Examination of the Patient With Weakness Or Sensory Loss

For a complaint of weakness, during the history, try to pinpoint
the areas involved in the weakness (e.g., which extremities are weak or which
movements of an extremity are weak), because lesions in various regions of the
central and peripheral nervous system produce characteristic patterns of
weakness (see Table 24-3). For example, weakness of one
side of the body suggests the possibility of a contralateral cerebral
hemispheric localization, whereas distal weakness in the lower extremities
suggests the possibility of a peripheral neuropathic process. When
neuromuscular junction disease (i.e., myasthenia gravis) is a consideration,
make sure to ask about any waxing and waning of the weakness, especially
worsening at the end of the day, as well as any symptoms of dysarthria,
dysphagia, ptosis, or diplopia.

For a complaint of sensory loss, ask the patient to point to the
area or areas involved, because lesions in various regions of the central and
peripheral nervous system produce characteristic patterns of sensory loss (see
Table 28-2). For example, analogous to weakness,
numbness of one side of the body suggests the possibility of a contralateral
cerebral hemispheric (or thalamic) localization, whereas distal numbness in
the lower extremities suggests the possibility of a peripheral neuropathic
process.

Ask questions during the history with the intent of determining
whether there are any additional nonmotor or nonsensory symptoms (such as
speech problems, headache, dizziness, visual changes, and bowel or bladder
dysfunction) that would further localize the problem to a particular area of
the central or the peripheral nervous system (see Table
2-2).

As in any neurologic history, ask about the temporal pattern of
symptom development, which may help you determine the most likely mechanisms
of the dysfunction (see Table 3-2).

While examining any patient with a complaint of weakness or
sensory loss, make sure that the patient’s arms and legs are visible (i.e., he
or she should be wearing a hospital gown). For the patient with weakness, this
allows you to see atrophy or fasciculations that would be consistent with a
lower motor neuron process. For the patient with sensory loss, this allows you
to do a more careful sensory examination, not necessarily restricted to the
distal extremities.

In any patient with weakness, do a thorough screen of motor
strength testing of proximal and distal muscles of the upper and lower
extremities (see the suggested general list of muscles to test in Chapter 40, Performing a Complete Neurologic Examination).
Obviously, don’t forget to test the extremities and muscles in which the
patient specifically complains of weakness.

In any patient with sensory symptoms, test sensation to pinprick
(see Chapter 29, Examination of Pinprick Sensation), as
well as to vibration and proprioception (see Chapter 30,
Examination of Vibration and Position Sensation); occasionally, cortical
sensation (see Chapter 31, Examination of Cortical
Sensation) may be helpful in situations in which a right hemispheric
localization is suggested.

Depending on your suspicion as it evolves from the history and
during the examination, hone your examination to try to look for
characteristic distributions of weakness (see Table
24-3) or sensation (see Table 28-2) to pinpoint
the most likely localization of your patient’s problem. For example, in the
motor examination of a patient in whom you suspect a radial nerve lesion, look
for weakness in other radial nerve-innervated muscles and look for preserved
strength in nonradial nerve-innervated muscles, even those that share similar
nerve root innervation as the weak muscles. In the sensory examination of a
patient in whom you suspect a radial nerve lesion, look for sensory loss in
the distribution of this nerve with normal sensation elsewhere.

Be aware that many lesions would be expected, by virtue of their
localization, to cause both motor and sensory findings on examination. Such
lesions often do not cause proportional changes in motor and sensory function,
however, and even lesions that would be expected to cause dysfunction of both
may cause predominant or only motor or sensory findings.

For example, peripheral polyneuropathies
most frequently cause only distal sensory symptoms, and only when severe is
distal motor weakness evident.

Look for significantly hyperactive or hypoactive deep tendon
reflexes, hypertonia (or hypotonia), or a Babinski sign (see Table 36-1) to support an upper motor neuron or lower motor
neuron localization of your patient’s symptoms, and look for characteristic
distributions of those reflex findings that would suggest particular
localizations (see Tables 36-1 and 37-2).

In addition to the motor, sensory, and reflex changes described
above, throughout your complete neurologic examination, look for any
additional findings that would further localize the problem to a particular
area of the central or the peripheral nervous system (see Table
2-2).

The assessment of weakness or sensory loss due to spinal cord
dysfunction is discussed in more detail in Chapter 51,
Examination of the Patient with a Suspected Spinal Cord Problem, and that due
to radiculopathy is discussed in more detail in Chapter
47, Examination of the Patient with a Radiculopathy.

The clinical diagnosis of a focal peripheral nerve entrapment
neuropathy can be aided by looking for Tinel’s sign. Tinel’s sign is a
sensation of tingling in the distribution of a nerve when the involved region
of nerve is lightly tapped with your finger or reflex hammer (the funny bone
sensation that we’ve all felt from an impact on our ulnar nerves at the elbows
is Tinel’s sign). In suspected carpal tunnel syndrome, test for Tinel’s sign
by tapping over the distal volar wrist in the midline, looking for tingling
into the median nerve-innervated fingers. Although not a very sensitive sign,
the finding of Tinel’s sign in the region of any clinically suspected
entrapment neuropathy can be a useful supportive clue to the
diagnosis.

See Chapter 24, Approach to the Motor
Examination, and Chapter 28, Approach to the Sensory
Examiniation, for further details regarding the evaluation of patients with
weakness or sensory loss.