Information about Encephalitis

Classification & external resources

ICD-10	A83.-A86., B94.1, G05.
ICD-9	323
DiseasesDB	22543
eMedicine	emerg/163
MeSH	D004660

Encephalitis is an acute inflammation of the brain, commonly caused by a viral infection. Sometimes, encephalitis can result from a bacterial infection, such as bacterial meningitis, or it may be a complication of other infectious diseases like rabies (viral) or syphilis (bacterial). Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Brain damage occurs as the inflamed brain pushes against the skull, and can lead to death.

Symptoms

Patients with encephalitis suffer from fever, headache and photophobia with weakness and seizures are also common. Less commonly, stiffness of the neck can occur with rare cases of patients also suffering from stiffness of the limbs, slowness in movement and clumsiness depending on which specific part of the brain is involved. The symptoms of encephalitis are caused by the brain's defense mechanisms activating to get rid of the infection. Another symptom of Encephalitis is hallucination.

Etiology

Encephalitis may be caused by a variety of afflictions. One such affliction is rabies.

Diagnosis

Adult patients with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures. Younger children or infants may present with irritability, anorexia and fever.

Neurological examinations usually reveal a drowsy or confused patient. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningeoncephalitis. Examination of the cerebrospinal fluid obtained by a lumbar puncture procedure usually reveals increased amounts of protein and white blood cells with normal glucose, though in a significant percentage of patients, the cerebrospinal fluid may be normal. CT scan often is not helpful, as cerebral abscess is uncommon. Cerebral abscess is more common in patients with meningitis than encephalitis. Bleeding is also uncommon except in patients with herpes simplex type 1 encephalitis. Magnetic resonance imaging offers better resolution. In patients with herpes simplex encephalitis, electroencephalograph may show sharp waves in one or both of the temporal lobes. Lumbar puncture procedure is performed only after the possibility of prominent brain swelling is excluded by a CT scan examination. Diagnosis is often made with detection of antibodies against specific viral agent (such as herpes simplex virus) or by polymerase chain reaction that amplifies the RNA or DNA of the virus responsible.

Treatment

Treatment is usually symptomatic. Reliably tested specific antiviral agents are available only for a few viral agents (e.g. acyclovir for herpes simplex virus) and are used with limited success for most infection except herpes simplex encephalitis. In patients who are very sick, supportive treatment, such as mechanical ventilation, is equally important.

Encephalitis lethargica

Main article: Encephalitis lethargica

Encephalitis lethargica is an atypical form of encephalitis which caused an epidemic from 1917 to 1928. There have only been a small number of isolated cases since, though in recent years a few patients have shown very similar symptoms. The cause is now thought to be either a bacterial agent or an autoimmune response following infection.

Limbic system encephalitis

In a small number of cases, called limbic encephalitis, the pathogens responsible for encephalitis attack primarily the limbic system (a collection of structures at the base of the brain responsible for basic autonomic functions).

See also

• Granulomatous amoebic encephalitis
• Japanese Encephalitis
• St. Louis Encephalitis
• Equine Encephalitis
• Rasmussen's encephalitis
• La Crosse encephalitis
• Murray Valley encephalitis virus
• California encephalitis virus
• meningoencephalitis
• Tick-borne meningoencephalitis
• Herpes simplex

External links

• http://www.encephalitis.info resource providing evidence based support to people affected and professionals
• WHO: Encephalitis
• eMedicine-1 and eMedicine-2 Information on the causes, symptoms, and treatment options for Encephalitis.
• Encephalitis Global, Inc. Website offering information and support to encephalitis survivors, caregivers and loved ones. Encephalitis Global Inc. is a USA 501(c)(3) public charity; annual FACES Encephalitis Conference information available at the website.
• A case study of a Limbic Encephalitis patient

[1] a website about Garrett Taylor a 2 year old who lost his life after a battle with encephalitis

•  • [ e] Nervous system pathology, primarily CNS (, )
Inflammatory diseases of the CNS	Meningitis (Arachnoiditis) - Encephalitis - Myelitis - Encephalomyelitis (Acute disseminated) - Tropical spastic paraparesis
Systemic atrophies primarily affecting the CNS	Huntington's disease - Spinocerebellar ataxia (Friedreich's ataxia, Ataxia telangiectasia, Hereditary spastic paraplegia) Spinal muscular atrophy: Werdnig-Hoffman disease - Kugelberg-Welander disease - Fazio Londe syndrome - MND (Amyotrophic lateral sclerosis (ALS), Progressive muscular atrophy (PMA), Progressive bulbar, Pseudobulbar, PLS)
Extrapyramidal and movement disorders	Parkinson's disease - Neuroleptic malignant syndrome - Postencephalitic parkinsonism - Pantothenate kinase-associated neurodegeneration - Progressive supranuclear palsy - Striatonigral degeneration - Dystonia (Spasmodic torticollis, Meige's syndrome, Blepharospasm) - Essential tremor - Myoclonus - Chorea - Restless legs syndrome - Stiff person syndrome
Other degenerative / demyelinating diseases	Alzheimer's disease - Pick's disease - Alpers' disease - Dementia with Lewy bodies - Leigh's disease - Multiple sclerosis - Devic's disease - Central pontine myelinolysis - Transverse myelitis
Seizure/epilepsy	Focal (Simple partial, Complex partial) - Generalised (Tonic-clonic, Absence, Atonic, Benign familial neonatal) - Lennox-Gastaut - West - Epilepsia partialis continua - Status epilepticus (Complex partial status epilepticus)
Headache	Migraine (Familial hemiplegic) - Cluster - Vascular - Tension
Vascular	Transient ischemic attack (Amaurosis fugax, Transient global amnesia) - Cerebrovascular disease (MCA, ACA, PCA, Foville's syndrome, Millard-Gubler syndrome, Lateral medullary syndrome, Weber's syndrome, Lacunar stroke)
Sleep disorders	Insomnia - Hypersomnia - Sleep apnea (Ondine's curse) - Narcolepsy - Cataplexy - Kleine-Levin syndrome
Other	Hydrocephalus (Normal pressure) - Idiopathic intracranial hypertension - Encephalopathy - Brain herniation - Cerebral edema - Reye's syndrome - Syringomyelia - Syringobulbia - Spinal cord compression