Positive CSF HSV PCR in patients with GBM: a note of caution

A Rare Case of Concurrent Herpes Simplex Encephalitis and Glioblastoma Multiforme

Herpes encephalitis superimposed on an intracranial malignancy has previously been described mainly in the context of malignancy imitating infection or in the postoperative setting after neurosurgical intervention. We report a rare case of de novo presentation of concurrent herpes encephalitis and glioblastoma. A 63-year-old man presented with status epilepticus and subsequent magnetic resonance imaging (MRI) brain showed a right temporal enhancing lesion with mass effect. He underwent a craniotomy and debulking of this lesion, which on subsequent histology was positive for herpes simplex virus (HSV) antigens and HSV DNA was confirmed by polymerase chain reaction analysis. The sample however also had some hypercellular areas with atypical astrocytes. Our patient recovered well from surgery and was eventually commenced on acyclovir albeit with a delay of 3 weeks due to the initial diagnostic dilemma. However, he re-presented with lethargy and confusion a further 3 weeks later and an MRI scan showed recurrence of the temporal lesion with MR spectroscopy more suggestive of high-grade glioma. He, therefore, underwent a further debulking surgery and the histology revealed a WHO Grade 4 glioblastoma with some residual areas of inflammation. A diagnosis of 2 co-existing pathologies namely HSV encephalitis and glioblastoma was thus reached. Unfortunately, due to poor performance status, he could not undergo chemo-radiotherapy and died 8 months after presentation. Immuno-modulators, expressed locally and globally in glioma patients, are likely to render them susceptible to infections. There are an increasing number of reports of HSV encephalitis in the glioma setting postoperatively. However, we report a de novo presentation which has only been recognized once before in the 1970s. Recognition of HSV encephalitis in glioma patients in the de novo and also the postoperative context is important for commencing early treatment and preventing poor outcomes.

Laboratory diagnosis of CNS infections by molecular amplification techniques

The initial presentation of symptoms and clinical manifestations of CNS infectious diseases often makes a specific diagnosis difficult and uncertain, and the emergence of polymerase chain reaction-led molecular techniques have been used in improving organism-specific diagnosis. These techniques have not only provided rapid, non-invasive detection of microorganisms causing CNS infections, but also demonstrated several neurologic disorders linked to infectious pathogens. Molecular methods performed on cerebrospinal fluid are recognized as the new 'gold standard' for some of these infections caused by microorganisms that are difficult to detect and identify. Although molecular techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations as well as strengths of these techniques must be clearly understood by both clinicians and laboratory personnel.

Herpes simplex virus encephalitis despite normal cell count in the cerebrospinal fluid

OBJECTIVES

To describe herpes simplex virus encephalitis despite normal cell count in the cerebrospinal fluid in patients with malignoma after whole brain irradiation.

INTERVENTIONS

Blood and cerebrospinal fluid analysis and magnetic resonance imaging.

MEASUREMENTS AND MAIN RESULTS

Three male and two female patients with malignoma and a recent history of whole-brain irradiation presented with impaired consciousness with or without epileptic seizure. Although cerebrospinal fluid analysis revealed a normal cell count, herpes simplex virus DNA was detected in all samples by polymerase chain reaction.

CONCLUSIONS

In patients with impaired consciousness, epileptic seizure, or temporal lobe symptoms of new onset and a recent history of brain irradiation with normal cerebrospinal fluid, an atypical anergic course of herpes simplex virus encephalitis should be considered. Herpes simplex virus polymerase chain reaction should be used as method of choice to detect herpes simplex virus genomes as early as possible rather than relying on routine cerebrospinal fluid parameters. Importantly, antiviral therapy should be started without delay in any case of faint suspicion and should be continued until herpes simplex virus encephalitis is clearly ruled out.

Herpes Simplex Encephalitis in Adults and Older Children

Herpes simplex encephalitis (HSE) is a neurologically devastating illness associated with substantial morbidity and mortality in adults and older children. The correct recognition of HSE, and distinguishing it from other forms of encephalitis, brain abscess or mimicking disorders early in the course of evaluation facilitates treatment decisions when neurologic complications occur. The combination of clinical characteristics, magnetic resonance imaging of the head, and polymerase chain reaction (PCR) analysis of cerebrospinal fluid for herpes simplex type 1 DNA is a sensitive and specific way of diagnosing HSE for proper treatment. Early treatment is essential. HSE is treated with acyclovir 10 mg/kg every 8 hours intravenously for 21 days, unless the illness is mild, or if nephrotoxicity occurs. Whether prolonged therapy with oral antiviral treatment after standard intravenous acyclovir offers any advantage from the standpoint of neurologic morbidity or mortality is unproven. PCR-negative typical cases and PCR-positive atypical cases of HSE can occur and require treatment with acyclovir.

Clinical assessment of a generic DNA amplification assay for the identification of respiratory adenovirus infections

BACKGROUND

respiratory adenoviruses are common, often resulting in serious sporadic and epidemic infections and impaired immunity can dramatically increase their severity. They are now thought capable of establishing latency. Diagnosis by culture is slow while direct antigen detection by immunofluorescence lacks sensitivity. Molecular diagnosis can be both rapid and sensitive but the genetic heterogeneity of adenoviruses poses problems.

OBJECTIVES

to design a generic adenovirus nested polymerase chain amplification assay designed to be capable of detecting all respiratory adenoviruses. This was achieved through optimised thermal cycling and the development of a generic degenerate primer set targeting the adenovirus hexon gene.

STUDY DESIGN

this was a cross-sectional study on 172 respiratory specimens from hospital-based patients, and one from a general practice, in Northern Ireland. A comparison was made between the amplification assay, virus culture and immunofluorescence.

RESULTS

the nested polymerase chain reaction (nPCR) assay had a generic capacity for adenovirus detection and an analytical sensitivity of 6.4x10(2) copies/ml. Using an expanded gold standard (defined as a true positive or a true negative where a specimen was positive or negative by at least two of the study assays, respectively), PCR had a clinical sensitivity and specificity of 46/46 (100%) and 15/126 (91.3%), respectively. Patients with acute respiratory adenovirus infections were more likely to be male (chi(2), p=0.005) and to present with a fever (chi(2), p=0.02) than patients diagnosed with another respiratory virus. Co-infection was identified in 12/172 patients.

CONCLUSIONS

the nested amplification assay proved highly sensitive in both the analytical and clinical settings for the detection of respiratory adenovirus infections.

Molecular Techniques in the Diagnosis of Central Nervous System Infections

Development of polymerase chain reaction (PCR)-based molecular techniques has initiated a revolution in the field of diagnostic microbiology. These techniques have not only provided rapid, noninvasive detection of microorganisms that cause central nervous system (CNS) infections, but have also demonstrated that several neurologic disorders are linked to infectious agents. While PCR-based techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations, as well as strengths, of these techniques must be clearly understood by both clinicians and laboratory personnel to ensure proper utilization.

Small-fiber neuropathy

Small-fiber neuropathy is a common disorder. It is often "idiopathic" and typically presents with painful feet in patients over the age of 60. Autoimmune mechanisms are often suspected, but rarely identified. Known causes of small-fiber neuropathy include diabetes mellitus, amyloidosis, toxins, and inherited sensory and autonomic neuropathies. Occasionally, small-fiber neuropathy is diffuse or multifocal. Depending on the type of small-fiber neuropathy, autonomic dysfunction can be significant or subclinical. Diagnosis is made on the basis of the clinical features, normal nerve conduction studies, and abnormal specialized tests of small-fiber function. These specialized studies include assessment of epidermal nerve fiber density as well as sudomotor, quantitative sensory, and cardiovagal testing. The sensitivities of these tests range from 59-88%. Each has certain advantages and disadvantages, and the tests may be complementary. Unless an underlying disease is identified, treatment is usually directed toward alleviation of neuropathic pain.

Clinical utility of a nested nucleic acid amplification format in comparison to viral culture for the diagnosis of mucosal herpes simplex infection in a genitourinary medicine setting

BACKGROUND

Nested nucleic acid amplification tests are often thought too sensitive or prone to generating false positive results for routine use. The current study investigated the specificity and clinical utility of a routine multiplex nested assay for mucosal herpetic infections.

METHODS

Ninety patients, categorised into those clinically diagnosed to (a) have and (b) not have herpetic infection, were enrolled. Swabs from oral and ano-genital sites were assayed by the nested assay and culture and the results assessed against clinical evaluation for diagnosing herpetic infections; cell content was also recorded.

RESULTS

Twenty-six and 64 patients were thought to (a) have and (b) not have mucosal herpetic infection. Taking the clinical evaluation as indicating the presence of herpetic infection, the nested polymerase chain reaction and culture had respective sensitivities of 19/26 (73%) and 12/26 (46%) (Chi2 p = 0.02). There was no significant difference in specificities between nPCR62/64 (97%) and culture 63/64 (98%) (Chi2 p = 1.0). Cell content was important for viral detection by nPCR (Chi2 p = 0.07) but not culture. Nesting was found necessary for sensitivity and did not reduce specificity. Assay under-performance appeared related to sub-optimal cell content (20%) but may have reflected clinical over-diagnosis. The results suggest the need for validating specimen cell quality.

CONCLUSIONS

This study questions the value of routine laboratory confirmation of mucosal herpetic infection. The adoption of a more discriminatory usage of laboratory diagnostic facilities for genital herpetic infection, taking account of cell content, and restricting it to those cases where it actually affects patient management, may be warranted.