Gustavo Lara

Bio: Gustavo Lara is an academic researcher from Harvard University. The author has contributed to research in topics: Swallowing & Mastication. The author has an hindex of 1, co-authored 1 publications receiving 363 citations.

Coordination of mastication and swallowing.

Abstract: The coordination of mastication, oral transport, and swallowing was examined during intake of solids and liquids in four normal subjects. Videofluorography (VFG) and electromyography (EMG) were recorded simultaneously while subjects consumed barium-impregnated foods. Intramuscular electrodes were inserted in the masseter, suprahyoid, and infrahyoid muscles. Ninety-four swallows were analyzed frame-by-frame for timing of bolus transport, swallowing, and phases of the masticatory gape cycle. Barium entered the pharynx a mean of 1.1 s (range −0.3 to 6.4 s) before swallow onset. This interval varied significantly among foods and was shortest for liquids. A bolus of food reached the valleculae prior to swallow onset in 37% of sequences, but most of the food was in the oral cavity at the onset of swallowing. Nearly all swallows started during the intercuspal (minimum gape) phase of the masticatory cycle. Selected sequences were analyzed further by computer, using an analog-to-digital convertor (for EMG) and frame grabber (for VFG). When subjects chewed solid food, there were loosely linked cycles of jaw and hyoid motion. A preswallow bolus of chewed food was transported from the oral cavity to the oropharynx by protraction (movement forward and upward) of the tongue and hyoid bone. The tongue compressed the food against the palate and squeezed a portion into the pharynx one or more cycles prior to swallowing. This protraction was produced by contraction of the geniohyoid and anterior digastric muscles, and occurred during the intercuspal (minimum gape) and opening phases of the masticatory cycle. The mechanism of preswallow transport was highly similar to the oral phase of swallowing. Alternation of jaw adductor and abductor activity during mastication provided a framework for integration of chewing, transport, and swallowing.

Pediatric feeding disorders.

Abstract: Pediatric feeding disorders are common: 25% of children are reported to present with some form of feeding disorder. This number increases to 80% in developmentally delayed children. Consequences of feeding disorders can be severe, including growth failure, susceptibility to chronic illness, and even death. Feeding disorders occur in children who are healthy, who have gastrointestinal disorders, and in those with special needs. Most feeding disorders have underlying organic causes. However, overwhelming evidence indicates that abnormal feeding patterns are not solely due to organic impairment. As such, feeding disorders should be conceptualized on a continuum between psycho-social and organic factors. Disordered feeding in a child is seldom limited to the child alone; it also is a family problem. Assessment and treatment are best conducted by an interdisciplinary team of professionals. At minimum, the team should include a gastroenterologist, nutritionist, behavioral psychologist, and occupational and/or speech therapist. Intervention should be comprehensive and include treatment of the medical condition, behavioral modification to alter the child's inappropriate learned feeding patterns, and parent education and training in appropriate parenting and feeding skills. A majority of feeding problems can be resolved or greatly improved through medical, oromotor, and behavioral therapy. Behavioral feeding strategies have been applied successfully even in organically mediated feeding disorders. To avoid iatrogenic feeding problems, initial attempts to achieve nutritional goals in malnourished children should be via the oral route. The need for exclusive tube feedings should be minimized.

Food Transport and Bolus Formation during Complete Feeding Sequences on Foods of Different Initial Consistency

Abstract: Food movements during complete feeding sequences on soft and hard foods (8 g of chicken spread, banana, and hard cookie) were investigated in 10 normal subjects; 6 of these subjects also ate 8 g peanuts. Foods were coated with barium sulfate. Lateral projection videofluorographic tapes were analyzed, and jaw and hyoid movements were established after digitization of records for 6 subjects. Sequences were divided into phases, each involving different food management behaviors. After ingestion, the bite was moved to the postcanines by a pull-back tongue movement (Stage I transport) and processed for different times depending on initial consistency. Stage II transport of chewed food through the fauces to the oropharyngeal surface of the tongue occurred intermittently during jaw motion cycles. This movement, squeeze-back, depended on tongue–palate contact. The bolus accumulated on the oropharyngeal surface of the tongue distal to the fauces, below the soft palate, but was cycled upward and forward on the tongue surface, returning through the fauces into the oral cavity. The accumulating bolus spread into the valleculae. The total oropharyngeal accumulation time differed with initial food consistency but could be as long as 8–10 sec for the hard foods. There was no predictable tongue–palate contact at any time in the sequence. A new model for bolus formation and deglutition is proposed.

Early Assessments of Dysphagia and Aspiration Risk in Acute Stroke Patients

Abstract: Background and Purpose— Dysphagia is common after stroke and is a marker of poor prognosis. Early identification is important. This article reviews the merits and limitations of various assessment methods available to clinicians. Methods— An electronic database search was performed of MEDLINE, EMBASE, and the Cochrane database using such terms as stroke, aspiration, dysphagia, and assessment; extensive manual searching of articles was also conducted. Results— Bedside tests are safe, relatively straightforward, and easily repeated but have variable sensitivity (42% to 92%), specificity (59% to 91%), and interrater reliability (κ=0 to 1.0). They are also poor at detecting silent aspiration. Videofluoroscopy gives anatomic and functional information and allows testing of therapeutic techniques. However, swallowing is assessed under ideal conditions that are different from clinical settings, and reliability is often poor (κ=0 to 0.75) in the absence of assessor training. Fiberoptic endoscopy allows swallow as...