PNS exam Flashcards
Scope of the nervous system: CNS
Cortex Basal Ganglion Brain Stem Cerebellum Spinal Cord
Scope of the nervous system: PNS
Cranial Nerves Motor Efferents Sensory Afferents Neuromuscular Junction Muscle itself
Narrowing the scope
Narrow the picture as much as possible using a good history. Look to answer these questions:
Local or diffuse?
Restricted to nervous system or include other systems? (fracture? Subdural hematoma? Tumor growth?)
CNS, PNS or Both?
Goal:
Get to WHERE the lesion is; the origin
Then you can develop a meaningful “WHAT the lesion is” differential. Don’t jump too fast!
What the central nervous system does
Mental Status and Cognition
Coordination
Cranial Nerves (technically peripheral nerves)
What the PNS does
Peripheral Nervous System
Motor: Strength and Motion
Sensation
Reflexes
The neuro exam should contain assessment 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
Peripheral nerves…
Nerves outside the Brain and Spinal Cord
Carry impulses to and from the Cord
Posterior Root = Sensory
Anterior Root = Motor
Peripheral Nerve is merged roots = Both
Sensory Pathway
Sensory fibers travel through peripheral nerves to the spinal cord.
Peripheral nerves enter the cord through the posterior horn.
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.
Both types of sensory tracts exit the thalamus to the sensory cortex for interpretation.
2 distributions your exam must include
dermatome and cutaneous peripheral
Where can sensory and motor abnormalities be traced to?
Sensory and motor abnormalities can be due to disease/lesion at any level of the central or peripheral nervous systems:
Cerebral hemisphere (sensory cortex or subcortical connecting fibers) Thalamus Brainstem Spinal cord Peripheral nerves or roots of nerves
Lesions in thalamus or cord may manifest as ipsilateral or contralateral depending on the fibers involved
Motor Pathway
Signal begins in the cortex as upper motor neurons.
These travel to the lower medulla to form the pyramids.
Decussation occurs and the tract continues downward as the corticospinal (pyramidal) tract.
Synapses occur along the way between the corticospinal tract and the lower motor neurons found in the anterior horn of the spinal cord at each vertebral level.
Lower motor neuron axons run out the anterior root, short spinal nerve, combine with efferent sensory fibers as peripheral nerves and end as a neuromuscular junction.
corticobulbar tract
Corticobulbar tract is the motor connection that ends in the medulla, exits for function there. (head, face)
2 divisions of the motor pathway
Upper Motor Neurons: Originate in the cortex to become the motor fibers above the anterior horn of the spinal cord or motor nuclei of the cranial nerves
Lower Motor Neurons: Emanate from the anterior horn of the spinal cord and take the motor signal peripherally to the muscle.
Peripheral motor sensory system
History and presentation of peripheral nerve disorders
Most Common Complaints
Pain
Weakness
Paresthesia (numbness/tingling)
Be specific, define the detail Associated Features: swelling, rash, spasm, deformities, mental status Trauma/Surgery/Medications/Supplements Personal/Family History autoimmune, dystrophies, diabetes, DJD
Not what just is at the moment, but what has changed will give good clues.
Most Common Causes
of PNS trouble
Ischemia (arterial stenosis)
Bleeding (TIA,CVA)
Mass/tumor (impingement)
Peripheral nervous disorders (MS, Guillian Barre)
Neuromuscular disorders (myasthenia gravis)
Muscular disorders (dystrophies)
Dysesthesia
all types of abnormal sensation including pain regardless of a stimulant being present or not
Paresthesia
mostly numb, tingling, pins & needles without pain and without apparent stimulus
Anesthesia
absence of sensation
Hypesthesia or hypoesthesia
reduced sensitivity
Hyperesthesia
Increased sensitivity
Hyperalgesia
significant pain in response to mildly painful stimulus (sharp)
Allodynia
non-painful stimulus perceived as painful on the skin, sometimes severe (soft touch)
5 types of sensation
Pain: pin or sharp end of broken Q-Tip
Temperature: Metal hammer handle is cool
Light touch: Q-Tip, Cotton wisp
Proprioception (Position): Large Toe: up? down?
Vibration: Tuning fork on boney prominence
COMPARE SIDE TO SIDE , proximal and distal in a pattern that covers both dermatomes and major peripheral cutaneous regions.
Instructing the patient to close their eyes enhances sensitivity
Map out any area found abnormal, find the boundaries
spinothalamic sensaion
pain and temperature
posterior column
proprioception, vibration
Discriminative Sensation Exam: Test cortical sensory function
Stereognosis: Identify an object by feel-a
2-point discrimination-b
Number Identification: Graphesthesia, Identify shapes/numbers-c
Motor exam
Side by side comparison: Inspection: atrophy Palpation: tone, soft, firm. Spasm? Strength testing: major muscle groups Reflexes: brainstem, superficial, deep, clonus
Muscle Strength (again)
Measurement Scale of 0-5 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
COMPARE SIDE TO SIDE
Name for joint motions or muscle group
“4/5 left bicep” or “4/5 flexion at left elbow”
