A STRANGE POSTURE ADOPTED BY DOWN'S SYNDROME INDIVIDUALS WHEN SLEEPING:
AN EPIDEMIOLOGICAL SURVEY ON A COHORT OF 432 SUBJECTS
Renato
COCCHI MD, neurologist and medical psychologist
Summary
In a
cohort of 432 Down's syndrome individuals, 33 Ss (7.64%;
Twenty-six
Ss sleep in a prone-supine position (i.e. "folded in two", with the
head finding its way down by the feet = 78.79 %); 4 Ss completely on is back
with the thighs and lower legs drawn up against the trunk (variant 1 = 12.12 %)
and 3 Ss in a face-down position with the thighs and legs tucked up under the
trunk (variant 2 = 9.09 %).
Compared
to a representative sample of 399 Down's syndrome individuals, the index group
significantly differs as regards to distribution of chromosomal anomaly and
prevalence of bruxism, but not in sex ratio, maternal age at birth,
prematurity, low birthweight or both.
The
different distribution of chromosomal anomalies was cautiously interpreted as
due to the small size of the index group.
The
need of taking this posture was hypothesized as a compensator working against
sleep hypotension.
Key
words: Sleep; posture; Down's syndrome.
Symptoms
Down's syndrome
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In the
course of the investigation into sleeping habits of indlviduals affected by
Down's syndrome (Trisomy 21), a rather odd and relatively frequent symptom was
reported.
This
consists in the adoption during sleep (not prior to sleep or in the falling
asleep stage), of a rather strange posture. Sometimes this position is taken up
around 4 or 5 o' clock in the morning, as reported the parents.
The
subject sleeps in a prone-supine position, but two less frequent variants have
also been described. In the most adopted posture the body, from the feet to the
pelvic girdle is in the supine position, while from the pelvic girdle to the
head, it is in a prone position (see Fig. 1).
It is as
if the subject in question is sleeping "folded in two" in such a way
that the head finds its way down by the feet.
There are
two variations of this position:
i. The
subject sleeps completely an his / her back, with the thighs and legs drawn up
against the trunk.
ii. The
subject sleeps in a face-down position with the thighs and legs tucked up under
the trunk, rather like a Moslem with his head to the ground saying his prayers.
An
epidemiological survey was carried out to assess the prevalence of this
symptom, trying to correlate it to risk factors or stress.
Materials and methods
During
the course of first consultation or check-ups which followed, the symptom was
investigated in a cohort of 432 Down's syndrome Ss which came from all over
Italy and which constitutes a consecutive non-selected series.
The following
data, among many others, were also collected: Sex; age at 1st consultation;
cytological diagnosis; mother's age at birth; prematurity (less than 38 weeks
of foetal life), low birthweight (less than
Statistics:
Chi Square and Poisson's distribution.
Results
Table
1:
epidemiological and clinical data of the two groups.
|
|
|||||
|
|
Index group |
% |
Control Group |
% |
|
|
No of Ss |
33 |
100.00 |
399 |
100.00 |
|
|
(share of the whole series) |
|
7.64 |
|
92.36 |
|
|
M |
24 |
|
230 |
|
|
|
F |
9 |
|
169 |
|
|
|
Sex ratio (M/F) (*) |
|
266.97 |
136.09 |
|
|
|
Age at 1st consultation (months) |
|
|
|
|
|
|
Range |
14 - 248 |
|
5-484 |
|
|
|
Average |
92 +/- 59 |
|
69 +/- 66 |
|
|
|
Distribution of cytodiagnoses (**) |
|
|
|
|
|
|
Pure trisomy 21 |
28 |
84.85 |
369 |
92.48 |
|
|
Transiocations |
0 |
0.00 |
15 |
3.76 |
|
|
Mosaicisms |
4 |
12.12 |
11 |
2.76 |
|
|
Unknown (only clinical diagnosis) |
1 |
3.03 |
4 |
1.00 |
|
|
Mean mother's age at delivery (months) |
376 +/- 78 |
|
405 +/- 94 |
|
|
|
Risk factors: (***) |
|
|
|
|
|
|
Prematurity |
5 |
15.15 |
53 |
13.28 |
|
|
Low birthweight |
1 |
3.03 |
24 |
6.02 |
|
|
Prematurity + low birthweight |
2 |
6.06 |
26 |
6.27 |
|
|
Bruxism (****) |
19 |
57.58 |
167 |
41.85 |
|
(*) Chi Square = 2.27; df = 1; N.S.
(**) Chi Square = 9.28; df = 2; p .01
(***) Chi Square = 0.55; df = 2; N.S.
(****) Probability of 19 events of bruxism in
index group, according to Piosson's Distribution (expected: 13.81) = p .0381
Prevalence of the investigated sleep habit
in index group:
Sleeps folded in two:
........................................................26 Ss = 78. 79 %;
Variant 1: .........................................................................4
Ss = 12.12 %;
Variant 2:
.........................................................................3 Ss =
9.09 %.
Discussion.
Taking into consideration the nationwide
area which the subjects came; the sex ratio close to 134 already established
for Italian Down Ss at birth [1] and the distribution of chromosomal anomalies
which parallel both Italian and International ranges [2-5], the control group
can be considered to be an adequate representation of Down's syndrome subjects
in Italy.
The two groups show no difference in
maternal age at birth or as regards the investigated risk factors. There does
seem to be however some tendency to a larger male prevalence.
The significant difference in the
distribution of chromosomal anomalies needs to be cautiously interpreted and
could be due only to the small size of the sample. The presence of 57.58 % of
bruxism as indicator of non-specific stress [6-7] seems a significant
difference.
This finding leads one to speculate that the
sleep habits reported could be a signal related to stress and if so, a possible
stress compensator. When studied more closely, in the three forms in which the
sleep habit presents itself two common features are found:
- the same posture is adopted in a
non-rationally conscious way during sleep, and completely out of any cultural
influence;
- an obvious reduction is noted in the angle
between the trunk and thighs, whether through flexion of the trunk on the
thighs (by far the most frequent) or thighs on trunk (variations 1 and 2).
The differing mean age of first examination,
being older in the index group, was hypothesized as merely casual; on the other
hand, it could be an indication of the stage of motor development needed in order
that the symptom manifests itself.
As regards stress, it must be noted that
Down's syndrome individuals are undergoing, from conception, an endogenous
biochemical stress due to the acceleration of all the metabolisms whose enzymic
control genes are allocated to chromosome 21; metabolisms which are increased
by 50 % due to "dosage effect" i.e. the presence of a third
functioning gene of enzimic control.[8]
Down's Ss have a tendency towards
hypotension [9] because of a central noradrenergic deficit [1], and increased
responses to stress stimuli [11-12], besides very evident signs of stress
(bruxism, hyponeophagia, short stature, decreased non-specific immune response,
etc.) [8].
I cannot exclude the theory that the
parasympathetic and hypotensive phase,
which normally comes with sleep, as it
intensifies towards early morning hours
makes some organisms of Down individuals
take up this posture.
The reported fact that this position in some
cases is only taken up in early morning seems a good support of this interpretation.
It should be interesting to know whether
this posture is exclusive of Down's syndrome subjects or not.
How and why this possible compensator works
is a a matter for more and mere speculation and merits its own experimental
investigation.
References
[1] Susser M., Sergievsky G.H., Hauser W.A.,
Kiely G.L., Paneth N., Stein Z.: Quantitative estimates of prenatal and
perinatal risk factors for perinatal mortality, cerebral palsy, mental
retardation and epilepsy. In: Freeman G.M. (ed): Prenatal and perinatal factors
associated with brain disorders. National Institute of Health Publications:
Washington D.C., 1985, 359-439.
[2] Camera G., Mastroiacavo P.:
Epidemiologia della Sindrome di Down. In: Ce.Pi.M.: Aspetti epidemiologici,
genetici, clinici, riabilitativi e sociali della Sindrome di Down. Ce.Pi.M.,
Genova 1984: 225-230.
[3] Lambert J.L., Rondal G.A.: Le
mongolisme. Mardaga, Bruxelles 1979.
[4] Hook E.B.: Rates of chromosomal
anomalies at different maternal ages. Obstet. Gynecol. 1981, 58: 282-285.
[5] Lindsten G., Marsk L., Berglund K.,
Iselius L., Ryman N., Anneren G., Kjessler D., Mitelman F., Vejlens L.:
Incidence of Down's Syndrome in Sweden during the years 1968~1977. In: Burgio
G.R., Fraccaro M., Tiepolo L., Wolff U.(eds): Trisomy 21. Hun. Genet. /
Suppl. 2, 1981: 195-210.
[6] Morses D.R.: Stress and bruxism: A
critical review and report of cases. J. Hum. Stress 1987, 8: 43-54.
[7] Cocchi R., Lamma A.: Bruxism in soggetti
affetti da sindrome di Down. Odontostomatol.. Implantoprot. 1987, no. 4,
66-69.
[8] Cocchi R.: Terapia farmacologica nella
sindrome di Down: inquadramento teorico. In: Cocchi R., Belacchi C., Cercolani
P. (eds): Risultati di 8 anni di terapia farmacologica nella sindrome di Down.
GISSTIMMAI, Pesaro 1987: 19-41.
[9] Richards B.W., Enver F.: Blood pressure
in Down's syndrome. J. Ment. Defic. Res. 1979, 23: 123-135.
[10] Nyberg P., Carlsson A., Winblad E.:
Brain monoainines in cases with Down' Syndrome with and without dementia. J.
Neural Transmission 1982, 55: 299-299.
[11] Lake C.R., Ziegler M.G., Coleman M.,
Kopin I.J.: Evaluation of the sympathetic nervous system in Trisomy-21 (Down's
Syndrome). J. Psychiat. Res. 1979, 15: 1-6.
[12] Udeschini G., Casatí G., Bassani F.,
Picotti G.B., Culotta P.: Plasma catecholaměnes in Downls Syndrome, at rest and
during sympathetic stimulation. J. Neurol. Neurosurg. Psychiat. 185, 48:
1060-1061
Printed on It. J. Intellect. Impair. 1989, 2: 21-24
Author's address: dr Renato COCCHI, via Rabbeno, 3
42100 Reggio Emilia
renatococchi@libero.it
Symptoms
Down's syndrome
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