory, perceptual, and/or cognitive or behavioral systems

Secondary: do not result from the CNS lesion directly, but cause further damage that worsen the initial insult

Paralysis vs Plegia vs Paresis

Paralysis: complete loss of muscle activity

Plegia: severe loss of muscle activity

Paresis: mild or partial loss of muscle activity

Paralysis Pathophysiology

Decreased voluntary motor unit recruitment
Inability or difficulty recruiting skeletal motor units to generate torque or movement

Does paresis result from a lesion with ascending or descending motor pathways? 

Descending 

Paraplegia vs Tetraplegia 

Paraplegia: weakness affecting the lower extremities

Tetraplegia: weakness affecting all four limbs (UE and LE) 

Spastic Diplegia 

Form of CP that causes stiffness and tightness in the LEs 

Impairments affect lower extremities more than the upper extremities (LE > UE) 

Abnormal Synergies

Inability to move a single joint without simultaneously generating movements in other joints 

Motor control impairments as a result of lesions to corticospinal centers

Can abnormal synergies be changed or adapted to changes in task or environmental demands? 

No

UE Flexion Synergy

Scapular retraction, elevation

Shoulder ABD, ER

Elbow flexion

Forearm supination

Wrist & finger flexion

LE Extensor Synergy

Hip extension, ADD, IR

Knee extension

Ankle PF, inversion

Toe PF

Is coactivation present in patients with neuro pathophysiology, neurologically intact individuals, or both?

Both; present in early stages of learning skilled movements in neurologically intact individuals and during early stages of postural development in health infants

What 3 conditions can we measure strength under?

1. Isometrically (muscle produces force without changing its length)

2. Isotonically (muscle changes length while contracting and moving a constant load or resistance)

3. Isokinetically (muscle contracts and changes length at a constant velocity)

What is the primary limitation of manual muscle testing? 

Does not examine muscle’s ability to participate in a functional movement pattern 

How is muscle tone clinically assessed?

By describing a muscle’s resistance to passive stretch

What are some strategies to improve recruitment of paretic muscles? 

• Biofeedback

• Functional electrical stimulation

• Bimanual training

What is the benefit of bimanual training in paretic limb function? 

One limb entrains the other, causing them to function as a unit 

Increases the peak velocity of paretic limb subject actions 

Homonymous Hemianopsia

The loss of visual information for one hemifield

What areas are examined in visual testing?

• Visual acuity

• Depth perception

• Visual fields

• Oculomotor control

What happens when a paretic muscle is in a shortened position? 

Muscle unloading (reduction in longitudinal tension); first step in muscle contracture

What are the negative effects of muscle unloading?

• Loss in muscle mass (atrophy)

• Loss in cross-sectional areas

• Loss of sarcomeres (shortening)

• Accumulation of connective tissues

• Increase in fat deposits

What are the 5 stages of movement in the Hedman model?

1. Initial conditions

2. Preparation

3. Initiating

4. Execution

5. Termination

How many times should we perform movement analysis tests?

At least twice

Gray Matter

Areas made up of cell bodies (communication between neurons in the CNS takes place here)

White Matter

Areas made up of myelinated axons (transmission of signals takes places here)

Which structure connects the two hemispheres of the brain?

Corpus callosum

Which landmark divides the frontal and parietal lobes?

Central sulcus

Cerebral Cortex

Processes sensory, motor and memory information

Responsible for reasoning, language, nonverbal communication, intelligence, personality

Basal Ganglia 

Involved in social and goal-oriented behaviors, movement 

Amygdala

Involved in emotions and motivation

Hippocampus

Involved in learning and memory

Where is the primary motor cortex located?

Frontal lobe (pre-central gyrus, anterior to central sulcus)

Where is the primary somatosensory cortex located?

Parietal lobe (post-central gyrus, posterior to central sulcus)

Where is the primary auditory cortex located? 

Temporal lobe

Where is the primary visual cortex located?

Occipital lobe

Frontal Lobe Functions

• Motor control

• Problem solving

• Speech production (Broca’s area)

Parietal Lobe Functions

• Touch perception

• Body orientation

• Sensory discrimination

Temporal Lobe Functions 

• Auditory processing 

• Language comprehension (Wernicke’s area) 

• Memory and information retrieval 

Occipital Lobe Functions

• Sight

• Visual reception and interpretation

Brainstem Function

Involuntary responses

Cerebellum Function 

Balance and coordination 

Association Cortex 

Carry out higher-order information processing (cognition) 

Both unimodal and multimodal areas 

Unimodal vs Multimodal Association Areas

Unimodal: single modality information processing areas

Multimodal: integrating functions from multiple modalities

Where do pyramidal tracts originate?

Cerebral cortex

What do pyramidal tracts control?

Conscious (voluntary) motor control

Where do extrapyramidal tracts originate? 

Brainstem

What do extrapyramidal tracts control?

Unconscious, reflexive motor control

What 2 groups comprise the lateral system tracts?

1. Lateral corticospinal tract

2. Rubrospinal tract

What 3 groups comprise the medial system tracts? 

1. Anterior corticospinal tract 

2. Vestibulospinal tracts 

3. Reticulospinal tract 

Reticulospinal Tract Origin 

Pons and medulla 

Reticulospinal Tract Termination

Medial ventral horn of spinal cord

Reticulospinal Tract Medial (Pontine) Function 

Extensors + flexor inhibition 

Reticulospinal Tract Lateral (Medullary) Function

Flexors + extensor inhibition

Vestibulospinal Medial Tract Origin

Medulla

Vestibulospinal Medial Tract Termination

Cervical spinal cord

Vestibulospinal Medial Tract Function 

Head and neck control - EXTENSORS

Vestibulospinal Lateral Tract Origin

Pons

Vestibulospinal Lateral Tract Termination

Entire spinal cord

Vestibulospinal Lateral Tract Function 

Proximal limb muscle control - EXTENSORS

Rubrospinal Tract Origin

Midbrain

Rubrospinal Tract Termination

Cervical spinal cord 

Rubrospinal Tract Function 

Distal upper limb muscles - FLEXORS

Which brainstem motor tracts control extensors? 

1. Vestibulospinal 

2. Pontine portion of reticulospinal 

Which brainstem motor tracts control flexors?

1. Rubrospinal

2. Medullary reticulospinal

What occurs with brainstem lesions in the rubrospinal tract? 

Excessive flexion (bias for flexor movement pattern) 

What occurs with brainstem lesions in the vestibulospinal tract? 

Excessive extension (uninhibited extensor posturing)

What occurs with loss of corticospinal and bulbospinal influences?

• Loss of fractionated movement (inability to move joints in isolation)

• Development of synergistic movement patterns

• Activation of either flexor or extensor muscle groups simultaneously

Abnormal Static Posturing/Rigidity 

Overactivity of gamma motor neurons by their release from descending centers that only occurs in very severe cases 

Domination of either flexor (decorticate) or extensor (decerebrate) tone 

Are there more nasal or temporal fibers?

Nasal

Optic Radiation

The projection between the lateral geniculate nucleus and the visual cortex

Optic Nerve

The projection between the retina and optic chiasm 

Optic Chiasm 

The site where nasal fibers cross over 

Does the lower division of the optic radiation carry information from the superior or inferior half of the visual field?

Superior

Cisterns

Cavities in the subarachnoid space where cerebrospinal fluid accumulates

Venous Sinuses

Large channels between the two layers of dura

Arachnoid Granulations 

Absorption sites for cerebrospinal fluid (CSF)

Choroid Plexus

Structures that produce cerebrospinal fluid (CSF)

True or False: Hemorrhagic transformation of ischemic stroke can occur spontaneously (even without treatment with tPA).

True

Coma

• Not awake or aware

• Absence of spontaneous eye opening

• No sleep wake cycles

• Behavior is limited to reflexive activity

Vegetative State (VS) 

• Awake but not aware 

• No evidence of sustained, reproducible, purposeful or voluntary behavioral responses to stimuli 

• No evidence of language comprehension or expression 

• Intermittent wakefulness manifested by the presence of sleep/wake cycles 

Minimally Conscious State (MCS)

• Awake with fluctuating awareness

• Minimal but definitive behavioral evidence of self-awareness or environmental awareness

• Follow simple commands

• Gesture or verbalize yes/np responses (regardless of accuracy)

• Intelligible verbalization

• Movement or affective behavior that are not reflexive (in response to environmental stimuli)