LIGAMENTOUS LAXITY AND
HYPOTONICITY IN DOWNS.
AN EPIDEMIOLOGICAL
INVESTIGATION ON 510 SUBJECTS.
Renato COCCHI, neurologist and medical
psychologist.
Summary.
At first
consultation, 142 Down subjects out of 510 ( 79 M and 63 F, M/F ratio = 125.40;
normal distribution of the chromosomal anomalies; average age: 35.98 +/- 35.53
months, with 6-164 months range) showed ligamentous laxity and/or muscle
hypotonicity, with 27.84% prevalence. The ligamentous laxity was more detected
in infant age.
The severity of the
symptom reduced with the age and it was found as marked in only 4 cases belonging
to the first three-year of life. With the age increasing the M/F ratio inclines
to diminish or to capsize, for which it seems that the males are free of this
motor difficulty in smaller times. This symptom was no more present after 14
years of age
Key words: Down syndrome, stress,
ligamentous laxity, muscle hypotonicity, hypotonia, epidemiology, gender, age.
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Ligamentous laxity and/or hypotonicity in
Downs are symptoms by now become stereotypes in the image of these subjects.
For which one expects that all Downs own it at the birth, as they must have always
some cardiac defect, for which to the first heart examination at least a heart
murmur is detected. Of fact, according to Medline 1960-2003, a systematic
investigation about it on a large sample does not exist.
I have a database on 510 subjects (This is
the limit of my old MS-DOS database) and I checked this symptom in more than
98% of the Downs seen in the outpatients'. So I decided to explore this aspect
from an epidemiological point of view.
Materials and methods
This investigation used the clinical
cards referring to a consecutive series of home reared and home living Downs as
seen in outpatients' clinic by the present author. Psychotic subjects were
excluded .
From all the records so pointed out
those pertaining to autistic or PDD DS Ss were discarded because we saw that
this second heavier pathology can modify every sympotm or behaviour.
From the remaining records I collected:
- sex; -
- chromosomal diagnosis; -
- age at 1st consultation;
- presence or absence of ligamentous laxity
and/or muscular hypotonicity.
I collected this symptom with a graduation
where
(+) = A light symptom, usually hypotonicity;
(++) Presence of moderate hypotonicity and
ligamentous laxity;
(+++) Marked presence of hypotonicity and
ligamentous laxity.
I worked the data statistically for sex,
chromosomal anomaly and age bands and I evaluated them, when possible, with the
Chi Square test.
Results.
I summarized the data of the subjects to
which belong the records in the following tables.
Tab. 1: Epidemiological data of the whole series.
|
Nr. of Ss |
510 |
100.00% |
|
Malesi |
292 |
57.25% |
|
Females |
218 |
42.57% |
|
M/F ratio |
133.94/100 |
|
|
|
||
|
Chromosomal diagnosis |
|
|
|
Standard trisomy 21 |
461 |
90.39% |
|
Mosaicisms |
16 |
3.14% |
|
Translocations |
16 |
3.14% |
|
Unknown, only clinical diagn. |
17 |
3.33% |
|
|
||
|
Age at 1st consultation (months) |
|
|
|
Range |
6-510 |
|
|
Mean +/- SD |
71.37 +/- 69.71 |
|
How we may see in the table 1, the M/F ratio
appears little different from what we know for Italian newborn and alive Down
children. Even the distribution of the chromosomal diagnosis, meets the ranges
of variability for Italian and international samples.
For these reasons, we may think the sample
here investigated as representative of at least the Italian population of
Downs.
Tab. 2: Distribution of the prevalence of the symptom "legamentous laxity
and/or muscle hypotonicity "according to gender, chromosomal diagnosis and
age at first consultation.
|
Ss nr. of the whole sample. |
510 |
100.00 % |
|
|
|
|||
|
Not investigated |
9 |
1.76 % |
|
|
Symptom presence |
142 |
27.84 % |
|
|
|
|||
|
Symptom presence |
142 |
100.00 % |
|
|
Males |
79 |
55.63 % |
|
|
Females |
63 |
44.37 % |
|
|
M/F ratio |
125.40 |
||
|
|
|||
|
Chromosomal diagnosis |
|
||
|
Standard trisomy 21 |
130 |
91.55 % |
|
|
Translocations |
6 |
4.22 % |
|
|
Mosaicisms |
4 |
2.82 % |
|
|
Only clinical diagnosis |
2 |
1.41 % |
|
|
|
|||
|
Age at first consultation |
|
||
|
Average +/- SD (months) |
35.98 +/- 35.33 |
||
|
Range (months) |
6-164 |
||
I detected the symptom only in 27.84% of
subjects. For which it cannot be a symptom that depends directly from the
chromosomal anomaly, otherwise all Downs should have it.
The usual male gender prevalence is kept,
even if slightly smaller of what reported by Camera and Mastroiacovo, 1984, for
Italian Down children at birth.
The distribution of the chromosomal
anomalies parallels what known for the Italian and international Down
populations.
Even the average age at first consultation
is the half that of the whole sample, and decidedly reduced is even the SD.
Moreover, I did not find this symptom in 14-and-more-years old patients (= 168
months).
Table 3: Distribution for gender of the symptom according to its severity.
|
Graduation of the symptom |
Nr. of Ss |
% |
|
|
||
|
Slight (+) |
|
|
|
Males |
50 |
35.22 |
|
Females |
41 |
28.88 |
|
|
|
|
|
Moderate (++) |
|
|
|
Males |
26 |
18.30 |
|
Females |
21 |
14.79 |
|
|
||
|
Marked (+++) |
|
|
|
Males |
3 |
2.11 |
|
Females |
1 |
0.70 |
|
Totals |
142 |
100.00 |
More of 60% of the investigated subjects,
show this symptom in a light form, nearly always as muscle hypotonicity.
Table 4: Distribution of the ligamentous laxity and/or
hypotonicity according to the age year.
|
Age (years) |
Nr. of Ss |
% |
(+) Ss nr. |
% |
(++) Ss nr. |
% |
(+++) Ss nr. |
% |
|
Totals |
142 |
100.00 |
91 |
100.00 |
45 |
100.00 |
4 |
100.00 |
|
--> 1 |
33 |
23.24 |
15 |
16.48 |
15 |
33.34 |
3 |
75.00 |
|
1-2 |
44 |
30.98 |
26 |
28.57 |
17 |
37.78 |
1 |
25.00 |
|
2-3 |
22 |
15.49 |
13 |
14.28 |
9 |
20.00 |
0 |
0.00 |
|
-->3 totals |
99 |
69.72 |
54 |
59.34 |
41 |
91.11 |
4 |
66.66 |
|
|
||||||||
|
3-4 |
8 |
5.63 |
5 |
5.49 |
3 |
6.67 |
0 |
0.00 |
|
4-5 |
10 |
7.04 |
10 |
10.99 |
0 |
0.00 |
0 |
0.00 |
|
5-6 |
3 |
2.11 |
3 |
3.30 |
0 |
0.00 |
0 |
0.00 |
|
3-6 totals |
21 |
14.79 |
18 |
19.78 |
3 |
6.67 |
0 |
0.00 |
|
|
||||||||
|
6-7 |
5 |
3.52 |
4 |
3.30 |
0 |
0.00 |
0 |
0.00 |
|
7-8 |
2 |
1.41 |
2 |
2.20 |
0 |
0.00 |
0 |
0.00 |
|
8-9 |
3 |
2.11 |
2 |
2.20 |
1 |
2.22 |
0 |
0.00 |
|
6-9 totals |
10 |
7.04 |
8 |
7.70 |
1 |
2.22 |
0 |
0.00 |
|
|
|
|
|
|
|
|
|
|
|
9-10 |
7 |
4.93 |
6 |
6.59 |
1 |
2.22 |
0 |
0.00 |
|
10-11 |
1 |
0.70 |
1 |
1.10 |
0 |
0.00 |
0 |
0.00 |
|
11-12 |
3 |
2.11 |
3 |
3.30 |
0 |
0.00 |
0 |
0.00 |
|
12-13 |
0 |
0.00 |
0 |
0.00 |
0 |
0.00 |
0 |
0.00 |
|
13-14 |
1 |
0.70 |
1 |
1.10 |
0 |
0.00 |
0 |
0.00 |
|
9-14 totals |
12 |
8.45 |
11 |
12.09 |
1 |
2.22 |
0 |
0.00 |
In nearly 70% I detected this symptom within
the first three years of age, and in nearly 85% the same within the first six
years of age
After three years the marked degree (+++) symptom
is no more present in this sample.
Table 5: Distribution for age, as related to gender and the
M/F ratio, in comparison with the whole sample of 510 Ss ( M/F ratio = 133.94)
|
Age (years) |
M Nr. |
F Nr. |
M/F ratio |
M/F direction |
|
-- > 1 |
17 |
16 |
106.25 |
Decreased |
|
1-2 |
27 |
17 |
158.82 |
Increased |
|
2-3 |
14 |
8 |
175.00 |
Decreased |
|
-->3, totals |
58 |
41 |
141.46 |
Increased |
|
|
|
|
|
|
|
3-4 |
4 |
4 |
100 |
Decreased |
|
4-5 |
2 |
5 |
40.00 |
Decreased |
|
5-6 |
5 |
1 |
500.00 |
Increased |
|
3-6 totals |
11 |
10 |
110.00 |
Decreased |
|
|
|
|
|
|
|
7-9 |
5 |
5 |
100.00 |
Decreased |
|
10-14 |
5 |
7 |
71.43 |
Decreased |
Chi Square = 6.505 with 7
df and p = 0.510 NS.
Although the distribution for age, as gender
indifferent, is overwhelming at least in 50% Ss, after the three years the M/F
ratio inclines to diminish. For which it seems that the age disappearance of
the symptom, is higher in the females.
Nevertheless, the two cases with moderate
severity (++), seen respectively at the age of nine and 10 years, are one for
gender.
Discussion.
Among the motor troubles that Down children
can show there are even the muscle hypotonicity and the ligamentous or articulations'
laxity.
Concerning the muscle hypotonicity and the
ligamentous laxity in Downs, I quote here what already I wrote in the past
(Cocchi, (1990).
Among various motor impairments the Down
child could have hypotonicity and articular laxity too. Hypotonicity seems a
symptom that comes out from a cerebellar trouble, already noted by some
researchers (Lambert & Rondal, 1979, Cocchi, 1987). Till now articular
laxity, sometimes not present, did not find its reason.
We can have at least two suggestions:
- First, for an unknown cause, tissues of
articular ligaments are more elastic then in normal people, so allowing a
greater excursion of that same articulation;
- Second, it could stand an impairment
between the possible normal growth of the articular tissue, and the possible
inhibition of the bones of that same articulation.
There is only one clinical report on the
positive effects of the SAMe on primitive muscular fibres' pain, as poor support
of the first suggestion. Its interpretation is quite doubtful since these
effects do not seem attributable to a local action but to the antidepressant
action of the SAMe (Tavoni et al. 1987).
As for the second hypothesis there are
more than one supportive element. First we need to remember that the bones'
growth depends on the activity of bones cartilages of growth, which is function
of available homocysteine.
Of there is homocysteine excess, as it
happens in homocystinuria - an illness where the enzyme
cystathionine-beta-synthetase is lacking -, people affected should be toll,
thin, with many folds in flexing surfaces (Groebe, 1980).
Although there are reports about a
collagen type, the VI, codified from a gene found on the chromosome 21, the ligamentous
laxity, which has to derive from it, not appears in mostly Downs. (Leshin,
2003). This last fact even confirmed by this investigation.
We know that the age reduces the ligamentous
laxity (Parker and James, 1985), another result here found. The same happens
for the hypotonicity, which may profit of psychomotor rehabilitative therapies
(Linkous and Stutts 1990). This rehabilitation intervention was common to every
one here investigated subject.
The usual male prevalence altogether rests,
even if is slightly smaller of what found at birth in the Italian children.
The distribution of the chromosomal
anomalies is not within the ranges reported for Italian and international Down
populations. This excludes, in the cases here investigated, an action of a form
trisomy 21 on the ligamentous laxity and/or muscle hypotonicity. On the other
hand, in a previous research non mosaicisms (Cocchi, 1996), I found this
symptom in four Ss out of 16 (25%) very close to the present rate (27.84%).
Eventually this research showed that the
time course inclines to capsize the M/F ratio, with a female prevalence, as if
the males succeeded to overcome first the ligamentous laxity and/or muscle
hypotonicity.
References.
Camera G., Mastroiacovo P.:
Epidemiologia della sindrome di Down. In. Ce.Pi.M. (ed): Aspetti
epidemiologici, genetici, clinici, riabilitativi e sociali della sindrome di
Down. Ce.Pi.M., Genova 1984: 225-230
Cocchi R.: Presenza di
scavengers e incidenza di paralisi cerebrali infantili da prematurita` e
basso peso alla nascita in 381 soggetti Down allevati in famiglia.
Giorn. Neuropsich. Eta` Evol. 1987, 7: 317-323.
Cocchi R. La
S-adenosil-L-metionina (SAMe) riduce la lassita` articolare nel
bambino Down? (Comunicazione preliminare) Riv. It. Disturbo Intellet. 1990,
3: 141-143.
Cocchi R. Mosaic
forms in Down's syndrome: A survey on sixteen cases. It. J. Intellect. Impair. 1996, 9:
45-54
Clopath P., Smith V.C.,
McCully K.S.: Growth promotion by homocysteic acid.
Science 1976, 192: 372-374.
Groebe H.:
Homocystinuria (cystathionine synthetase deficiency). Results of
treatment in late-diagnosed patients. Eur. J. Pediatr. 1980, 135: 199-203.
Lambert J.L., Rondal J.A.:
Le mongolisme. Mardaga, Bruxelles 1979.
Lejeune J.:
Investigations biochimiques et trisomie 21. Ann. Genet. (Paris) 1979, 22:
67-75.
Leshin L. Musculoskeletal
Conditions in Down Syndrome. Musculoskeletal Disorders in Down Syndrome. In
Internet, 2003.
Linkous LW, Stutts RM.
Passive tactile stimulation effects on the muscle tone of hypotonic,
developmentally delayed young children.Percept Mot Skills 1990,71(3 Pt
1):951-954.
Parker AW, James B. Age
changes in the flexibility of Down's syndrome children. J Ment Defic Res 1985,
29 (Pt 3): 207-218
Tavoni A., Vitali C.,
Bombardiere S., Pasero G.: Evaluation of S-adenosylmethionine in
primary fibromyalgia: A double-blind crossover study. Am. J.
Med. 1987. 83 (suppl. 5A): 107-110.
Posted Internet on September 2003.
Copyright by Renato Cocchi 2003.
Author's address: dr Renato Cocchi, via Mercalli 10
42100 Reggio Emilia.
renatococchi@libero.it
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