PNS Flashcards
what does screening neuro exam composed of?
- Mental Status: alertness, appropriate responses, orientation to date and place
- Cranial Nerves: acuity, pupillary light reflex, eye motion, hearing, facial strength
- Motor: major muscle group strength upper and lower extremity, gait, coordination (finger to nose)
- Sensory: test toes/feet – one modality of light touch, pain, temp or proprioception
- Reflexes: DTR upper/lower, Babinski
posterior root
sensory
- Fibers conducting pain, temperature and crude touch cross over and ascend as the spinothalamic tract to the thalamus.
- Fibers conducting position, vibration and fine touch ascend on ipsilateral side as the posterior column to the medulla, then decussate and go to the thalamus.
anterior root
motor
dermatome
band of skin/tissue innervated by the sensory root of a single spinal nerve.
- The strength of this knowledge is being able to distinguish the source of the complaint more quickly: if Pt complains of lateral lower leg numbness only, and your exam finds localization in this area, it is more likely (but not 100%) to be a common peroneal nerve issue than L5 nerve root impingement.
UMNs
Originate in the cortex to become the motor fibers above the anterior horn of the spinal cord or motor nuclei of the cranial nerves
LMNs
Emanate from the anterior horn of the spinal cord and take the motor signal peripherally to the muscle.
- Peripheral motor sensory system
Paresthesia
numbness/tingling
Most common causes of PNS sx:
Ischemia (arterial stenosis)
Bleeding (TIA,CVA)
Masses (impingement)
Peripheral nervous disorders (MS, Guillian Barre)
Neuromuscular disorders (myasthenia gravis)
Muscular disorders (dystrophies)
dysethesia
sensation described by patient
- all types of abnormal sensation including pain regardless of a stimulant being present or not
paresthesia
any sensation that doesn’t include pain, mostly tingling, pins and needles without apparent stimulus
- this is described by patients
hypesthesia/hypoeshesia
sensations found on exam
: reduced sensation to a particular test (touch,sharp)
herperesthesia
sensation found on exam
pain in response to mostly touch
hyperalgesia
sensation found on exam
severe pain in response to mildly painful stimulus (sharp)
allodynia
sensation found on exam
non-painful stimulus perceived as painful on the skin, sometimes severe
5 types of sensation ?
Pain: pin or sharp end of broken Q-Tip (spinothalamic)
Temperature: Metal hammer handle is cool (spinothalamic)
Light touch: Q-Tip Cotton wisp
Proprioception (Position): Large Toe: up? down? (posterior column)
Vibration: Tuning fork on boney prominence (posterior column)
stereognosis
close patients eyes and have them feel and identify common objects
- this is a discriminative sensation exam to test cortical sensory function
what are discriminitive sensation exmas
test cortical sensory function - stereognosis - 2 point discrimination - number identification - extinction: The student will simultaneously touch two corresponding areas on both sides of the patient’s body, asking where they feel the touch. Normally both sides are felt. If not, the side that isn’t felt is considered extinct in sensation.
muscle strength scale
0= no movement 1= muscle twitch without joint movement 2= movement with gravity eliminated 3= full strength against gravity only 4= partial strength against resistance 5= full strength against resistance
clonus reflex check
- seen in UMN lesions of the CNS
- is a series of involuntary, rhythmic, muscular contractions and relaxations.
- ex. quick dorsiflexion of ankle, and let go, will see the foot tremor
monosynaptic reflexes
occurs at the level of the cord only, not processed in the brain
Muscle spindle fires a signal along sensory efferents, they connect specifically to alpha motor neurons in cord and fire back directly
plantar (babinski) reflex
downgoing is normal = toes curl
- problem in L5-S1
- Babinski may be positive in CNS disorders as a part of upper motor neuron problems: ALS, CVA, Head Injury, MS
anal “wink” reflex
cauda equina
S2-4
- Dysesthesia/paresthesia in a saddle distribution: think cauda equina issues, check an anal reflex
abdominal reflex
T8-10 or T10-12
DTRs in CNS vs PNS disease….
CNS, DTS are usually increased
PNS, DTS is usually decreased
Brachioradialis
C5, C6
Point end into proximal muscle belly
Flat end on distal tendon
Biceps
C5, C6
Point end onto thumb lying over tendon