Radiculopathies Flashcards
The sensory and motor fibers exit the spinal cord in small groups termed rootlets, which fuse to form roots (31 root pairs emanate from the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal). Note that the dorsal and ventral roots fuse within the intervertebral foramina to form a mixed spinal nerve
Upon exiting the intervertebral foramen, an MSN fives off a posteriorly direct branch, the posterior primary ramus, and then continues as the anterior primary ramus
Note the muscles covered by the median nerve
Strength is the most important exam and pain is the least helpful
Since the spinal cord between L1 and L2 vertebrae, the nerve roots yet to exit must traverse greater and greater distance to reach their respective foramine. This accumulation of nerve roots is termed the cauda equina. Disorders at this level commonly affect more than one nerve root
What are the 2 most common causes of radiculopathies?
–Disk herniation and degeneration
•Cervical radiculopathies
–HNP: C7 >> C6
–Spondylosis
»C5 and C6 > frequent
»By age 60 years, 70% of women and 85% of men
»After age 70 years, 93% of women and 97% of men
–Lumbosacral radiculopathies
•> 95% of HNPs affect either L5 or S1
Radiculopathies tend to produce paracentral axial (e.g. neck, lower back) pain that is radiating in nature
the pain is often aggravated by maneuvers that stretch the affected nerve root
For the upper extremity, one of the best maneuvers is sustained neck extensions (15-20 seconds), which narrows the intervertebral foramina, thereby exacerbating the symptoms
Note that a dermatone represents the sensory domain of a nerve root while a myotome represents the muscular domain the root
For the lower extremity, SLR (used when L5 or S1 nerve involvement is suspected) and reverse SLR (when L4 is suspected)
Staright leg raise is NOT that helpful (but crossed raise may be helpful)
Bike riding thats worse would suggest ichemia
Note that radicular pain is often relieved y maneuvers that open the neural foramina (walking uphill is less painful than walking downhill, bike riding (torso forward) is less painful than walking
Motor and sensory nerve fibers disruption tends to produce negative symptoms such as weakness, atropy, and loss of sensation whereas nerve irritation tends to produce positive symptoms such as tingling
Note that when initially confronted by a pt with new-onset lower back pain, its important to determine whether the underlying etiology could representa neurologic emergenery (e.g. spinal cord compression or cauda equina syndrome)
Spinal cord infection, termed myelitis, is a neurologic emergency
Neoplastic processes may progress rapidly and may not be functionally reveresible if not recognized and tx early
Pertinent positives
Certain situations msut be addresses mroe urgnetly than others, such as cute LBP in a pt with known cancer or new urinary continence
Standing and walking result in spinal column extension and narrow the intervertebral foramine, whereas sitting produces spinal flexion and expansion of the foramine. (walking uphill less painful than downhill and bicycling tends to be easier than walking)
If you are unable to localizes the lesion after taking a Hx, its a good idea to repeat the hx before going on to exam
Can kind of see the scottie dog
MRI is the most useful imaging modality for assessing anatomic structure
EDX testing is the most helpful study for assessing nerve fiber function. It’s much more sensitive than the clinical exam and false positive studies are extremely uncommon when it is used as an independent study
Conservative tx usually is initiated. Prolonged bed rest should be avoided; the pt should be isntructed to perform as many routine activities as possible
The brachial plexus is divided into 5 elements.
The brachial plexus is an emormous structure that extends from the spinal cord to the distal aspects of the axilla. With the upper extremity in the anatomical position, its 6 divisions lie posterior to the clavicle
Thus, the brachial plexus is frequently divided into a supraclavicular plexus, a retroclavicular plexus, and an infraclavicular plexus. The root and trunk elements constitute the supraclavicular plexus, the divisions, the retroclav, and the cords and terminal nerves (branches), the infraclav. plexus
Although the lumbar and sacra plexuses are seperate structures, they are typically discusses together as the lumbosacral plexus
Neuropathy symptoms
Its important to determine whether bilateral limb involvement is symmetric or is related to individiual acquired lesions b/c the DDx varies between these two
Most acquired, slowly progressive, sensory > motor, stocking-glove neuropathies are toxic/metabolic in etiology (#1 is diabetes, #2 is EtOH abuse)
Most subacute onset, generalized weakness with superimposed distal sensory abnormalities represent acquired demyelinating neuropathies
Most chronic, stocking-glove distribution weakness that is out of proportion to the degree of sensory loss id due to hereditary dysmyelination
A list of diagnostic categories for pts with a multifocal presentation is provided in the slide
Understanding EMG is best approached via two analogies, a cable analogy for the NCS, and a tree analogy for the needle electrode examination
The size of the recorded motor unti action potentials reflects the innervation ratio of the unit. Different diseases produces innervation ratio changes that are of diagnostic utility.
The innervation ratio is inversely related to the dexterity required of the muscle
Its important to know the order that the sensory and motor branches depart from the major extremity nerves, as this is important in localization, and, thus, diagnosis and management. The branch orders are shown from the major extremity nerves for the radial nerve.
Just remember that some variation exists among people
Weakness is the best test!
With motor neuron damage you see weakness, wasting, and fasciculations (no sensory)
Polyneuropathy: (Stocking glove; toxic metabolic cause): symmetric, lower limb before upper, sensory before motor; feet before hands
stocking glove is usually chronic and not acute
There are variants of GBS (note the red!!)
Neck flexor - C3,4
Guillian Barre Syndrome
GBS- they should improve!
