Acute disseminated encephalitis

Neurology

Clinicals - History

Fact Explanation
History of preceding infection Patients can develop acute disseminating encephalitis following measles, smallpox, rubella, mycoplasma, Epstein-Barr virus, Cytomegalovirus, HIV, rotavirus diarrhea and chickenpox infections and less commonly following non-specific upper respiratory tract infections (Influenza A or B). History of preceding infection
Patients can develop acute disseminating encephalitis following measles, smallpox, rubella, mycoplasma, Epstein-Barr virus, Cytomegalovirus, HIV, rotavirus diarrhea and chickenpox infections and less commonly following non-specific upper respiratory tract infections (Influenza A or B).
History of immunization Rabies, diphtheria, tetanus, pertussis, smallpox, measles, japanese B encephalitis, polio, hepatitis B, BCG and influenza vaccines are known to cause acute disseminating encephalitis. History of immunization
Rabies, diphtheria, tetanus, pertussis, smallpox, measles, japanese B encephalitis, polio, hepatitis B, BCG and influenza vaccines are known to cause acute disseminating encephalitis.
Fever Fever usually appear 4–21 days after the precipitating event and it is often accompanied by malaise and myalgia. Fever
Fever usually appear 4–21 days after the precipitating event and it is often accompanied by malaise and myalgia.
Seizures Seizures are common in acute haemorrhagic disseminating encephalomyelitis. Seizures
Seizures are common in acute haemorrhagic disseminating encephalomyelitis.
Altered mental status Mental status of the patient may vary from lethargy to coma. These neurological symptoms rapidly develop. Altered mental status
Mental status of the patient may vary from lethargy to coma. These neurological symptoms rapidly develop.
Headache Headache is often associated with nausea, and vomiting in most of the patients. Headache can be a part of meningismus. Headache
Headache is often associated with nausea, and vomiting in most of the patients. Headache can be a part of meningismus.
Focal neurological signs Patients can present with hemiparesis, cranial nerve palsies, and paraparesis. Focal neurological signs
Patients can present with hemiparesis, cranial nerve palsies, and paraparesis.
Meningismus Signs of meningismus include neck pain, photophobia, and headache. Meningismus
Signs of meningismus include neck pain, photophobia, and headache.
Movement disorders Affected patients present with ataxia and difficulty in walking. Cerebral ataxia is commonly associated with varicella infection. Movement disorders
Affected patients present with ataxia and difficulty in walking. Cerebral ataxia is commonly associated with varicella infection.
Symptoms of optic neuritis Optic neuritis causes acute loss of vision (over hours to days), eye pain, and loss of color vision. Optic neuritis in acute disseminating encephalitis is often bilateral. Symptoms of optic neuritis
Optic neuritis causes acute loss of vision (over hours to days), eye pain, and loss of color vision. Optic neuritis in acute disseminating encephalitis is often bilateral.
Facial weakness Facial weakness occurs due to facial nerve lesions. Patients complain of facial asymmetry, difficulty in speaking and closing eyes. Facial weakness
Facial weakness occurs due to facial nerve lesions. Patients complain of facial asymmetry, difficulty in speaking and closing eyes.

Clinicals - Examination

Fact Explanation
Altered mental state Most of the affected patients are irritable, and lethargic. Some may even progress to coma. Altered behavior and personality changes can also be detected. Other neuropsychiatric symptoms include aggression, agitation, auditory hallucinations, catatonic waxy flexibility, delusions, disorganized behaviour, disorganized thinking, disorientation, inappropriate laughter, hostility, irritability, mania, mood lability, mutism and paranoia. Altered mental state
Most of the affected patients are irritable, and lethargic. Some may even progress to coma. Altered behavior and personality changes can also be detected. Other neuropsychiatric symptoms include aggression, agitation, auditory hallucinations, catatonic waxy flexibility, delusions, disorganized behaviour, disorganized thinking, disorientation, inappropriate laughter, hostility, irritability, mania, mood lability, mutism and paranoia.
Language disturbances Language disturbances is commonly seen in children rather adults. Aphasia is a common examination finding. Language disturbances
Language disturbances is commonly seen in children rather adults. Aphasia is a common examination finding.
Fever Some patients are febrile. Fever
Some patients are febrile.
Signs of meningismus Neck stiffness and photophobia can be elicited in some patients. Signs of meningismus
Neck stiffness and photophobia can be elicited in some patients.
Signs of optic neuritis Patients with optic neuritis can have reduced visual acuity or blindness, double vision and visual field defects. Signs of optic neuritis
Patients with optic neuritis can have reduced visual acuity or blindness, double vision and visual field defects.
Ophthalmoplegia Demyelination of the third, fourth and sixth cranial nerves leads to ophthalmoplegia. Ophthalmoplegia
Demyelination of the third, fourth and sixth cranial nerves leads to ophthalmoplegia.
Signs of facial nerve palsy Facial nerve is the commonest cranial nerve that is involved. Upper motor type of facial nerve palsy leads to reduced power of orbicularis oculi (reduced force of eye closure), muscles of mastication (deviation of mouth towards the side of lesion) and platysma sparing the function of occipitofrontalis muscle. Signs of facial nerve palsy
Facial nerve is the commonest cranial nerve that is involved. Upper motor type of facial nerve palsy leads to reduced power of orbicularis oculi (reduced force of eye closure), muscles of mastication (deviation of mouth towards the side of lesion) and platysma sparing the function of occipitofrontalis muscle.
Palatal palsy Demyelination of the vagus nerve causes palatal palsy. The patient finds it difficult to raise the palate with open mouth. Palatal palsy
Demyelination of the vagus nerve causes palatal palsy. The patient finds it difficult to raise the palate with open mouth.
Hemiparesis Upper motor type lesions produce increased muscle tone, increased tendon reflexes, extensor plantar response and positive ankle clonus. Hemiparesis
Upper motor type lesions produce increased muscle tone, increased tendon reflexes, extensor plantar response and positive ankle clonus.
Ataxia Cerebral ataxia can be detected especially in patients with a recent history of varicella infection. Ataxia
Cerebral ataxia can be detected especially in patients with a recent history of varicella infection.

Investigations - Diagnosis

Fact Explanation
Complete blood count Leucocytosis can be detected from the complete blood count. Mild thrombocytosis can be seen in some patients. Complete blood count
Leucocytosis can be detected from the complete blood count. Mild thrombocytosis can be seen in some patients.
Cerebrospinal fluid (CSF) full report CSF pressure is increased. Lymphocytic count is raised (as much as 1000/mm3) Polymorphonuclear leucocytosis can be an initial finding. CSF protein is usually less than 1.0 mg/l.
Increased amounts of gammaglobulin and IgG and myelin basic protein can also be noted. CSF glucose content is usually normal. Rarely oligoclonal band of IgG may be demonstrated in CSF.
Cerebrospinal fluid (CSF) full report
CSF pressure is increased. Lymphocytic count is raised (as much as 1000/mm3) Polymorphonuclear leucocytosis can be an initial finding. CSF protein is usually less than 1.0 mg/l.
Increased amounts of gammaglobulin and IgG and myelin basic protein can also be noted. CSF glucose content is usually normal. Rarely oligoclonal band of IgG may be demonstrated in CSF.
Electroencephalography (EEG) EEG changes are often non-specific. Frequent slow-wave activity can also be detected in some patients. EEG can even be normal. Electroencephalography (EEG)
EEG changes are often non-specific. Frequent slow-wave activity can also be detected in some patients. EEG can even be normal.
MRI MRI of brain is more informative than the CT scan which shows patchy areas of white matter lesions. Involvement of the cerebellum and brainstem is more common in children. MRI
MRI of brain is more informative than the CT scan which shows patchy areas of white matter lesions. Involvement of the cerebellum and brainstem is more common in children.
CT scan CT scan is usually normal during the initial periods of illness. After about 5 to 14 days CT scan shows, multifocal lesions in the subcortical white matter. CT scan
CT scan is usually normal during the initial periods of illness. After about 5 to 14 days CT scan shows, multifocal lesions in the subcortical white matter.
Brain biopsy This is a very invasive investigation which is rarely done in the presence of diagnostic uncertainty. There is complete loss of myelin with preserved axons of the neurons. Inflammatory infiltrate consists of B and T lymphocytes, plasma cells, eosinophils and macrophages scattered around the small blood vessels. Brain biopsy
This is a very invasive investigation which is rarely done in the presence of diagnostic uncertainty. There is complete loss of myelin with preserved axons of the neurons. Inflammatory infiltrate consists of B and T lymphocytes, plasma cells, eosinophils and macrophages scattered around the small blood vessels.

Management - Supportive

Fact Explanation
Airway protection Airway protection should be done in patients who are semiconscious or comatosed, to minimize the risk of aspiration of gastric contents. Additionally, insertion of a nasogastric tube will allow free drainage of gastric contents and reduce the risk of aspiration. Tracheal intubation and mechanical ventilation is important in patients with respiratory paralysis. Airway protection
Airway protection should be done in patients who are semiconscious or comatosed, to minimize the risk of aspiration of gastric contents. Additionally, insertion of a nasogastric tube will allow free drainage of gastric contents and reduce the risk of aspiration. Tracheal intubation and mechanical ventilation is important in patients with respiratory paralysis.
Antiepileptics Antiepileptics are indicated for the treatment when seizures are present. Antiepileptics
Antiepileptics are indicated for the treatment when seizures are present.
Prophylactic anticoagulation Prophylactic anticoagulation with heparin or warfarin is indicated to minimize the risk of deep vein thrombosis. Prophylactic anticoagulation
Prophylactic anticoagulation with heparin or warfarin is indicated to minimize the risk of deep vein thrombosis.
Maintenance of electrolyte homeostasis This is a common reversible cause for the development of seizures. Maintenance of electrolyte homeostasis
This is a common reversible cause for the development of seizures.
Immunization Post infectious acute disseminated encephalitis can be prevented by use of effective vaccines against mumps, measles, rubella, and chickenpox. Immunization
Post infectious acute disseminated encephalitis can be prevented by use of effective vaccines against mumps, measles, rubella, and chickenpox.
Health education Patients with acute disseminated encephalitis usually shows complete resolution within a few days, or over a period of few weeks to months.
The necessity of developmental assessment for children and psychological and behavioral therapy should also be told to the patient as they are beneficial for some patients.
Health education
Patients with acute disseminated encephalitis usually shows complete resolution within a few days, or over a period of few weeks to months.
The necessity of developmental assessment for children and psychological and behavioral therapy should also be told to the patient as they are beneficial for some patients.

Management - Specific

Fact Explanation
Intravenous corticosteroids To reduce the inflammation and suppress immune reaction.
Intravenous methyl prednisolone (10–30 mg/kg/day, up to a maximum of 1 g/day) is the first line drug in the treatment of acute disseminated encephalitis. Treatment should be continued for about 3 to 5 days.
Intravenous corticosteroids
To reduce the inflammation and suppress immune reaction.
Intravenous methyl prednisolone (10–30 mg/kg/day, up to a maximum of 1 g/day) is the first line drug in the treatment of acute disseminated encephalitis. Treatment should be continued for about 3 to 5 days.
Plasmapheresis Plasmapheresis is the second line treatment option once the intravenous corticosteroids fail to relieve symptoms. Plasmapheresis helps in removing the circulating autoantibodies. Plasmapheresis
Plasmapheresis is the second line treatment option once the intravenous corticosteroids fail to relieve symptoms. Plasmapheresis helps in removing the circulating autoantibodies.
Intravenous immunoglobulin (IVIg) IVIg is given 0.4 gm/kg/day for 5 days. Intravenous immunoglobulin (IVIg)
IVIg is given 0.4 gm/kg/day for 5 days.
Cyclophosphamide Cyclophosphamide is used in the treatment of fulminant disease. Acts as an immunosuppressant. Cyclophosphamide
Cyclophosphamide is used in the treatment of fulminant disease. Acts as an immunosuppressant.
Hypothermia Although less commonly practiced this is also an effective mode of treatment. Hypothermia
Although less commonly practiced this is also an effective mode of treatment.

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  15. ischemic lesions detectable by MRI may be indistinguishable from those seen with ADEM. A history of recurrent arterial or venous thrombosis, fetal loss, and the detection of specific anticardiolipin antibodies and lupus anticoagulants