Exam 1 Flashcards
what are the 2 distinct classes of cells?
- Neurons (nerve cells)
* Glia (supporting cells)
What are the parts of the neuron?
- Dendrites
- Cell body
- Axon hillock
- Axons
- Presynaptic terminal
What is the axon hillock?
Where the axon meets the cell body before it synapses
*The closer they are to this then the more likely they are to get the neuron to fire
What is the Node of Ranvier?
*The gap between the myelin sheath and its important bc Na+ will go in and K+ will go out and cause depolarization. It’s quicker bc of saltatory conduction. With an unmyelinated neuron you have to do the Na+/K+ exchange all the way down the neuron instead of just in the places you’d like.
What types of neurons are there?
- Bipolar (interneuron)
- Unipolar (sensory)
- Multipolar (motorneuron)
- Pyrimidal cell
What are the glial cells?
- Schwan cells (PNS)
- Oligodendrocytes (CNS)
- Astrocytes (CNS)
- Microglia (CNS)
What is the function of a purkinje cell?
- Takes sensory info from all over the body (through dendritic arborization) to help the body with coordination. It does sensory integration
- There are many dendrites to one axon
What are the 4 main functions of glial cells?
- Provides structure for the neurons
- surrounds neurons and holds them in place - Forms the (lipid) myelin sheath
- Speeds NCV
- Insulates one neuron from another - Supplies nutrients and oxygen to neurons
- Destroys pathogens and removes dead neurons
What are the characteristics of a Schwann cell?
- Usually only myelinates one neuron
- Myelin spirals around axon to form the myelin sheath
- at Nodes of Ranvier
- NCV= 100 m/s for myelinated neuron, and 1 m/s for unmyelinated
What are the characteristics of oligodendrocytes?
- One cell myelinates many CNS neurons
- Insulates and protects nerves
- Increase NCV
- Involved in pathologies such as alzheimers disease and multiple sclerosis
What are the characteristics of Astrocytes?
- Supporting cells in the CNS
- Most common glia
- Fill most of brain space not occupied by neurons
What are the functions of astrocytes?
- Provide structural support and insulating neurons from each other
- Maintenance of the blood brain barrier
- During inflammation and injury, they divide and wall off damaged areas
- Acts as scavengers by removing neurotransmitters from synaptic cleft
- Clean up other debris during both early development and during recovery after injury
What do Microglia do?
*They contain branched cytoplasmic processes and play an important phagocytic role?
What are the protective roles of Microglia?
- Activated and mobilized after injury, infection or disease
- Important during brain development
- Function as phagocytes (Ingest and destroy bacteria, cells and other materials)
What are the destructive roles of microglia?
- In diseases such as Alzheimer’s and aging
- release of toxic compounds into the neural environment
- HIV/AIDS can activate microglia and stimulate a cascade of cellular breakdown
What is Multiple Sclerosis (MS)?
- Autoimmune disease in which the oligodendrocytes are attacked by the person’s own antibodies
- Produce patches of demyelination = plagues in the white matter
What are the signs of LMN injury?
- Atrophy
- Weakness or paralysis
- Hypotonic DTRs
- Decreased muscle tone
- Fasiculations
- In a peripheral nerve distribution
What are the signs of UMN injury?
- Spasticity
- Hypertonic or hypotonic DTRs
- Clonus
- Babinski or Hoffman’s reflexes
- Weakness
- Synergistic movement patterns
- Effects one or both sides of body
What is a fasciculation?
- Rapid, fine, painless or painful contraction of groups of muscle fibers
- Visible but not strong enough to move limbs
- Commonly seen in anterior horn cell disorders (ex. ALS)
If a stroke occurs in the pre-central gyrus what would the symptoms be?
*you would have motor loss
If a stroke occured in the post-central gyrus what would the symptoms be?
- Glove/sock like sensory loss
* Sensory loss in general
If you have an UMN injury in the brain what can be the signs and symptoms?
- Motor/sensory loss of body part
- Glove/sock like sensory loss
- Hypo/hypertonic reflexes
If you have an UMN injury in the spinal cord what can be the signs?
- Motor loss: mytotome or loss below level of injury
- Sensory loss: dermatome or loss below level of injury
- Hypo/hypertonic reflexes
If you have a LMN injury at the nerve root what can be the signs?
- Motor loss: myotome
- Sensory loss: dermatome
- Reflexes: Hypotonic
If you have a LMN injury at the peripheral nerve what can be the signs?
- Motor Loss: Nerve distribution
- Sensory loss: nerve distribution
- Reflexes hypotonic
- Peripheral nerve compression somewhere after the plexi (after the nerves have been formed)
- Perform sensory and motor exam to determine which nerve has a compression site and where
If you have an injury to the radial nerve what would be the signs?
- Motor loss: elbow extension, wrist and finger extension, supination
- Sensory loss
If you have an injury to the median nerve what would be the signs?
Motor loss: Pronation, wrist flexion, long finger flexors
Sensory loss
If you have an injury to the ulnar nerve what would be the signs?
Motor loss: little finger abduction, interossei
Sensory loss
If you have an injury to the deep peroneal nerve what would be the signs?
Motor loss: dorsiflexion, toe extension
Sensory loss
If you have an injury to the superficial peroneal nerve what would be the signs?
Motor loss: Eversion
Sensory loss
If you have an injury to the tibial nerve what would be the signs?
Motor loss: Ankle plantarflexion, inversion, toe flexion
Sensory loss
What are two neuromuscular junction diseases?
- Botulism
* Myasthenia Gravis
What is the etiology of botulism?
- Neurotoxin produced by Clostridium Botulinum
- Anaerobic, gram-positive rods
- Found in improperly preserved or canned foods and contaminated wounds
What is the classification (mode of acquisition) of botulism?
- Food borne (ingested ex. Honey)
- Wound
- Unclassified
What is the mechanism of botulism?
- Botulinum toxin enters presynaptic terminals
- Blocks the fusion of ACh vesicles with presynaptic membrane (myoneural junction)
- Inhibits ACh release into neuromuscular junction
- Nerve impulse fails to transmit across the neuromuscular junction
- Muscle paralysis
What is the Incidence of Botulism?
- 10 adult and 100 infant cases in US each year (infant is 3 wk to 9 mo)
- Signs and symptoms- develop within 12-36 hours following ingestion
- Mortality rate- respiratory failure can occur in 6-8 hours so immediate treatment is crucial
- Gradual recovery over weeks/months- typically full recovery occurs
What are the Signs and symptoms of botulism?
- *Develop within 12-36 hours of ingestion
- Flaccid symmetrical paralysis of face
- Blurred and double vision, photophobia, ptosis (drooping of eyelids)
- Dry mouth, nausea, vomiting
- Lethargy
- Difficulty swallowing (dysphagia) and speech (dysarthria)
- can progress to respiratory failure in 6-8 hrs
- -No sensory involvement
- -Autonomic involvement
How do you prevent botulism?
- Boil food x 10 min will destroy the toxin
- Avoid honey for children under one year of age
- Appropriate wound care and sterile technique
What is the intervention for botulism?
- 8-20% overall mortality rate (fatal within 24 hours secondary to respiratory failure)
- ABE serum antitoxin
- Debridement and antibiotics for wound
- Removal of toxin from GI/pumping of stomach
- Supportive measures (ex. IV, mechanical Vent)
- Recovery: sprouting of new terminal nerve filaments and formation of new synapses
What is BoTox used for and who should prescribe it?
- It’s used for the management of spasticity after botulism or other injuries
- Physician should have experience in use, knowledge of indications, effects and safety in clinical practice
- Dysport and Botox type A toxins are both license medications for the treatment of focal spasticity
BoTox is used to treat spasticity in individuals with what injuries?
*Spinal cord injury
*Multiple sclerosis
*Dystonia
*Cerebral vascular accident
Traumatic Brain Injury
How does BoTox work?
- Prevents the relese of ACh from the presynaptic nerve terminal, thus blocking peripheral cholinergic transmission at the neuromuscular junction (NMJ)
- Dose-dependent, reversible reduction in muscle power
- The clinical effects are TEMPORARY. the toxin degrades and becomes inactive within the nerve terminal
- The NMJ atrophies and then regenerates with re-sprouting
- The muscle weakness resolves over 3-4 months
How is BoTox administered?
*Injected intramuscularly into specifically selected muscles so it can generate highly focal weakness
What should be considered when determining dosage of BoTox?
- Larger doses carry increasing risk of systemic adverse effects
- Dose should be reduced if target muscles are already weak or if there is an increased risk of side effects
- Pre-existing local tissue distruption, or conditions causing systemic weakness such as in myopathy, myasthenia gravis, motor neuron disease, or neuropathy should provoke extreme caution
When administering BoTox how do you plan the site of injections?
- Larger superficial muscles may be identified with knowledge of surface anatomy
- EMG, nerve or muscle stimulation or ultrasound my be needed for smaller muscles
- BEST site are the nerve end-plate zones deep in the muscle bulk
- Small and moderate sized muscles will respond to injection into muscle belly
- Some authorities recommend multiple scattered smaller injections
What are the duration of effects with BoTox?
- Botox is taken up by the NMJ within 12 hours
- Clinical effect occurs gradually over 4-7 days, occasionally longer
- Botox interferes with neuromuscular synaptic transmission for about 12-16 wks and causes clinically detectable weakness for 3-4 months, sometimes longer
What is the post-injection management for Botox?
- PT is Mandatory!
- Assess need for orthotics/splinting or review existing orthoses and assess pt compliance
- Provide pt education on stretching
- Take care not to over-stretch weakened muscles
- intensity should be graded over time to prevent intramuscular hematomas due to tearing of stiffened muscle fibers - Increase muscle strength of the opposing muscle groups; faciliate activity in opposing muscle groups
- consider other treatments that might enhance effects of botox like constraint therapy or Estim
What are the side effects of botox?
- Problems swallowing, speaking, or breathing due to weakening of associated muscles, can be severe and result in loss of life
- When given an inappropriate dose the effect of botox may affect areas away from the injection site and cause loss of strength and overall muscle weakness, double vision, blurred vision and ptosis, hoarseness or change/loss of voice (dysphonia), trouble speaking (dysarthria), loss of bladder control, trouble breathing, trouble swallowing
What is Myasthenia Gravis?
- Post-synaptic membrane disease at neuromuscular junction
- Acquired autoimmune disease
- 70% hyperplasia (overgrowth) of the thymus
- 10-15% tumors of the thymus
What is the mechanism of Myasthenia Gravis?
- Widened synaptic cleft
- Loss of folds- muscle endplate membrane
- Reduction in number and density of ACh receptors
- Results in weakness or paresis
- ACh neurotransmitter is less likely to find a receptor before it is hydrolyzed by ACHesterase
What is the prevalence of Myasthenia Gravis?
- 1 in 10-20,000
- Onset: 15-30 (women) years and 60-75 (men)
- Disease of younger females and older males (bimodal)
What is the disease progression of myasthenia gravis?
- Slow, progressive weakness (max weakness occurs in first year in 2/3 of all cases)
- after 15-20 years, weakness becomes fixed
- Remissions occur in about 25% of cases
What are the classifications of MG?
- Ocular Myasthenia (10-15%)
- Symptoms confined to extra-ocular muscles, mostly see diplopia and ptosis - Generalized weakness (85%)
- Myasthenic crisis: respiratory failure
What are the signs and symptoms of MG?
- Ptosis (CN 3)
- Diplopia
- Facial weakness (CN 7)
- Oropharyngeal weakness
- Chewing, swallowing and speaking difficulties
If you have MG where might you have weakness?
- BUE or BLE (proximal before distal)
- Respiratory muscles
- Weakness fluctuates (over hours, days, weeks)
- Better in AM, declines as the day progresses or during exercise
- Remissions and exacerbations
- Normal reflexes, sensory function and coordination
- Crisis- respiratory distress or swallowing crisis
What occurs with a diagnosis of MG?
- Presence of circulating antibodies to ACH receptors have been identified in the blood of 90% of MG pts
- antibodies cause ACH receptor changes and block ACH binding to receptors - Increased incidence of diabetes, lupus, RA, thyrotoxicosis and cancer in the MG population
- EMG
- Normal at rest
- Decremental response to repeated stimulation (mirrors fatigue with exercise)
What is the Tensilon Test with MG?
- Repetitive movements or holding a position
- Compare performance following giving Tensilon (Anticholinesterase) vs. Placebo (saline)
- Tensilon inhibits acetylcholinesterase (hydrolyzes ACH so it stays in the synapse longer)
- If strength/endurance is improved, then MG
**Muscle biopsies can be done: count the ACH receptors at motor end plates
What does anti-cholinesterase do?
*Slows down the breakdown of ACH which leaves acetate and choline in cleft (ACh is around longer, thus has an increased chance of binding to the receptor)
What are the immunosuppressive drugs used as an intervention in MG?
- Prednisone
- Cyclosporine
- Myophenolate Mofetil
- Azathioprine
What are the interventions used in MG?
- Anticholinesterase drugs
- Immunosuppressive drugs
- Intravenous Immunoglobulin (IVIG)
- Plamaphoresis
- Thymectomy
What is Plasmaphoresis?
- Blood is routed to a machine that separates the plasma and cells
- Plasma filtration: two venous lines are used. The plasma is filtered using standard hemodialysis equipment. This continuous process requires less than 100 ml of blood to be outside the body at one time
- Temporarily (4-6 wks) reducing anti-ACh receptors antibodies
What is a thymectomy?
- Mainly carried out in adults
- Role of the thymus: cause T-cell specific response
- 70% of MG pts have hyperplasia of thymus while 10-15% have tumors in the thymus
How should a PT care for a pt with MG?
- Have pts swallow with chin tucked to avoid aspiration
- Don’t speak with food in mouth
- Monitor tidal volume, vital capacity, and inspiratory force during PT
- Plan PT for time periods when have the most energy
What precautions should a PT show when working with a pt with MG?
- PT focus is usually supportive, obtain equipment, maintain health and function, exercise as tolerated
- Avoid strenuous exercise
- Excessive exposure to heat or cold can exacerbate symptoms
- Allow for regular rest periods for muscle recovery
- Osteoporosis may be a secondary complication from prolonged steroid use
What are the signs of impending MG crisis?
- *You should call EMS!!
- Increased muscle weakness
- Respiratory weakness
- Difficulty talking, chewing, or swallowing
What are the hyperkinetic disorders due to basal ganglia system pathology?
- Huntington’s Chorea
- Tourette’s Syndrome
- Dystonia- generalized and local
What are the hypokinetic disorders due to basal ganglia system pathology?
*Parkinson’s Disease
What is the basal ganglia composed of?
- Caudate Nucleus
- Putamen
- Globus Pallidus with related structures of Sub-thalamic nucleus and substantia nigra
How does the neural network of the basal ganglia work?
- There is no direct output to motor units (always through cerebral cortex)
- Mainly indirect effects on movement through cortex
*Basal ganglia output is to the thalamus, and thalamus influences the cortex. Any descending tracts that influence muscles come from the cortex. The BG system doesn’t directly effect the body, it’s through the thalamus/cortex
What are the parts to the substantia nigra and globus pallidus?
- Substantia nigra has two parts
- Substantia nigra pars compacta (SNc)
- Substantia nigra pars reticulata (SNr)
- Substantia nigra pars compacta (SNc)
- Globus Pallidus has two parts
- Lateral or external globus pallidus (LGP or EGP)
- Medial or internal globus pallidus (MGP or IGP)
What does the substantia nigra pars compacta do?
*This is the nucleus that degenerates and produces dopamine that happens over time with PD
What parts of the BG essentially function together?
*The caudate and Putamen = Striatum
The output from the thalamus to the cortex is what?
*Facilitory
The output from the cortex to the thalamus is what?
*Inhibitory
What is GABA?
*An inhibitory neurotransmitter
What is Huntington’s Chorea?
*Involuntary small amplitude, rapid movements
What occurs in Huntington’s Chorea?
- Results from degeneration of the striatal neurons to the SNr and LGP
- The thalamus inhibition is much less so it’s hyperkinetic and is overdriving the cortex
- The end result is the cerebral cortex is on over-drive (facilitated much more)
What are the symptoms of Huntington’s Chorea?
- Chroea
- Akinesia and bradykinesia
- Hypotonia
- Wide, staggering gait
- Cognitive Problems
What is Tourette’s Syndrome?
- Impulsions and compulsions to perform fragments of motor programs (Ex. touching, vocalizations, jumping, skipping)
- “Tics”
What does Tourette’s Syndome result from?
- Results from disturbance in the limbic circuits of the basal ganglia
- The limbic system inhibits the sunstantia nigra pars compacta so less excitation of direct pathways of BG system > End results is that the cortex is on overdrive
What is Dystonia?
*A movement disorder characterized by sustained muscle contraction in an extreme end range of motion, frequently with a rotational component