Complications of encephalitis

Acute complications and life-threatening conditions

In the acute phase, inflammation of brain tissue can provoke critical conditions requiring immediate intensive care intervention.

• Cerebral edema and swelling — a most severe complication leading to intracranial hypertension and the risk of brain structure herniation.
• Coma — develops with massive damage to the central nervous system.
• Acute respiratory failure (ARF) — occurs as a direct consequence of respiratory muscle paresis.
• Hypostatic pneumonia — joins secondarily due to impaired normal chest excursion and pulmonary congestion against the background of paresis.

The transformation of localized purulent encephalitis is worth noting separately. Within a few weeks, such a focus can encapsulate, turning into a brain abscess. This condition is accompanied by severe headache, and in severe cases, by confusion of consciousness, vomiting, and progressive focal symptoms (aphasia, ataxia, central paresis). Mortality in abscesses reaches 15–25%, and around 50% for multiple foci.

Long-term sequelae and neurological deficit

After the acute period concludes, a significant proportion of surviving patients retain persistent impairments that reduce quality of life.

• Motor disorders: manifest as paretic syndrome (decreased muscle strength) and hyperkinetic syndrome (involuntary movements).
• Epileptiform syndrome: the formation of foci of pathological activity leading to seizures. For instance, half of the patients who have suffered a brain abscess retain symptomatic epilepsy.
• Specific consequences of measles encephalitis: this complication occurs with a frequency of 1 in 1000 measles cases. It can develop either at the peak of the infection or days to weeks later via a demyelination mechanism. Among extremely rare but fatal long-term consequences is subacute sclerosing panencephalitis — a slow neuroinfection that manifests years after the primary disease.

Chronic progressive course

The ability of certain viruses to persist in the nervous system poses a particular danger. In tick-borne encephalitis (TBE), chronization is observed in 3–11% of cases. The process spans years or decades, gradually forming severe neurological syndromes:

• Kozhevnikov's epilepsy and hyperkinetic syndrome.
• Amyotrophic lateral sclerosis (ALS) syndrome.
• Syringomyelia and progressive polioencephalomyelitis.
• Chronic encephalitis or arachnoencephalitis.

Laboratory picture of chronic TBE: Signs of inflammation persist in the cerebrospinal fluid (CSF). Blood tests reveal a moderate increase in ESR, mild leukocytosis, and a left shift in the formula towards lymphocytes (absolute and relative).

Forms of progression:

1. Primary progressive form: develops from the subclinical (inapparent) form, which is frequently found in residents of endemic areas (long-term antigenemia is detected in 25% of them). Manifestation is triggered by stress, physical or mental trauma, abortions, as well as spa and physiotherapeutic treatments.
2. Secondary progressive form: occurs in patients who have undergone the manifest form of TBE. Neurological symptoms return during the convalescence period — weeks or months after apparent clinical recovery.

Class and exam questions

What else to study on this topic

• Brain abscess: neuroimaging and surgical treatment
• Subacute sclerosing panencephalitis as an outcome of measles
• Clinical picture and forms of tick-borne encephalitis
• Subdural empyema and epidural abscess
• Kozhevnikov's epilepsy and hyperkinetic syndrome

Other topics in the "Additional Topics" section

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