Case Report: Event-Related Desynchronization Observed During Volitional Swallow by Electroencephalography Recordings in ALS Patients With Dysphagia

Abstract

Dysphagia is a severe disability affecting daily life in patients with amyotrophic lateral sclerosis (ALS). It is caused by degeneration of both the bulbar motor neurons and cortical motoneurons projecting to the oropharyngeal areas. A previous report showed decreased event-related desynchronization (ERD) in the medial sensorimotor areas in ALS dysphagic patients. In the process of degeneration, brain reorganization may also be induced in other areas than the sensorimotor cortices. Furthermore, ALS patients with dysphagia often show a longer duration of swallowing. However, there have been no reports on brain activity in other cortical areas and the time course of brain activity during prolonged swallowing in these patients. In this case report, we investigated the distribution and the time course of ERD and corticomuscular coherence (CMC) in the beta (15–25 Hz) frequency band during volitional swallow using electroencephalography (EEG) in two patients with ALS. Case 1 (a 71-year-old man) was diagnosed 2 years before the evaluation. His first symptom was muscle weakness in the right hand; 5 months later, dysphagia developed and exacerbated. Since his dietary intake decreased, he was given an implantable venous access port. Case 2 (a 64-year-old woman) was diagnosed 1 year before the evaluation. Her first symptom was open-nasal voice and dysarthria; 3 months later, dysphagia developed and exacerbated. She was given a percutaneous endoscopic gastrostomy. EEG recordings were performed during volitional swallowing, and the ERD was calculated. The average swallow durations were 7.6 ± 3.0 s in Case 1 and 8.3 ± 2.9 s in Case 2. The significant ERD was localized in the prefrontal and premotor areas and lasted from a few seconds after the initiation of swallowing to the end in Case 1. The ERD was localized in the lateral sensorimotor areas only at the initiation of swallowing in Case 2. CMC was not observed in either case. These results suggest that compensatory processes for cortical motor outputs might depend on individual patients and that a new therapeutic approach using ERD should be developed according to the individuality of ALS patients with dysphagia.

Swallow-related Brain Activity in Post-total Laryngectomy Patients: A Case Series Study

“…Significant ERDs were observed in multiple cortical areas during volitional swallowing but in spatial distributions that were different from the ERDs of healthy subjects. All patients showed cortical activation in both frontal areas involved in a cognitive effort during swallowing 19 ) and sensorimotor areas that were active in voluntary swallowing in healthy people, 18 ) although the distribution was different for each case. These patterns of cortical activation after total laryngectomy might suggest the existence of divergent and multiple paths of neural recovery processes among individuals with swallowing dysfunction.…”

“…35) We have also found ERD in the prefrontal area during volitional swallowing in ALS patients with dysphagia with decreased swallowing pressure. 19) Given that the patient in Case 3 also reported that he made no effort in swallowing, ERD in the prefrontal area may reflect unconscious cognitive process 44,45) to achieve more forceful tongue movements with decreased propulsion after removal of the pharyngeal muscles. The superior premotor area and the bilateral medial somatosensory areas also showed significant ERD.…”

“…14,15) With agerelated alteration, the cortical activation, especially in the somatosensory cortex, becomes more symmetrical and extensive during volitional swallowing. 16,17) We have also successfully recorded event-related desynchronization (ERD) using electroencephalography (EEG) in the beta frequency band (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) in the bilateral sensorimotor, premotor, and inferior prefrontal areas in healthy people, and the abnormal distribution in patients with amyotrophic lateral sclerosis (ALS). 18,19) ERD is a power decrease in the alpha and beta frequency bands during voluntary movements when compared with the power during rest (non-movement) [20][21][22][23][24] and reflects cortical activation during voluntary movements.…”

“… 16 , 17 ) We have also successfully recorded event-related desynchronization (ERD) using electroencephalography (EEG) in the beta frequency band (15–25 Hz) in the bilateral sensorimotor, premotor, and inferior prefrontal areas in healthy people, and the abnormal distribution in patients with amyotrophic lateral sclerosis (ALS). 18 , 19 ) ERD is a power decrease in the alpha and beta frequency bands during voluntary movements when compared with the power during rest (non-movement) 20 , 21 , 22 , 23 , 24 ) and reflects cortical activation during voluntary movements. 22 ) In previous studies, ERD was observed in the alpha and beta frequency bands during volitional swallows.…”

“… 22 ) In previous studies, ERD was observed in the alpha and beta frequency bands during volitional swallows. 25 , 26 , 27 , 28 , 29 ) The emergence of ERD was changed in ALS patients with dysphagia, 19 ) patients with Parkinson’s disease without dysphagia, 26 ) in post-stroke patients with dysphagia after transcranial direct-current stimulation therapy, 29 ) and in healthy subjects after electrical stimulation of the pharynx. 28 ) These findings suggest that ERD within the beta band frequency is an index of swallowing-related cortical activities.…”