Lecture 8: Peripheral Nervous System Disorders Flashcards
UMN lesion
* What are reflexes like? (2)
* What is tone like (2)
* What happens to babinski sign?
* What happens to muscles innervates from these nerves
Reflexes are normal or hyperactive
Tone = spasticity or hypertonicity
Positive babinski sign
Muscle atrophy
LMN
* what are reflexes like? (2)
* What is tone like (2)
* What is babinski sign like?
* What happens to muscles innervated by these nerves
Reflexes are normal or hypoactive
Tone = hypotonicity or flaccidity
Negative babinski sign
muscle atrophy
Spinal region segmental signs occur when what two areas are compromised?
* sensation is lost in what kind of pattern?
* Muscle power is lost in what kind of pattern
* What happens to phasic stretch reflex?
Compromised:
* Nerve roots
* Spinal nerves
Sensation is lost in a dermatomal pattern
Muscle power is lost in a myotomal pattern
Decreased or lost phasic stretch reflex
* where hyporeflexive w/ LMN
Nerve root vs peripheral nerve PNS
Combined sensory and motor monosynaptic stretch reflex
reflex requires sensory and motor to come together and work
* goes to the SC then back to motor units (skips brain)
This is differentiating CNS from PNS
Spinal region/vertical tract signs:
* Where is snsation lost?
* What happens to tone below the level of lesion?
* what happens to muscle power
* if the corticospinal tract is involved what two things hapens?
Sensation is lost below level of lesion (NOT AT LEVEL OF LESION)
KNOW: They’re also going to lose decending control of BP, pelvic viscera and thermoregulation
hypertonia/spasticity
Decrease in muscle power
corticospinal tract invovled = babinski / clonus
Peripheral region lesions produce deficits in the distribution of a peripheral nerve
* What kind of distribution is sensation lost in?
* What is muscle power loss distribution?
* Are there vertical tract signs?
* What happens to phasic stretch reflex? (think patellar reflex)
In a peripheral nerve distribution loss of sensation
Loss/decrease in muscle power in a peripheral nerve distribution
No vertical tract signs - SC unaffected here
Decreased or lost phasic stretch reflex
Dermatomes
L2 spinal cord injury will the pt have hip flexion?
Yes, its loss below the level of the lesion
knowledge check: our damage is in a dermatomal distribution. What is likely injured a peripherl nerve or a spinal nerve
spinal nerve presents in a dermatomal fashion
Complete transection/serverd neuron?
Neurotmesis
Neuropraxia means
Compression
crush or stretch injury of nerve
axonotmesis
Case: A tennis player fell on her shoulder during a tennis match. Her shoulder was tractioned away from her head resulting in a traumatich stretch on the C5 and C6 nerve roots
* Which movements of the arm will likely be weak
* Where are on her arm will she have altered sensation?
* What type of damage in this
Elbow flexion/Wrist extension and down
* for dermatomes / myotomes its at the level of the lesion. This makese sense, if the spinal nerve is impinged it will go out in that pattern
Altered sensation on the side of the arm (learn new dermatomes I guess)
Axonomesis - think stretch
In a spinal cord injury where is the pathology
In a Spinal nerve injury where is the pathology
SC = below level of lesion
Spinal nerve = pathology at level of lesion
* spinal nerves go streaight out to innervate what they need. This makes sense
Case: A 32 year old computer programmer developed 2 months of worsening tingling and numbness in his left fith digit, in the medial aspect of his left fourth digitm and along the medial surface of his left hand and forearm. Symptoms were worse upon awakening in the morning, and were exacerbated after resting his elbows on a hard surface
* which nerve is involved
* What type of dmaage
* Where is the damage coming from?
Nerve = ulnar n
Type of damage = neuropraxia (hes resting his arm down)
Damage is coming from the nerve (peripheral nerve)
Knowledge checK: stretch to nerve = axonomesis
What records the activity of the muscle at rest, with voluntary movement and with e-stim
* looking for damage related to the striated muscle (skeletal muscle)
* EX = myopathy - damage to the muscle or neuromuscular junction
EMG
Measures the conduction time and amplitude of an electrical stimulus along a peripheral nerve (sensory or motor nerves)
* looking for damage to the nerve cell body or the nerve axon
* EX: peripheral nerve injury
Nerve conduction velocity (NCV)
EMG
* Invasive?
Tests muscle activity?
Tests nerve activity?
Looking for?
Yes
Tests muscle activity not nerve activity
Looking for motor unit potential
NCV
* invasive?
Tests muscle activity?
Tests nerve activity?
Looking for?
No
Does not test muscle activity but may produce a muscle contraction due to the electricity
Tests nerve activity
CMAP or SNAp (compound motor action potentail or sensory nerve action potential)
notice - nerve conduction velocity is not invasive, you’re not actually stucking a needle into a nerve. its that tool that hes putting over the skin to the right on the picture below
in nerve conduction velocity testing how much of the nerve being blocjed constiutes a block?
40% being blocked
NOTE: EMGs not always invasive, could be a surface electorde
Needle is inserted into the muscle belly at multiple points to get the EMG reading
KNOW: Nerve conduction velocity = asseses the action of nerves not muscles
Cranial nerve function
Know: Cranial nerve disorders = peripherla nerve disorders
Anosmia
* what nerve dysfunction?
* 3 causes
Inability to smell
Olfactor (CN1) dysfunction
causes:
* Common cold
* Trauma to the cribiform plate
* Meningioma
KNOW: The right half of each eyes visual field is recorded by the left half of each retina
* right half of each eye goes to the left vision field
The left half of each eyes visual field is recorded by the right half of each retina
Diplopia
double vision
What nerve is damaged in monocular blindness
optic nerve
Visual field cut/visual loss
Hemianopsia/Hemianopia (hemi meaning half)
* Can can bitemporal (lost the temporal region of each side) but not binasal
* can be homonymous (same visual field in both eyes) - homo means the same
Explain L homonymous Hemianopsia
Explain R homonymous Hemianopsia
* what treatment would you use?
Left Homonymous Hemianopsia
* Means they cant see the left visual field - named for the visual field that they cannot see
* Meaning the right half of each eye isnt working
* Meaning the right optic tract is damaged
Right Homonymous Hemianopsia
* Means they cant see the right visual field
* Meaning the left half of each eye isnt working
* Meaning the left optic tract is damaged
Issue with the left cerebral cortex (stroke)
Have pt do visual scanning
* just tell them to turn their head
* i can scan to take in other side of visual field
* So it is treatable, we can treat someone w/ this
Example of R homonymous Hemianopsia
What homonoys hemianopsia is this
* Which visual field of the right eye is imapcted
* Which visual field of the left eye is imapcted
* which side of each eye is impacted
* Which optic tract is impacted
Remember its named for the side they cannot see. This is left homonyous hemianopsia
* Nasal visual field deficit of the right eye
* Temporal visual field deficit of left eye
Left visual field isnt working (can tell becase they cant see to the left side)
This means the right side of each eye is not working
Meaning the right optic tract is damaged
A lesion in the optic nerve yields what?
Monocular vision (ipsilatearl vision loss)
What is ipsilateral vision loss?
Monocular vision (due to optic n lesion)
A lesion in the optic chiasm yields what kind of vision loss?
Bitemporal hemianopsia aka tunnel vision
* named for what they cant see, so they can’t see the temporal portion bilatearlly
Lesion in the optic tract/optic radiation leads to what?
Homonymous Hemianopsia
the lump near the optic tract = optic radiation