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Condition/Disorder Synonyms

  • Meningoencephalitis

  • Acute disseminated encephalomyelitis

ICD-9-CM Code

  • 323.9 Unspecified cause of encephalitis, myelitis, encephalomyelitis

ICD-10-CM Code

  • G04.90 Encephalitis and encephalomyelitis, unspecified

Preferred Practice Patterns1

Key Features


  • Infection of the brain parenchyma

  • Most commonly results in infection of the entire brain, but some viruses attack specific nervous system structures

Essentials of Diagnosis

  • May occur with meningitis; some overlap of signs and symptoms

  • Two primary forms: viral and bacterial

  • Post-infectious encephalitis: autoimmune reaction to systemic viral infection

  • Causative factor must be identified to initiate appropriate medical treatment prior to physical therapy involvement

  • Common forms include

    • Herpes simplex encephalitis (most common in adults: sporadic encephalitis)

    • Arboviral encephalitis

      • Most common epidemic forms: West Nile virus, Eastern and Western equine encephalitis, rabies

General Considerations

  • Rapid differential diagnosis of encephalitis vs. meningitis should be made due to similarities of initial symptoms and response to medication

  • Severity may progress over a period of 1 week; PT should monitor for changing neurologic signs and symptoms, refer accordingly


  • Approximately 20,000 cases of acute viral encephalitis are reported annually in the United States

  • Death occurs in 5 to 20%

  • All ages and genders susceptible; some forms more common in specific geographic locations

Clinical Findings

Signs and Symptoms

  • Fever

  • Headache

  • Nuchal rigidity

  • Vomiting

  • General malaise

  • Coma

  • Cranial nerve palsy

  • Hemiplegia

  • Involuntary movements

  • Ataxia

Functional Implications

  • Inability to perform ADLs independently

  • Loss of independent functional mobility

  • Inability to perform age and education appropriate cognitive tasks

  • Inability to execute fine and gross motor tasks independently

Possible Contributing Causes

  • Increased risk to individuals who are

    • Immunosuppressed

    • Perinatal to early childhood period

  • Prior meningitis

Differential Diagnosis

  • Stroke

  • Subdural empyema

  • Cerebral abscess

  • Cerebral venous thrombosis

  • Septic embolism

  • Meningitis

Means of Confirmation or Diagnosis

Laboratory Tests

  • Cerebral spinal fluid testing

  • Intracranial pressure


  • CT scan for detailed imaging

  • MRI with gadolinium enhancement



  • Antiviral agents

  • Corticosteroids if ...

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