COVID-19-associated encephalopathy

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Muhammad Adnan Haider, M.B.B.S.[2] Wajeeha Aiman, M.D.[3]

Synonyms and keywords:

Overview

Encephalopathy is an alteration of the level or contents of consciousness due to brain dysfunction and can result from global or focal brain lesions. SARS-CoV-2 which is the member of coronavirus family has caused many neurological complications including encephalopathy. Acute toxic encephalopathy is caused by toxemia, hypoxia and metabolic disorders due the systemic viral infection (viral sepsis).

Historical Perspective

COVID-19, a disease caused by SARS-CoV-2 first emerged in Wuhan, China in December 2019. It then spread so rapidly that it was declared as pandemic in Feb, 2020. It mostly presents with respiratory symptoms like flue, dry cough, fever, fatigue, dyspnea. Although rare but neurological manifestations have been reported throughout the spectrum of COVID-19 pandemic. These neurological symptoms range from headache, anosmia, meningitis, encephalitis, Guillain Berre Syndrome,and stroke. Encephalopathy is rare and few case has been reported with acute encephalopathy during the severe systemic SARS-CoV-2 infection.

Classification

• There is no established system for the classification of COVID-19-associated encephalopathy.
• On the basis of presentation, COVID-19-associated encephalopathy can be classified as acute.

Pathophysiology

• Severe COVID-19 infection can lead to dysfunction of multiple organs of the body that can lead to hypoxic or metabolic insults to brain and cause encephalopathy.
• Encephalitis/meningitis are caused by neurotropism of SARS-CoV-2 to brain and meninges through ACE2 receptors.
• Encephalopathy is caused by hyper inflammation of brain by following three mechanisms;

• cytokine storm
• Hypoxic brain injury
• molecular mimicry

Cytokine storm

• SARS-CoV-2 causes several neurological complications through production of inflammatory cytokines (mainly IL-6) from glial cells called cytokine storm syndrome.
• SARS-CoV-2 activates CD4 cells of the immune system and CD4 cells activate macrophages by producing granulocyte-macrophage colony stimulating factors. Actiavted macrophages now produce IL-6.
• IL-6 is a major cytokine of cytokine storm syndrome and leads to multiple organ failure. This severe organ damage leads to metabolic and toxic changes in the body which causes brain dysfunction and leads to SARS-CoV-2 related encephalopathy.
• This fact can be supported by the evidence that tocilizumab which is IL-6 antagonist is used in severe COVID-19 infections.

Hypoxic Brain Injury

• The hall mark of severe COVID-19 infection is dyspnea and hypoxemia due Acute Respiratory distress syndrome (ARDS).
• This hypoxia and hypoxemia is sometimes enough to cause diffuse brain injury and cause encephalopathy.

Molecular Mimicry

• Post-infectious encephalomyelitis, an autoimmune demyelinating disease of the brain, can be triggered by the SARS‐CoV‐2 virus.

• SARS-CoV-2 is considered to have similar antigenic determinants as that of some antigens present on human neuronal cells.
• Immunological response to the SARS‐CoV‐2 virus cross-react with the myelin autoantigens, resulting in post-infectious encephalomyelitis.
• Neuropathological findings confirmed vascular and demyelinating pathology in a patient who died from COVID-19.

Causes

• COVID-19-associated encephalopathy may be caused by SARS-CoV-2.
• To read more about this virus, click here.

Differentiating COVID-19-associated encephalopathy from other Diseases

• COVID-19-associated encephalopathy must be differentiated from other causes of headache, seizure and loss of consciousness.

The symptoms of encephalopathy may overlap with the symptoms of other diseases:

• Encephalitis which is differentiated from encephalopathy by the presence of fever and other signs and symptoms of a viral infection.
• Meningitis which is differentiated from encephalopathy by the presence of neck stiffness, headache, meningeal signs, fever

• Postictal state which would be differentiated by the presence of seizures

• Intracranial lesions like tumors, masses, granulomas which are differentiated by the presence of focal neurologic signs and symptoms

Diseases	Symptoms				Physical Examination					Past medical history	Diagnostic tests			Other Findings
	Headache	↓LOC	Motor weakness	Abnormal sensory	Motor Deficit	Sensory deficit	Speech difficulty	Gait abnormality	Cranial nerves		CT /MRI	CSF Findings	Gold standard test
Meningitis	+	-	-	-	-	+	+	-	-	History of fever and malaise	-	↑ Leukocytes, ↑ Protein ↓ Glucose	CSF analysis	Fever, neck rigidity
Encephalitis	+	+	+/-	+/-	-	-	+	+/-	+	History of fever and malaise	+	↑ Leukocytes, ↓ Glucose	CSF PCR	Fever, seizures, focal neurologic abnormalities
Brain tumor	+	-	-	-	+	+	+	-	+	Weight loss, fatigue	+	Cancer cells	MRI	Cachexia, gradual progression of symptoms
Hemorrhagic stroke	+	+	+	+	+	+	+	+	-	Hypertension	+	-	CT scan without contrast	Neck stiffness
Subdural hemorrhage	+	+	+	+	+	-	-	-	+	Trauma, fall	+	Xanthochromia	CT scan without contrast	Confusion, dizziness, nausea, vomiting
Neurosyphilis	+	-	+	+	+	+	-	+	-	STIs	+	↑ Leukocytes and protein	CSF VDRL-specifc CSF FTA-Ab -sensitive	Blindness, confusion, depression, Abnormal gait
Complex or atypical migraine	+	-	+	+	-	-	+	-	-	Family history of migraine	-	-	Clinical assesment	Presence of aura, nausea, vomiting
Hypertensive encephalopathy	+	+	-	-	-	-	+	+	-	Hypertension	+	-	Clinical assesment	Delirium, cortical blindness, cerebral edema, seizure
Wernicke’s encephalopathy	-	+	-	-	-	+	+	+	+	History of alcohal abuse	-	-	Clinical assesment and lab findings	Ophthalmoplegia, confusion
CNS abscess	+	+	-	-	+	+	+	-	-	History of drug abuse, endocarditis, immunosupression	+	↑ leukocytes, ↓ glucose and ↑ protien	MRI is more sensitive and specific	High grade fever, fatigue,nausea, vomiting
Drug toxicity	-	+	-	+	+	+	-	+	-	-	-	-	Drug screen test	Lithium, Sedatives, phenytoin, carbamazepine
Conversion disorder	+	+	+	+	+	+	+	+		History of emotional stress	-	-	Diagnosis of exclusion	Tremors, blindness, difficulty swallowing
Metabolic disturbances (electrolyte imbalance, hypoglycemia)	-	+	+	+	+	+	-	-	+	-	-	Hypoglycemia, hypo and hypernatremia, hypo and hyperkalemia	Depends on the cause	Confusion, seizure, palpitations, sweating, dizziness, hypoglycemia
Multiple sclerosis exacerbation	-	-	+	+	-	+	+	+	+	History of relapses and remissions	+	↑ CSF IgG levels (monoclonal bands)	Clinical assesment and MRI	Blurry vision, urinary incontinence, fatigue
Seizure	+	+	-	-	+	+	-	-	+	Previous history of seizures	-	Mass lesion	Clinical assesment and EEG	Confusion, apathy, irritability,

Other differentials

Toxic encephalopathy must also be differentiated from other diseases that cause personality changes, altered level of consciousness and hand tremors (asterixis). The differentials include the following:

Diseases	History and Symptoms			Physical Examination				Laboratory Findings
	Personality changes	Altered level of consciousness	Hand tremors (asterixis)	Slurred speech	Writing disturbances	Voice monotonous	Impaired memory	Elevated blood ammonia	Hyponatremia	hypokalemia
Hepatic encephalopathy	++	++	++	++	++	++	++	++	++	++
Alcohol intoxication	+	+	-/+	++	+	-	+	-	-/+	-/+
Alcohol withdrawal	+	+	-	++	+	-	+	-	-/+	-/+
Uremia	++	++	+	-/+	-/+	-/+		-	++	Hyperkalemia
Wernicke encephalopathy	+	+	-/+	+	+	+	++	-	-	-
Toxic encephalopathy from drugs	+	+	-/+	-/+	+	-/+	+	+	-/+	-/+
Altered intracranial pressure	+	-/+	-	-/+	-/+	-	-/+	-	-	-
Intoxication by chemical agents	-/+	-/+	-/+	-/+	-/+	-	-	-	-/+	-/+
Malnutrition	-/+	-	-	-	-/+	-	-/+	-	-/+	-/+
Hypoxic brain injury	-	-/+	-	-/+	-/+	-/+	-/+	-	-	-
Meningitis and encephalitis	-/+	-/+	-	-/+	+	-	-	-	-/+	-
Hypoglycemia	-/+	-/+	-	-/+	-/+	-	-	-	-/+	-/+

Epidemiology and Demographics

The incidence/prevalence of [disease name] is approximately [number range] per 100,000 individuals worldwide.

OR

In [year], the incidence/prevalence of [disease name] was estimated to be [number range] cases per 100,000 individuals worldwide.

OR

In [year], the incidence of [disease name] is approximately [number range] per 100,000 individuals with a case-fatality rate of [number range]%.

Patients of all age groups may develop [disease name].

OR

The incidence of [disease name] increases with age; the median age at diagnosis is [#] years.

OR

[Disease name] commonly affects individuals younger than/older than [number of years] years of age.

OR

[Chronic disease name] is usually first diagnosed among [age group].

OR

[Acute disease name] commonly affects [age group].

There is no racial predilection to [disease name].

OR

[Disease name] usually affects individuals of the [race 1] race. [Race 2] individuals are less likely to develop [disease name].

[Disease name] affects men and women equally.

OR

[Gender 1] are more commonly affected by [disease name] than [gender 2]. The [gender 1] to [gender 2] ratio is approximately [number > 1] to 1.

The majority of [disease name] cases are reported in [geographical region].

OR

[Disease name] is a common/rare disease that tends to affect [patient population 1] and [patient population 2].

Risk Factors

There are no established risk factors for COVID-19-associated encephalopathy.

Screening

There is insufficient evidence to recommend routine screening for COVID-19-associated encephalopathy.

Natural History, Complications, and Prognosis

If left untreated, [#]% of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].

OR

Common complications of [disease name] include [complication 1], [complication 2], and [complication 3].

OR

Prognosis is generally excellent/good/poor, and the 1/5/10-year mortality/survival rate of patients with [disease name] is approximately [#]%.

Diagnosis

Diagnostic Study of Choice

The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met: [criterion 1], [criterion 2], [criterion 3], and [criterion 4].

OR

The diagnosis of [disease name] is based on the [criteria name] criteria, which include [criterion 1], [criterion 2], and [criterion 3].

OR

The diagnosis of [disease name] is based on the [definition name] definition, which includes [criterion 1], [criterion 2], and [criterion 3].

OR

There are no established criteria for the diagnosis of [disease name].

Signs and symptoms

The COVID-19 associated encephalopathy cases have been analyzed in the table below

Patient No.	Early symptoms	Later presentation	GCS	Lab. Findings		Specific Tests	Imaging studies
				CBC	CSF		MRI/CT scan

Physical Examination

Patients with [disease name] usually appear [general appearance]. Physical examination of patients with [disease name] is usually remarkable for [finding 1], [finding 2], and [finding 3].

OR

Common physical examination findings of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

The presence of [finding(s)] on physical examination is diagnostic of [disease name].

OR

The presence of [finding(s)] on physical examination is highly suggestive of [disease name].

Laboratory Findings

An elevated/reduced concentration of serum/blood/urinary/CSF/other [lab test] is diagnostic of [disease name].

OR

Laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].

OR

[Test] is usually normal among patients with [disease name].

OR

Some patients with [disease name] may have elevated/reduced concentration of [test], which is usually suggestive of [progression/complication].

OR

There are no diagnostic laboratory findings associated with [disease name].

Electrocardiogram

There are no ECG findings associated with [disease name].

OR

An ECG may be helpful in the diagnosis of [disease name]. Findings on an ECG suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

X-ray

There are no x-ray findings associated with [disease name].

OR

An x-ray may be helpful in the diagnosis of [disease name]. Findings on an x-ray suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

There are no x-ray findings associated with [disease name]. However, an x-ray may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].

Echocardiography or Ultrasound

There are no echocardiography/ultrasound findings associated with [disease name].

OR

Echocardiography/ultrasound may be helpful in the diagnosis of [disease name]. Findings on an echocardiography/ultrasound suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

There are no echocardiography/ultrasound findings associated with [disease name]. However, an echocardiography/ultrasound may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].

CT scan

There are no CT scan findings associated with [disease name].

OR

[Location] CT scan may be helpful in the diagnosis of [disease name]. Findings on CT scan suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

There are no CT scan findings associated with [disease name]. However, a CT scan may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].

MRI

There are no MRI findings associated with [disease name].

OR

[Location] MRI may be helpful in the diagnosis of [disease name]. Findings on MRI suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

There are no MRI findings associated with [disease name]. However, a MRI may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].

Other Imaging Findings

There are no other imaging findings associated with [disease name].

OR

[Imaging modality] may be helpful in the diagnosis of [disease name]. Findings on an [imaging modality] suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

Other Diagnostic Studies

There are no other diagnostic studies associated with [disease name].

OR

[Diagnostic study] may be helpful in the diagnosis of [disease name]. Findings suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

Other diagnostic studies for [disease name] include [diagnostic study 1], which demonstrates [finding 1], [finding 2], and [finding 3], and [diagnostic study 2], which demonstrates [finding 1], [finding 2], and [finding 3].

Treatment

Medical Therapy

There is no treatment for [disease name]; the mainstay of therapy is supportive care.

OR

Supportive therapy for [disease name] includes [therapy 1], [therapy 2], and [therapy 3].

OR

The majority of cases of [disease name] are self-limited and require only supportive care.

OR

[Disease name] is a medical emergency and requires prompt treatment.

OR

The mainstay of treatment for [disease name] is [therapy].

OR

The optimal therapy for [malignancy name] depends on the stage at diagnosis.

OR

[Therapy] is recommended among all patients who develop [disease name].

OR

Pharmacologic medical therapy is recommended among patients with [disease subclass 1], [disease subclass 2], and [disease subclass 3].

OR

Pharmacologic medical therapies for [disease name] include (either) [therapy 1], [therapy 2], and/or [therapy 3].

OR

Empiric therapy for [disease name] depends on [disease factor 1] and [disease factor 2].

OR

Patients with [disease subclass 1] are treated with [therapy 1], whereas patients with [disease subclass 2] are treated with [therapy 2].

Surgery

Surgical intervention is not recommended for the management of [disease name].

OR

Surgery is not the first-line treatment option for patients with [disease name]. Surgery is usually reserved for patients with either [indication 1], [indication 2], and [indication 3]

OR

The mainstay of treatment for [disease name] is medical therapy. Surgery is usually reserved for patients with either [indication 1], [indication 2], and/or [indication 3].

OR

The feasibility of surgery depends on the stage of [malignancy] at diagnosis.

OR

Surgery is the mainstay of treatment for [disease or malignancy].

Primary Prevention

There are no established measures for the primary prevention of [disease name].

OR

There are no available vaccines against [disease name].

OR

Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].

OR

[Vaccine name] vaccine is recommended for [patient population] to prevent [disease name]. Other primary prevention strategies include [strategy 1], [strategy 2], and [strategy 3].

Secondary Prevention

There are no established measures for the secondary prevention of [disease name].

OR

Effective measures for the secondary prevention of [disease name] include [strategy 1], [strategy 2], and [strategy 3].

References

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