Table 1. Clinical profile and demographic data of the 24 studies including 33 cases.

Author	Country	Age and sex	Respiratory/ systemic symptom onset	Symptoms	Onset	Method of COVID-19 diagnosis	CSF profile	Brain imaging (CT/MRI)	EEG	Cytokines profile
Duong et al.11	USA	41 years, female	NR	Seizure	NR	RT-PCR	Lymphocytic pleocytosis, increased RBC	Normal brain CT with contrast	Generalized slowing with no epileptic discharge	NR
Bernard-Valnet et al.12	Switzerland	64 years, female	5 days	Tonic-clonic seizures, disorientation, psychosis	Acute (not specified)	RT-PCR	Lymphocytic pleocytosis, increased protein	Normal brain MRI	Nonconvulsive focal status epilepticus	NR
		67 years, female	17 days	Headache, confused	Few hours before admission	RT-PCR	Lymphocytic pleocytosis, increased protein	Normal brain MRI	NR	NR
Ye et al.13	China	Male (age NR)	4 days	Altered consciousness, confusion	Acute (not specified)	RT-PCR	Normal	Normal brain CT	NR	NR
McAbee et al.14	USA	11 years, male	2 days	Status epilepticus	Acute (not specified)	RT-PCR	Neutrophilic pleocytosis, increased protein and RBC	Normal brain CT	Frontal intermittent delta activity	NR
Andriuta et al.15	France	Middle-aged female	7 days	Gait disturbance, hypopallesthesia, bladder and bowel incontinence	Progressively developed on day 16 of admission	RT-PCR	NR	Brain MRI: medial mesencephalic hyperintensity	Normal	NR
		Middle-aged male	NR	Altered consciousness, flaccid tetraparesis	NR	RT-PCR	NR	Brain MRI: bilateral diffuse white-matter hyperintensities	NR	NR
Chaumont et al.16	France	69 years, male	7 days	Confusion, headache	1 day before admission	RT-PCR/CT	Lymphocytic pleocytosis, increased protein	Normal brain MRI	Bilateral slowing	NR
Sohal and Mansur17	USA	72 years, male	NR	Weakness, lightheadedness, seizure	Day 3 of admission	RT-PCR	NR	Brain CT: chronic microvascular changes	Six left temporal seizures	NR
Pilotto et al.18	Italy	60 years, male	2 days	Altered consciousness	5 days before admission	RT-PCR	Lymphocytic pleocytosis, increased protein	Normal brain CT	Generalized slowing with reduced reactivity to acoustic stimuli	Increased IL-6, IL-8, TNF-α, and β2-microglobulin
Al-Olama et al.19	UAE	36 years, male	2 days	Drowsy, headache	4 days after respiratory symptom	RT-PCR	NR	Brain CT: right frontal intracerebral hematoma with subarachnoid hemorrhage in ipsilateral sylvian fissure and frontal and temporal lobes suggestive of viral encephalitis	NR	NR
Moriguchi et al.20	Japan	24 years, male	1 day	Generalized seizure, unconsciousness	9 days after respiratory symptom	CT/RT-PCR CSF	Increased opening pressure, mononuclear pleocytosis	Right lateral ventriculitis and encephalitis in right mesial lobe and hippocampus	NR	NR
Vandervorst et al.21	Belgium	29 years, male	7 days	Generalized weakness, disorientation	10 days after respiratory symptom	RT-PCR	Normal	Hyperintensity in the left medial temporal lobe with mild gyral expansion	General excess beta rhythm with left temporal delta activity	NR
Wong et al.22	UK	40 years, male	10 days	Unsteady gait	Day 3 of admission	RT-PCR	Normal	Suggestive of inflammatory rhombencephalitis/ myelitis	NR	NR
Zandifar and Zandifar23	Iran	49 years, male	2 days	Tonic–clonic seizure, altered consciousness	Acute (not specified)	Clinical, imaging, and exclusion of other possibilities	Pleocytosis, increased protein	Diffuse brain edema	NR	NR
		39 years, male	5 days	Tonic seizure, altered consciousness, disorientation	Day 3 of admission	RT-PCR	NR	NR	NR	NR
Farhadian et al.24	USA	78 years, female	2 days	Uncontrolled limb movements	3 days before admission	RT-PCR		Brain MRI: atrophy and patchy periventricular and subcortical white matter hyperintensities	Mild generalized slowing	Increased IL-6, IL-8, and IFN-γ-induced protein 10
Chalil et al.25	Canada	48 years, female	14 days	Altered consciousness	Day 15 of admission	RT-PCR+CT	Neutrophilic pleocytosis	Brain CT: extensive bilateral parietal and occipital intraparenchymal hemorrhage and interventricualr extension with hydrocephalus	NR	NR
Afshar et al.26	Iran	39 years, female	9 days	Altered consciousness, tonic–clonic seizure	1 day after respiratory symptom	Clinical, imaging, and serology	Normal	Brain MRI: hyperintensities in bilateral thalami, medial temporal lobe, and pons	NR	NR
Bodro et al.27	Spain	25 years, male	1 day	Confusion and agitation	12 hours after respiratory symptom	RT-PCR	Lymphocytic pleocytosis, increased protein	Normal brain CT and MRI	NR	NR
		49 years, male	7 days	Disorientation	Few hours after admission	RT-PCR	Lymphocytic pleocytosis, increased protein	Normal brain CT and MRI	NR	NR
Abdi et al.28	Iran	58 years, male	No complaint	Altered consciousness	1 month, progressive over 2 days	RT-PCR	Increased glucose	Brain MRI: diffuse confluent white-matter hyperintensities	NR	NR
Delamarre et al.29	France	51 years, male	10 days	Altered consciousness	11 days after respiratory symptom	RT-PCR	Albumin-cytological dissociation	Brain MRI: bilateral hyperintensities in bilateral thalami	Low-voltage symmetrical delta activity
Huang et al.30	USA	40 years, female	NR	Syncope and altered mental status	NR	RT-PCR	Normal	NR	NR	NR
Khoo et al.31	UK	65 years, female	Respiratory symptoms at 2 weeks before admission	Involuntary movements, diplopia, cognitive decline	7 days before admission	RT-PCR	Normal	Normal brain MRI	Normal	NR
Zambreanu et al.32	UK	66 years, female	NR	Altered consciousness, confusion	Few hours before admission	RT-PCR	Increased protein	Hyperintensities in mesial temporal lobes and medial thalami	NR	NR
Panariello et al.33	Italy	23 years, male	NR	Psychosis	3 days	RT-PCR	Normal	Normal	6 Hz theta activity	Increased IL-6
Dogan et al.34	Turkey	49 years, male	NR	Altered consciousness	NR	RT-PCR	Increased protein	Suggestive of encephalitis	NR	Increased IL-6
		59 years, male	NR	Altered consciousness	NR	RT-PCR	Increased protein	Suggestive of encephalitis	NR	Increased IL-6
		59 years, male	NR	Altered consciousness	NR	RT-PCR	Increased protein	Normal	NR	Normal
		51 years, female	NR	Altered consciousness	NR	RT-PCR	Increased protein	Normal	NR	Normal
		55 years, male	NR	Altered consciousness	NR	RT-PCR	Increased protein	Normal	NR	Normal
		22 years, male	NR	Altered consciousness	NR	RT-PCR	Increased protein	Suggestive of encephalitis	NR	Increased IL-6

COVID-19, coronavirus disease 2019; CSF, cerebrospinal fluid; CT, computed tomography; EEG, electroencephalography; IFN-γ, interferon gamma; NR, not reported; RBC, red blood cells; RT-PCR, reverse-transcription PCR.