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
Triceps
Triceps- C6, C7
Flat or point end on triceps tendon above olecranon
Patellar
Patellar- L2,3,4
Flat end on patellar tendon below patella above tibia
Achilles
Achilles- S1
Flat end on achilles tendon above calcaneus
DTR scales
0 = Absent 1+ = Diminished 2+ = Normal/Average 3+ = Mildly over-active 4+ = Highly over-active
What are common exam findings in UMN lesion?
Spasticity is hallmark hypertonic muscle DTR increased Loss of dexterity Up Going Babinski (abnormal) Loss of superficial reflexes Weakness without atrophy of muscle Hyperreflexia of deep tendon reflex (DTR) only slight atrophy from disuse
- could be: stroke, MS, traumatic brain inj, amyotrophic lateral sclerosis
What are common exam findings in LMN lesion?
Flaccid paralysis Muscle atrophy/wasting is pronounced Hyporeflexia Flaccid/hypotonic DTR is low or absent superficial reflexes are fine
- could be polio,
- guillain-barre (see progressive weakness),
- amyotrophic lateral sclerosis (ALS- rapidly progressive weakness, muscle atrophy and fasciculations, muscle spasticity, difficulty speaking)
what do you see with polio, or ALS?
- Anterior Horn Cell: Polio, Amyotrophic Lateral Sclerosis (ALS)
- Fasciculations (small, local contractions seen through the skin)
- weakness in a segmental pattern
- Sensation intact
- Weak DTR
sx of herniated disc?
problem with spinal nerve roots
Dermatomal Sensory Changes
Weakness ⇨ Atrophy
Weak DTR
sx of carpal tunnel syndrom and bells?
peripheral mononeuropathy
Weakness and sensory loss in that peripheral nerve distribution
Weak DTR
sx of diabetes, alcoholic neuropathy?
peripheral neuropathy
Distal weakness and stocking-glove distribution sensory loss
Weak DTR
mononeuropathy vs. polyneuropathy?
Mononeuoropathy = single nerve involved
Polyneuropathy = “peripheral neuropathy” = multiple tracts involved
Can also have pain only in the same distribution
myasthenia gravis?
- problems at the NMJ
Muscular fatigability
Sensation intact
DTR intact
muscular dystrophy?
muscle fiber itself deteriorates
Weakness primarily in proximal muscles
Sensation intact
DTR intact or possibly decreased
skin pathches of hand?
radial nerve? mostly on dorsum of hand, fingers 1-4
ulnar nerve? fully pinky and half of fourth finger
median nerve? fingers 1-4 of palm and upper portion of fingers 1-4 on hand.
- know these * look at picture
upper brachial plexus injurty
- stretching of the neck away from the shoulder: birth trauma (pulling out by head), falling on neck
- cause damage to C5,C6 nerve root motor and sensory problem
- results in waiters tip position commonly seen: he will not have equal contraction of C5,6
lower brachial plexus injury
(less common) - results from arm being pulled superiorly, catching something overhead, birth trauma (pulling out by arm)
- creates thoracic outlet syndrome
- C8,T1 motor palsy/weakness
Thoracic outlet syndrome
Cause: Compression of the brachial plexus
- Between anterior scalene and medial scalene or cervical rib
- Between the clavicle and 1st rib
- Between the ribs and the pectoralis minor m.
Results: Weakness and numbness of the hands and arms due to compressed neurovascular supply.
You’ll be thinking of TOS often when seeing people for neck, shoulder and arm symptoms either paresthesia or pain
Tests for TOS?
Roo’s test: Arms abducted to 90°, externally rotated with elbows bent at 90°, and extended to feel tension across the chest. Then the patient slowly opens and closes his hands for 3 minutes. If there is weakness, numbness or tingling of the hand or arm the test is positive. (trying to reproduce the symptoms)
Adson’s Test: - The same position as above but with one arm. Feel the pulse at the wrist then ask the pt. to turn their head to the opposite direction. If the pulse disappears then the test is positive. Some versions have patient turn head toward the same side.
long thoracic nerve injury
Causes:
Compression between clavicle and 1st rib
Axillary surgery
Results:
Damage in C5-7 region
Weak Serratus Anterior m. (winging of the scapula)
median nerve injury
- Crush Injury
- Pronator syndrome
- Carpal tunnel syndrome
- Entrapment of median nerve in the carpal tunnel
- Wrist slashing
- Palm injury/laceration
- Recurrent Branch of the Median Nerve
will result in ape hand deformity: Damage in the C6-T1 region proximally or distally
- Weak forearm pronation, wrist and digit flexion, thumb abduction and opposition; dropping things.
- Atrophy of the thenar muscles
- Paresthesias or loss of sensation to lateral palm, thumb, index & middle finger
resisted pronation test?
pronator syndrome = (Median N. pinched between the two heads of the pronator teres from trauma, m. hypertrophy, fibrous bands)
Resisted Pronation : Examiner resists the patient’s effort to pronate. Tingling along the forearm and lateral hand indicates a positive test for median nerve impingement by the pronator teres (the most powerful pronator m)
anterior interosseus neuropathy
test for median n.
Causes:
- Pronator teres impingment of Anterior Interosseus N.
- Trauma; Tennis Elbow strap too tight
Results:
- Weak flexor digitorum profundus & flexor pollicis longus
Test: Pinch grip “OK” sign
Inability to pinch the fingers together tip to tip
tests for median n?
Tinel’s sign at the wrist- The examiner taps the palmar side of the wrist with their finger or reflex hammer. It is a positive test is pain or tingling occurs in the thumb and first two fingers (carpal tunnel syndrome).
Phalen’s Test- Patient flexes both wrists by putting the back sides of the hands against each other for about one minute. Pain, numbness or tingling in the hands and indicates median nerve impingement.
Reverse Phalen’s (Prayer Test)- The same result as above can be obtained by extending the wrists and putting the palms together in a “praying position
what causes ulnar nerve injury?
Fracture of the humerus near medial epicondyle
Cubital Tunnel Syndrome
Trauma or entrapment of the ulnar nerve as it passes behind the medial epicondyle
Laceration near the wrist
Entrapment at Guyon’s canal
Guyons canal syndrome
This syndrome is also known as an ulnar nerve entrapment at the wrist. At the wrist, The ulnar nerve enters Guyon’s canal along with the ulnar artery, which runs just lateral to the nerve. This canal runs along the lower edge of the palm, on the little finger side of the hand. In the middle of the canal, the ulnar nerve splits into its two terminal branches (deep and superficial) that go on to the palm, ring and little fingers.
ulnar nerve injury results
Damage in the C6-8 region
Paresthesias or loss of sensation of the medial part of the palm and 4th & 5th digits
Weak wrist flexion and adduction (weak flexor carpi ulnaris)
Weak finger abduction & adduction (weak interossei)
Loss of thumb adduction (lost adductor pollicis)
Loss of MCP flexion in 4th & 5th digits (lost lumbricals)
CLAW HAND
claw hand
Extended 4th and 5th MCP joints (lost 3rd and 4th lumbricals)
Flexed 4th and 5th PIP (functional flexor digit. Superficialis)
Weak flexion of 4th and 5th DIP joints (weak flexor digit. profundus)
radial nerve injury
Causes
Fracture of the humerus near the radial groove
“Saturday Night Palsy”: compression by sleeping with arm under head
Results: Damage in the C7-T1 region Sensory loss to the back of the hand Wrist Drop Weak brachioradialis, supinator, wrist & digit extensors
cubital tunnel syndrome tests?
Tinel’s sign at the elbow- Tap on the ulnar nerve where it runs behind the medial epicondyle of the elbow. A tingling in the medial hand indicates a positive test for ulnar nerve impingement. This is what usually occurs when “you hit your funny bone” and your forearm and hand tingles.
Wartenberg’s Sign- Passively abduct the patients fingers and then resist the patient’s attempt to bring them back together. Inability to bring adduct the pinky finger indicates a positive test for ulnar neuropathy.
Sciatic nerve injury? causes? results?
Causes:
Disc compression on the L4 &/or L5 nerve roots
Piriformis Syndrome
Posterior hip dislocation
Misplaced intramuscular injection
Gunshot or stab wounds to the medial buttock
Surgery
Results:
SCIATICA- pain in the path of the sciatic nerve
STEPPAGE GAIT- weakness or paralysis of hamstring muscles and thigh extensors and all muscles below the knee (hamstring paralysis = loss of thigh extension and knee flexion)
superior gluteal nerve injury tests?
TRENDELENBURG GAIT- weak hip abductors and external rotators (gluteus medius)
- Weak gluteus medius on standing side: cannot hold the opposite hip level.
lateral femoral cutaneous nerve injury?
Causes: Compression at the iliac crest (belts, seats, large bellies)
Results:
Numbness over the lateral thigh
common fibular/peroneal nerve injury?
Causes:
- Impingement by piriformis (sciatic n.)
- Proximal fibular fracture
- Stretched from a varus stress (with lateral collateral ligament )
- Compressed by casting
- Surgery
Results:
- Paralysis of dorsiflexors and everters
- Loss of sensation of anterolateral leg & dorsum of foot
- FOOT DROP: Patient displays HIGH STEPPING GAIT and FOOT SLAP
superficial fibular/peroneal nerve injury?
Causes:
- Proximal fibular fracture
- Stretched with varus stress
- Compressed by casting
- Surgery
Results:
- Paralysis of foot everters; NO foot drop
- Loss of sensation of the anterolateral leg and dorsum of the foot
deep fibular/peroneal nerve injury?
Causes:
- Anterior Compartment Syndrome
- Anterior Tarsal Tunnel Syndrome
- Pes Cavus (high arch)- less space under the retinaculum
- Tight shoelaces
- Trauma
Results:
Weak dorsiflexors
FOOT DROP
when do you see foot drop?
both with common or deep fibular n. (not superficial!)
medial plantar nerve injury?
- often seen in runners
Causes: - Entrapment in the longitudinal arch
- Joggers Foot- valgus hindfoot & pes planus
Results: - Aching pain in arch and burning/paresthesia in the medial plantar surface
diabetic peripheral neuropathy?
Estimated 42% of DM patients will develop neuropathy 10 years after diagnosis.
SX:
- Paresthesias and pain of feet > hands : Intense burning especially at night in the distal extremities (Bilateral Stocking and Glove distribution)
- Loss of vibratory, pain, temperature, light touch sensations.
- Loss of proprioception can cause ataxia and steppage gait
- Decreased reflexes may occur
- Weakness and atrophy of interossei mm. (later stages)
Myasthenia Gravis?
Myasthenia Gravis: fatigability, not weakness
- Autoimmune disorder of neuromuscular junction with antibodies against postsynaptic acetylcholine receptor and disturbed T cell function
Common presenting complaint/signs: Fatigue or proximal muscle weakness Droopy eyelids (ptosis) Double vision (diplopia) Trouble swallowing (dysphagia) Trouble speaking (dysarthria) Dyspnea and respiratory muscle weakness (later stages) No sensory loss or altered reflexes.
