ダウン症候群児の粗大運動能と摂食に関わる口腔異常習癖との関連

ダウン症候群患者の多くが舌突出や口唇閉鎖不全などの特有の症状を呈する．これらは保護者が発見しやすい症状であるため，摂食指導の主訴となることも多い．舌突出や口唇閉鎖不全は咀嚼や嚥下機能の阻害因子であり，長期化すると歯列や咬合状態にも影響を及ぼし，さらに摂食機能を低下させることが想定される．したがって，ダウン症候群児に特有の症状が習癖化する前にこれらの症状を改善または予防することが重要である．
そこで今回，ダウン症候群児の口腔機能や摂食に関する実態を把握し，摂食指導に役立てることを目的に研究を行った．
対象は，経口摂取をしているダウン症候群児51名（男児32名，女児19名）とした．対象者の保護者から，初回の摂食指導受診日にダウン症候群児に関する質問票を記載してもらい，当日回収した．質問票の内容を検討した結果，対象者は，座位以降の粗大運動能の獲得時期が健常児より遅れる傾向にあった．対象者の約7割が摂食指導を受けた経験があったが，その指導内容の大半は食形態の指導であり，間接訓練や直接訓練の指導を受けた者は約2割であった．舌突出の有無は，年齢，歩行，筋訓練，おもちゃしゃぶりとの間に有意な関連が認められた．一方，口唇閉鎖不全の有無は，直接訓練であるかじりとり訓練との間に有意な関連が認められた．以上の結果よりダウン症候群児の舌突出と粗大運動能の発達には関連がみられ，さらに，筋訓練の導入や，一定の時期に行うおもちゃしゃぶりのようなさまざまな感覚入力が有効であることが示唆された．

Children with Down’s syndrome generally have specific complications and unique development；most have some oral parafunctional habits, including mouth opening, tongue thrusting, and swallowing food without chewing. These parafunctional activities can be caused by muscle hypotonia and developmental retardation of gross motor function. However, the relationship between the development of gross motor function and oral parafunctional habits remains unclear. The purpose of the present study was to investigate the relationship between gross motor function and oral parafunctional habits in children with Down’s syndrome in order to perform effective dysphagia therapy.
The subjects were children with Down’s syndrome receiving dysphagia therapy at the Tama Oral Rehabilitation Clinic at Nippon Dental University from Octber 18, 2012 to January 11, 2014. Fifty-one children（mean age 3.2 ± 1.7 years）who were able to eat orally were enrolled in the study with the consent of their parents. Parents completed a questionnaire about their child’s gross motor function and oral parafunctional habits relevant to eating at their initial clinic visit.
Most children had developmental retardation of gross motor function and more than half displayed mouth opening and/or tongue thrusting. The subjects had received prior dysphagia therapy at other clinics, involving many different teaching contents. Most had received information on appropriate food choices；few had received instruction on muscle training. Tongue thrusting was significantly associated with age, development of the gross motor functions of age and walking, experience of muscle exercises, and the oral habit of sucking on toys. On the other hand, there was a significant relationship between mouth opening and biting exercises.
We conclude that the development of gross motor function might be an important factor in improving oral parafunctional habits, including mouth opening and tongue thrusting for children with Down’s syndrome. Muscle exercises and sensible stimuli exercises during a specified period should be initiated as part of dysphagia therapy at an appropriate developmental stage in children with Down’s syndrome.