THE NYSTAGMUS IN  DOWN CHILDREN: PRESENCE,

 IMPLICATIONS AND RESULTS AFTER DRUG THERAPY.

 

Renato COCCHI, a neurologist and a medical psychologist

Roberta BRANCHESI, an orthoptist.

(Traduzione italiana)

  Summary.

  Out  of  a not selected consecutive series  of  432  Down's  syndrome subjects, 26 = 6.02% presented horizontal nystagmus. Sex distribution  revealed 61.54%  of female prevalence. Pre- and perinatal risk factors and concomitant squint are doubled as compared to the whole series of Down subjects.

 A  polydrug therapy always using l-glutamine, pyridoxine, biotin and diazepam among other drugs led to  disappearance of the nystagmus in 10 subjects, after, average, one year and half treatment. It led to its reduction  in other eight, at checkups after 18-42 months.  

 Key words: Down’s Syndrome; nystagmus; sex  prevalence; risk  factors; drug therapy.

 

 Down’s syndrome

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The nystagmus is a term that refers on rhythmical and unintentional movements of the eyes [1]. To understand the nystagmus we need know that the eye follows a mobile object, or examines  with the look an object (even a written line ) with a slow movement, said even pursuit movement or, better,  fixative movement [2].   

In other words, the slow movement comes from the effort to maintain the fixation on the object that moves. When reading, it follows the need to move the fixation point on every word, or on every letter of the line. In the first case the fixation  follows the object. In the second the fixation moves on objects that are in spins long a line, as it happens for our writing, which goes from left to right, in a horizontal sense.

The return to the departure position, to follow an other object (or the next line) happens instead with a rapid movement, said saccadic movement [2]. In the pathological nystagmus this type of movement is independent from their normal purpose, but on the contrary they work against  the pupil fixation on the object to explore. According to the speed of these eyeballs' movement we can find two types of pathological nystagmus, the pendular one, when the deviation of the pupil, and its return to the intermediate position, both  happen with the same speed [1].   

There is instead a jerk nystagmus  when the deviation of the slow movement alternates with the rapid movement. The pathological nystagmus can be horizontal, vertical and rotatory [1].  

Since the will does not control them, the eyeballs' movements of any nystagmus hinder the object fixation. We recalled reading and  writing because two basic activities in school learning, and we can understand how a visual trouble of these two fields can drive to negative effects on learning.

The nystagmus can be a symptom that comes out in an isolate way [1], but usually it is present in various pathological conditions, such as the  cerebral palsy, and the syndrome of Down. Since long time collaboration, one of us, as orthoptist,  is doing examinations of the eyeballs' mobility in the Down children. They come examined for the first time by the coauthor or they come back for checkup, after drug therapy started.   Therefore this research concerns children suffering from this illness.

Two were the investigated aspects. The first refers on the presence of the nystagmus and its possible correlation with risk factors or symptoms that usually accompany it.  Secondarily we will report the results on the nystagmus, of the drug therapies prescribed.  

 

Materials and methods.

We reexamined clinical reports of 432 Down subjects, of both sexes, and coming from all the Italian regions.

We sorted all with the nystagmus symptom. From them we collected the following  data:

  - sex;

- age at the first examination;

- chromosomal diagnoses;

-  presence of prematurity or postmaturity [5];

- presence of low birthweigh [5];

- presence of other complications in embryonic or fetal period, during labour or in the neonatal period [5];

-  presence of squint.    

Besides all that we transcribed:

- the drugs used;

- the duration of the drug therapy, up to the last checkup;

- the results of the therapy on the nystagmus.  

 

Results.

Here are the results, divided following of the investigated field.   

 

  Table 1: Epidemiological and clinical  data.  

Nystagmus presence

26/432 Ss

6.02%

Nystagmus type:  horizontal jerking

26 Ss

100.00%

Sex distribution

16 F

61.54%

 

10 M

38.46%

Chromosomal diagnosis

 

 

  Trisomy 21 frees

25 Ss

96.15%

  Mosaicisms

 1 S

3.85%

Age at the first examination (in months)

16-199

average: 67

   

Table 2: Risk factors and squint presence .

 

Prematurity

7 Ss

31.82%

Postmaturity

1 S

3.85%

Low birthweigh

0 Ss

0.00

Prematurity + low birthweigh

2 Ss

7.69%

 

Other risk factors pre-, peri- and neonatal

 

 

Presence

22 Ss

84.62%

No. for any S.

1-8

Average: 2.27%

Squint presence

16 Ss

61.54%

   

Table 3: Individually taylored therapy, with the following common drugs.  

l-glutamine

 90-250 Mg/die

Pyridoxine

125-250 Mg/die

Biotin

5 Mg/die

Diazepam

1-2 Mg/die

      Table 4: Results on nystagmus and duration of the drug therapy.  

Clinical result

Nr. of Ss and %

Therapy duration

Therapy average

Disappeared

10 Ss = 38.46%

  6-48 months

18 months

Clearly diminished

8 Ss = 30.77%

18-42 months

 

Unchanged

5 Ss = 19.23%

  3-46 months

 

No checkup

3 Ss = 11.54%

 

 

 

Discussion.

  For what concerns the prevalence of the nystagmus in Down persons, that found  by us resulted less than that reported in 1985 in an exhaustive review on the ocular characteristics in the syndrome of Down, where the presence of the nystagmus have been reported in a rate that ranges from the 9 to  22% [4].    . The sex distribution reveals an unusual feature.

Females seem affected in a decidedly higher rate than males, even if in Downs representative samples, as it happens in our 432 subjects, the males/females ratio is always favourable in the males, which are,  average one third more [6-7].

The chromosomal diagnoses here found, for that modest  sample, can well reenter  in the normal distribution.

The horizontal nystagmus type,  is that usual of the syndrome of Down. As for the prevalence of prematurity and/or low birthweigh, always about our series of the first 424 cases [7], they range from 21.23% to 39.51% in this subgroup.

The squint, as the more frequent symptom accompanying the nystagmus, was in 61.54%,  twice of what we had found again in the first 424 subjects of this same series.  

As for the common drugs  everyone took, three of them, glutamine, pyridoxine and diazepam are respectively a precursor of the glutamate and of the GABA the first;

The second is the catalyst of the enzyme (GAD) that transforms the glutamate into GABA; The third works as a  sensitizer of the type A post-synaptic GABA receptor.

Pyridoxine and biotin are found again increased, in normal people, exactly in the midbrain and in the pons [8], the brain structures that seem involved in this type of nystagmus.

The horizontal nystagmus, in facts, can have its starting point in troubles of the pons-cerebellar angle and of the brain trunk [1], nervous structures which, since 1890, were found again more atrophic in Downs [9].   For what concerns the results, as a whole, 18 children out 23, which is to say in 78.26% of the cases where the drug therapy was assumed, got a diminution or a disappearance of the nystagmus.

 This datum is completely new, and of difficult interpretation.  It opposes with what habitually known on the fate of this symptom, which it can improve with the age but rarely disappears [10].  This fact however that there was a reduction or a disappear in over three/quarters of treated  cases, if not other, reduced in this 18 subjects, a visual obstacle to their possibility of learning.

This result is much more important, because in the subject Down the visual memory works better than that auditory one and it can have closer links with the structures working to speech production.  Finally we can ask ourselves if this result is only obtainable in Down children, or even in other school age subjects with a horizontal nystagmus. The correction of possible sensory defects is still one   first remedy to set in action, when from these defects  troubles of  learning come out.  If what have here reported would be confirmed by further research, perhaps we found an other tool in this field.  

 

References.

[1] Adams R.D., Victor M.: Principles  of Neurology.  3rd Edition. McGraw-Hill, Singapore 1985: 204-206.

[2]  Cambier  J., Masson M., Dehen H.: Neurologia. 4’ edizione italiana. Masson, Milano 1984:  74-75.

[3] Lowe R.F.: The eyes in Mongolism. Br. J. Ophthalm. 1949, 33:  131-174.

[4] Shapiro M.B., France T.D.: The ocular features of Down’s Syndrome. Amer. J. Ophthalmol. 1985, 659-663.  

[5] 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.

 [6] 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. 

 [7] Cocchi R., Branchesi R.: Is there a causal non-connection  between squint  and  cerebral palsy through prematurity and/or low birthweight  in  Down  Syndrome children?  It. J. Intellect. Impair. 1988, 1: 141-144.

 

Paper presented at the 1st refreshing course "Il disturbo cognitivo in età scolare", San Costanzo 25 April 1989. Published on Internet on November 2002. Copyright by Renato Cocchi 2002.  

 

 

Author’s address: dr Renato COCCHI, via Rabbeno,3

42100 Reggio Emilia (Italy)

renatococchi@libero.it

 

Testo in italiano

Down’s syndrome

Mental retardation

Symptoms

Drug modulation of stress reactions

World congresses on stress and other congresses

Home Page  / /  Pagina iniziale