Emergency Department’s
Case of the Month
“ Am I having a stroke?”
Katrina Hurley, MD and; Dave Petrie, MD, FRCPC
Natalie’s wrist
• Natalie, 77, presents to the ED with
concerns that she has had a
stroke.
• Upon waking in her Lazyboy chair
in the morning, she noticed a
weakness in her left arm and hand.
• She denies having any other
symptoms and is otherwise feeling
well.
• She has a history of hypertension,
diet-controlled diabetes and a
remote myocardial infarction.
• Her medications include:
- enteric coated acetylsalicylic acid
- metoprolol
- atorvastatin
• A visual examination reveals an
apparent wrist-drop (Figure 1).
Figure 1. The patient is asked to hold up her
hands (extend wrists and fingers). She
has a noticeable left-sided wrist-drop.
Questions & Answers
How is an upper motor neuron lesion (UMNL)
differentiated from a lower motor neuron lesion
(LMNL) in a physical examination?
1.
Upper motor neurons project from the cerebral cortex to the anterior
horn of the spinal cord (proximal to the -motor neuron). Classic signs
of an UMNL include muscle weakness, increased muscle tone and
increased reflexes. Lower motor neurons project from the anterior horn
of the spinal cord via peripheral nerves to directly innervate skeletal
muscle. Signs of a LMNL include muscle weakness, atrophy, fasciculations and decreased reflexes (Table 1).
What are the features of radial neuropathy?
2.
The radial nerve (C5-T1 roots) arises at the brachial plexus, passes
through the spiral groove and divides into the posterior interosseous
nerve and superficial radial nerve at the antecubital fossa. The radial
nerve innervates the muscles that extend the fingers, thumb, wrist and
elbow. The superficial radial nerve innervates the skin over the first
interosseous muscle.
Patients with classic wrist-drop have weak extensors (wrist, fingers
and thumb) and impaired sensation over the first interosseous muscle.
Depending on the cause of the neuropathy, the deficits may be incomplete. For example, a compressive neuropathy may spare some fascicles.
The superficial radial nerve may be variably affected, making sensory
loss an inconsistent finding. Axillary radial neuropathy is distinguished
from classic wrist-drop by the addition of tricep involvement. Tricep
weakness in the context of a radial neuropathy implies a lesion proximal
to the spiral groove.
The length of recovery depends on the degree of damage.
Demyelination should improve over several weeks while axonal loss
may take months or more.
For more on Natalie see page 4.
2
The Canadian Journal of Diagnosis / May 2006
Case of the Month
What is the differential diagnosis for radial
mononeuropathy?
3.
More on Natalie
• On examination, the patient has a
decreased brachioradialis reflex. The
biceps and triceps reflexes are symmetric.
Decreased power is limited to extensors
of wrist, fingers and thumb. There is no
discernable sensory deficit.
In general, isolated mononeuropathies result from trauma. The most
common etiology of radial mononeuropathy is compression. It occurs
in several well-described scenarios: improper use of crutches causing
axillary radial neuropathy; Saturday night palsy from malposition dur• Based on the history and physical
ing drunken sleep, compressing the nerve in the spiral groove and
findings, the patient is diagnosed with
Bridegroom’s palsy inflicted on a sleeping groom as his bride’s head
compression radial mononeuropathy.
compresses the nerve in the spiral groove. Other causes of compression
• Natalie was splinted in wrist and finger
include mass lesions, as in neurofibromatosis or a fibrous band. Wristextensions and referred to both physioand occupational therapists.
drop is also a reported manifestation of lead poisoning.
Mononeuropathy can be associated with the use of Dapsone, excessive
use of Ergotamine and abuse of opiates, sedatives and amphetamines.
The differential diagnosis for neuropathy is broad,
including diabetes mellitus, Lyme disease, numerous toxins
Table 1
and entities like acute intermittent porphyria.
Using physical examination to differentiate
an UMNL from a LMNL
UMNL
LMNL
Fasciculations
Absent
Present
Muscle bulk
Symmetric or
slight atrophy
Pronounced
focal atrophy
Motor tone
Increased
Decreased
Motor power
Non-focal weakness
(distributed over
muscle groups)
Focal weakness
(peripheral nerve or
root distribution)
Reflexes
Increased
Decreased
Coordination
Ataxia, dysmetria
Not affected
Dr. Hurley is a fourth-year resident in Emergency Medicine and a
graduate student in Health Informatics, Dalhousie University, Halifax,
Nova Scotia.
Dr. Petrie is the Director, Division of EMS, Dalhousie University,
Halifax, Nova Scotia.
This department covers selected points to avoid pitfalls and
improve patient care by family physicians in the ED.
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4
What is the role of investigations in
patients with mononeuropathy?
4.
The physical examination is the most important
tool to delineate the nature of a neuropathy.
Consider a complete blood count, blood lead levels and serum glucose. If the patient fails to
improve in a matter of weeks, an electromyograph would be prudent to confirm the diagnosis
and localize the lesion.
What treatment should be provided
to patients with wrist-drop?
5.
The most important treatment is to remove
offending factors (i.e. compression). Supportive
care, such as splinting to keep the wrist and fingers extended, is important during convalescence. Consultation with an occupational therapist would ensure a properly fitted splint. Failure
to improve over the short term should also
prompt a consultation with a physiotherapist. Dx
References
Available upon request
The Canadian Journal of Diagnosis / May 2006