Patho Chapter 10 Altered Neural Function

Neuron #1

Components:

Cell body

Dendrites

Axon

Neural Communication

Information flows across synapse: electrical & chemical

Synapse structures: presynaptic terminal, synaptic cleft, postsynaptic membrane

Neural Injury: Chromatolysis

Swelling of neuron

Neural Injury: Atrophy

Decrease in neuron size

Neural Injury: Neuronophagia

Damaged or dying neurons are destroyed and consumed by phagocytic cells

Neural Injury: Intraneuronal inclusions

Damage inside neuron

Developmental considerations: Embryo

Neural tubes develops

Developmental considerations: Newborn

All needed neurons are present

Developmental considerations: Age 2

Brain 80% of adult size

Developmental considerations: With aging

• Decrease in number of neurons

• Enlargement of ventricle system

• Widening of sulci

• Decreased brain volume and weight

• Sensory changes (vision, hearing)

CNS: Brain

• 4 lobes

• 2 Hemispheres

Ventral horns

• Anterior extensions

• Efferent (“effect”) motor neurons leaving cord

Dorsal horns

• Posterior extensions

• Sensory neurons receiving afferent impulses (bring info in “affect)

White matter

Axons and dendrites 

Grey matter

Cell bodies

Pyramidal motor system

Extends from the sensorimotor areas of the brain to the motor neurons of the ventral horn of spinal cord

Voluntary movement 

Extrapyramidal system

Basal ganglia

Fine-tubes and stabilizes movement

Nervous system protection

• CNS

• Cerebrovascular circulation

• Blood-brain barrier

• Cerebrospinal fluid (CSF)

Neural injury

Injury response depends on type of CNS cell affected

ALL result in an alteration in neural transmission

Traumatic

Brain injury

Spinal cord injury

Ischemic

Inadequate perfusion

Excitation

Hyperexitable neurons cause altered signal transmission (neurons not sending clear signals)

Pressure

Inside the skull and vertebral column

Somatic

• Motor and sensory impulses between the CNS and periphery

• Cranial nerves

• Spinal nerves

  • Dermatomes

  • Plexus formation

• Peripheral nerves

CN l: Olfactory

Smell

CN ll: Optic

Vision

CN lll: Oculomotor

Eye movement & pupil response

CN lV: Trochlear 

Eye movement (downward & inward)

CN V: Trigeminal

Sensation & chewing

CN Vl: Abducens

Lateral eye movement (side to side)

CN Vll: Facial

Facial expressions and taste

CN Vlll: Vestinulocochlear  

Hearing & balance

CN lX: Glossopharyngeal

Gag reflex, swallowing, taste (posterior of tongue)

CN X: Vagus

Regulates PNS “rest and digest”, functions & gag reflex

CN Xl: Accessory

Shoulder shrug & head turn

CN Xll: Hypoglossal

Tongue movement

Autonomic

• Preganglionic neurons

• Autonomic ganglion

• Postganglionic neurons

• Sympathetic

• Fiber lengths: Short preganglionic, long postganglionic

• Spinal nerves exit between T1 and L2

Reflex arc

Arm, hand, knee 

Newborns have different reflexes (rubbing cheek will turn inwards —> breastfeeding)

Cerebral palsy cause

Event during the antenatal or postnatal periods damaging upper motor neurons

Motor dysfunction types

• Spastic

• Athetoid/dyskinetic

• Ataxic

Anatomic involvement

• Hemiplegia

• Diplegia

• Quadriplegia

Cerebral palsy clinical manifestations

• Variable severity

• Limited fine motor skills

• Lack or coordination and balance

• Impaired cognitive function

• Speech disorder

• Seizure disorder

Cerebral palsy diagnostic criteria

• History

• Physical exam

• Neurological exam: motor skills, reflexes

• Developmental milestones

Cerebral palsy treatment

• No known cure

• Pharmacologic: controls seizures, reduces muscle spasms

• Assistive devices: enhance ability to complete activities of daily living

MS

• Central nervous system demyelination

• Etiology combines

  • Genetics

  • Environmental factors

  • Triggering event

  • Autoimmunity

  • Regional Variation

MS clinical manifestations 

• Related to slowed nerve conduction

• Clinical course variation

  • Clinically isolated syndrome

  • Relapsing-remitting

  • Primary progressive

  • Secondary progressive

MS diagnosis

• History

• Physical examination: neurologic

• Imaging: MRI

• Labs: lumbar punctures and CSF analysis

MS treatment

• Pharmacologic: disease-modifying drugs

• Nonpharmacologic: balanced rest and activity, assistive devices

Incomplete spinal cord transection

• Spinal cord injury altering neuronal transmission

Categories:

• Complete transection

• Partial transection

  • Central cord syndrome

  • Anterior cord syndrome

  • Brown-sequard syndrome 

Central cord syndrome

Shoulders and arms: Loss of motor power and sensation

Abdomen area: Incomplete loss 

Anterior cord syndrome 

Abdomen to the feet: Loss of motor power, pain, and temperature sensation, with preservation of position, vibration, and touch sense

Brown-sequard syndrome 

One side of body: Loss of voluntary motor control on the same side as the cord damage

Opposite: Loss of pain and temperature sensation on opposite side

Incomplete spinal cord transection clinical manifestations

Variable

• Spinal segment level

• Types of injury

• Degree of cord transection

Incomplete spinal cord transection diagnosis

• Physical examination

• Cognitive function

• Motor function

• Sensory function

• Imaging studies

Incomplete spinal cord transection treatment

• Immobilization of the spine: Traction

• Surgery: To correct fractures and decompress spinal cord

• Promotion of functional abilities