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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Common encephalidites include:

Viral encephalitis

Vector-borne encephalitis

Fungal encephalitis

Protozoan encephalitis

Bacterial encephalitis

Differential diagnosis

Encephalitis must be differentiated from other causes of headache, seizures and loss of consciousness.

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,


↓ Glucose

CSF analysis[1] Fever, neck


Encephalitis + + +/- +/- - - + +/- + History of fever and malaise + Leukocytes, ↓ Glucose CSF PCR Fever, seizures, focal neurologic abnormalities
Brain tumor[2] + - - - + + + - + Weight loss, fatigue + Cancer cells[3] MRI Cachexia, gradual progression of symptoms
Hemorrhagic stroke + + + + + + + + - Hypertension + - CT scan without contrast[4][5] Neck stiffness
Subdural hemorrhage + + + + + - - - + Trauma, fall + Xanthochromia[6] CT scan without contrast[4][5] Confusion, dizziness, nausea, vomiting
Neurosyphilis[7][8] + - + + + + - + - STIs + Leukocytes and protein CSF VDRL-specifc

CSF FTA-Ab -sensitive[9]

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 [10] Blurry vision, urinary incontinence, fatigue
Seizure + + - - + + - - + Previous history of seizures - Mass lesion Clinical assesment and EEG [11] Confusion, apathy, irritability,

Comprehensive List of Causes of Encephalitis & Encephalopathy

Cardiovascular Kawasaki disease
Chemical / poisoning Arsenic, heavy metal toxicity, icaridin, organophosphate poisoning, poison hemlock, thallium
Dermatologic Behcet disease, systemic lupus erythematosus, Vogt-Koyanagi-Harada syndrome
Drug Side Effect Acyclovir, interferon, kynurenic acid, levodopa, methamphetamine, trimethobenzamide, zanamivir
Ear Nose Throat Cholesteatoma, labyrinthitis, sinusitis
Endocrine Myasthenia gravis
Environmental No underlying causes
Gastroenterologic Porphyria, Reye's syndrome
Genetic Aicardi-Goutières syndrome, biotinidase deficiency, familial histiocytic reticulosis, hemophagocytic reticulosis, ornithine transcarbamylase deficiency, porphyria, Smith disease, Tourette syndrome
Hematologic Familial histiocytic reticulosis, hemophagocytic reticulosis, lymphoproliferative syndrome, porphyria, x-linked agammaglobulinemia
Iatrogenic No underlying causes
Infectious Disease alkhurma virus, Borrelia burgdorferi, botulism, brome mosaic virus, California encephalitis virus, campylobacter fetus, capnocytophaga canimorsus, cardiovirus, cat scratch disease, cercopithecine herpesvirus 1, Chagas disease, chandipura virus, chicken pox, coccidioides spp, Colorado tick fever, congenital herpes simplex, congenital rubella syndrome, congenital syphilis, coxiella burnetii , coxsackievirus, Creutzfeldt-Jakob disease, cryptococcosis, cryptococcus neoformans, cysticercosis, cytomegalovirus, dengue fever, diphtheria, duvenhage virus, Eastern equine encephalitis virus, Ebstein-Barr virus, ehrlichia chaffeensis, ehrlichiosis, elizabethkingia meningoseptica, enterobacter sakazakii, enterovirus 70, enterovirus 71, enteroviruses, escherichia coli, feline viral rhinotracheitis, fetal parainfluenza virus type 3, flavivirus infections, flu, gnathostoma hispidum infection, gnathostoma spinigerum, gnathostoma spinigerum infection, gnathostomiasis, streptococcus, group B, haemophilus influenzae, hand-foot-and-mouth disease, hantavirosis , hemorrhagic fever, hendra virus, henipavirus, hepatitis E virus, herpes B virus, herpes simplex virus, histoplasma capsulatum, HIV, human granulocytotrophic ehrlichiosis, human herpesvirus 6, human monocytotrophic ehrlichiosis, immunosuppressive measles encephalitis, infectious canine hepatitis, influenza virus, Japanese encephalitis, JC virus, klebsiella, kumlinge virus encephalitis, kunjin virus, La Crosse encephalitis, labyrinthitis, lassa fever, listeria monocytogenes, listeriosis , louping ill, Lyme disease, lymphocytic choriomeningitis, lyssavirus, malaria, measles, mokola virus, mononucleosis , mumps , mumps virus, Murray Valley encephalitis virus, mycobacterium avium-intracellulare, mycobacterium tuberculosis, mycoplasma pneumoniae, naegleria fowleri, neisseria meningiditis, neonatal herpes, nipah virus, nocardia, pertussis, phlebovirus, pneumococcus, poliomyelitis, pontiac fever, Powassan virus, poxviridae disease, primary amoebic meningoencephalitis , primary encephalitis, progressive multifocal leukoencephalopathy, pseudomonas aeruginosa, psittacosis, Q fever, Queensland tick typhus, rabies, Rasmussen's encephalitis, rickettsiae, Rift Valley fever, rocio encephalitis, Rocky Mountain spotted fever, rubella, salmonella typhi, schistosoma japonicum, secondary encephalitis, shingles, Simian B virus infection, sinusitis, St. Louis encephalitis, staphylococcus aureus, streptococcus pneumoniae, streptococcus suis, subacute sclerosing panencephalitis, taenia solium, tick-borne encephalitis, togaviridae disease, TORCH syndrome, toxocariasis, toxoplasma gondii, toxoplasmosis, trench fever, treponema pallidum, trichinella, trichinosis, tropheryma whipplei, trypanosoma brucei gambiense, trypanosomiasis, typhoid fever, vaccinia, varicella zoster, varicella zoster virus, Venezuelan equine encephalitis, viral encephalitis, visna virus, West Nile fever, Western equine encephalitis, whooping cough, yersinia pestis
Musculoskeletal / Ortho Metabolic myopathies, multiple sclerosis, skull fracture
Neurologic Aicardi-Goutières syndrome, amyotrophic lateral sclerosis, aseptic meningitis, cauda equina syndrome, cerebral palsy, chronic inflammatory demyelinating polyneuropathy, conus medullaris, Creutzfeldt-Jakob disease, Lennox-Gastaut syndrome, multiple sclerosis, opsoclonus myoclonus syndrome, paraneoplastic neurologic disorders, poliomyelitis, progressive multifocal leukoencephalopathy, Rasmussen syndrome, Schilder's disease, St. Louis encephalitis, status epilepticus, subacute sclerosing panencephalitis, temporal lobe epilepsy, Tourette syndrome, tourettism, Vogt-Koyanagi-Harada syndrome
Nutritional / Metabolic Biotinidase deficiency, metabolic myopathies, ornithine transcarbamylase deficiency
Obstetric/Gynecologic TORCH syndrome
Oncologic Paraneoplastic neurologic disorders
Opthalmologic Vogt-Koyanagi-Harada syndrome
Overdose / Toxicity Heavy metal toxicity, Reye's syndrome
Psychiatric Progressive multifocal leukoencephalopathy, shaken baby syndrome, Tourette syndrome
Pulmonary Flu, pertussis, whooping cough
Renal / Electrolyte Systemic lupus erythematosus
Rheum / Immune / Allergy Behcet disease, chronic inflammatory demyelinating polyneuropathy, multiple sclerosis, systemic lupus erythematosus, x-linked agammaglobulinemia
Sexual No underlying causes
Trauma Cauda equina syndrome, shaken baby syndrome, skull fracture
Urologic No underlying causes
Miscellaneous Porphyria
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