Dysphagia Following Posterior Fossa Surgery in Adults

Dysphagia in multiple sclerosis: pathophysiology, assessment, and management-an overview

Dysphagia is a frequent and life-threatening complication of multiple sclerosis (MS). Swallowing disturbances may be present at all stages of MS, although their prevalence increases with age, with disease duration, and in progressive phenotypes. The pathophysiology of dysphagia in MS is likely due to a combination of factors, including the involvement of corticobulbar tracts, the cerebellum, and the brainstem. Accurate diagnosis and early management of swallowing disorders improve quality of life and may delay complications or invasive therapeutic interventions. Here we provide an overview of the pathophysiology, the assessment, and the management of MS dysphagia, also examining the possible role of novel therapeutic strategies. Although studies using imaging and neurophysiological techniques have contributed to better characterize swallowing alterations in MS, the treatment of dysphagia is still challenging. Rehabilitation represents the main therapeutic approach for swallowing disorders. Recently, some innovative neurophysiological approaches, such as pharyngeal electrical stimulation (PES), repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS), have been proposed as a supplement to swallowing therapy in different neurological conditions. However, only few studies have explored the role of neuromodulation for MS dysphagia.

Incidence and Risk Factors for Dysphagia Following Cerebellar Stroke: a Retrospective Cohort Study

The cerebellum is known to play a supportive role in swallowing-related functions; however, wide discrepancies about the incidence rate of swallowing disorders following cerebellar strokes exist within the literature. This study aimed to investigate the incidence rate of dysphagia and the factors which may affect the presence of dysphagia and clinical recovery in individuals diagnosed with cerebellar stroke. A retrospective chart audit of 1651 post-stroke patients (1049 males and 602 females) admitted with a cerebellar stroke to a comprehensive tertiary hospital in China was conducted. Data on demographics, medical, along with swallowing function assessment were collected. Differences between dysphagic and non-dysphagic groups were evaluated using t-tests and Pearson's chi-square test. Univariate logistic regression analysis was performed to establish factors associated with the presence of dysphagia. A total of 11.45% of participants were identified with dysphagia during inpatient admission. Individuals with mixed types of stroke, multiple lesions in the cerebellum, and ages older than 85 years old were more likely to develop dysphagia. Moreover, the prognosis of dysphagia following a cerebellar stroke was associated with lesions in different parts of the cerebellum. The cumulative recovery rates from the best to worse were the right hemisphere group, the cerebellum vermis or peduncle group, and both the hemisphere group and the left hemisphere group, respectively.

Understanding the variability of the electrophysiologic laryngeal adductor reflex

OBJECTIVE

The laryngeal adductor reflex (LAR) is vital for airway protection and can be electrophysiologically obtained under intravenous general anesthesia (IGA). This makes the electrophysiologic LAR (eLAR) an important tool for monitoring of the vagus nerves and relevant brainstem circuitry during high-risk surgeries. We investigated the intra-class variability of normal and expected abnormal eLAR.

METHODS

Repeated measures of contralateral R1 (cR1) were performed under IGA in 58 patients. Data on presence/absence of cR2 and potential confounders were also collected. Review of neuroimaging, pathology and clinical exam, allowed classification into normal and expected abnormal eLAR groups. Using univariate and multivariate analysis we studied the variability of cR1 parameters and their differences between the two groups.

RESULTS

In both groups, cR1 latencies had coefficients of variation of <2%. In the abnormal group, cR1 had longer latencies, required higher activation currents and was more frequently desynchronized and unsustained; cR2 was more frequently absent.

CONCLUSIONS

cR1 latencies show high analytical precision for measurements. Delayed onset, difficult to elicit, desynchronized and unsustained cR1, and absence of cR2 signal an abnormal eLAR.

SIGNIFICANCE

Understanding the variability and behavior of normal and abnormal eLAR under IGA can aid in the interpretation of its changes during monitoring.

Intraoperative Neurophysiologic Monitoring in Predicting Dysphagia After Brainstem and Fourth Ventricle Surgery

OBJECTIVE

Dysphagia represents the main complication of posterior fossa neurosurgery. Adequate diagnosis of this complication is warranted to prevent untimely extubation with subsequent aspiration. Intraoperative neurophysiologic monitoring (IONM) modalities may be used for this purpose. However, it is not known which IONM modality may be significant for diagnosis. This study aimed to define the most significant IONM modality for dysphagia prognostication after posterior fossa neurosurgery.

METHODS

The analysis included 46 patients (34 with tumors of the fourth ventricle and 12 with brainstem localization) who underwent surgical excision of the tumor. Neurologic symptoms before and after neurosurgery were noted and magnetic resonance imaging with the subsequent volume estimation of the removed mass was performed, followed by an IONM findings analysis (mapping of the nucleus of the caudal cranial nerves [CN] and corticobulbar motor-evoked potentials [CoMEP]).

RESULTS

Aggravation of dysphagia was noted in 24% of the patients, more often in patients with tumor localization in the fourth ventricle (26%) than in those with brainstem mass lesions (16%). Mapping of the caudal cranial nerve nuclei did not correlate with the dysfunction of these structures. CoMEP was significantly associated with the neurologic state of the CN. The decrease in CoMEP is a significant prognostic factor for postoperative bulbar symptoms appearance or aggravation.

CONCLUSIONS

Mapping the CN is an important identification tool. The CoMEP modality should be used intraoperatively to determine the functional state of the CN and predict postoperative dysphagia.

Utility of Dual Monitoring of the Lower Cranial Nerve Motor-Evoked Potentials Threshold Level Criterion to Predict Swallowing Function in Skull Base and Brainstem Surgery

PURPOSE

Evaluate the value of bilateral final/baseline threshold level changes of lower cranial nerve MEPs in postoperative swallowing function deterioration prediction.

METHODS

Bilateral lower cranial nerve motor-evoked potentials (MEPs) were recorded in 51 patients who underwent treatment for skull base and brainstem tumors. Corkscrew-like electrodes were positione 2 cm below C3/C4 and Cz. The MEPs were recorded from different muscle groups, including the posterior pharyngeal wall muscle, tongue muscle, genioglossus muscle, and cricothyroid muscle through paired needle electrodes. Swallowing function was assessed clinically using the Mann Assessment of Swallowing Ability score before and after the procedure at 7 days, 1 month, and 3 months.

RESULTS

Bilateral final/baseline threshold level increases in lower cranial nerve MEPs under the dual monitoring were significantly correlated with postoperative swallowing function deterioration ( r = 0.660 at 7 days, r = 0.735 at 1 month, and r = 0.717 at 3 months; p < 0.05). Bilateral final/baseline threshold level changes of more than 20% were recorded in 23 of the 51 patients, with 21 patients experiencing swallowing function deterioration postoperatively. The other 28 patients had bilateral threshold level changes of less than 20%, with 26 patients maintaining or improving their swallowing function, and 12 of those patients presented transient deterioration of swallowing function in the early postoperative period.

CONCLUSIONS

Dual monitoring of lower cranial nerves and their different muscle groups MEPs was a safe and effective way to predict postoperative swallowing function. An increase in bilateral final/baseline threshold level change of more than 20% was predictive of permanent swallowing deterioration, especially in patients with poor swallowing function preoperatively.

Pre- and Post-Surgical Dysphagia in Adults with Tumors of the Posterior Fossa: A Prospective Blinded Study

BACKGROUND

While swallowing disorders are frequent sequela following posterior fossa tumor (PFT) surgery in children, data on dysphagia frequency, severity, and outcome in adults are lacking. The aim of this study was to investigate dysphagia before and after surgical removal of PFT. Additionally, we tried to identify clinical predictors for postsurgical swallowing disorders. Furthermore, this study explored the three-month outcome of dysphagic patients.

METHODS

In a cohort of patients undergoing PFT surgery, dysphagia was prospectively assessed pre- and postoperatively using fiberoptic endoscopic evaluation of swallowing. Patients with severe dysphagia at discharge were re-evaluated after three months. Additionally, clinical and imaging data were collected to identify predictors for post-surgical dysphagia.

RESULTS

We included 26 patients of whom 15 had pre-operative swallowing disorders. After surgery, worsening of pre-existing dysphagia could be noticed in 7 patients whereas improvement was observed in 2 and full recovery in 3 subjects. New-onset dysphagia after surgery occurred in a minority of 3 cases. Postoperatively, 47% of dysphagic patients required nasogastric tube feeding. Re-evaluation after three months of follow-up revealed that all dysphagic patients had returned to full oral intake.

CONCLUSION

Dysphagia is a frequent finding in patients with PFT already before surgery. Surgical intervention can infer a deterioration of impaired swallowing function placing affected patients at temporary risk for aspiration. In contrast, surgery can also accomplish beneficial results resulting in both improvement and full recovery. Overall, our findings show the need of early dysphagia assessment to define the safest feeding route for the patient.

Nutrition & Exercise Interventions in Pediatric Patients with Brain Tumors: A Narrative Review

Brain tumors have been the most common pediatric solid tumor and leading cause of morbidity and mortality. Improved survival emphasizes the importance of adverse treatment effects especially related to nutrition and exercise. Although studies have examined nutrition and exercise outcomes, few randomized trials exist. This narrative review included a systematic literature search with analysis of controlled or single group studies examining clinical and quality-of-life impact of nutrition or exercise interventions. Seven articles were included. Three nutrition studies demonstrated improvement with proactive feeding tubes, nutritional supplementation, and nutritional status. Two exercise studies showed improvement in measures of fitness and neuroanatomy with exercise in pediatric brain tumor survivors; two cohort studies demonstrated a link between quality of life and physical activity. Preliminary studies show nutrition and exercise may improve physical well-being and quality of life, suggesting future controlled studies are warranted to inform clinical care of children with brain tumors.

A Prospective Evaluation of Swallowing and Speech in Patients with Neurofibromatosis Type 2

Objective  Neurofibromatosis type 2 (NF2) patients report that swallowing and speech problems significantly affect their quality of life, but the etiology of these phenomena is poorly understood. Swallowing and speech deficits may arise due to the neuropathy of involved nerves, due to posterior fossa tumor growth, or as iatrogenic effects from neurosurgical procedures to remove these tumors. This study aims to identify the natural history of swallowing and speech deficits in an NF2 cohort and to characterize the factors that may lead to those deficits. Methods  Subjects ( n  = 168) were enrolled in a prospective, longitudinal study of NF2 with yearly imaging and clinical exams. The patients completed a self-reported questionnaire that included responses regarding subjective swallowing and speech dysfunction. A formal speech-language pathology evaluation and modified barium swallow (MBS) study (reported as American Speech-Language Hearing Association [ASHA] swallowing independency score from 1 through 7) was obtained when a speech/swallowing deficit was reported on the questionnaire. Results  Of the 168 enrolled subjects, 55 (33%, median age = 31 years) reported subjective speech and/or swallowing deficits. These patients underwent one ( n  = 37) or multiple ( n  = 18) MBS studies during 44.8 ± 10.4 months follow-up. During MBS, a majority demonstrated near-normal swallowing (ASHA score >6, 82%), and no evidence of aspiration (aspiration/laryngeal penetration score = 1, 96%). Prior to initial MBS consultation, 38 (69%) patients had undergone relevant neurosurgical procedures. In those with recent (<1 week) posterior fossa surgery ( n  = 12), 2 (17%) patients had severe dysphagia and high aspiration risk on postoperative MBS. Both of these patients recovered to functionally independent swallowing status. Unilateral ( n  = 10) or bilateral ( n  = 6) tongue deficits unrelated to previous history suggestive of hypoglossal nerve injury were detected on clinical examination. There was a correlation between the presence of dysarthria and tongue deficits and tumors associated with the hypoglossal canal noted on imaging. Conclusion  A large proportion of patients with NF2 report speech and swallow deficits that are not evident on objective measurements. We also found hypoglossal neuropathy unrelated to prior surgical interventions. Our findings suggest that swallowing and speech problems in NF2 are associated with lower cranial nerve neuropathy, some due to compressive effects of posterior fossa tumors. Adaptation over the course of the disease allows for the compensation of these deficits and subsequent normal findings on objective testing.

Cerebellar repetitive transcranial magnetic stimulation restores pharyngeal brain activity and swallowing behaviour after disruption by a cortical virtual lesion

Key points

Despite evidence that the human cerebellum has an important role in swallowing neurophysiology, the effects of cerebellar stimulation on swallowing in the disrupted brain have not been explored.

In this study, for the first time, the application of cerebellar neurostimulation is characterized in a human model of disrupted swallowing (using a cortical virtual lesion).

It is demonstrated that cerebellar stimulation can reverse the suppressed activity in the cortical swallowing system and restore swallowing function in a challenging behavioural task, suggesting the findings may have important therapeutic implications.

Abstract

Repetitive transcranial magnetic stimulation (rTMS) can alter neuronal activity within the brain with therapeutic potential. Low frequency stimulation to the ‘dominant’ cortical swallowing projection induces a ‘virtual‐lesion’ transiently suppressing cortical excitability and disrupting swallowing behaviour. Here, we compared the ability of ipsi‐lesional, contra‐lesional and sham cerebellar rTMS to reverse the effects of a ‘virtual‐lesion’ in health. Two groups of healthy participants (n = 15/group) were intubated with pharyngeal catheters. Baseline pharyngeal motor evoked potentials (PMEPs) and swallowing performance (reaction task) were measured. Participants received 10 min of 1 Hz rTMS to the pharyngeal motor cortex which elicited the largest PMEPs to suppress cortical activity and disrupt swallowing behaviour. Over six visits, participants were randomized to receive 250 pulses of 10 Hz cerebellar rTMS to the ipsi‐lesional side, contra‐lesional side or sham while assessing PMEP amplitude or swallowing performance for an hour afterwards. Compared to sham, active cerebellar rTMS, whether administered ipsi‐lesionally (P = 0.011) or contra‐lesionally (P = 0.005), reversed the inhibitory effects of the cortical ‘virtual‐lesion’ on PMEPs and swallowing accuracy (ipsi‐lesional, P < 0.001, contra‐lesional, P < 0.001). Cerebellar rTMS was able to reverse the disruptive effects of a ‘virtual lesion’. These findings provide evidence for developing cerebellar rTMS into a treatment for post‐stroke dysphagia.

Despite evidence that the human cerebellum has an important role in swallowing neurophysiology, the effects of cerebellar stimulation on swallowing in the disrupted brain have not been explored.

In this study, for the first time, the application of cerebellar neurostimulation is characterized in a human model of disrupted swallowing (using a cortical virtual lesion).

It is demonstrated that cerebellar stimulation can reverse the suppressed activity in the cortical swallowing system and restore swallowing function in a challenging behavioural task, suggesting the findings may have important therapeutic implications.

Etiology and prognosis of acute respiratory failure in patients with primary malignant brain tumors admitted to the intensive care unit

PURPOSE

Acute respiratory failure (ARF) is common and potentially fatal in patients with primary malignant brain tumors (PMBT). However, few data are available regarding its precipitating factors and prognosis. We sought to: (1) compare the causes of ARF and the outcome between patients with PMBT and patients with other peripheral solid tumors (PST), (2) identify the factors influencing ICU survival in PMBT patients.

METHODS

Two-center retrospective case-control study from March 1996 to May 2014. Primary central nervous system lymphomas were also included.

RESULTS

Eighty-four patients with PMBT and 133 patients with PST were included. Acute infectious pneumonia was more frequent in PMBT than PST patients (77 vs. 36%, p < 0.001). Pulmonary embolism was also more frequent in PMBT patients (13% vs. 5%, p = 0.042), while cardiogenic pulmonary edema and acute-on-chronic respiratory failure were more frequent in PST patients (37 vs. 10%, p < 0.001). Among acute infectious pneumonia, Pneumocystis pneumonia and aspiration pneumonia were more frequent in PMBT patients (19 vs. 2%, p < 0.001 and 19 vs. 8%, p < 0.001, respectively). ICU mortality was similar between PMBT and PST patients (24% vs. 24%, p = 0.966). In multivariate analysis, cancer progression (OR 7.25 95% CI 1.13-46.45, p = 0.034), need for intubation (OR 7.01 95% CI 1.29-38.54, p = 0.022), were independently associated with ICU mortality in PMBT patients.

CONCLUSIONS

The cause of ARF in patients with PMBT differs significantly than those with PST and up to 50% may have been prevented. Mortality did not differ between the two groups. These results suggest that PMBT alone is not a relevant criterion for ICU recusal.

Cerebellar Mutism Syndrome and Other Complications After Surgery in the Posterior Fossa in Adults: A Prospective Study

BACKGROUND

Cerebellar mutism syndrome (CMS) is rarely described in adults; however, data on self-assessed linguistic complications after posterior fossa surgery do not exist.

METHODS

Through a prospective single-center study, data on 59 tumor operations in the posterior fossa were collected preoperatively as well as 1 week and 1 month postoperatively. Data on self-assessed problems in 5 CMS-related domains, CMS scores, and neurology as well as surgical procedure and complications were obtained.

RESULTS

Data on CMS-related complications were obtained on 56 of the 59 operations. None was found to have CMS according to the CMS score. Within each of the 5 domains, at least 9 operations (16%) were followed by development or worsening of self-assessed CMS-related complications. Self-assessed complications were found to be most frequent after primary tumor surgeries, although they were significant only for speech and motor complications (P value = 0.01 and 0.02). Speech and language complications occurred more frequently in midline tumors compared with lateral tumors (40% vs. 7%; P = 0.004). Surgical complications were similar to other studies.

CONCLUSIONS

We propose that speech and language problems in adults undergoing surgery in the posterior fossa occur more frequently than previously assumed. Some of the self-assessed complications might reflect components of the cerebellar cognitive affective syndrome. Our findings are consistent with the fact that midline location of the tumor is one of the few known risk factors for CMS in children. Thus, the cerebellar midline seems to be a vulnerable region for speech and language complications also in adults.

Risk factors for postoperative pneumonia after microsurgery for vestibular schwannoma

OBJECTIVES

Postoperative complications occurred in about 30% patients after vestibular schwannoma (VS) microsurgical excision. Although many specific complications have been extensively studied, postoperative pneumonia (POP) has received little attention. This study was designed to identify the risk factors for POP after microsurgery for VS.

PATIENTS AND METHODS

Patients undergoing VS microsurgical resection (n=244) between December 2014 and November 2016 at West China Hospital of Sichuan University were retrospectively assessed for POP. Univariate and multivariate analyses were performed to identify the risk factors for POP.

RESULTS

POP (Clavien-Dindo grade II or higher) was diagnosed in 29 (11.9%) patients. Univariate analysis revealed that age (≥60years; p=0.013), diabetes mellitus (DM; p=0.040) and Koos grade IV (p=0.017) were significantly associated with POP. Multivariate analysis revealed that these factors were all independent risk factors for POP. Association between POP and prolonged postoperative hospitalization was also revealed. However, no risk factor associated with severity of POP was found in this study.

CONCLUSION

Older age, DM and Koos grade IV were identified as independent risk factors for POP after microsurgery for VS Moreover, POP caused a prolonged hospital stay.

High-frequency focal repetitive cerebellar stimulation induces prolonged increases in human pharyngeal motor cortex excitability

KEY POINTS

Neurostimulation is a rapidly emerging approach to swallowing rehabilitation, but cerebellar stimulation has not been explored as a treatment. Such proposed therapies for post-stroke dysphagia have required confirmation of physiological effects and optimisation of parameters in healthy humans prior to translational progression into patient groups. There is strong evidence for a role of the cerebellum in swallowing physiology, but this relationship has been under-explored. Recently, single pulses of cerebellar magnetic stimulation have been shown to directly evoke responses from pharyngeal musculature and produce short-term enhancement of cortico-pharyngeal motor evoked potentials, suggesting the feasibility of a cerebellar approach to neurostimulation in the swallowing system. We therefore examined multiple parameters of repetitive cerebellar magnetic stimulation and have described the optimal settings to provoke longer-lasting changes in swallowing neurophysiology. Based on evidence from the post-stroke dysphagia neurostimulation literature, these changes may have a therapeutic potential for swallowing rehabilitation.

ABSTRACT

Brain neurostimulation has been shown to modulate cortical swallowing neurophysiology in post-stroke dysphagia with therapeutic effects which are critically dependent on the stimulation parameters. Cerebellar neurostimulation is, however, a novel, unexplored approach to modulation of swallowing pathways as a prelude to therapy for dysphagia. Here, we randomised healthy human subjects (n = 17) to receive one of five cerebellar repetitive TMS (rTMS) interventions (Sham, 1 Hz, 5 Hz, 10 Hz and 20 Hz) on separate visits to our laboratory. Additionally, a subset of subjects randomly received each of three different durations (50, 250, 500 pulses) of optimal frequency versus sham cerebellar rTMS. Prior to interventions subjects underwent MRI-guided single-pulse transcranial magnetic stimulation (TMS) to co-localise pharyngeal and thenar representation in the cortex and cerebellum (midline and hemispheric) before acquisition of baseline motor evoked potential (MEP) recordings from each site as a measure of excitability. Post-interventional MEPs were recorded for an hour and compared to sham using repeated measures ANOVA. Only 10 Hz cerebellar rTMS increased cortico-pharyngeal MEP amplitudes (mean bilateral increase 52%, P = 0.007) with effects lasting 30 min post-intervention with an optimal train length of 250 pulses (P = 0.019). These optimised parameters of cerebellar rTMS can produce sustained increases in corticobulbar excitability and may have clinical translation in future studies of neurogenic dysphagia.