Week 3
11:00-12:0
MOTOR SYSTEM
Case 1: A
65-year-old man complained of weakness in the right arm.
For three months, he had been dropping objects from his
right hand. He was unsure of the exact time of onset of
symptoms, but noted that they were "getting worse." He
complained of no symptoms in the other limbs, no sensory
abnormalities, no difficulty with gait, and no neck or
head pain. On exam, the patient was mildly confused and
speech was slow and slurred. There was flattening of the
right nasolabial fold. Muscle bulk was normal. Passive
movement of the right or leg met with resistance which
would "give way." Strength was minimally diminished in
the right intrinsic hand muscles, wrist dorsiflexors,
triceps and deltoids. A right pronator drift was
observed. Right finger movements were slow. The right
iliopsoas, hamstrings and tibialis anterior were 5-/5
versus 5/5 on the left. The right leg circumducted
during walking. Reflexes were hyperactive on the right.
The right plantar response was extensor. Sensation was
normal to touch, pin, cool and vibration. Two-point
discrimination and graphesthesia were performed poorly
on the right in comparison to the left.
1. Contrast the symptoms and signs of an
upper motor
neuron lesion vs. a
lower motor neuron lesion?
2. Where would you localize the lesion in this case?
3. What is the differential diagnosis for this
65-year-old man?
Case 2: A
70-year-old, right-handed man complained of weakness in
the right arm, and a six-month history of dropping
objects from the right hand. On occasion, he would drag
his right foot, and he once tripped going up stairs. The
symptoms had been steadily progressive, so that he
recently had become unable to open jars or doorknobs
with his right hand. There were no left-sided symptoms
except for cramps in the calf and thigh. Sensory
symptoms, headache and back pain all were denied.
Examination showed decreased muscle bulk in the right
forearm, with wasting of the interosseous muscles of the
right hand. Strength was 4/5 in the upper limb,
including the interossei, finger extensors, wrist
dorsiflexors, triceps, deltoids and neck flexors. There
was minimal weakness of the left arm. He could not walk
on his heels or toes and he had a subtle right foot
drop. Fasciculations were noted in the right deltoid,
right pectoralis, right calf and left quadriceps.
Reflexes were diffusely brisk. Sensory signs were
lacking.
1. Does this man have evidence for a lower motor
neuron or upper motor neuron lesion?
2. In what conditions are fasciculations and cramps
seen?
3. What is the likely diagnosis in this 70-year-old man?
4. What investigations are indicated?
Case 3: : A
65-year-old, right-handed man complained of weakness of
the right arm. About six months earlier, he had noticed
that he could not brush his hair or teeth as rapidly as
he had in years past. His wife reported a general
slowing down of his daily activities, such as dressing,
eating and climbing stairs. Affect was flat. There was a
general paucity of movement and facial expression. He
blinked infrequently. Upgaze was limited. The remaining
cranial nerve examination was within normal limits.
Sensation was normal. An obvious tremor was seen at the
metacarpophalangeal joints of the right hand when the
patient was at rest. The tremor attenuated with
movement. Tone was increased in the right arm,
especially during contralateral movement. Tone in the
left arm was normal. Leg tone was increased bilaterally.
Gait was slow and shuffling. Turning was clumsy. Power
was normal in all limbs. Reflexes were 1+ and
symmetrical.
1. Define "tone." Contrast the
differences between
increased tone from a) upper motor neuron lesions, b)
basal ganglia lesions, and c) frontal lobe lesions?
2. What are the general symptoms of basal ganglia
disease?
3. What are the "frontal release signs" and their
significance?
4. What is the differential diagnosis in this case?
Case 4:
A 37-year-old, right-handed woman began to stumble
yesterday. Today, she is completely unable to walk, and
can barely sit without support. Her arm and face
strength are normal. There is no sensation below the
level of the umbilicus except to deep pain stimuli. She
has no control of her bowel or bladder. Tone is flaccid,
and knee and ankle jerks are absent.
1. Is there any evidence in this case of neuropathy,
myelopathy, or hemisphere disease?
2. What is a "sensory level" and what is its
significance?
3. Does flaccid areflexia in this setting rule out an
upper motor neuron lesion?
4. What is the likely site of the lesion in this woman?
5. What is the differential diagnosis?
Extra Case if Time Permits
Case 5: A 45-year-old, right-handed man
complained of progressive difficulty with walking of six
months' duration. He would occasionally fall, especially
in the dark. He also noted that his right arm would
shake when drinking Thunderbird wine. Mental status were
normal. Speech was slightly dysarthric. Coarse nystagmus
was evoked by eccentric gaze in any direction. Sensory
exam was normal except for a mild stocking-pattern
decrease in pin and vibration sensation. Tone was
diminished in all four limbs. No rest tremor was seen,
but there was a side-to-side intention tremor of both
upper extremities. Tremor was noted on heel-to-shin
testing bilaterally. Rapid alternating movements of the
hands were impaired. Muscle strength was normal.
Reflexes were present and normal other than absent ankle
reflexes bilaterally. Gait was broad-based and unsteady.
A Romberg sign was present.
1. What areas in the neuraxis are likely affected in
this patient?
2. What symptoms and signs occur with
damage to the
cerebellar hemisphere and what symptoms and signs occur
with damage to the cerebellar vermis?
3. What is the likely diagnosis in this man?
4. If this man had a family history of similar problems
in a brother and father, what other diagnosis should be
considered?
5. If this man had lung cancer, what other diagnoses
should be considered? |
