Faculty Bibliography

Purpose: Age-related loss of muscle bulk and strength has been documented in the tongue and geniohyoid. Our goal was to explore this phenomenon in the pharynx, specifically by measuring pharyngeal wall thickness (PWT) and pharyngeal lumen area (PLA) in a sample of young vs older women. Method(s): MRI scans of the neck were retrospectively reviewed from 60 women equally stratified by 3 age groups (20s, 60s, 70+). Exclusion criteria included dysphagia, c-spine surgery, neurological illness, head and neck malignancy and obstructive sleep apnea. Three de-identified axial slices were extracted per scan for randomized, blinded analysis: at the levels of the anterior inferior border of C2 and C3, and at the pit of the vallecula (Vpit). Pixel-based measures of PWT and PLA were completed using ImageJ and converted to metric units using the calibration markers on the original images. Measures of PWT and PLA (at three levels) were compared between age groups with one-way ANOVAs using Sidak adjustments for post-hoc pairwise comparisons. Result(s): A significant main effect of age was observed for all variables whereby PWT decreases and PLA increases with advancing age (Table 1). Pairwise comparisons revealed significant differences between 20s vs 70+ for all variables and 20s vs 60s for all variables except PWT and PLA at C2. Effect sizes ranged from 0.56-1.34. Conclusions (Including Clinical Relevance): Consistent with the existing sacropenia literature, the pharyngeal muscles appear to atrophy with age and consequently, PLA increases as well. Future work should explore the relationship between pharyngeal muscle size/ atrophy and functional swallowing outcomes. (Table Presented)

Purpose: Dynamic MRI has been used to examine swallowing in sagittal and axial planes with good temporal resolution. However, few studies have examined temporal measures and none have compared upright vs. supine swallowing in both positions with the MBSImP. We report physiologic variables and swallow safety upright and supine with MBSImP and Penetration/Aspiration scales in healthy subjects. Method(s): Twenty healthy subjects (mean = 28 years) underwent VFS study upright and supine with a C-Arm. Subjects were viewed in the sagittal plane and swallowed 5 mL liquid and pudding barium. Pen/Asp scores and 14 MBSImP variables were analyzed (overall Impression score) in both positions, with means and ranges across subjects upright and supine. Paired t-tests compared MBSImP scores upright vs. supine. Level of significance: p<.05. Result(s): All subjects tolerated the supine position while swallowing. Mean MBSImP scores were WNL across subjects for both positions, except Component 6, Initiation of the Pharyngeal Swallow (Table 1). Nosignificant differences were found for MBSImP scores upright vs. supine. Although the range of Pen/Asp scores was higher for supine, 3 subjects penetrated upright only, 1 penetrated supine only, and 1 aspirated on 1 supine swallow. Pearson coefficients for inter/intra-judge reliability:0.94, 0.91. Conclusions (Including Clinical Relevance): Physiologic measurse revealed a pharyngeal delay in both positions with scores not significantly different. Although Pen/Asp range was higher in supine, more subjects penetrated upright. Future research should examine swallow physiology in both positions in dysphagic and older healthy subjects. (Table Presented)

Purpose: This study investigated whether time post-RT or other variables impacted dysphagia severity at time of enrollment and after an aggressive swallow therapy program in HNC patients Method(s): A multi-site RCT enrolled 170 HNC patients with moderate to severe dysphagia 3+ months after RT into 2 treatment groups: estim+swallow exercises vs. sham stimulation+swallow exercises. Results showed few significant differences between the 2 groups. Secondary analyses using ANCOVA sought to identify any subgroups that benefitted from therapy. Type of radiation, cancer site, cancer stage, and time post-RT were analyzed. All subjects were pooled and re-analyzed regardless of treatment group. Result(s): Time post-RT had an impact on performance. At enrollment, patients <6 months post-RT had the best swallow scores and patients>10 years had the worst scores. Longitudinal analyses over the 13 week program showed no significant change in PAS scores at any time post-RT. Hyoid excursion worsened in patients >1 year post-RT (p = 0.04). Residue scores improved slightly in patients 6 mos-1 year post-RT. Diet scores significantly improved in patients 3 mos-1yr post RT (p = 0.0007). Conclusions (Including Clinical Relevance): At time of enrollment, patients with less time post-RT had better swallow function than patients who were several years post-RT. Therapy did not improved swallow function by most measures; patients who were 10 yrs+ post even declined in some measures. Reports that dysphagia worsens over time was supported by this study. Lack of response to treatment suggests that earlier intervention may be the best alternative

The representation of acoustic cues involves regions downstream from the auditory cortex (ACx). One such area, the perirhinal cortex (PRh), processes sensory signals containing mnemonic information. Therefore, our goal was to assess whether PRh receives auditory inputs from the auditory thalamus (MG) and ACx in an auditory thalamocortical brain slice preparation and characterize these afferent-driven synaptic properties. When the MG or ACx was electrically stimulated, synaptic responses were recorded from the PRh neurons. Blockade of type A gamma-aminobutyric acid (GABA-A) receptors dramatically increased the amplitude of evoked excitatory potentials. Stimulation of the MG or ACx also evoked calcium transients in most PRh neurons. Separately, when fluoro ruby was injected in ACx in vivo, anterogradely labeled axons and terminals were observed in the PRh. Collectively, these data show that the PRh integrates auditory information from the MG and ACx and that auditory driven inhibition dominates the postsynaptic responses in a non-sensory cortical region downstream from the ACx.

HYPOTHESIS: Intrinsic differences in neurons of the vestibular ganglia result in the increased likelihood of superior vestibular ganglion involvement in vestibular neuritis. BACKGROUND: Vestibular neuritis is hypothesized to result from herpes simplex type I (HSV1) infection or reactivation in vestibular ganglia. Involvement of the inferior vestibular ganglion is extremely rare in patients with vestibular neuritis. METHODS: Primary cultures of rat superior and inferior vestibular ganglion neurons (VGNs) were cultivated separately. Neurons were lytically and latently infected with HSV1 with a US11-green fluorescent protein (GFP) chimera. Percentage lytic infection and baseline reactivation was assessed by microscopy for GFP fluorescence. Trichostatin-A (TSA) was used to stimulate HSV1 reactivation. Virion production was assessed by viral titers. Relative numbers of latency-associated (LAT) transcripts were determined by real-time reverse-transcription polymerase chain reaction (real-time RT-PCR). RESULTS: Lytic infection rates were equivalent between the two ganglia (p > 0.05). Lytic infections yielded similar amounts of plaque-forming units (p > 0.05). Relative amounts of LAT transcripts did not differ between latently infected superior and inferior VGNs. Latently infected cultures showed no differences in rates of baseline and TSA-induced HSV1 reactivation (p > 0.05). Production of virions was not significantly different between reactivated, latently infected superior versus inferior VGNs (p = 0.45). CONCLUSION: Differences in prevalence of superior and inferior vestibular neuritis do not result from intrinsic differences in HSV1 infection or virion production of these neurons. Other factors, such as the length and width of the bony canal containing the ganglia and nerves, account for the greater involvement of the superior vestibular ganglion in vestibular neuritis.

Vocal communication is negatively affected by neurodegenerative diseases, such as Parkinson disease, and by aging. The neurological and sensorimotor mechanisms underlying voice deficits in Parkinson disease and aging are not well-understood. Rat ultrasonic vocalizations provide a unique behavioral model for studying communication deficits and the mechanisms underlying these deficits in these conditions. The purpose of this review was to examine the existing literature for methods using rat ultrasonic vocalization with regard to the primary disease pathology of Parkinson disease, dopamine denervation, and aging. Although only a small amount of papers were found for each of these topics, results suggest that both shared and unique acoustic deficits in ultrasonic vocalizations exist across conditions and that these acoustic deficits are due to changes in either dopamine signaling or denervation and in aging models changes to the nucleus ambiguus, at the level of the neuromuscular junction, and the composition of the vocal folds in the larynx. We conclude that ultrasonic vocalizations are a useful tool for studying biologic mechanisms underlying vocal communication deficits in neurodegenerative diseases and aging.

OBJECTIVES/HYPOTHESIS: Cross-innervation patterns to the thyroarytenoid (TA) muscle have long been sought after. We have identified in the porcine model, cross-innervation by way of the external branch of the superior laryngeal nerve (eSLN). STUDY DESIGN: Experimental study. METHODS: TA contraction was electromyographically recorded when electrically stimulating the eSLN in six porcine necks. The recurrent laryngeal nerve (RLN) was subsequently transected. The insertion of the cricothyroid (CT) muscle on the cricoid was then subsequently removed as well. RESULTS: Stimulation of the eSLN rendered a response from the TA muscle in 6/6 subject necks, with a mean latency of 2.76 msec. TA muscle contraction by way of eSLN stimulation persisted after the RLN was transected and after CT insertion release. CONCLUSIONS: The TA muscle is directly cross-innervated by a branch of the eSLN in the porcine model. This finding may have implications regarding possible future laryngeal pacing strategies and could be a target nerve for rehabilitation.

Objectives Intraoperative vagus nerve monitoring during skull base surgery has been reported with the use of an oral nerve monitoring endotracheal tube. However, the intraoral presence of an endotracheal tube can limit exposure by its location in the operative field during transfacial approaches and by limiting superior mobilization of the mandible during transcervical approaches. We describe a transnasal vagus nerve monitoring technique. Design and Participants Ten patients underwent open skull base surgery. Surgical approaches included transcervical (five), transfacial/maxillary swing (three), and double mandibular osteotomy (two). The vagus nerve was identified, stimulated, and monitored in all cases. Main Outcome Measures Intraoperative nerve stimulation, pre- and postoperative vagus nerve function through the use of flexible laryngoscopy in conjunction with assessment of subjective symptoms of hoarseness, voice change, and swallowing difficulty. Results Three patients had extensive involvement of the nerve by tumor with complete postoperative nerve deficit, one patient had a transient deficit following dissection of tumor off of nerve with resolution, and the remaining patients had nerve preservation. One patient experienced minor epistaxis during monitor tube placement that was managed conservatively. Conclusions Transnasal vagal nerve monitoring is a simple method that allows for intraoperative monitoring during nerve preservation surgery without limiting surgical exposure.