Essential TremorとParkinson’s diseaseの合併
Essential TremorとParkinson’s diseaseの合併
ET患者の20%にPismを合併する
To study the demographic and clinical
correlates of essential tremor (ET), we analyzed a comprehensive database of
350 patients evaluated at the Movement Disorders Clinic at Baylor College of
Medicine from 1982 to 1989. The age at onset of tremor showed bimodal
distribution for both male and female patients, with peaks in 2nd and 6th
decades. ET appeared most frequently in hands, followed by head, voice, tongue,
leg, and trunk. Half of the patients (47%) had associated dystonia, including
cervical dystonia, writer's cramp, spasmodic dysphonia, and cranial dystonia,
and 20% of the patients had associated parkinsonism.
At least one 1st-degree relative of 62.5% of ET patients reported tremor.
Alcohol relieved tremor in 2/3 of ET patients. Sixty-eight percent of patients
who had adequate follow-up improved with propranolol, and 72% with primidone.
There was no significant difference in various clinical variables between the
219 patients with familial ET and 131 with sporadic ET. Patients with
early-onset ET were more likely to have hand involvement and associated
dystonia than patients with late-onset ET. Dystonia was more frequently
associated with mild ET than with severe ET. Patients with low-frequency tremor
were older and had more head but less hand involvement than patients with
high-frequency tremor. The lack of relevant differences between ET subgroups
suggests that, despite variable expression, ET represents a single disease
entity.
(Lou JS. Neurology. 1991 Feb;41(2 ( Pt
1)):234-8.)
Results: Fewer ETRPD than ET patients had
widespread postural and/or action tremor (2/17 [11.8%] vs. 11/17 [64.7%];
p50.001) and marginally fewer had cerebellar signs (1/15 [6.7%] vs. 6/18
[33.3%], p50.06). ETRPD patients required fewer ET medications than did their
counterparts with ET (p50.001). ETRPD patients and PD patients did not differ
in UPDRS, Hoehn and Yahr, or Schwab and England scores (each p>0.14).
Discussion: ET patients who develop PD may
have distinct pre-PD motor features compared to their counterparts with ET who
do not develop co-existing PD. Prospective studies are needed to evaluate the
predictive value of these clinical features for the emergence of PD.
(Examining the Motor Phenotype of Patients
with Both Essential Tremor and Parkinson’s Disease)
機序は結局よくわかっていない
There is considerable evidence for an
association between essential tremor (ET) and Parkinson’s disease (PD),
although the topic remains somewhat controversial. An important issue, not
previously addressed, is what seems to be the uni-directional nature of the
relationship (ET→ET +PD and not PD→PD+ET). The aims of this review are (1) to discuss the evidence for
and against a uni-directional relationship and (2) to discuss the implications
of such a uni-directional relationship, if it exists, for disease mechanisms.
Evidence “for” a uni-directional relationship includes: (1) abundant clinical
anecdotal observation, (2) clinical and epidemiological studies. Evidence
“against” is theoretic rather than empiric. Overall, the evidence “for” is
stronger, though additional studies are needed in order to be certain; for the
time being, it might be best to leave this as an open question. The biological
ramifications/extensions of such a unidirectional relationship include: (1)
that the association is causal (i.e., some aspect of ET pathophysiology
predisposes an individual to develop PD), (2) that some ET cases may have a
circumscribed form of Lewy body disease, and the secondary development of PD
may represent a spread of those Lewy bodies in the brainstem. The presence and
nature of the links between ET and PD are controversial. Further primary data
(epidemiological and pathological) are needed to improve understanding of the
relationship and its implications for the pathogenesis of both disorders.
(Eur J Neurol. 2013 November ; 20(11):
1440–1444. doi:10.1111/ene.12256.)
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