The Neurological Impact of COVID-19: An Investigation of Cortical Activation During Control of Vision and Posture Following COVID-19 Infection

Abstract

Declared a global pandemic in March of 2020, coronavirus disease 2019 (COVID-19) continues to impact our world. Initially thought to exert acute effects primarily on the respiratory tract and lungs, there are increasing reports of individuals experiencing a wide range of long-term symptoms following infection, many of which indicate involvement of the central nervous system (CNS). Increasing reports of long-term symptoms following COVID-19 infection and strong evidence for brain-related pathologies indicate a more expansive disease course. Interestingly, the presentation of long-term symptoms and evidence of CNS involvement is similar to that seen following mild traumatic brain injury (mTBI). Alterations in sensorimotor control, particularly in postural control, oculomotor control, and accompanying cortical activation, are often present following mTBI. Given the similarities between long-term COVID-19 symptomatology and CNS involvement with that of mTBI, exploration of the full impact of COVID-19 infection on these areas is necessary. PURPOSE: The purpose of this study is to investigate the neurological impact of COVID-19 infection through the assessment of neural activity during oculomotor and postural control performance. The researchers expect alterations in mean event-related spectral power similar to those seen following mTBI to be present in participants with a history of COVID-19 infection, with greater changes seen among the long COVID group. METHODS: Cortical activation was assessed using a 32-channel dry electrode EEG cap during completion of a series of seated oculomotor control tasks and quiet standing postural control tasks. Participants completed six oculomotor control tasks in a custom-built virtual reality environment, including circular smooth pursuit (CSP), vertical smooth pursuit (VSP), horizontal smooth pursuit (HSP), vertical saccade (VSA), horizontal saccade (HSA), and vergence (VRG). Each task was completed three times for 30 seconds (s) each with a ten second rest in between. For postural control, participants completed two quiet standing tasks with no virtual reality (NVR) and three with virtual reality (YVR). The NVR task block consisted of a 30s eyes open (EO) measurement followed by a 30 second eyes closed (EC) task. This sequence was repeated for a total of 3 times. Next, participants completed 3 rounds of the YVR task. This included a 30 second eyes open measurement in a virtual replication of the lab (VR) followed by a 30 second perturbation in which the virtual lab oscillated at 0.5 Hz along the anterior-posterior axis (MR). Upon cessation of movement of the virtual lab, a 30 second recovery period was collected (RC). EEG data was then processed and analyzed using EEGLAB. RESULTS: Oculomotor control results identified significant differences in mean event-related spectral power between the CONTROL and at least one of the COVID groups in at least one frequency band (theta, alpha, mu, beta, and gamma) across all smooth pursuit and saccade tasks (p < 0.05). For postural control, the results identified significant differences in cortical activation in at least one of the COVID groups during performance of all the postural control tasks across at least one frequency band of interest (theta, alpha, mu, and beta) (p < 0.05). Additionally, the results also identified significant differences between the ACUTE and LONG groups across all postural control tasks in at least one frequency band. CONCLUSION: COVID-19 infection exerts long-lasting alterations in cortical activation during oculomotor control and postural control performance, regardless of acute or long infection. These alterations indicate a disruption in the neural networks responsible for sensorimotor processing and specifically predictive control mechanisms. This pattern of change is not entirely clear but resembles other models of neural injury, including mTBI and aging. It is unknown whether these changes affect performance outcomes or if they reflect an adaptation or compensation of the brain due to the impacts of the infection. Further research should include examination of specific performance outcomes, more complex, dynamic, and dual-task activities, as well as longitudinal effects.