Cerebospinal fluid examination Dr Amany Abbass Abdallah CSF

Cerebospinal fluid examination Dr. Amany Abbass Abdallah

CSF formation and function �CSF is a clear fluid that bathes the brain and spinal cord. It is secreted by the choroid plexus into the subarachnoid space. More than 80% of CSF proteins originate from the plasma by ultrafiltration through the wall of the capillaries, the remainder (20%) originate from intrathecal synthesis.

Function of CSF: �Provides a fluid support to protect the brain and spinal cord. �Carries nutrients to brain, spinal cord and remove waste products. �Maintains a constant pressure inside the head and around the spinal cord.

Clinical significance of CSF examination: �Diagnosis of meningitis, subarachnoid hemorrhage, and multiple sclerosis. �Diagnosis of malignancy involving the meninges.

Site of puncture: Lumbar between L 3 and L 4 (common site). Under complete aseptic conditions.

Examination of CSF: �CSF is collected into 3 sterile containers that are labeled as. �No 1: for microbiologic examination. �No 2: chemistry and immunological examination. �No 3: Microscopic examination and cell count

Physical examination: A. Colour: CSF is normally crystal clear and colorless with appearance and viscosity comparable to water

1 - Bright red color: results from �Recent hemorrhage into subarachnoid space. �Traumatic damage to blood vessel during lumber puncture, and to differentiate between them Traumatic CSF Hemorrhage CSF is less stained with blood in the 3 rd tube CSF is equally stained with blood in the three tubes After centrifugation: Supernatant is clear and colorless Supernatant is yellow i. e. xanthochromic

Traumatic CSF

2. Xanthochromic CSF: Yellow discoloration �Cerebral hemorrhage (altered hemoglobin several days after hemorrhage). �Large amount of pus (meningitis). �CSF obtained below a spinal canal block i. e. Froin’s syndrome(Marked increase of protein with spontaneous clotting, no cells and xanthochromia). �Overt jaundice (neonatal jaundice). �Carotenoids in CSF due to systemic hypercarotenemia. �Melanin in CSF due to meningial melanosarcoma. �Contamination of CSF by merthiolate used to disinfect the skin.

xanthchromia

B. Aspect: �Turbid or cloudy CSF: -Caused by leucocytes (over 200 cells /μl) or erythrocytes (> 400 cells / μl) or microorganisms. -Radiographic contrast media. -Aspiration of epidural fat during lumbar puncture.

2 - Clot formation : Due to increased fibrinogen is cases of : �Meningitis either pyogenic or T. B ( cob web clot ). �Spinal canal block. �Hemorrhage. �Rare causes as neurosyphilis and demylinating diseases

Microscopic Examination : �Total cell count : - Normal range: 0 -5 cells / μl (lymphocytes and monocytes), in -neonates may reach up to 30 cells /μl.

Causes of increased neutrophils in CSF �Bacterial meningitis. �Cerebral abscess. �Subdural empyema. �Following seizures, CNS infarction and hemorrhage. �Injection of foreign material in the subarachnoid space e. g contrast media, methotrexate. �Metastatic tumors in contact with CSF

Causes of lymphocytosis in CSF �Viral meningitis. �Tuberculous meningitis. �Fungal meningitis. �Syphilitic meningeoencephalitis. �Parasitic infestation of CNS e. g toxoplasmosis, trichinosis. �Degenerative disorders: Multiple sclerosis, Guillian. Barrè syndrome. �Sarcoidosis of meninges.

Causes of increased eosinophils in CSF �Parasitic infestations e. g Schistosoma, Fasciola heptica. �Fungal infection. �Rickettsial infection �Forgein material : myelography, or other cells in the CSF as tumour cells, LE cells, and leukemic cells.

Chemical examination: � Analytes Normal values � 1 - Protein : adult 15 - 45 mg/d. L neonate 10 - 90 mg/d. L(even up to 150 mg/d. L) � 2 - Glucose : 2/3 of blood glucose � 40 – 70 mg/d. L � 3 - Chloride : 120 – 130 mmol/L � 700 – 760 mg/d. L

Causes of increased proteins in CSF: -Increase in vascular and meningeal permeabilities allowing more protein to enter CSF. -Immunoglobulins may be synthesized within cereobrospinal canal by inflammatory or invading cells. Marked increase in protein occurs in : 1. Meningitis. 2. Froin’s syndrome. 3. Guillian-Barrè syndrome(cytoalbuminous dissociation). Moderate increase in : 1. Demylinating disease. 2 - Tumours. 3 - Blood in CS 4 - Metastases. 5 - Subarachnoid and intracerebral hemorrhage

Glucose in CSF �Increased when plasma glucose elevated within 2 hours preceding the puncture. Decreased in: 1. Hypoglycemia 2. Infection (due to glucose utilization by leucocytes and organisms). 3. Neoplasms involving the meninges e. g. leukemia, lymphoma. Note: in viral meningitis CSF glucose is often normal.

Chloride �Normal in septic meningitis. �Decreased in T. B. meningitis.

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