Herpes simplex encephalitis

Herpes simplex encephalitis (HSE) is a viral encephalitis caused by HSV-1 which causes haemorrhagic necrosis of the temporal lobe. It’s an urgent condition because it progresses very quickly and treatment must be initiated early to improve the prognosis. However, despite early treatment, the mortality rate is high, and many retain significant deficits.

Clinical features

Onset is rapid (less than 48 hours) with a fever of 40°C, altered mental status, headaches, as well as symptoms of temporal lobe lesion, like hemiparesis, aphasia, amnesia, and seizures.

Diagnosis and evaluation

MRI shows inflammation and necrosis of the temporal lobe and EEG shows slow activity and epileptic discharges over the temporal regions, but these findings are not present in the first days.

In the first days, only CSF analysis can be used for diagnosis. The CSF shows increased lymphocytes and protein, and PCR gives the diagnosis.

Treatment

Acyclovir should be initiated immediately in case of clinical suspicion, even before the lumbar puncture. The dosage is 10 mg/kg i.v. every 8 hours. The treatment must be continued for weeks. Antiepileptics may be necessary for the seizures.

Postherpetic neuralgia

Postherpetic neuralgia is a type of chronic neuropathic pain which occurs in an area previously affected by herpes zoster rash. It occurs in 10% of herpes zoster cases and is more frequent in elderly.

Clinical features

The pain is severe, and of shooting, burning, or stabbing characteristic. It persists for more than three months.

Treatment

Treatment is as for other neuropathic pains. Local treatments like lidocaine or capsaicin patches can be used. Carbamazepine, pregabalin, gabapentin, amitriptyline, and duloxetine may also be used.