case files neurology
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case files neurology


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ET appear to occur because of an
autosomal dominant genetic mutation, associated with a disorder referred
to as benign familial tremor. Exactly what causes ET in people without a
known genetic mutation is not clear. Positron emission tomography (PET)
scanning shows that certain parts of the brain\u2014including the thalamus\u2014have
increased activity in people with ET. More research is needed to understand
the precise mechanism behind the disease.
Diagnosis
In addition to ET and PD, other etiologies for tremors should be considered.
Tremor as part of dystonic conditions is typically more asymmetric than ET and
has a jerky quality, as opposed to the more sinusoidal movement in ET. Purely
kinetic or intention tremors are seen with disruption of the output from the neo-
cerebellum (most commonly noted in multiple sclerosis patients) or red nucleus
(commonly after closed-head injury). Hyperthyroidism, and other conditions
associated with increased adrenergic activity can cause tremors that resemble ET.
Essential tremor is a clinical diagnosis; however, laboratory studies can be
indicated to rule out thyroid disease, heavy metal poisoning, or other condi-
tions. Neuroimaging can also be indicated if degenerative or structural changes
of the nervous system are suspected. Common types of tremor include resting
tremor that occurs when a body part is at complete rest against gravity, seen
in PD. Tremor amplitude decreases with voluntary activity, such as in postural
tremor that occurs during maintenance of a position against gravity and
increases with action; action or kinetic tremor that occurs during voluntary
movement; task-specific tremor that emerges during specific activity (e.g.,
writing tremor); and intention or terminal tremor that manifests as a marked
increase in tremor amplitude during a terminal portion of targeted movement
(seen in tremor of multiple sclerosis or cerebellar disease).
Management
For some people, ET may be distressing but not debilitating. Others may find
that their tremors make it difficult to work, perform everyday tasks that require
20 CASE FILES: NEUROLOGY
fine-motor skills, or do the things they enjoy. Severe tremors can lead to social
withdrawal and isolation. Fortunately, a variety of treatments exist that may
help bring the tremors under control.
Medications provide relief from tremors roughly half the time. The main-
stay of ET treatment are beta-blockers and primidone.
Beta-blockers. Normally used to treat high blood pressure, beta-blockers,
such as propranolol (Inderal), help relieve tremors in some people. Because
beta-blockers are especially likely to cause dizziness, confusion, and memory
loss in older adults, they may be a better choice for younger people. They may
also not be an option for patients with asthma, diabetes, or certain heart problems.
Other medications include anti-seizure medications such as primidone
(Mysoline), which may be effective in patients who do not respond to beta-
blockers; they are usually given at much lower doses than in epilepsy, typically
50 to 700 mg per day. The main side effects are drowsiness and flu-like symp-
toms, which usually disappear within a short time. Tranquilizers such as
diazepam (Valium) and alprazolam (Xanax) are sometimes used to treat peo-
ple whose tremors are made much worse by tension or anxiety. Side effects
can include confusion and memory loss. Botulinum toxin type A (Botox)
injections can also be useful in treating some types of tremors, especially of
the head and voice. Botox injections can improve problems for up to 3 months
at a time. When used to treat hand tremors, Botox can sometimes cause weak-
ness in the fingers. For severe disabling tremor, surgery may be an option for
patients who do not respond to medications. Deep brain stimulation (DBS) is
a treatment involving a brain implant device called a thalamic stimulator that
may be appropriate if the patient has severe tremors and if medications are not
effective.
Comprehension Questions
[1.1] A 59-year-old man is diagnosed with a probable ET. A PET scan is per-
formed on the brain. Which of the following is most likely to be high-
lighted on the imaging?
A. Cerebellum
B. Cerebral cortex
C. Pituitary gland
D. Thalamus
[1.2] A 45-year-old woman is noted to have a distinct tremor with voluntary
activity. Multiple family members also are noted to have tremors. If ET
is diagnosed, what pattern of inheritance is most likely?
A. Autosomal dominant
B. Autosomal recessive
C. X-linked dominant
D. X-linked recessive
E. Y-linked
CLINICAL CASES 21
22 CASE FILES: NEUROLOGY
[1.3] A 58-year-old man is noted to have a noticeable tremor that has pro-
gressed over 5 years. The tremor occurs in the hands, there are some prob-
lems with his gait, and there is also presence of tremor of the head. Which
of the following helps to support of the diagnosis of ET rather than PD?
A. Gait disturbance
B. Male gender
C. Slow progression of the tremor over 5 years
D. Tremor in the head
Answers
[1.1] D. The thalamus tends to be highlighted on PET imaging in individu-
als with ET. It should be noted however, that no imaging studies have
a definitive positive predictive value.
[1.2] A. An apparently autosomal dominant history of tremor is often seen
in ET. A familial tendency may also be seen in PD.
[1.3] D. The tremor involving the head is more typical of ET. There can be
gait problems and also slow onset of tremor in both ET and PD.
CLINICAL PEARLS
\u2756 Essential tremor is the most common movement disorder and
affects up to 10 million adults.
\u2756 The latency (time of onset) for the tremor to appear in PD is signi-
ficantly longer than the latency for ET (9 seconds vs. 1\u20132 seconds)
and helps to distinguish the two disorders.
\u2756 There is a familial predisposition to both ET and PD.
\u2756 Essential tremor is often relieved with low doses of alcohol.
\u2756 The mainstay of treatment of ET is beta-blockers.
\u2756 Severe cases of ET may require surgery, such as placement of a
deep brain stimulator.
REFERENCES
Louis ED. Essential tremor. Lancet Neurol 2005;4:100\u2013110.
Lyons K, Pahwa R, Comella C, et al. Benefits and risks of pharmacological treat-
ments for essential tremor. Drug Saf 2003;26:461\u2013481.
Pahwa R, Lyons KE, Wilkinson SB, et al. Comparison of thalamotomy to deep brain
stimulation of the thalamus in essential tremor. Mov Disord 2001;16:140\u2013143.
Zesiewicz TA, Elble R, Louis ED, et al and the Quality Standards Subcommittee of
the American Academy of Neurology. Practice parameter: therapies for essential
tremor: report of the Quality Standards Subcommittee of the American Academy
of Neurology. Neurology 2005;64:2008\u20132020.
\u2756 CASE 2
A 40-year-old man presents to the psychiatry emergency room for inappropri-
ate behavior and confusion. He works as a janitor and has had reasonably good
work attendance. His coworkers say that he has appeared \u201cfidgety\u201d for several
years. They specifically mention jerky movements that seem to affect his
entire body more recently. His mother is alive and well, although his father
died at age 28 in an auto accident. On examination, he is alert but easily dis-
tracted. His speech is fluent without paraphasias but is noted to be tangential.
He has trouble with spelling the word \u201cworld\u201d backwards and serial seven\u2019s,
but recalls three objects at 3 minutes. His constructions are good. When he
walks, there is a lot of distal hand movement, and his balance is precarious,
although he can stand with both feet together. His reflexes are increased bilat-
erally, and there is bilateral ankle clonus. A urine drug screen is negative.
\u25c6 What is the most likely diagnosis?
\u25c6 What is the next diagnostic step?
\u25c6 Molecular or genetic basis of this disorder?
ANSWERS TO CASE 2: Huntington Disease
Summary: A 40-year-old man is seen in the emergency room for inappropriate