Steven L.
Guide to the Neurologic Examination, 1st Edition
Wilkins
Neurologic Examination in Common Clinical Scenarios > Chapter 47 –
Examination of the Patient With a Radiculopathy
possible radiculopathy is to look for evidence that the patient’s symptoms are
likely due to nerve root dysfunction and to try to localize the symptoms and
signs to the distribution of a particular nerve root.
cause of nerve root dysfunction, which can occur due to a structural
(compressive) process or nonstructural (noncompressive) process.
Structural causes of radiculopathy include any process that
causes mechanical compression of nerve roots, such as herniated discs (most
common in the cervical or lumbar spine), degenerative disease of the spine
(e.g., spondylosis), or tumor.
Nonstructural causes of radiculopathy include diabetic
radiculopathy, which likely occurs due to infarction of a nerve root (most
commonly affecting the thoracic or lumbar nerve roots), or Herpes zoster, which causes radiculopathy due to
viral-mediated inflammation of a nerve root.
Radiculopathy due to Herniated Discs
Cervical nerve roots exit the cord to enter their foramen at the
disc space above their respective vertebra, where they are vulnerable to
compression from disc herniation or foraminal stenosis. For example, the C7
nerve root exits the cord at the C6-C7 disc space level (i.e., above C7) and
is susceptible to compression from this disc or by foraminal stenosis at this
level.
Lumbar nerve roots exit the cord to enter their foramen below
their respective vertebra. For example, the L5 nerve root exits the cord at
the L5-S1 disc space level (i.e., below L5). The root actually exits above the
disc, however, so a herniated disc will affect the next root that is
descending within the spinal canal to exit at the next foramen. In other
words, a herniated disc at the L5-S1 disc level will most likely affect the S1
root, but foraminal stenosis at the L5-S1 intervertebral foramen level will
affect the exiting L5 root.
Radiculopathic pain is characterized by sharp, shooting
discomfort, which may include paresthesias or dysesthesias, radiating
proximally to distally in the distribution of the affected nerve root. There
may or may not be associated neck or back pain.
Cervical radiculopathies typically begin in the lateral
neck/trapezius region, and lumbar radiculopathies typically begin in the
buttock/hip region; both radiate downward within the distribution of the
affected
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nerve root. Tables
47-1 and 47-2 summarize the clinical features of
cervical and lumbar radiculopathies.
TABLE 47-1 Clues to the
Localization of Cervical Radiculopathy
Cervical
Root
Level
Probable
Site
of
Herniated
Disc
Distribution of Pain
and Paresthesiasa
Easily Testable
Muscles That May
Be
Affectedb
Reflex That
May Be
Diminishedc
C5
C4-C5
Scapula, deltoid, upper arm
Deltoid, biceps
Biceps
C6
C5-C6d
Biceps region, lateral forearm, dorsal thumb and second
finger
Biceps, brachioradialis, extensor carpi radialis (wrist
extension)
Biceps
C7
C6-C7d
Triceps region, dorsal forearm to dorsal third (and possibly
also second and fourth) finger(s)
Triceps, extensor digitorum communis (finger extension)
Triceps
C8
C7-T1
Medial (inner) forearm to fifth and fourth fingers
Interossei, finger flexors
Triceps
T1e
T1-T2
Axilla to medial (inner) upper arm
Interossei, abductor pollicis brevis (thumb abduction),
abductor digiti minimi (little finger abduction)
None
a
All of the cervical radiculopathies can begin in lateral
neck/trapezius/shoulder region before radiating into
arm.
b See Chapter
25, Examination of Upper Extremity Muscle Strength, for
details on testing these muscles.
c See Chapter 37, Examination of the Muscle Stretch
Reflexes, for details on testing these reflexes.
d These
are the most common sites for cervical disc
herniation.
e T1 root lesions are uncommon and
are more likely to occur due to lesions other than disc
herniation, including other spinal lesions or apical chest lesions
(i.e., Pancoast tumor, in which there usually is also ipsilateral
Horner’s
syndrome).
Pain due to cervical and lumbar radiculopathies from herniated
discs is often worsened with coughing, sneezing, or other Valsalva maneuvers,
so patients should be specifically asked about this.
Historical clues to the possibility of a noncompressive
radiculopathy include a recent rash in the same distribution to suggest Herpes zoster or a radiculopathy in an unusual
distribution (e.g., a thoracic root) in a patient with
diabetes.
Patients with cervical or lumbar radiculopathy may or may not
have weakness in the distribution of muscles supplied by the involved nerve
root. If weakness is present, the distribution of weakness (Tables 47-1 and 47-2) should aid in the
localization of the patient’s radiculopathy to a particular root
level.
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TABLE 47-2 Clues to the
Localization of Lumbar Radiculopathy
Lumbar
Root
Level
Probable
Site
of
Herniated
Disc
Distribution of
Pain
and
Paresthesias
Easily Testable Muscles
That May Be
Affecteda
Reflex That
May Be
Diminishedb
L4c
L3-L4
Knee, medial leg, medial ankle, medial foot
Quadriceps (knee extension), tibialis anterior (foot
dorsiflexion)
Knee jerk (patellar reflex)
L5
L4-L5d
Buttock, posterolateral thigh, anterolateral shin, dorsum of
foot, large toe
Tibialis anterior (foot dorsiflexion), extensor hallucis longus
(large toe dorsiflexion), peroneus longus (foot eversion),
tibialis posterior (foot inversion)e
No testable reflex
S1
L5-S1d
Buttock, posterior thigh, posterior calf, lateral foot, little
toe, sole of foot
Gastrocnemius (plantar flexion)
Ankle jerk (Achilles reflex)
a
See Chapter 26, Examination of
Lower Extremity Muscle Strength, for details on testing these
muscles.
b See Chapter
37, Examination of the Muscle Stretch Reflexes, for details
on testing these reflexes.
c This is an
uncommon localization for a lumbar radiculopathy.
d These
are the most common sites for lumbar disc
herniation.
e The finding of foot inversion
weakness is important in clinically differentiating a severe L5
radiculopathy from a peroneal nerve palsy; both can cause foot
drop, but inversion of the foot should be spared in a peroneal
nerve
palsy.
Although it is common for patients with cervical or lumbar
radiculopathy to have paresthesias in the distribution of the affected nerve
root, it’s less common to find significant sensory loss on examination,
probably due to overlap from the dermatomes of adjacent healthy roots. When
sensory loss is found, the dermatomal distribution (Fig.
28-1) is helpful as a further clue to localization to a particular root
level.
Patients with cervical or lumbar radiculopathies may have a
diminished reflex in the territory of the involved root if a testable reflex
is served by that root (see Table 37-2). L5
radiculopathies do not have a testable reflex to aid in
localization.
The diagnosis of lumbar radiculopathies due to herniated discs
may be aided by performing the straight-leg-raising test, which causes
discomfort due to stretching of the irritated (compressed) lumbar root. To
perform this procedure:
Have the patient lie flat on his or her back (supine) on the
examining table.
On the side of the probable radiculopathy, slowly lift the
patient’s leg by holding it up from the ankle, so that you are passively
flexing the patient’s hip while the leg remains stiff and extended (locked)
at the knee.
Note whether there is radiculopathic-type pain or paresthesias
as you lift the leg up (a positive straight-leg-raising test), whether it
recapitulates
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the patient’s presenting symptoms, and
note the approximate angle at which the discomfort occurred. Tightness in
the hamstrings when the leg is lifted is normal and not specific for
radiculopathy.
Patients with possible Herpes zoster
should be examined for a vesicular rash. In any patient with possible
radiculopathy from diabetes or Herpes zoster, look
for cutaneous dysesthesias to gross touch or pinprick in the involved
dermatome. This is particularly helpful when a thoracic radiculopathy is
present, because pain in this distribution can be confused with a visceral
process; the finding of cutaneous dysesthesias or sensory loss is an important
clue to a radiculopathic cause of symptoms.
referring to any pain radiating within the distribution of the sciatic nerve
(i.e., from the buttock down the leg). Patients with symptoms of sciatica are
much more likely to have a radiculopathy (affecting the L5 or S1 root) than a
lesion of the sciatic nerve.