Radiculopathy Flashcards
Radiculopathy is most commonly caused by compression of _____ or _____
nerve root, or disc herniation
What are the different degenerative changes of the spine (3)
- osteophytes
- facet hypertrophy
- ligamentous hypertrophy
also disc herniation or less commonly, trauma (root avulsion)
____ is the cutaneous area supplied by one sensory nerve root level
dermatome
Long thoracic nerve supplies which muscle
serratus anterior
subscapular nerve supplies which 2 muscles
teres major
subscapularis
which muscle does the lateral pectoral nerve supply?
pectoralis major
which two muscles does the axillary nerve supply
deltoid
teres major
what muscle does the dorsal scapular nerve supply
rhomboids
____ All the muscles that are innervated by a single ventral root
myotome
name the types of herniation:
Central
Paramedian (Lateral recess): subarticular (anterior SAP)
Foraminal (Far lateral): between pedicles
Extraforaminal: lateral to pedicle
Lateral herniation: compresses ____
Medial herniation compresses the _____
Lateral herniation: compresses the lower nerve root (radiculopathy)
Medi1al herniation: compresses the spinal cord (myelopathy)
midline herniaion compresses the
parasagittal herniation compresses the
far lateral herniation compresses the
Midline herniation: compresses the traversing nerve roots and/or cauda equina (L4-5 disc bulge = L5/S1/S2 radiculopathy)
Parasagittal herniation: compresses the traversing nerve root (L4-5 disc bulge = L5)
Far lateral herniation: compresses the exiting nerve root (L4-5 disc bulge = L4)
Most common location for disc herniation
type?
which nerve root?
posterolateral disc herniation
L4-5 disc herniation = L5 radiculopathy
Nerve root:
Pain location: paraspinal muscles, superior shoulder
Sensory disturbance: neck
Weakness: diaphragm, nuchal muscles, strap muscles
Reflex change: None
C3-4
Nerve root:
Pain location: neck shoulder, anterior arm
Sensory disturbance: shoulder
Weakness: deltoid, SS/IS, rhomboids, biceps, brachoradiolis
Reflex change: Biceps, BR
C5
Root:
Pain Location: neck, shoulder, anterior upper arm, extending to antecubital fossa
Sensory disturbance: Thumb, index finger, radial forearm
Weakness: deltoid, SS, IS, biceps, BR, PT, FCR, ECR
Reflex change:
Biceps, BR
all muscles are innervated by atleast 2 root levels except:
rhomboids C5
Root:
Pain Location: neck, shoulder, dorsum of forearm
Sensory disturbance: middle finger
Weakness: triceps, lats, PT, FCR, ECR
Reflex change: Triceps
C7
Root:
Pain Location: neck, shoulder, ulnar forearm
Sensory disturbance: ring, little fingers, hypothenar eminence
Weakness: intrinsic hand muscles, finger extensors, finger flexors
Reflex change: none
C8
Root:
Pain Location: neck, shoulder, ulnar arm
Sensory disturbance: ulnar forearm
Weakness: intrinsic hand muscles (horners syndrome)
Reflex change: none
T1
Root:
Pain Location: anterior thigh, groin
Sensory disturbance: anterior thigh
Weakness: iliopsoas, adductors, quads
Reflex change: knee
L3
Root:
Pain Location: anterior thigh
Sensory disturbance: medial calf, medial foot
Weakness: quads, adductors (iliopsoas)
Reflex change: knee
L4
Root:
Pain Location: Posteriolateral thigh and calf, extending into great toe and dorsum of foot
Sensory disturbance: dorsum of foot, great toe, lateral calf
Weakness: tib ant, tib posterior, ext hallucis longus, peronei, gluteus medius, TFL
Reflex change: None
L5
Root:
Pain Location: posterolateral thigh and calf, extending into lateral toes and heel
Sensory disturbance: lateral foot, posterior calf, sole of foot
Weakness: gastroc-soleus, hamstrings, gluteus maximus
Reflex change: ankle
S1
What is the most common radiculopathy?
1. with percentage
2nd most common?
Lumbar 62-90%
L5
S1
Thoracic < 2%
Cervical 5-36% of all radiculopathies
What are the most common cervical radiculopathies?
C7: 70%
C6: 19-25%
C8: 4-10%
C5: 2%
What are the elecrodiagnostic criteria for radiculopathy? (3)
which gives definitive diagnosis?
Abnormal findings in two or more muscles that receive innervation from the same root, preferably via different peripheral nerves
Normal findings directly above and below the affected root level
Definitive Diagnosis: paraspinal involvement
what is the protocol for assessing radiculopathy
1 At least 1 motor and 1 sensory NCS in most relevant area
(If abnormal, or if polyneuropathy suspected, further evaluation should be performed of either ipsilateral or contralateral limbs to define the cause of the abnormality)
2 Examine at least 5 muscle of involved limb
3 Examine at least 1 muscle innervated by each root level
- Examine 1 or 2 additional muscles innervated by the suspected root and a different peripheral nerve
- Demonstrate normal muscles above and below the involved root
4 Examine paraspinal muscles (except for sacral radiculopathies or prior posterior spine surgery)
Which is the deepest paraspinal muscle?
a. semispinalis
b. multifidus
c. longissimus
d. spinalis
why is it tested during radiculopathy exams
b multifidus
Considered by some as the only paraspinal muscle one to have monosegmental innervation but overlap likely exists
Abnormalities are not pathognomotic of radiculopathy
other disorders can cause paraspinal abnormalities (diabetes, motor neuron disease, local muscle trauma, etc)
on radic study, if needle EMG abnormal, what should you do next? (2)
If needle EMG abnormal, needle 1 or more contralateral muscles
Perform median F-waves and compare with contralateral side if necessary
Option 1: to exclude bilateral radiculopathy, or to differentiate b/t radiculopathy and polyneuropathy, motor neuron disease, etc.
what are the typical findings on sensory and motor NCS for radic?
sensory - normal
motor: Usually normal unless severe axonal loss leads to reduction in amplitude
SNAPs normal b/c continuity b/t peripheral nerve and cell body (DRG) remains intact… so Wallerian degeneration does not occur
Disc herniation proximal to the dorsal root ganglion results in sparing of the continuity between the distal sensory nerve fibers (to digits) and the cell body within the dorsal root ganglion.
H reflex for S1 radiculopathy;
Significant if
- latency difference > _____
- Amplitude difference if > _____
Relevance:
Sensitivity:
Specificity:
Significant if:
- Latency difference > 1.0-1.8ms
- Amplitude difference > 50%
Relevance:
- Sensitivity: 36.4% if absent, 18.2% if asymmetric
- Specificity: 91% if absent, 100% if asymmetric
So helpful if positive due to high specificity
Why are F-waves so low in sensitivities
Sensitivity low b/c:
Only assess motor fibers
Affected portion of pathway is so small compared with total pathway being assessed, abnormalities may be obscured
The muscle tested also contains motor axons derived from more than one root, so any slowing may be masked by normal conduction along fibers traversing the unaffected root. I.e., the shortest latency (which is what is measured) may just represent the healthy axons
specificity is anywhere between 62-95.5 depending upon study
Needle EMG for lumbosacral radiculopathy:
Sensitivity:
Specificity:
PPV:
NNV:
Sensitivity: 29-92%
Specificity: 37-100%
PPV: 66-100
NNV: 33-66
Research results vary depending upon ‘gold standard’ used (MRI, surgical visualization, history, exam, etc)
Sensitivity goes way up if there is weakness (motor involvement) on exam
Sensitivity goes up with more muscles tested (to a certain point)
Needle EMG for cervical radiculopathy:
Sensitivity:
Correlation with radiological findings:
Sensitivity (moderate): 50-71%
Correlation with radiological findings (high specificity): 65-85%
The study of paraspinals improves ______
Limitations:
- Sensitivity:
- Specificity:
Improves localization
Limitations:
Sensitivity: 50-66%
Specificity: 85-90%
Localization: suggests lesion proximal to plexus
- Can occur in normal aging/asymptomatic patients
- Should not be used as sole criteria for diagnosis
- Cannot exclude radic if findings are absent
What are three factors affecting EMG findings?
Muscle sample selection
Timing
Type of fibers involved (sensory, motor, both)
what is the goal for muscle selection for EMG (radic study)
find 2 muscles innervated by the same root level but different peripheral nerve while demonstrating that the level above and below are normal
PSW/Fibs indicate _____
CRD indicate ____
Neuropathic MUAPs indicate ____
ongoing denervation
chronic denervation
chronic
If radiculopathy causes axonal damage, wallerian degeneration causes distal axon death.
Neuropathic MUAPs = chronic denervation with subsequent reinnervation
What will you see on EMG during denervation process?
1 week
3 weeks
5-6 weeks
1 week
- Reduced recruitment (can be seen immediately)
- Paraspinals with PSWs and fibs
3 weeks
- Proximal limb muscles with PSWs and fibs
5-6 weeks
- Distal limb muscles with PSWs and fibs
- Proximal-to-distal sequence
Reinnervation occurs ____ direction
begins after _____
Can be seen ______ after injury
Results in ____ units
Occurs proximally-to-distally
Reinnervation begins after denervation
Can be seen months to years after injury
Results in neuropathic units
