Case Presentation: The patient is a 33 year old woman with no significant past medical history who presented with recurrent encephalitis. She initially collapsed while walking with her toddler. She was unresponsive and had seizure like activity at the scene. In the ED, she was intubated for airway protection. Her physical exam revealed that she was febrile and had increased body tone with decerebrate posturing. She was treated empirically for bacterial meningitis, but the lumbar puncture was more consistent with viral encephalitis/aseptic meningitis. The EEG demonstrated mild to moderate encephalopathy with intermittent rhythmic slowing. Although she was successfully extubated and returned back to baseline after a few days at inpatient rehab, her recovery was complicated by visual hallucinations. Imaging, including CT head, MRI/MRV brain did not demonstrate any pathological processes.The autoimmune/infectious workup was unrevealing except for rhinoenterovirus being positive on the respiratory viral panel. She returned one year later with a similar presentation. LP and EEG were similar to the previous year. Toxicology was negative. Once again, the autoimmune (NMDA, ANCA, ANA, RF) workup was negative. The only positive finding on the infectious workup was adenovirus on the respiratory viral panel. The rest, including Herpes Simplex Virus, cryptococcus, HIV, syphilis, CSF studies (fungal stain/Acid Fast Bacillus/West Nile IgM, Brucella, Lyme, Arbovirus) were all negative. She was found to have low total CD4 count, and it was postulated that T-cell immunodeficiency may have contributed to her recurrent episodes of encephalitis.

Discussion: Viruses such as herpesvirus, enterovirus, and alphavirus have been implicated in causing acute viral encephalitis. Enterovirus has been associated with outbreaks of encephalitis throughout history. Similarly, adenovirus has been associated with a number of neurological conditions such as Reye-like syndrome and subacute focal encephalitis. These are commonly encountered viruses for the general population. This case demonstrates that if a patient has recurrent episodes of encephalitis, there may be an underlying immunodeficiency that makes them more susceptible to common viruses. Recognizing why a patient would develop repeated similar infections can lead to earlier diagnosis of the underlying condition and lead to faster initiation of treatment such as IVIG.

Conclusions: Encephalitis is a disease that can lead to significant morbidity and mortality in the hospital setting. It can be due to a variety of causes, including infectious (viral, bacterial, fungal) and autoimmune. Early diagnosis and targeted treatment play important roles in reducing the residual effect on the patient. Immunodeficiency can be a cause of recurrent episodes of encephalitis and should be considered as an underlying cause in the in-patient setting.