Chapter 016. Back and Neck Pain (Part 4) docx

Chapter 016. Back and Neck Pain
(Part 4)

The neurologic examination includes a search for focal weakness or muscle
atrophy, focal reflex changes, diminished sensation in the legs, and signs of spinal
cord injury.
The examiner should be alert to the possibility of breakaway weakness,
defined as fluctuating strength during muscle testing. Breakaway weakness may
be due to pain or a combination of pain and underlying true weakness.
Breakaway weakness without pain is due to lack of effort. In uncertain
cases, electromyography (EMG) can determine whether or not true weakness is
present. Findings with specific nerve root lesions are shown in Table 16-2 and are
discussed below.

Table 16-2 Lumbosacral Radiculopathy—Neurologic Features

Examination Findings
Lumbo
sacral Nerve
Roots
Reflex Sen
sory
Motor Pain
Distribution
L2
a


— Up
per
anterior

thigh

Psoas (hip
flexion)
Anteri
or thigh
L3
a
— Lo
wer
anterior
thigh
Ant
erior knee

Psoas (hip
flexion)
Quadriceps
(knee extension)
Thigh
Anteri
or thigh, knee

adduction

L4
a


Quadriceps

(knee)
Me
dial calf
Quadriceps
(knee extension)
b

Thigh
adduction
Tibialis
anterior (foot
dorsiflexion)

Knee,
medial calf
Antero
lateral thigh
L5
c


— Dor
sal
surface—
foot
Lat
eral calf
Peroneii
(foot eversion)
b

Tibialis
anterior (foot
dorsiflexion)
Gluteus
Lateral
calf, dorsal
foot,
posterolateral
thigh,
buttocks
medius (hip
abduction)
Toe
dorsiflexors
S1
c


Gastrocnemi
us/soleus (ankle)
Pla
ntar
surface—
foot
Lat
eral
aspect—
foot
Gastrocnemi

us/soleus (foot
plantar flexion)
b

Abductor
hallucis
(toe
flexors)
b

Gluteus
maximus (hip
extension)

Botto
m foot,
posterior calf,
posterior
thigh,
buttocks

a
Reverse straight leg–raising sign present—see "Examination of the Back."
b
These muscles receive the majority of innervation from this root.
c
Straight leg–raising sign present—see "Examination of the Back."