From the Guidelines
A lumbar puncture (LP) can reveal numerous conditions affecting the central nervous system by analyzing cerebrospinal fluid (CSF), including meningitis, subarachnoid hemorrhage, multiple sclerosis, encephalitis, neurosyphilis, Guillain-Barré syndrome, and certain cancers. The procedure can diagnose these conditions by showing elevated white blood cells, protein, and decreased glucose, along with identifying specific pathogens through culture or PCR 1. LP can also detect fungal infections like cryptococcal meningitis, and identify autoimmune conditions like autoimmune encephalitis, and help diagnose CNS vasculitis. Additionally, LP can detect viral infections such as herpes simplex virus and HIV-related neurological complications. The analysis typically includes measuring protein and glucose levels, cell counts, cultures, and specialized tests like cytology and PCR, providing crucial diagnostic information for neurological conditions.
Some of the key conditions that can be diagnosed with LP include:
- Meningitis: elevated white blood cells, protein, and decreased glucose
- Subarachnoid hemorrhage: presence of red blood cells or xanthochromia
- Multiple sclerosis: oligoclonal bands and elevated IgG index
- Encephalitis: inflammatory CSF, and detection of specific pathogens through PCR or culture
- Neurosyphilis: detection of treponemal antibodies in CSF
- Guillain-Barré syndrome: elevated protein levels and presence of oligoclonal bands
- Certain cancers: detection of malignant cells in CSF
The most recent and highest quality study on this topic is from 2021, which highlights the importance of LP in diagnosing autoimmune encephalitis 1. This study recommends that LP should be performed in all patients with suspected encephalitis, unless there is a significant contraindication. The study also emphasizes the importance of analyzing CSF for various parameters, including cell count and differential, protein, glucose, and oligoclonal bands, to aid in diagnosis.
In terms of the analysis of CSF, the study recommends that it should include:
- Cell count and differential
- Protein and glucose levels
- CSF/serum glucose ratio
- Albumin quotient
- IgG index and synthesis rate
- Oligoclonal bands
- Broad viral studies, including HSV1/2 PCR and varicella zoster virus (VZV) PCR and IgG/IgM
- Bacterial/fungal cultures when appropriate
- Cytology and flow cytometry
- NAAs panel (e.g., Autoimmune encephalopathy/encephalitis panel, etc)
- Prion disorder panel (preferably RTQuIC when available) 1.
From the Research
Conditions Diagnosable by Lumbar Puncture
A lumbar puncture (LP) can show various conditions, including:
- Meningoencephalitis and subarachnoid hemorrhage, as indicated by the presence of blood or infectious agents in the cerebrospinal fluid (CSF) 2
- Central nervous system infection, such as bacterial or viral meningitis, characterized by changes in CSF white blood cell counts, protein levels, and glucose ratios 3
- Subarachnoid hemorrhage, identified by xanthochromia and elevated red blood cell count in the CSF 3, 4
- Multiple sclerosis, although the diagnostic value of LP in this context is debated, with some studies suggesting that unique oligoclonal IgG-bands in the CSF can confirm the diagnosis 5, 6
- Leptomeningeal carcinomatosis, a condition with a poor prognosis, diagnosed through large-volume CSF cytology 3
- Metastases to the leptomeninges, often detected by repeated cytopathological analysis of the CSF 5
- (Hereditary) metabolic encephalopathies in childhood, diagnosed through CSF examination 5
- Spontaneous intracranial hypotension, idiopathic intracranial hypertension, Guillain-Barré syndrome, and malignancy, which can be evaluated through CSF analysis 3
Complications and Considerations
The procedure is contraindicated in cases of soft-tissue infection adjacent to the puncture site, increased intracranial pressure due to a mass lesion, and coagulopathy 2. Complications of LP include postlumbar puncture headache, spinal hematoma, diplopia, and intraspinal dermoid tumor formation 2. Meningitis can also occur as a complication of LP, particularly in children with bacteremia 2.