Down's Syndrome

Original Editor - Abdul Jemal Top Contributors - {{Abdul Jemal/Template:Down' s Syndrome}}

Definition

Down syndrome is a chromosomal disorder resulting in 47 chromosomes instead of 46; commonly called trisomy 21. [1]

Aetiology

Result from faulty cell division affecting the 21st pair of chromosomes either owing to a nondisjunction (95%), translocation (3%) to 4%), or least commonly as mosaic presentation (1%).[2]

Pathophysiology

  1. Neuropathologies - CNS disorder in children with Down syndrome is owing to several well-documented brain abnormalities. Overall brain weight in an individual with Down syndrome is 76% of normal with the combined weight of cerebellum in brainstem being even smaller 66% of normal. There is also microcephaly and the brain is abnormally rounded and short with a decreased A-P diameter specially called microbrachycephaly.[3] There are also structural abnormalities in the dendritic spines in the pyramidal tracts of the motor cortex that possibly underlying the motor incoordination so often seen in children with Down syndrome. [4] Research shows evidence of a lack of myelination as well as a delay in the completion of myelination between 2 months and 6 years of age which explain the overall developmental delay typically seen in Down syndrome.[2]Some studies claim that up to 8% of children with Down syndrome have some form of seizure disorder.[2]
  1. Musculoskeletal Problems - In addition to general hypotonia, ligamentous laxity is hallmark musculoskeletal characteristic of Down syndrome and commonly results in pes planus, patellar instability, hip luxation, scoliosis 52% and atlantoaxial instability.[5]
  2. Cardiopulmonary Pathologies - Forty percent of children with Down syndrome are born with congenital heart defects most commonly atrioventricular canal defect.[6] Usually repaired in infancy, heart defect not corrected by age 3 years are highly associated with greater delays in motor skill development.[7]

Other associated Problems

  • Visual
  • Hearing
  • Speech impairments
  • Obesity
  • Umbilical hernia

Motor Development

Activity Down Syndrome Typical Developmental Milestones
Mean age Range of age Mean age Range of age
Head control 5 m 3-9 m 3 m 1-4 m
Rolling 8 m 4-12 m 5 m 2-10 m
Sitting without support

for 1 minute

9 m 6-16 m 7 m 5-9 m
Pulls to stand 15 m 8-26 m 8 m 7-12 m
Walk with help 16 m 6-30 m 10 m 7-12 m
Standing without support 18 m 12-38 m 11 m 9-16 m
Walk without help 19 m 13-48 m 12 m 9-17 m
Activity Down Syndrome Typical Developmental Milestones
Mean age Range of age Mean age Range of age
Walking stairs with help 30 m* 20-48 m 17m 12-24 m
Walking stairs without help 36 m 24-60+ m 17 m 13-24 m
Running 48 m 18 m
Jumps on place 48-60 m 24 m

Development Delay

Clinically, hypotonia has been well established to highly correlated with development delay, including delay in attainment of gross motor and fine motor milestones.[9] Studies also have shown the persistence of primitive reflexes beyond the time when they should disappear. [10] Additional studies by Harris and Rast and Shumway-Cook also demonstrated difficulties in posture control, antigravity control, deficits in postural response synergies when balance perturbations were introduced and consequently the development of compensatory movement strategies as children with Down syndrome attempted to learn to move and stabilize themselves. [11]↵Example include “ W” sitting where the child will characteristically spread his or her legs to a full 180 degrees split while in prone and then advance to sitting posture by pushing up with his or her hands into sitting. [12] Gait acquisition is delayed and is immature characterized by a persistent wide base and out-toeing.[13] Hypotonia has been shown to contribute to slower reaction time and depressed kinesthetic feedback. [14] Children who have motor impairments are at subsequent risk of secondary impairment because of their restricted ability to explore the environment especially cognition, communication and psychosocial development.[15]


Assessment and Treatment

Therapist must be aware of coexisting medical problems and alert to those typically associated with Down syndrome such as cardiac, atlantoaxial stability, hearing and visual and presence of seizure disorder and must also integrate child’s cognitive capacity into evaluation process.Treatment goal: Anticipate gross and fine motor delay and provide intervention to minimize it; Position and handling activities throughout early infancy and childhood to promote antigravity control and weight bearing.Facilitate antigravity extension in prone and weight shifting within and as transition from prone.Supine and supported sitting encourage midline orientation, antigravity bi manual activities including eye-hand coordination in most children with Down syndrome.1[16]

Reference

  1. Harris SR, Shea AM. “Down syndrome” paediatric neurology physical therapy 2nd Ed, Churchill Livingstone; 1991
  2. 2.0 2.1 2.2 Pueschel SM. Cause of Down syndrome. In: Pueschel SM . “A parent’s guide to Down syndrome toward a brighter future” Baltimore; Brookes Publishing Co; 1990
  3. Penrose LS,et al. Down’s Anomaly, London: Churchill Livingstone; 1966.
  4. Marin Padilla M. “Pyramidal cell abnormalities in the motor cortex of child with Down’s syndrome” J.Comp. Neural 1976; 67:63.
  5. Diamond LS,et al. “Orthopedic disorder in patient with Down’s syndrome.” Orthop.clin.North. Am. 1981; 12:57
  6. Dummer GM. “Strength and flexibility in Down’s syndrome” In American Association for Health, Physical Education and Recreation, Research consortium Paper: Movement Studies, Vol 1, book 3; 1978. Washington, DC.
  7. Zausmer EF, Shea A. Motor development. In: Pueschel SM.The young child with Down syndrome. New York; Human Science Press Inc; 1984.
  8. Children with Down Syndrom. Motor development and intervention. P. Lauteslager et al. 2000
  9. Harris SR. “Relationship of mental and motor development in Down’s syndrome Infants.” Phy. Occup. Therapy Paediatric 1981;1:13.
  10. Ciechetti D, Strowle LA. “The relationship between effective and cognitive development in Down’s syndrome infants. Child Dev.1976; 47:920.
  11. Shumway-Cook A. Woollacott M: “Dynamics of postural control in the child with Down syndrome.”Physical Therapy 1985; 65:1315-1322.
  12. Lydic JC, Steele C. “Assessment of the quality of sitting and gait pattern in children with Down’s syndrome.” Phys.Ther. 1979;59 (12): 1489-1494.
  13. Parker AW, Bronks R. “Gait of children with Down syndrome. Phys. Med. Rehabil. 1980;61:345-351.
  14. O’Connor N, Hermelin B. “Speech and thought in severe subnormality.” London. Oxford Press; 1963.
  15. Affotter FD. “Perception, Interaction, and Language, Interaction of daily living:” The Road of development. New York. Springer Verlag; 1991
  16. Jan Stephen Tecklin “Paediatric Physical Therapy” 3rd edition; 1999.

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