Disorders of Swallowing

Feeding difficulty is not an uncommon symptom in children, reportedly occurring in 25% of children (Miller and Willging 2003). The causes of pediatric dysphagia are varied and complex, and may be physiologic or behavioral. The majority of children with dysphagia have a neurological cause, and may be due to cranial nerve palsies, cerebral palsy and meningomyelocele. Structural craniofa-cial anomalies predispose to dysphagia (Lifschitz 2001; Miller and Willging 2003). Swallowing dysfunction with aspiration is common in full-term infants less than 1 month of age and improves with age (Vazquez and Buonomo 1999).

The video esophagram, or modified barium swallow, is the standard technique to evaluate dyspha-gia. This examination is more sensitive than clinical evaluation of aspiration (DeMatteo et al. 2005), and is also more sensitive than the conventional upper GI series for the detection of aspiration (Vazquez and Buonomo 1999). A scout radiograph of the chest should be obtained to assess for evidence of aspiration. For the examination, the child must be securely maintained sitting in the true lateral position, best accomplished in an infant feeding seat. Participation of the parents and caregivers helps to reassure the child, and recreates some aspect of daily feeding. The child's own speech therapist or feeding therapist should optimally be present during the examination to witness the events. The therapist can observe the optimal food volume and consistency and compensatory maneuvers that assist swallowing (FerNbAcH 1994). Boluses of different consistencies are fed. Young children are given liquids, though the density of various liquids may vary. The examination in older children begins with thin liquid barium, proceeding to feeds with a mixture of barium thickened with pudding or pureed food, and finally with more solid food such as barium-coated crackers. Barium density influences the swallowing mechanism. High-density barium has a slower transit time, causing the upper esophageal sphincter to open later, to remain open for longer and to delay its closure (DANtAS et al. 1989). The actions of swallowing occur too rapidly to be observed fluoroscopically, therefore the entire examination is recorded on videotape, or if unavailable, with standard fluoroscopy set at a frame rate of 2-3/s. The recorded examination can be repeatedly reviewed without additional radiation. Review of the tapes is important when there is a need to assess the patient multiple times as treatment or the disease progresses. Multiple swallows in each series must be reviewed because changes can occur in the same cycle after episodes of normal swallowing. Infants may tire as feeding progresses, and may have difficulty maintaining their airway so the study should be continued after the first few uneventful swallows (NewmAN et al. 2001). Pulsed fluoroscopy cannot be used during video esophagrams as it may prevent detection of fleeting episodes of penetration and microaspiration (MercAdO-DeANe et al. 2001). The unfortunate necessity of using standard fluoroscopy results in the child's receiving a higher radiation exposure to the thyroid gland than during a conventional esophagram.

Abnormalities occur at all levels during swallowing: in the oral, pharyngeal and esophageal phases. The modified barium swallow is used to identify the level of pathology so that therapy or treatment can be given. In the oral phase of swallowing, the abnormality may have an anatomic etiology such as micrognathia or macroglossia. Children on long term tube feeding may be unused to feeding, and they may simply refuse to eat. Severely neurologically impaired children may be unable to suck or they may lack sufficient tongue control to latch onto and maintain control of the nipple. Suckling deficits also manifest with weak and deficient tongue motion, inability to compress the nipple and early tiring (KrAmeR 1989). Oral motor dysfunction occurs with moderate or severe cerebral palsy and developmental delay. Incomplete buccal closure leads to drooling, and abnormal tongue and jaw motion (KrAmer 1989). Those neurologically impaired children unable to elevate the soft palate experience nasopharyngeal incoordination and nasopharyngeal reflux (Fig. 2.4). Occasional nasopharyngeal incoordination is most commonly due to transient swallowing incoordination. Retropharyngeal masses such as teratoma, lymphoma and abscess can rarely cause dysphagia. Cricopharyngeal achalasia, or failure of relaxation of the cricopharyngeus muscle, is most commonly secondary to gastroesophageal reflux. Signs of cri-copharyngeal achalasia include absent, delayed or incomplete opening or early closure of the sphincter. Laryngeal penetration occurs when barium enters an incompletely protected airway below the level of the vocal cords and trachea during swallowing. It is important to document whether aspiration induces

Nasopharyngeal Penetration
Fig. 2.4. Nasopharyngeal and tracheal aspiration. Barium outlines the nasopharynx (n) and the trachea (t). Only a trace of barium remains in the esophagus

a cough reflex. Penetration is different from aspiration, which occurs during respiration (KRAmER 1989). Aspiration should be documented with a postexamination chest radiograph. The examination must be terminated if aspiration occurs and causes changes in vital signs. If the child remains stable after aspiration, the examination can proceed. The aim of the study is to determine if there is a safe way that food can be given, and after aspiration, it may be necessary to change to barium of another density, to use another type of nipple or to change the pace of feeding. Co-ordination of swallowing improves with age, and follow up examinations are an effective means to monitor improvement.

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