WHICH RELATIONSHIP
BETWEEN TONGUE PROTRUSION AND JOINT LAXITY / HYPOTONIA IN DOWNS? AN
EPIDEMIOLOGICAL INVESTIGATION ON 452 SUBJECTS.
Renato Cocchi, a neurologist and a medical
psychologist.
Summary.
As derived from the
same series of 510 Down Ss, two subsamples, the first with joint
laxity/hypotonia (142 Ss, 79 M + 63 F, M/F ratio = 125.40; normal distribution
of the chromosomal diagnoses; average age at the first visit: 35.98 +/- 35.33
months, range: 6-308 months) and the second one with tongue protrusion (141 Ss,
74 M + 67 F, M/F ratio = 110.45; normal distribution of the chromosomal
diagnoses; average age at the first visit: 46.10 +/- 41.59 months, range: 6-266
months) were compared each to another for evaluating which relationship between
these two symptoms. The conclusion is that 1. They are two symptoms that do not
depend from the extrachromosome 21; 2. There is no correlation between them; 3.
They inclined to disappear in the second life decade, but not in all the cases;
4. There exists the prevalence of the joint laxity/hypotonia till the second
year of life, and of the protrusion of the tongue after it.
Key words: Down syndrome; joint laxity,
hypotonia, tongue protrusion, stress.
In the last times, using an electronic database
where I collected information and symptoms referring to 510 subjects with Down
syndrome, I did epidemiological investigations on the joint laxity / hypotonia
(Cocchi, 2003) and on the tongue protrusion (Cocchi, 2004).
As for the tongue protrusion, I thought that
"we are dealing with an overstimulation of the hypoglossus nerve nucleus,
with unintentional repetition of the protrusion movement of the tongue."
(Cocchi, 2004).
It is of interest to note a common datum in
both investigations. The two symptoms incline to disappear with the age
growing.
Following neuro-physiological reasons and
the analogy with what happens in the tongue protrusion elicited by neuroleptic
drugs and antidepressants, I excluded, in this supported by my clinical
experience, that tongue protrusion is a passive movement, from hypotonicity of
the genioglossus and ioglossus muscles.
With this research I intend crossing the
data of Ss with the ligamentous laxity / hypotonia with them with the tongue
protrusion. If the ligamentous laxity / hypotonia has a role as a cause of the
tongue protrusion it should be possible to find that the population where both
symptoms appear, is the same, and that there is a statistically meaningful
level of correlation between these same symptoms.
Materials and methods.
This investigation used the clinical cards
referring to two previous investigations, both derived from a consecutive
series of home reared and home living Downs as seen in outpatients' clinic by
the present author. Psychotic subjects were excluded.
During their 1st consultation I reported the
presence of ligamentous laxity/hipotonia and tongue protrusion.
From this research, I dropped out the cards
where one or both these symptoms did not have their records.
From the remaining cards I collected:
- gender;
- chromosomal diagnosis;
- age at 1st consultation;
- positive or negative presence of the
symptom "lagamentous laxity/ hypotonia (I evaluated its presence according
to three degrees of severity: +, ++, +++) and positive or negative presence of
the symptom "tongue protrusion" (I evaluated its presence according
to two degrees of severity: +/-, +).
I statistically processed data by gender,
chromosomal diagnoses, age bands. I applied Chi Square Test, when suitable or
the test of correlation.
Results.
The data derived from the 510 clinical
cards, drove to a first selection of 452 cards suitable for this investigation
and the related data appear in the tables and in the graph that follow.
Tab. 1: Epidemiological data of the whole
series.
|
Nr. of Ss |
510 |
100.00% |
|
Males |
292 |
57.25% |
|
Females |
218 |
42.57% |
|
M/F ratio |
133.94/100 |
|
|
|
||
|
Chromosomal diagnoses |
|
|
|
Standard trisomy 21 |
461 |
90.39% |
|
Mosaicisms |
16 |
3.14% |
|
Translocations |
16 |
3.14% |
|
Unknown, only clinical diagnosis |
17 |
3.33% |
|
|
||
|
Age at 1st consultation (months) |
|
|
|
Range |
6-510 |
|
|
Mean +/- SD |
71.37 +/- 69.71 |
|
As 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: Comparison between the
epidemiological data of the two subsamples where a symptom was present,
independently from the presence of the other one (Cocchi, 2003; Cocchi 2004).
The rates come out from the whole series of 510 Ss.
|
|
Ligamentous laxity / hypotonia |
Tongue protrusion |
||
|
Presence of the symptom |
No. of Ss |
% |
No of Ss |
% |
|
Totals |
142 |
100.00 |
141 |
100.00 |
|
|
||||
|
Males |
79 |
55.63 |
74 |
52.48 |
|
Females |
63 |
44.37 |
67 |
47.52 |
|
M/F ratio |
125.40 |
110..45 |
||
|
Chi Square: 0.623 with 2 df and p = 0.732 NS |
||||
|
|
||||
|
Chromosomal diagnoses |
|
|
|
|
|
Standard Trisomy 21 |
130 |
91.55 |
130 |
92.21 |
|
Translocations |
6 |
4.22 |
5 |
3.54 |
|
Mosaicisms |
4 |
2.82 |
5 |
3.54 |
|
Only clinical diagnosis |
2 |
1.41 |
1 |
0.71 |
|
Chi Square: 0.532 with 3 df and p = 1.00 NS |
||||
|
|
||||
|
Age at first consultation |
|
|
||
|
Average (months) |
35.98 |
46.10 |
||
|
Standard Deviation |
35.33 |
41.59 |
||
|
Range (months): Minimum |
6 |
6 |
||
|
Maximum |
266 |
308 |
||
|
Chi Square: 0.257 with 3 df and p = 1.00 NS |
||||
Considered hypothetically as two independent
subsamples, they don't differ in a statistically meaningful way as for the
Males/Females distribution, the distribution of the chromosomal diagnoses and
for the parameters related to the age at the first consultation.
Tab. 3: Epidemiological data of the group of
Ss with annotation, positive or negative, of both these symptoms.
|
|
No. of Ss |
% |
|
Both symptoms recorded |
452 |
100.00 |
|
Males |
265 |
58.63 |
|
Females |
187 |
41.37 |
|
M/F ratio |
136.90 |
|
|
|
||
|
Chromosomal diagnoses |
|
|
|
Standard Trisomy 21 |
409 |
90.49 |
|
Translocations |
14 |
3.10 |
|
Mosaicisms |
13 |
2.88 |
|
Only clinical diagnosis |
16 |
3.54 |
|
|
||
|
Age at first consultation |
|
|
|
Average +/- SD (months) |
73.24 +/- 71.70 |
|
|
Range (months) |
6-510 |
|
At a first look the differences between the
distributions of the Tab.1 and the Tab. 3 are very little. From which it comes
out that the derived subsample of the Tab. 3 has the same epidemiological features
of the whole series. This last one, in its turn, was representative at least of
the Italian population of Down Ss.
Tab 4: Distribution of the relationships
between these two symptoms.
|
Joint laxity / Hypotonia vs tongue protrusion |
No. of Ss |
% |
|
- vs - |
240 |
53.10 |
|
- vs + / - |
4 |
0.88 |
|
- vs + |
84 |
18.58 |
|
+ vs - |
45 |
9.96 |
|
+ vs +/ - |
1 |
0.22 |
|
+ vs + |
30 |
6.65 |
|
++ vs - |
24 |
5.31 |
|
++ vs + |
18 |
3.98 |
|
+++ vs - |
2 |
0.44 |
|
+++ vs + |
4 |
0.88 |
|
Totals |
452 |
100.00 |
Chi Square: 158.411 with 8
df and p = 0.0001, when 0 = 0.01 calculation needs.
Correlation: r = -0.94; t =
-0.524 with 7 df and p = 0.617 NS.
Apart from the absence of both symptoms in 240
cases (53.10%), the joint laxity/hypotonia is present in 71 cases without the
contemporary tongue protrusion (15.71%).
On the other hand, the tongue protrusion is
present in 53 cases with contemporary ligamentous laxity/hypotonia (11.73%) and
in 88 cases without ligamentous laxity/hypotonia (19.47%).
For every case of tongue protrusion with
contemporary ligamentous laxity/hypotonia, 1.66 is without any ligamentous
laxity/hypotonia.
Tab 5: Distributions of the presence or
absence of the two symptoms, excluded the double absence.
|
Type of relationship |
Ligamentous laxity / hypotonia |
Tongue protrusion |
|
|
No. of Ss |
No. of Ss |
|
- vs + / - |
0 |
4 |
|
- vs + |
0 |
84 |
|
+ vs - |
45 |
0 |
|
+ vs +/ - |
1 |
1 |
|
+ vs + |
30 |
30 |
|
++ vs - |
24 |
0 |
|
++ vs + |
18 |
18 |
|
+++ vs - |
2 |
0 |
|
+++ vs + |
4 |
4 |
Chi Square: 158.411 with 8
df and p = 0.0001, when 0 = 0.01 for calculation needs
Correlation: r = -0.94; t =
-0.524 with 7 df and p = 0.617 NS.
With higher statistic probability, the two
distributions belong to two different populations, poorly correlated. That
means that the ligamentous laxity/hypotonia and the tongue protrusion have to
be considered as two independent phenomena between each other.
Tab. 6: Correlation between more severe
ligamentous laxity/hypotonia and tongue protrusion.
|
Type of relationship |
Ligamentous laxity / hypotonia |
Tongue protrusion |
|
|
No. di Ss |
No. di Ss |
|
++ vs - |
24 |
0 |
|
++ vs + |
18 |
18 |
|
+++ vs - |
2 |
0 |
|
+++ vs + |
4 |
4 |
Chi Square: 18.903 with 3 df
and p = 0.0009, when 0 = 0.01 for calculation needs.
Correlation : r = 0.277; t =
0.408 with 2 df and p = 0.723 NS.
Also the Ss with greater ligamentous laxity/hypotonia,
have a very high statistic probability of not belonging to the same population
of the Ss with related tongue protrusion.
Although with the increase of the
ligamentous laxity/hypotonia severity we find an increase of the index of
correlation with the tongue protrusion, the same is still far from the lowest
level of statistic significance.
Tab 7. Distribution, by yearly age bands; of
the number of subjects in each band; of the number of subjects with ligamentous
laxity/hypotonia, and related rates; of the number of subjects with tongue
protrusion and related rates; and of the ratio between subjects with
ligamentous laxity/hypotonia and subjects with tongue protrusion.
|
Age band (months) |
Ss No. |
Laxity / hypotonia |
Tongue protrusion |
Joint laxity / hypotonia and tongue protrusion ratio |
||
|
|
No. of Ss |
% |
No. of Ss |
% |
||
|
1-12 |
50 |
28 |
56.00 |
24 |
50 |
166.67 |
|
13-24 |
72 |
42 |
38.34 |
28 |
38.89 |
150 |
|
25-36 |
65 |
18 |
27.69 |
22 |
33.85 |
81.82 |
|
37-48 |
33 |
8 |
24.24 |
16 |
48.48 |
50.00 |
|
49-60 |
39 |
5 |
12.82 |
11 |
28.21 |
45.45 |
|
61-72 |
23 |
4 |
17.30 |
4 |
17.39 |
100 |
|
73-84 |
21 |
4 |
19.05 |
10 |
47.62 |
40.00 |
|
85-96 |
17 |
2 |
11.76 |
5 |
29.41 |
40.00 |
|
97-108 |
14 |
2 |
14.29 |
3 |
21.43 |
66.67 |
|
109-120 |
30 |
5 |
16.67 |
8 |
26.67 |
62.50 |
|
121-132 |
14 |
1 |
7.14 |
2 |
14.29 |
50 |
|
133-144 |
11 |
1 |
5.36 |
2 |
11.11 |
50 |
|
145-156 |
10 |
0 |
|
0 |
|
|
|
157-168 |
7 |
1 |
11.28 |
0 |
|
|
|
169-180 |
9 |
0 |
|
1 |
11.11 |
|
As we may see in the tab.7, the contemporary
presence of the two symptoms progressively lows with the age growing and
disappears after twelve years. The contemporary presence of two cases of ligamentous
laxity/hypotonia and one case of tongue protrusion among the ten cases of 15-16
years, was judged casual coincidence.
Graph 1.
Being the line of the 1:1 ratio = 100, till
two years there is a prevalence of the ligamentous laxity/hypotonia, but since
already three years this ratio reverses, with the prevalence of the tongue
protrusion.
Discussion.
In the two preceding epidemiological
searches (Cocchi, 2003; Cocchi 2004) I excluded with elevated statistic
probability, that either ligamentous laxity/hypotonia either tongue protrusion
were symptoms directly elicited by the extrachromosome 21. Moreover, I saw that
both symptoms decidedly inclined to disappear with the age growing, and this
was a common datum.
The working sample here used (Tab 3: 452
cases) as for the M/F ratio, distribution of the chromosomal diagnoses and age
at the first consultation has the same features of the whole series (Tab. 1:
510 cases), for which it may be assumed as representative at least of the
Italian population of Down Ss.
In their turn, the two subsamples of 142
ligamentous laxity/hypotonia cases and the 141 cases of tongue protrusion, both
directly taken from two preceding searches (Cocchi 2003; Cocchi 2004), do not
differ in statistically meaningful way. It is so either for the gender
distribution and compare M/F ratio, either for the distribution of the
chromosomal diagnoses, either for the age at the first consultation (Tab. 2).
The Tab. 4 starts to let and see the type of
relationship between these two variables. Both symptoms are not present in
53.10%. The ligamentous laxity/hypotonia belongs to 15.71% of the cases without
contemporary tongue protrusion. In 19.47% tongue protrusion without ligamentous
laxity/hypotonia appeared and only in 11.73% both symptoms met contemporarily.
Already this is enough to exclude a
dependence of the tongue protrusion from the ligamentous laxity/hypotonia. A
cause and effect relationship that goes wrong in 88.27% of cases is hardly
affordable.
The distributions of the presence or absence
of the two symptoms, excluding the double absence (Tab. 5) allowed a refinement
of this affirmation. Now, the two investigated subsamples belong with high statistic
probability to two different populations. Their correlation overcomes a few
than 61% probability of being statistically meaningful.
When applied the same tests to the
relationships where the severity of the ligamentous laxity/hypotonia was greater
(Tab. 6), the difference of the two populations rests while the correlation
increases to a few more than 72%. There is more than 27% probability that we
are dealing with a casual result, and therefore a statistically meaningful
correlation is to be rejected.
We however should take in consideration the
datum coming out from this last comparison in the tab. 6. If it increases the
severity of the ligamentous laxity/hypotonia, it inclines to increase even the
tongue protrusion presence. By excluding a close correlation, we may say that
possible mediate but independent mechanisms, show the effects of a more serious
primitive condition, which it has nothing directly to do with a third the
chromosome 21.
Personally, I think that the
continually induced metabolic stress from an increase of all the body
metabolisms that have their gene of control on the chromosome 21, plays a
fundamental role. On the other hand, I am always more convinced that it would
be other variables that can act upon the stress. For example, one of them could
be the individual resistance to the stress.
From the Tab. 7 it results evident that the
presence of the two symptoms is going to lower with the age, till to disappear
since 13 years. That would drive to think even to a some influence of the
sexual development. Nevertheless, the ligamentous laxity/hypotonia and tongue
protrusion ratio, - that is already reversed since 3 years with the prevalence
of this last -, is confirmation that they are two different phenomena, and they
differently profit from the usual rehabilitation therapies.
Conclusions.
Coming from the same series of 510 Down
subjects, the comparison between two subsamples, one with ligamentous
laxity/hypotonia and the second with tongue protrusion, supported these
conclusions. 1. The two symptoms do not depend from the extrachromosome 21; 2.
They are not correlating each other; 3. They are going to disappear in the
second life decade, but not always; 4. There is prevalence of the ligamentous
laxity/hypotonia till two years, and of tongue protrusion after two years.
References.
Cocchi R. Ligamentous laxity and hypotonicity in Downs. An
epidemiological investigation on 510 subjects. 2003 <
www.stress-cocchi.net/Down34.htm >.
Cocchi R. Tongue protrusion in Downs. An epidemiological survey on 510
subjects. 2004 <www.stress-cocchi.net/Down42.htm>.
Posted on
Internet on May 2004. Copyright by Renato Cocchi, 2004.
Author's address: dr Renato Cocchi, via Rabbeno, 3
42100 Reggio Emilia (Italy).
renatococchi@libero.it