Viral encephalitis lurking behind the veils of schizophrenia, a BMJ case report

A case report published by Zheng et al. in British Medical Journal (General Psychiatry), describes the case of a 16-year-old male patient who was previously hospitalised and diagnosed and treated for schizophrenia but failed to respond. The patient was then given antiviral therapy and recovered after 2 weeks, reminding clinicians to consider organic causes like viral encephalitis, as a differential diagnosis in such confusing presentations.

Viral encephalitis (VE) is an infectious disease of the central nervous system (CNS), which refers to inflammation involving the meninges and brain parenchyma. The clinical manifestations vary as different parts of the CNS are involved. The clinical manifestations of mental disorders caused by VE, including neurological and/or psychiatric symptoms, are complicated. The proportion of mental disorders caused by VE is 70%.

Studies have discovered that about 81% of patients with VE have varying degrees of mental disorders and mental symptoms that are seen in various stages of the disease course. These symptoms are easily confused with schizophrenia, and the misdiagnosis rate is as high as 45%. The symptoms of organic mental disorders caused by VE mainly include cognitive dysfunction, attention disorder, perceptual disorder, thinking content change and mood and personality change. It is different from functional mental disorders, in that, it is accompanied by different levels of disorders of consciousness.

The patient discussed here had symptoms of paranoid ideation, anxiety, fear and hallucination for a period of 3 months. He was diagnosed with schizophrenia at the local psychiatric hospital and treated with aripiprazole 15 mg/day. After 14 days of treatment, the patient developed symptoms of stiff limbs, difficulty in moving limbs and flushing. Along with these symptoms, patient presented had headache and 3 days of limb rigidity. Physical examination revealed facial flushing, uncoordinated gait, increased muscle tone and Babinski sign presented on the right side. These are important positive signs, which may hint the diagnosis of organic brain disease. But all the auxiliary investigations like blood routine, biochemical analysis, MRI brain, EEG, ECG etc all were within normal limits.

Psychiatric examination found that patient had auditory hallucinations, loosening of association, delusion, inattention and lack of self-insight. The patient was then diagnosed with schizophrenia again and treated with haloperidol 1.25 mg and promethazine 12.5 mg, both intramuscular injection two times per day. However, the patient's symptoms of anxiety and fear worsened in 2 days, alongside agitated and violent behaviour. Treatment was adjusted to haloperidol 2.5 mg and promethazine 25 mg intramuscular injection two times per day. After 2 days, the patient's agitated behaviour improved, but he developed symptoms of unsteadiness while standing, sweating discontinued due to the prominent extrapyramidal side and headaches. In addition, there was no improvement of the psychiatric symptoms, and tolerance to low-dose antipsychotic drugs remained poor.

A CSF examination was then planned, which revealed increase in WBCs-0.07×10^9/L. Combined with the previous symptoms these indicated towards a CNS infection. Thus, antipsychotic treatment was discontinued and a ganciclovir 0.3 g intravenous injection, two times per day, was given instead.

After 2 weeks of antiviral treatment, CSF examination was carried out again which revealed the CSF leucocyte count to be reduced. The patient's headache disappeared, muscle tone returned to normal and Babinski sign was absent on the right side. His psychiatric symptoms including auditory hallucinations and delusions disappeared as well, and self-insight was present.

The case was then diagnosed as 'mental disorder caused by viral encephalitis'. The antiviral treatment was discontinued and mecobalamin 0.5 mg, three times per day, was started. After 3 weeks of observation in the hospital, the patient recovered and was discharged. At 1 month of follow-up, physical examination, laboratory test and mental examination were normal. Three months later, the patient reported normal social function and excellent academic performance in a telephone follow-up.

To summarise, no typical signs of cerebral infection, such as fever, headache and nerve injury, were found in the early stages of the disease, which led to misdiagnosis. This reminds physicians to take VE into consideration when dealing with a chronic functional mental disorder.

Source: General Psychiatry journal: Zheng M, Bi R, Lin Y, et al. Case report of the treatment and experience of mental disorders due to chronic viral encephalitis. General Psychiatry 2021;34:e100340. doi:10.1136/ gpsych-2020-100340