From the Guidelines
Aseptic pleocytosis is primarily caused by viral infections, particularly those caused by herpesviruses and enteroviruses, as well as other conditions such as partially treated bacterial meningitis, fungal infections, and non-infectious etiologies like autoimmune disorders and central nervous system malignancies. The diagnosis of aseptic pleocytosis involves the evaluation of cerebrospinal fluid (CSF) samples, which typically reveals a mild mononuclear pleocytosis, although a polymorphonuclear cell predominance may initially be seen if the sample is obtained early in the course of illness 1. Some key causes of aseptic pleocytosis include:
- Viral infections, such as herpes simplex encephalitis, which can be diagnosed using CSF PCR with reported sensitivities and specificities of 96%–98% and 95–99%, respectively, in adults 1
- Partially treated bacterial meningitis
- Fungal infections
- Tuberculosis
- Non-infectious etiologies, such as autoimmune disorders like multiple sclerosis and systemic lupus erythematosus, certain medications, central nervous system malignancies, and post-surgical or post-procedural reactions
- Chemical irritation from substances like blood in subarachnoid hemorrhage or contrast media The pathophysiology of aseptic pleocytosis involves inflammation in the meninges that increases vascular permeability, allowing white blood cells to migrate into the cerebrospinal fluid, and diagnosis typically requires lumbar puncture showing elevated white blood cells with negative bacterial cultures, along with additional testing to identify the specific underlying cause 1.
From the Research
Aseptic Pleocytosis Causes
Aseptic pleocytosis, also known as aseptic meningitis, is defined as meningeal inflammation with cerebrospinal fluid (CSF) pleocytosis not related to an infectious process 2. The causes of aseptic meningitis can be classified into three main groups:
- Systemic diseases with meningeal involvement, such as sarcoidosis, Behçet's disease, Sjögren's syndrome, systemic lupus erythematosus, and granulomatosis with polyangiitis 2
- Drug-induced aseptic meningitis, mostly reported with non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, intravenous immunoglobulin, and monoclonal antibodies 2
- Neoplastic meningitis, either related to solid cancer metastasis or malignant hemopathy (lymphoma, leukemia) 2
Viral Etiologies
Viral etiologies of aseptic meningitis include:
- Herpes simplex virus type 2 (HSV-2), which shows female predominance and is associated with higher CSF white blood cell counts and protein levels, but lower C-reactive protein (CRP) levels 3
- Enterovirus, which is a common cause of aseptic meningitis in immunocompetent adults 3
- Varicella zoster virus (VZV), which is also a notable cause of aseptic meningitis 3
Clinical Characteristics
The clinical characteristics of aseptic meningitis include: