Clinical relevance of polymerase chain reaction (PCR) assays and antigen-driven immunoblots for the diagnosis of neurological infectious diseases

Acute haemorrhagic leukoencephalitis (Hurst disease) in severe COVID- 19 infection

Coronavirus Disease 2019 (COVID-19) is well documented as a cause of respiratory tract infection. Increasingly, multi-systemic effects, including COVID-19-related neurologic features, are being reported. Here we report, what we believe to be, the first reported case of acute haemorrhagic leukoencephalitis (AHLE) with presence of oligoclonal bands in the cerebrospinal fluid. AHLE is a rare fulminant demyelinating disease, associated with severe COVID-19 infection.

[A case of probable cytomegalovirus encephalitis who restored from persistant disturbance of consciousness]

A 50-year-old woman presented with confusion, fever and drowsiness following an episode of headache and dizziness. On admission, neurological examination found positive pyramidal tract signs, meningeal irritation, and bilateral myoclonus in her arms. Laboratory tests revealed liver dysfunction, positive inflammatory reaction, elevated serum IgM antibody against cytomegalovirus, and increased cerebrospinal fluid protein of 67 mg/dl. MRI of brain by diffusion weighted imaging showed a wide spread hyperintense lesion in white matter and limbic areas. We administered aciclovir, ganciclovir and steroid pulse therapy that showed a limited effect in the initial stage. In spite of all these therapies, she suffered from status epilepticus, followed by persistent disturbance of consciousness for about 2 months. However, her level of consciousness and motor deficit were gradually improved by continuous administration of ganciclovir. The present case indicates that prolonged disturbance of consciousness due to cytomegalovirus encephalitis could be restored with continuous ganciclovir administration.

Polymerase chain reaction analysis and oligoclonal antibody in the cerebrospinal fluid from 34 patients with varicella-zoster virus infection of the nervous system

OBJECTIVE

To study cerebrospinal fluid (CSF) and serum samples from 34 consecutive patients suspected of having varicella-zoster virus (VZV) infection of the central nervous system (CNS).

POPULATION AND METHODS

The patients were divided into three groups. The first group consisted of 27 patients with a rash in one to three dermatomes and clinical suspicion of meningitis and radiculitis; among them, three subgroups were distinguished according to the affected dermatome: ophthalmicus (n = 9), oticus (n = 11) and cervico-thoraco-lumbar zoster (n = 7). Four cases of zoster sine herpete (ZSH) were included in the second group: these patients presented with either radiculitis (n = 2) or meningoencephalitis (n = 2), without cutaneous eruption. The third group consisted of three patients with a generalised rash and encephalitis. A polymerase chain reaction (PCR) for VZV DNA and antigen-driven immunoblots for oligoclonal anti-VZV antibodies were carried out on all CSF samples.

RESULTS

PCR of the CSF was positive in 44% of the patients from the first group, mainly within the first 7 days after eruption. In addition, intrathecal synthesis of anti-VZV antibodies was detected in 37% of patients, always after an interval of 7 days (p<0.0001). Among the four patients with ZSH, a positive VZV PCR was detected in three patients and CSF-specific oligoclonal anti-VZV antibodies in two. PCR was also positive in the CSF of two of the three patients with generalised rash and encephalitis; local production of anti-VZV antibodies was seen in a second CSF sample in one patient, and was also present in the third patient.

CONCLUSION

Amplification of VZV DNA by PCR in the CSF and antigen-driven immunoblots have important diagnostic value in suspected VZV infection, although their presence depends on the timing of the CSF sampling. VZV is thought to be a causative agent in unexplained cases of meningitis associated with radiculitis or focal CNS symptoms, even in the absence of skin manifestations. In such patients, rapid diagnosis by this combined approach permits early antiviral treatment.

Chronic herpes simplex virus encephalitis in childhood

Although herpes simplex virus is a major cause of acute encephalitis in childhood, chronic herpes simplex virus encephalitis has only rarely been reported. This report presents a case of chronic herpes simplex virus encephalitis in a 6-year-old female. Diagnosis was based on the detection of herpes simplex virus deoxyribonucleic acid by polymerase chain reaction in combination with the cerebrospinal fluid/serum ratio of herpes simplex virus-specific immunoglobulin G, the presence of herpes simplex virus-specific oligoclonal immunoglobulin G bands in cerebrospinal fluid, and calcifications in the temporal regions found on cerebral computed tomographic scan. Prolonged antiviral therapy was beneficial to later mental development.

[Detecting infectious agents in central nervous system inflammation by cerebrospinal fluid analysis]

Cerebrospinal fluid analysis is the method of choice in CNS infection and provides the basis for appropriate treatment. Due to the proximity of CSF and CNS, the infectious agent may be detected directly by microscopy or antigen or nucleic acid detection--the latter by polymerase chain reaction--in native CSF or after culture. Furthermore, intrathecal antibody synthesis against the infectious agent may identify the cause of infection. This indirect antigen detection method requires correction for a systemic antibody response and a blood-CSF barrier disturbance. The following text gives an overview of appropriate detection methods and their relevance to the most important CNS infections.