Table 1.

Diagnostic criteria for herpes zoster-associated encephalitis, adapted from Venkatesan et al.

Diagnostic criteria for HZAE[10]
Major criterion (required)
Altered mental status lasting ≥24 h, examples include
Decreased or altered level of consciousness
Lethargy
Personality change
Minor criteria (2 required for possible encephalitis; ≥3 required for probable or confirmed encephalitis)
Documented fever ≥38°C (100.4°F) within 72 h of presentation
Generalized or partial seizures not fully attributable to a preexisting seizure disorder
New onset of focal neurologic findings
CSF leukocyte count ≥5/mm3
Abnormality of brain parenchyma on neuroimaging suggestive of encephalitis that is either new from prior studies or appears acute in onset
Abnormality on EEG that is consistent with encephalitis and not attributable to another cause

EEG – Electroencephalography; CSF – Cerebrospinal fluid; HZAE – Herpes zoster-associated encephalitis