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”
Dysesthesia/paresthesia in a saddle distribution:
think cauda equina issues, check an anal reflex
Babinski may be positive in CNS disorders as a part of upper motor neuron problems: ALS, CVA, Head Injury, MS
Deep Tendon Reflexes
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- C6, C7
Flat or point end on triceps tendon above olecranon
Patellar- L2,3,4
Flat end on patellar tendon below patella above tibia
Achilles- S1
Flat end on achilles tendon above calcaneus
Deep tendon grading scale
0 = Absent 1+ = Diminished 2+ = Normal/Average 3+ = Mildly over-active 4+ = Highly over-active
DTR exam tips
Make sure patient is relaxed
Palpate location of DTR strike prior to striking
Use a quick wrist flick of moderate strength
NO MORE THAN 3 strikes on any one DTR location
Use distraction/reinforcement techniques
jaw clinch for bicep/tricep
clasped hand pull for knee/ankle
Reinforcement: engage bilateral muscle groups ABOVE the level being tested to block any run away motor neuron signals going up to enhance the reflex signal.
Upper Motor Neuron Lesion
Spasticity is hallmark (not 100%)
Loss of dexterity
Up Going Babinski (abnormal)
Loss of superficial reflexes
Weakness without atrophy of muscle
Hyperreflexia of deep tendon reflex (DTR)
Etiologies:
Stroke
Multiple Sclerosis
Cerebral Palsy
Traumatic Brain Injury
Amyotrophic Lateral SclerosisLower Motor Neuron Lesions
Lower Motor Neuron Lesions
Flaccid paralysis
Muscle atrophy/wasting
Hyporeflexia
Etiologies:
Polio
Guillain-Barre
Amyotrophic Lateral Sclerosis (ALS)
Spinal cord injuryUMN synopsis
Paralysis of movement, not muscle Atrophy from disuse, slight Spasticity, hypertonic DTR increased Babinski up going
LMN synopsis
Paralysis from muscle atrophy Wasting pronounced Flaccid, hypotonic DTR decreased or absent Absent Babinski
Peripheral nervous system disorders
Polio, Amyotrophic Lateral Sclerosis
- Herniated Disc
- Carpel Tunnel Syndrome, Bell’s Palsy
- Diabetes, Alcoholic Neuropathy
- Myesthenia Gravis
- Muscular Dystrophy
Where do ALS and polio affect?
anterior horn
where do carpal tunnel and bells affect?
along the course of the nerve
where does myasthenia gravis affect?
Neuromuscular junction
Anterior Horn Cell problems
Polio, Amyotrophic Lateral Sclerosis (ALS)
Fasciculations and weakness in a segmental pattern
Sensation intact (why?)
Weak DTR
Spinal nerve root problems
Herniated disc
Dermatomal Sensory Changes
Weakness ⇨ Atrophy
Weak DTR
Peripheral mononeuropathy
Carpal Tunnel Syndrome, Bells
Weakness and sensory loss in that peripheral nerve distribution
Weak DTR
Peripheral polyneuropathy
Diabetes, Alcoholic Neuropathy
Distal weakness and stocking-glove distribution sensory loss
Weak DTR
. Neuromuscular junction trouble
Myasthenia Gravis
Muscular fatigability
Sensation intact
DTR intact
Muscle trouble
Muscular Dystrophy
Weakness primarily in proximal muscles
Sensation intact
DTR intact or possibly decreased
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.
Thoracic outlet syndrome tests
Roos and Adson’s
Upper brachial plexus injury
waiter’s tip
Lower Brachial Plexus Injury (less common)
The arm being pulled superiorly Catching something overhead Birth trauma (pulling out by the arm) Thoracic outlet syndrome C8,T1 motor palsy/weakness
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 causes
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
tests for carpal tunnel
(median nerve)
Tinel’s sign
Phalen’s test
Reverse Phalen’s (Prayer Test)
“Do you get symptoms during sleep?”
MEdian nerve injury results
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
Ape hand deformity
test for pronator syndrome
(median nerve)
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
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
Can also check muscle strength
5-10% difference in strength in normal persons between dominant and non-dominant
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
Ulnar nerve injury
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
Tinel’s sign
(at the elbow)
“funny bone”
Sciatic nerve injury
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: Bates 11th p. 759
Superior Gluteal Nerve Injury
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, prolonged standing)
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
Medial Plantar Nerve Injury:
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.
Multiple etiologies suspected to damage peripheral nerves faster than they can heal
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 (Bates p. 730)
Decreased reflexes may occur
Weakness and atrophy of interossei mm. (later stages)
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.
screening neurologic exam
The 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
