Telemedicine was studied in the epilepsy field before the COVID-19 pandemic era (Table 1). Prior research showed that telemedicine is not inferior for caring for epilepsy patients compared to conventional in-person visits. Between 2009 and 2012, a pilot study among 24 patients with epilepsy was conducted in Arkansas, a nonmetropolitan area in the United States [11]. The authors established a telemedicine epilepsy clinic at the University of Arkansas for Medical Sciences and connected with peripheral sites in the state of Arkansas more than 160 kilometers distant. Two-thirds of the patients in the study had favorable outcomes, with seizure-free or frequency reduction, even patients with refractory epilepsy. In 2017, a prospective randomized study was published comparing the outcomes of epilepsy patients in an Indian single tertiary hospital [12]. For 36 weeks, the authors randomly assigned 465 patients with epilepsy to groups reviewed by telephone and by in-person visits and compared the frequency of breakthrough seizures between them, and found no significant difference between the two groups. Moreover, for the telephone group treatment was more cost-effective and patients were more compliant than the in-person visit group. The accuracy of smartphone-based epilepsy diagnosis was also demonstrated by a prospective multicenter masked clinical trial at eight academic epilepsy centers in the United States [13]. Using only smartphone videos submitted by 44 patients, experts were able to differentiate epileptic seizures from psychogenic or physiologic non-epileptic events with 89.1% accuracy and 93.3% sensitivity.

The COVID-19 pandemic has accelerated research into telemedicine in epilepsy. During the pandemic era, access to in-person visits by patients has been limited around the world, increasing the relative importance of telemedicine. According to the International League Against Epilepsy (ILAE), questionnaires distributed worldwide indicate that the use of telemedicine in epilepsy clinics dramatically increased from 37.8% to 87.3% of respondents during the pandemic [3]. In a Norwegian study, 87% of neurologists answered that they had shifted from in-person visit clinics to telemedicine clinics during the pandemic [14]. Among neurological disorders, telemedicine was particularly satisfactory for the treatment of epilepsy, both for clinicians and patients. Making dosage changes of antiseizure medication (ASM) via telemedicine was effective according to 92% of the clinicians who answered the survey.

It is not surprising that epilepsy was suitable for treatment via telemedicine, given that history taking is the core of medical care for epilepsy patients. More than 90% of clinicians who were involved in a recent study agreed that obtaining a patient history by telemedicine was similar to in-person visits for both new patients (90%) and follow-up patients (98%) [15]. This trend was even stronger in epilepsy because patient consultations are mainly discursive. Several clinicians felt that video-based clinics were sufficient to perform physical examinations of epilepsy patients including mental status, eye movement, shakiness, and unsteady gait.

We hypothesize that telemedicine can be successfully adopted for epilepsy patients in Korea as well. Korea consists mostly of urban areas, and tertiary medical institutions are relatively easy to access compared to other countries. This was one of the objections raised in the debate over whether telemedicine needs to be introduced in Korea. However, studies have shown that telemedicine for epilepsy has high satisfaction in metropolitan as well as nonmetropolitan areas [3,11,15], and the need for remote options is highlighted in the COVID-19 pandemic era. In particular, poor connection or no access to the internet, which is an obstacle to telemedicine, is not a major problem in Korea, which has the highest internet penetration rate of any country in the world.

Encephalitis can be broadly classified into infectious and autoimmune origins according to cause. Infectious encephalitis, including viral and bacterial, generally has a much graver course and most cases require intensive care with poor prognosis. Therefore, this review focuses on telemedicine for autoimmune encephalitis, which requires long-term treatment and outpatient care.

Autoimmune encephalitis was discovered relatively recently [16], with the most prevalent forms being N-methyl-D-aspartate receptor (NMDAR)-antibody encephalitis followed by leucine-rich glioma inactivated-1 (LGI1)-antibody encephalitis [17]. More than 30 types of autoantibodies have been found [17,18], but most autoimmune encephalitis is seronegative [19]. Patients with autoimmune encephalitis are hospitalized for thorough investigations to determine etiology and receive intensive immunotherapy. After primary treatment, patients undergo long-term follow-up care for at least one year, and according to their response to treatment, alternative and boost immunotherapies are often administered. For patients with NMDAR-antibody encephalitis, the follow-up care for full recovery is generally maintained for 12 months [20], and for those with LGI1-antibody encephalitis, many clinicians continue to follow up for 24 months to monitor sequelae regarding the patient's cognition [21,22]. Because of the rarity and specificity of the disease, the evaluation and management for autoimmune encephalitis are performed only at regional base tertiary hospitals or a few specialized tertiary institutions. Therefore, autoimmune encephalitis is an appropriate disease for which telemedicine can be particularly useful, not just during the COVID-19 pandemic era but also in general.

However, compared to its potentiality, telemedicine research in autoimmune encephalitis is limited. Currently, only one study of telemedicine for LGI1-antibody encephalitis has been performed [23]. This study included 37 patients with LGI1-antibody encephalitis who were diagnosed at a single tertiary hospital in Spain and assessed the patients’ cognitive reserve by telephone interview. The questionnaire was composed to measure different aspects of cognitive domains including verbal memory, executive function, and language. Then, the patients’ mood, sleep, and quality of life were also estimated. The authors successfully interviewed 36 patients (97%) and found that 75% of patients had cognitive deficits. The Mini-Mental State Examination and cognitive battery were sufficient to diagnose mild cognitive impairment (MCI) and dementia when administered by telephone. Among the patients, 17% complained of emotional distress and 39% had poor quality of sleep. However, quality of life was not significantly different from healthy controls except for dementia patients. Noticeably, 17 of the 26 patients with good functional status on the modified Rankin Scale (mRS) had MCI. In outpatient clinics, the recovery of patients with autoimmune encephalitis is often evaluated only according to functional status assessed by mRS or Clinical Assessment Scale in Autoimmune Encephalitis (CASE) [24]. This finding suggests that a telephone interview can provide detailed assessments of cognitive reserve, which cannot be clearly identified by impressions in outpatient clinics alone. In summary, telemedicine has the potential to be a sufficient and useful tool for autoimmune encephalitis patients, because monitoring cognitive function sequelae during the long-term follow-up period is important.

Telemedicine is recommended for patients with epilepsy in stable condition who have been sufficiently investigated for etiology and do not require additional management other than ASM (Table 2, Figure 1). When a physician prescribes a new ASM to a patient for the first time, in-person visits are favored to titrate the dose and monitor adverse effects. For example, lamotrigine may result in serious skin rash [27,28], but as the patient may not be aware of this side effect it is required to manage the patient face-to-face. In addition, for drugs that may cause dose-related adverse events and oxcarbazepine, which requires hyponatremia measurement [29-32], in-person visits are recommended until dose titration is completed. Telemedicine is applicable for stable patients without breakthrough seizures over a period of ≥3 months. If a breakthrough seizure has occurred but the cause is clear (medication skip, sleep deprivation, emotional stress, etc.), continued management to increase the ASM dose is possible through telemedicine according to physician discretion. However, if the cause is not clear and additional evaluation including an electroencephalogram is required, an in-person visit is strongly recommended.

Telemedicine might be possible in patients who undergo full investigation regarding the etiology of autoimmune encephalitis, and whose condition improves steadily after adequate primary and secondary immunotherapy (Table 2, Figure 2). Encephalitis with known autoantibodies such as NMDAR-antibody encephalitis and LGI1-antibody encephalitis are suitable for treatment via telemedicine due to their relatively well-known prognosis. As noted in the literature review, cognitive function evaluations performed through telemedicine are not significantly different from in-person visits. Therefore, if more frequent evaluation through telemedicine is possible, a better prognosis can be expected. In addition, mRS and CASE, which are function-evaluation items, can be measured by video. If a patient is in stable status without deterioration, remnant seizures and psychiatric symptoms of patients are areas that can be managed with telemedicine according to the physician’s judgment. On the other hand, if aggravation or recurrence is suspected, an in-person visit clinic is recommended for more accurate management and legal liability.