Traumatic cervical spinal cord injury: recovery of penetration/aspiration and functional feeding outcome

Using Reference Values to Identify Profiles of Swallowing Impairment in a Case Series of Individuals With Traumatic Spinal Cord Injury

PURPOSE

In this article, we illustrate use of a systematic approach to rating videofluoroscopic swallowing studies (VFSS), the Analysis of Swallowing Physiology: Events, Kinematics and Timing (ASPEKT) method. The method is applied to a clinical case series of individuals with a history of traumatic spinal cord injury (tSCI) requiring surgical intervention using a posterior approach. Previous studies suggest that swallowing is highly variable in this population given heterogeneity in mechanisms, location and extent of injury, and in surgical management approaches.

METHOD

The case series involved 6 individuals who were at least 1 month postsurgery for management of tSCI. Participants completed a VFSS using a standardized bolus protocol. Each VFSS was blindly rated in duplicate using the ASPEKT method and compared with published reference values.

RESULTS

The analysis revealed considerable heterogeneity across this clinical sample. Penetration-aspiration scale scores of 3 or higher were not observed in this cohort. Of note, patterns of impairment did emerge, suggesting there are some commonalities across profiles in this population, including the presence of residue associated with poor pharyngeal constriction, reduced upper esophageal opening diameter, and short upper esophageal sphincter opening duration.

CONCLUSIONS

Although the participants in this clinical sample shared a history of tSCI requiring surgical intervention using a posterior approach, there was great heterogeneity in swallowing profile. Using a systematic method to identify atypical swallowing parameters can guide clinical decision making for determining rehabilitative targets and measuring swallowing outcomes.

Deglutition and the Regulation of the Swallow Motor Pattern

Despite centuries of investigation, questions and controversies remain regarding the fundamental genesis and motor pattern of swallow. Two significant topics include inspiratory muscle activity during swallow (Schluckatmung, i.e., "swallow-breath") and anatomical boundaries of the swallow pattern generator. We discuss the long history of reports regarding the presence or absence of Schluckatmung and the possible advantages of and neural basis for such activity, leading to current theories and novel experimental directions.

Videofluoroscopic Profiles of Swallowing and Airway Protection Post-traumatic Cervical Spinal Cord Injury

Videofluoroscopic analyses of swallowing in survivors of traumatic cervical spinal cord injury (tCSCI) have been largely limited to case reports/series and qualitative observations. To elucidate the disrupted physiology specifically underlying dysphagia post-tCSCI, this prospective observational study analyzed videofluoroscopic swallow studies (recorded at 30 frames per second) across 20 tCSCI survivors. Norm-referenced measures of swallow timing or displacement, and calibrated area measures of laryngeal vestibule closure (LVC) were explored in relation to the severity of aspiration or pharyngeal residue. Videofluoroscopic performance was compared by injury level, surgical intervention, tracheostomy status, and in relation to clinical bedside assessments. Reduced pharyngeal constriction, delayed hyoid elevation, and impaired LVC characterized post-tCSCI dysphagia. Reduced extent of hyoid excursion and of pharyngoesophageal segment (PES) opening were not as prominent, only present in approximately half or less of the sample. Ten participants aspirated and 94% of aspiration events were silent. Severity of aspiration significantly correlated with pharyngeal constriction and prolonged pharyngeal transit times. Post-swallow residue correlated with delayed PES distention/closure and prolonged pharyngeal transit. Clinical inference regarding the integrity of the pharyngeal phase at bedside was limited; however, EAT-10 scores demonstrated promise as an adjuvant clinical marker of post-tCSCI dysphagia. This exploratory study further describes the pathophysiology underlying post-tCSCI dysphagia to promote deficit-specific rehabilitation and functional recovery.

Voluntary Cough Testing as a Clinical Indicator of Airway Protection in Cervical Spinal Cord Injury

OBJECTIVE

Voluntary cough testing (VCT) may be useful for determining aspiration risk in neurogenic dysphagia; however, has yet to be investigated in traumatic cervical spinal cord injury (tCSCI). The study explored if VCT may elucidate swallowing safety and kinematics related to airway protection in tCSCI survivors.

METHODS

Ten inpatients, 13-73 days post-tCSCI (7 incomplete injuries), completed VCT and a modified barium swallowing study that was analyzed via the Penetration Aspiration Scale (PAS) and norm-referenced measures of swallowing events related to airway protection. Spearman rho correlations explored relations among cough airflow, median PAS, and airway protection. Mann-Whitney U tests explored group differences based on clinical airway invasion (PAS > 2) and receiver operating characteristic statistics probed the sensitivity/specificity of VCT measures.

RESULTS

Safe (PAS > 2) and unsafe swallowers differed by cough volume acceleration (CVA) for the total sample and by inspiratory duration for incomplete injuries (p = 0.03, r > 0.7). A cut-off value of 24.8 L/s for CVA predicted airway invasion (AUC = 0.917, p = 0.03) with sensitivity = 100%/specificity = 75%. CVA correlated with delayed laryngeal vestibule closure during swallowing for both the total sample and for incomplete injuries (r_s  > 0.6, p < 0.05). Blunted peak flow and prolonged cough phases were associated with disordered laryngeal kinematics and prolonged bolus transit during swallowing (p < 0.05).

CONCLUSIONS

Reduced CVA, blunted peak flow, and prolonged cough phases reflected PAS and disrupted mechanisms of airway protection in tCSCI survivors, demonstrating promise for VCT as a clinical assessment for post-tCSCI dysphagia.

LEVEL OF EVIDENCE

3 Laryngoscope, 2022.

Laryngeal and swallow dysregulation following acute cervical spinal cord injury

Laryngeal function is vital to airway protection. While swallow is mediated by the brainstem, mechanisms underlying increased risk of dysphagia after cervical spinal cord injury (SCI) are unknown. We hypothesized that loss of descending phrenic drive affects swallow and breathing differently, and loss of ascending spinal afferent information alters swallow regulation. We recorded electromyograms from upper airway and chest wall muscles in freely breathing pentobarbital-anesthetized cats and rats. Inspiratory laryngeal activity increased ~two-fold following C2 lateral-hemisection. Ipsilateral to the injury, crural diaphragm EMG amplitude was reduced during breathing (62 ± 25% change post-injury), but no animal had complete termination of activity; 75% of animals increased contralateral diaphragm recruitment, but this did not reach significance. During swallow, laryngeal adductor and pharyngeal constrictor muscles increased activity, and diaphragm activity was bilaterally suppressed. This was unexpected because of the ipsilateral-specific response during breathing. Swallow-breathing coordination was also disrupted and more swallows occurred during early expiration. Finally, to determine if the chest wall is a major source of feedback for laryngeal regulation, we performed T1 total transections in rats. As in the C2 lateral-hemisection, inspiratory laryngeal recruitment was the first feature noted. In contrast to the C2 lateral-hemisection, diaphragmatic drive increased after T1 transection. Overall, we found that SCI alters laryngeal drive during swallow and breathing, and reduced swallow-related diaphragm activity. Our results show behavior-specific effects, suggesting SCI affects swallow more than breathing, and emphasizes the need for additional studies on the effects of ascending afferents from the spinal cord on laryngeal function.

A case of unilateral recurrent laryngeal nerve palsy caused by neck extension injury

A 63-year-old man collided with a vehicle while riding a motorcycle. At an emergency hospital, he was diagnosed with cerebral concussion, incomplete cervical cord injury, C6 fracture, facial bone fractures, and lacerations. Radiographical findings indicated that his neck was forced into an extended position. At our rehabilitation hospital, we evaluated the patient’s hoarseness and dysphagia 1 month posttrauma and determined the diagnosis to be due to “traumatic right recurrent laryngeal nerve palsy (RLNP).” We followed the patient’s RLNP during admission and at our outpatient clinic. His right RLNP gradually recovered and finally disappeared 6 months after the accident. We describe this case within the context of a review of the literature.

The time course of dysphagia following traumatic cervical spinal cord injury: a prospective cohort study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To elucidate serial changes in dysphagia and elucidate the critical period for dysphagia following acute traumatic cervical spinal cord injury (CSCI).

SETTING

Spinal Injuries Center, Fukuoka, Japan.

METHODS

We prospectively examined individuals with acute traumatic CSCI admitted within 2 weeks after injury. Severity of dysphagia was evaluated using both the dysphagia severity scale (DSS) and functional oral intake scale (FOIS) at 2 weeks, 1 month, 2 months, and 3 months after injury. Condition of oral intake before injury was assessed by history taking. American Spinal Injury Association (ASIA) impairment scale grade and motor scores were also assessed at the same timepoints, and the correlation between dysphagia and paresis was analyzed.

RESULTS

Sixty-five individuals with CSCI were assessed consecutively for 3 months after injury. Swallowing function, evaluated using both the DSS and FOIS, was significantly decreased at 2 weeks after injury, but significantly improved thereafter. Significant correlations between severity of dysphagia (DSS and FOIS scores) and motor scores were found at 2 weeks after injury (r_s = 0.66 and 0.61; p < 0.001 and p < 0.001, respectively), indicating that individuals with lower motor scores had more severe swallowing dysfunction.

CONCLUSIONS

Dysphagia occurred immediately after injury, but gradually improved over time. Individuals with more severe paralysis had significantly more severe dysphagia. Special attention for dysphagia should be paid to individuals with severe paralysis in acute phase.