Lumbar Puncture CSF Analysis PDF

Leading the world to better health Lumbar puncture, CSF analysis and interpretation Dr. Louise Kelly Clinical Microbiology SpR & PhD Candidate Dept. of Clinical Microbiology, RCSI  RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn...

Leading the world to better health Lumbar puncture, CSF analysis and interpretation Dr. Louise Kelly Clinical Microbiology SpR & PhD Candidate Dept. of Clinical Microbiology, RCSI  RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn SESSION ID: CNSLP Lumbar puncture, CSF analysis and interpretation Class Year 2, Semester 1 Course Undergraduate Medicine Lecturer Dr. Louise Kelly Date 15th November 2024 LEARNING OUTCOMES BY THE END OF THIS SESSION, YOU WILL BE ABLE TO...... Recognise when it is necessary to perform a lumbar puncture (LP) Recognise the contraindications to performing a LP and discuss the risks to health Use the appropriate precautions to protect the patient and yourself from infection while performing a LP Describe the diagnostic pathway for processing a CSF specimen from a patient with a CNS infection Interpret the biochemical, cellular and preliminary microbiological findings of the CSF analysis PRE-SESSION WORK You should have reviewed the pre-session PowerPoint and video NOW YOU SHOULD BE ABLE TO........... – Recognise when it is necessary to perform a lumbar puncture (LP) – Recognise the contraindications to performing a LP and discuss the risks to health – Use the appropriate precautions to protect the patient and yourself from infection while performing a LP CLINICAL CASE 1 A 63yo female presents to the ED with new onset headache, photophobia, neck stiffness & fever On examination: – She has a fever of 39ºC, heart rate is 120/min – There is neck stiffness & a positive Kernig’s sign – No localising neurological signs or rash Investigations: – White cell count is 16 x 109/l (4-11) WHAT IS YOUR DIFFERENTIAL DIAGNOSIS? THE MOST LIKELY DIAGNOSIS Why is bacterial meningitis your top choice? The history of: – Headache Suggests meningeal irritation – Photophobia & possibly raised ICP – Neck stiffness Neck stiffness & a positive Kernig’s sign are evidence of meningeal irritation She is systemically unwell (fever, tachycardia) with a high WCC – Suggests bacterial infection WHAT INVESTIGATIONS WILL YOU DO TO AID YOUR DIAGNOSIS?  CASE 1: WHAT SPECIMENS WILL YOU SEND & WHAT MICROBIOLOGICAL INVESTIGATIONS WILL YOU REQUEST? 1. CSF for: 1. Gram stain 2. Cell count 3. Protein & glucose 4. Culture 5. PCR (if available) 1. Bacterial – N. meningitidis, Strep. pneumoniae, L. monocytogenes 2. Viral 2. Blood culture 3. Blood for PCR (if available, as above) TRANSPORTING CSF Ensure CSF specimen bottles tightly sealed in leak- proof bag Hand deliver to the microbiology laboratory ASAP Do not send via the chute system WHAT HAPPENS WHEN A CSF SAMPLE IS RECEIVED IN THE LABORATORY? Appearance – clear, cloudy, purulent, bloody Microscopy – Cell count and differential – Gram stain Biochemistry – Protein – Glucose – Spectrophotometry Culture and Susceptibility Additional tests – PCR for bacteria/virus/fungi – Antigen/antibody e.g Cryptococcal, neuroborreliosis – Cytology – Biomarkers Costerus JM, Brouwer MC, van de Beek D. Technological advances and changing indications for lumbar puncture in neurological disorders. Lancet Neurol. 2018 Mar;17(3):268-278. doi: 10.1016/S1474- 4422(18)30033-4. PMID: 29452686.  NORMAL CSF FINDINGS IN AN ADULT Clear and colourless Normally acellular – However if obtained by LP: 50), immunocompromised, pregnant Steroids – prior to or with first dose of antibiotics CASE 1: CSF RESULTS DAY 1 Cell count: 540 white cells/mm3 Normal: WCC: 0 - 5 cells/mm3 (Adult) 90% polymorphs CSF protein: 80 mg/dl Normal: 15-45 mg/dl (Adult) Glucose: – CSF - 0.3 mmol/l – Serum - 5.7 mmol/l Normal ratio 0.6 Meningitis → CSF glucose < 60% of serum glucose Remember normal values vary with age BASED ON THE INITIAL CSF FINDINGS WHICH ONE OF THE FOLLOWING IS THE LIKELY PATHOGEN? A. Bacterial B. Viral WHAT IS THE BIOCHEMICAL/ CELLULAR PROFILE OF CSF FOR THE DIFFERENT FORMS OF MENINGITIS I.E. BACTERIAL, VIRAL & TUBERCULOUS? Aetiology Protein Glucose Cells