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Atlanto-Axial Instability in Down Persons. Neurologic Risks in the Sport Practice, Mainly in Judo
Giuseppe Tassani*, Renato Cocchi**, Paolo Alberto Pagani***
*Specialist in Sport Medicine, Sport Medicine Unit of the USL 3-Pesaro; **Neurologist; ***Orthopaedist
Italian Journal of Intellective Impairment 5 (2): 239-44 (1992)
Reprinted with the permission of Renato Cocchi|
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About 20% Down children are carriers of atlanto-axial instability, a risky condition for physical activities or sports such as gymnastics, diving and Judo. This malformation is inversely age related and is prevailing among male children. Although it could be intuitively linked to laxity, no more than 10% of lax Down children are also affected by atlanto-axial instability. This instability can be detected by screening X-ray examination of the lateral cervical spine both in neutral position and in flexing.
Over four mm forwarding dislocation of the odontoidal tip lead to suspicion, but over 5 mm is overtly assumed as pathological. Symptoms of medullary compression can be detected after neurological examination and confirmed by ACT of the atlanto-axial region. The screening of atlanto-axial instability in Down children should be included in preliminary routine tests before medical certification of fitness for school gymnastics and sports. Key words: Atlanto-Axial instability; Down's syndrome; Risky physical activities; Judo; Detection.
Down syndrome, also called Trisomy 21, works for more than 30% of the mental retardation forms from chromosomal anomalies. The discovery and the use of the antibiotics deeply modified the life hope of these individuals. Before 1945 it was difficult to meet a Down person aged more than ten years. Mostly of them died before this age, for bronchopulmonary infections.
The possibility of a longer life grew parallelling to a general habit of better acceptance of this disability. The spreading of the idea and of the practice of what is call of "normalization" is driving their parents to start the children even towards sport activities.
In such direction there was already the push of the diffused practice of swimming, often started in early childhood as a support of motor rehabilitation.
The meeting of both the parents wishful idea and an always greater availability of either half-public or private sporting trainers are bringing these subjects to be put in many sporting disciplines compatible with their motor situation.
The motor skills of in Downs on one hand are close to those of other mentally retarded without any motor damage. Their features are primarily motor awkwardness, some balance troubles, a reduced ability in fine motor actions.
On the other hand their motility can show own negative aspects, in particular for the rare presence of pure hypotonia (Favuto and Cocchi, 1992), primarily of cerebellar origin, and the more spread ligamentous laxity.
The atlanto-axial instability, which would be observed with a frequency of about 15-20%, is a recent finding (Vermeer and coll., 1992).
In these Down persons to take up gymnastics, diving and judo could have some danger, for an exaggerate excursion of the tooth of the epistropheus, leading to compression or the lesion of medullary nervous pathways. The damage, besides its clinical evidence, can be confirmed by CAT (Alvarez and Rubin, 1986) and by NMR imaging.
This ligamentous anomaly has a higher incidence in males with less than eleven years, but even this datum is in contrast with preceding assertions (Alvarez and Rubin, 1986). Instead it is in accord, as for the age, with an investigation on the presence of pure hypotonicity in Downs, one of us carried on (Favuto and Cocchi, 1992).
Although we can think at once that the atlanto-axial instability recalls the presence of ligamentous laxity (Semine and co., 1987; Collacott et al., 1989), recent specific investigations observed no more than 10% of Downs with ligamentous laxity is also the carrier of this anomaly (Cremers, 1992).
As for the prevention of it, besides its description and the spreading of the knowledge of the warnings symptoms (Howard, 1985) it has tried a X-ray evaluation of the atlanto-axial instability. It can be done by comparing the X-graphic examination of the head in a neutral position and in bending.
An excursion of more than 3mm of the epistropheus tooth peak became already considered as suspected, if more than 4mm as frankly pathological and a sign of atlanto-axial instability (Wang and coll., 1984; Cremers, 1992).
Very new studies on this specific aspect led the X-ray screening as doubtful, at least for distances less than 5mm (Cremers, Ramos and Boll, 1992). On the other side, specific alternate investigations with greater sensibility did not have been proposed.
The problem however exists, and the X-ray investigation-graphic, even if controversial, still stands up as the only way of checkup in order of prevention.
Finding an excursion larger than 4mm forces therefore to caution in the gymnastic practice and in sports where is bending and forced extensions of the neck can occur.
Non traumatic atlanto-axial instabilities are rare events, and they can add to severe congenital pathology, as we are observing in the Down syndrome of Down. They also can appear in late states of degenerative illnesses, as it happens in the rheumatoid arthritis.
Being greater body of knowledge available, for an easier explanation we refer on what happens in this last illness. Now, there is not any evidence in the Down syndrome this phenomenon gives rising to symptoms or to a specific pathological frame.
Most of these patients tolerate the instability for long, without signs of neurologic troubles.
The capsule-ligamentous lesion of the occipital-cervical joint and of the C1 and C2 vertebras, is going on in some persons, with a deceitful onset of the symptoms. So because the loosening of ligamentous formation without any bony compression, occurs in a zone where the medullary channel is ample.
The atlanto-axial subdislocation till to a move of 3.5mm in every direction, may be considered as not being to threaten. A greater measure is an evident mark of joint instability.
For the evaluation of the instability we may apply the clinical criteria described by Ranawat and coll. in 1979, and by Conaty and Mongan in 1981. At least for what concerns the rheumatoid arthritis in the II stage, we can already observe weakness, hyperaesthesias and dysthesias. In the IIIa stage, it arrives to paresis, medullary damage, with maintenance of the walking. At IIIb stage we may find evident tetraparesis and walking inability.
The prevailing therapeutic approach, now, is surgery aiming to stabilize the cervical tract, to take place when the paresis starts, according to Louis, 1983.
Some sports are particularly prone to the skull-cervical traumas. We have to exclude, of course, the motorcycle sports, while we have to pay consideration diving, the American football, and generally the "in touch" sports.
Among last ones, our attention goes to the Judo, and mainly to the techniques of immobilization that involve the strangulation, or Shime-Wasa of the traditional Judo language. In the following examples there are enough risk elements.
The biomechanics' solicitation imposes at once an attitude in bending of the head on the neck, with an exaggerate distracting component that can even associate to a neck hyperextension.
As for these immobilization techniques, it is easily to sense how to the muscle-ligaments apparatus of the neck, generally, and the cervical rachis joints are strongly solicited also in static conditions, when the held person has enough time to oppose the resistance of a valid muscular tone.
If the same technique is applied during fighting, when the gesture develops to elevated speed to make it unpredictable to the adversary, the adjustment of the muscular tone of the sufferer could be late and not incomplete. In this way the cervical joints are vulnerable to high risks.
As it concerns us, these subjects can own some systemic muscular hypotonus, added to ligamentous atlanto-axial instability. The biomechanics solicitations applied there can involve the risk of a true, anterior, roundabout or mixed dislocation. On the other hand the back dislocation can occur only when accompanied from the epistropheus tooth's fracture.
The improvement of a diagnostic technique is a wishful thing, and it will allow of appraising the risk of a partial incontinence of the atlanto-axial joint, to which to undergo Down subjects inclined to practise Judo.
On the other hand it is a sport with interesting aspects, beyond to get defense and attack techniques.
The control of the bodily scheme, for example, the way to the dexterity, the study and the approach to the adversary, the discipline and the behaviour in the Dojo, or the room of practising, the personal hygiene and the respect for the teacher and for the adversary, are all elements that make the judo an excellent educational proposal.
The investigation on the possible presence of atlanto-axial instability should usually be integrated within the preliminary examinations for the medical certification of suitability for the school physical education and for sport practising in Down children (Howard, 1985).
Since the difficulties met till now and above exposed, it is always better to have false positive to whom giving advices to avoid certain sport practices as the Judo (Gunasingham and Akuffo, 1988), than ignore this problem. The personal risks for the subject and that legal ones for the pediatrician, for the general practitioners, or the sport physician, could become too high.
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