Deglutitive aspiration is common after stroke and can have devastating consequences. While the application of oral sensory stimulation as a treatment for dysphagia remains controversial, data from our laboratory have suggested that it may increase corticobulbar excitability, which in previous work was correlated with swallowing recovery after stroke. Our study assessed the effects of oral stimulation at the faucial pillar on measures of swallowing and aspiration in patients with dysphagic stroke. Swallowing was assessed before and 60 min after 0.2-Hz electrical or sham stimulation in 16 stroke patients (12 male, mean age = 73 +/- 12 years). Swallowing measures included laryngeal closure (initiation and duration) and pharyngeal transit time, taken from digitally acquired videofluoroscopy. Aspiration severity was assessed using a validated penetration-aspiration scale. Preintervention, the initiation of laryngeal closure, was delayed in both groups, occurring 0.66 +/- 0.17 s after the bolus arrived at the hypopharynx. The larynx was closed for 0.79 +/- 0.07 s and pharyngeal transit time was 0.94 +/- 0.06 s. Baseline swallowing measures and aspiration severity were similar between groups (stimulation: 24.9 +/- 3.01; sham: 24.9 +/- 3.3, p = 0.2). Compared with baseline, no change was observed in the speed of laryngeal elevation, pharyngeal transit time, or aspiration severity within subjects or between groups for either active or sham stimulation. Our study found no evidence for functional change in swallow physiology after faucial pillar stimulation in dysphagic stroke. Therefore, with the parameters used in this study, oral stimulation does not offer an effective treatment for poststroke patients.

Evaluating oral stimulation in the treatment of dysphagia after stroke

Research using animal models has contributed significantly to realizing the goal of understanding dysfunction and improving the care of patients who suffer from dysphagia. But why should other researchers and the clinicians who see patients day in and day out care about this work? Results from studies of animal models have the potential to change and grow how we think about dysphagia research and practice in general, well beyond applying specific results to human studies. Animal research provides two key contributions to our understanding of dysphagia. The first is a more complete characterization of the physiology of both normal and pathological swallow than is possible in human subjects. The second is suggesting of specific, physiological, targets for development and testing of treatment interventions to improve dysphagia outcomes.

/pdf/animal-models-for-dysphagia-studies-what-have-we-learnt-so-5dh60plqlv.pdf

Animal Models for Dysphagia Studies: What Have We Learnt So Far.

Preterm infants face a variety of challenges associated with safe feeding, but obtaining high-resolution longitudinal data to understand these challenges in humans is challenging. We used a pig mod...

Preterm birth disrupts the development of feeding and breathing coordination

Safe, efficient liquid feeding in infant mammals requires the central coordination of oropharyngeal structures innervated by multiple cranial and spinal nerves. The importance of laryngeal sensatio...

https://www.physiology.org/doi/pdf/10.1152/japplphysiol.00946.2015

Central nervous system integration of sensorimotor signals in oral and pharyngeal structures: oropharyngeal kinematics response to recurrent laryngeal nerve lesion.

The timing of the occurrence of a swallow in a respiratory cycle is critical for safe swallowing, and changes with infant development. Infants with damage to the recurrent laryngeal nerve, which receives sensory information from the larynx and supplies the intrinsic muscles of the larynx, experience a significant incidence of dysphagia. Using our validated infant pig model, we determined the interaction between this nerve damage and the coordination between respiration and swallowing during postnatal development. We recorded 23 infant pigs at two ages (neonatal and older, pre-weaning) feeding on milk with barium using simultaneous high-speed videofluoroscopy and measurements of thoracic movement. With a complete linear model, we tested for changes with maturation, and whether these changes are the same in control and lesioned individuals. We found (1) the timing of swallowing and respiration coordination changes with maturation; (2) no overall effect of RLN lesion on the timing of coordination, but (3) a greater magnitude of maturational change occurs with RLN injury. We also determined that animals with no surgical intervention did not differ from animals that had surgery for marker placement and a sham procedure for nerve lesion. The coordination between respiration and swallowing changes in normal, intact individuals to provide increased airway protection prior to weaning. Further, in animals with an RLN lesion, the maturation process has a larger effect. Finally, these results suggest a high level of brainstem sensorimotor interactions with respect to these two functions.

/pdf/maturation-of-the-coordination-between-respiration-and-1fphc0efe7.pdf

Maturation of the Coordination Between Respiration and Deglutition with and Without Recurrent Laryngeal Nerve Lesion in an Animal Model.

Recurrent laryngeal nerve (RLN) injury in neonates, a complication of patent ductus arteriosus corrective surgery, leads to aspiration and swallowing complications. Severity of symptoms and prognosis for recovery are variable. We transected the RLN unilaterally in an infant mammalian animal model to characterize the degree and variability of dysphagia in a controlled experimental setting. We tested the hypotheses that (1) both airway protection and esophageal function would be compromised by lesion, (2) given our design, variability between multiple post-lesion trials would be minimal, and (3) variability among individuals would be minimal. Individuals' swallowing performance was assessed pre- and post-lesion using high speed VFSS. Aspiration was assessed using the Infant Mammalian Penetration-Aspiration Scale (IMPAS). Esophageal function was assessed using two measures devised for this study. Our results indicate that RLN lesion leads to increased frequency of aspiration, and increased esophageal dysfunction, with significant variation in these basic patterns at all levels. On average, aspiration worsened with time post-lesion. Within a single feeding sequence, the distribution of unsafe swallows varied. Individuals changed post-lesion either by increasing average IMPAS score, or by increasing variation in IMPAS score. Unilateral RLN transection resulted in dysphagia with both compromised airway protection and esophageal function. Despite consistent, experimentally controlled injury, significant variation in response to lesion remained. Aspiration following RLN lesion was due to more than unilateral vocal fold paralysis. We suggest that neurological variation underlies this pattern.

/pdf/the-physiologic-impact-of-unilateral-recurrent-laryngeal-txqpszabmo.pdf

The Physiologic Impact of Unilateral Recurrent Laryngeal Nerve (RLN) Lesion on Infant Oropharyngeal and Esophageal Performance

Background: Acute interstitial nephritis (AIN) is a clinico-pathological syndrome associated with a variety of infections, drugs, and sometimes with unknown causes. It is a common cause of acute kidney injury (AKI) and subsequent renal impairment, which often times is under-diagnosed. Infection-associated AIN occurs as a consequence of many systemic bacterial, viral, and parasitic infec-tions; however, its incidence has decreased significantly after the advent of antimicrobials. Infection-associated AIN presents with both oliguric or non-oliguric renal insufficiency, without the classical clinical triad of AIN (fever, rash, and arthralgia). In this scenario the renal function is usually reversible after the infection is treated. In most cases, patients with acute renal failure present with extra-renal manifestations typically detected in underlying infections. Renal biopsy serves as the most definitive test for both the diagnosis and prognosis of AIN. Case Presentation: In this paper, we will address one such case of biopsy-proven AIN. In this case, the patient presented with severe AKI induced by anaerobic streptococcus, leading to a periodontal abscess, which was successfully treated with corticosteroids and requiring renal replacement therapy (RRT). Conclusions: AIN should be considered in the differential for unexplained AKI. Initial management should include conservative therapy by withdrawing any suspected causative agent. Renal biopsy is needed for confirmation in cases where kidney function fails to improve within 5–7 days on conservative therapy. Risk of immunosuppression is very important to consider when giving steroids in patients with infection induced AIN, and steroids may have to be delayed until the active infection is completely controlled.

Luke Fraley

Papers

The Physiologic Impact of Unilateral Recurrent Laryngeal Nerve (RLN) Lesion on Infant Oropharyngeal and Esophageal Performance

Central nervous system integration of sensorimotor signals in oral and pharyngeal structures: oropharyngeal kinematics response to recurrent laryngeal nerve lesion.

Infection associated acute interstitial nephritis; a case report.