Question

Case 1

A 7-year-old boy has a 2-day history of severe headache, nausea, fever, and photophobia. He appears lethargic and ill. His temperature is 40^oC, and he has some nuchal rigidity. The most likely diagnosis in this case is bacterial meningitis.

In order to find the causative agent, a lumbar puncture is requested by the physician. Laboratory analysis confirms bacterial growth in the cerebrospinal fluid (CSF). Appropriate antibiotic therapy is administered and the patient recovers without any complications.

1. Where along the vertebral column is the needle typically inserted in order to perform a lumbar puncture? Provide an anatomical explanation for your answer.  

2. Explain why the needle is inserted in the median plane.

3. Following the procedure, the patient complains of a severe headache. Explain the possible causes for this complication.

4. Identify the most common causative organisms of meningitis.

5. Explain the various anatomical pathways of the bacteria from the external environment to the CSF inside the brain ventricles.  

6. Outline two reasons for the boy’s nausea, and photophobia.

7. Explain the structures, site of production and pattern of circulation of CSF throughout the brain.

Reference APA style

Answer 1

1) For lumbar puncture, needle should be inserted between L3-L4 or L4-L5 as spinal cord ends below L1 or above L 2. It's performed in this level to avoid injury to spinal cord.

2) Median plane is better to insert to avoid damage to nerve roots during needle insertion.

3) Cause of headache is because of leakage of CSF from the needle insertion area to subarachnoid space. It causes decreased CSF volume and leads to headache.

4) meningitis can be due to virus, bacteria. Bacterial meningitis is due to streptococci, mycobacterium, pneumococci.

5)Most bacterial infections spread to the brain by the bloodstream. Bacteria can penetrate into the brain from the environment if there is a break in the continuity of these protective layers. Such a discontinuity may be due to congenital defects (encephalocele, meningomyelocele) or may be caused by trauma or a shunt. Bacteria can also spread to the brain from infected adjacent air sinuses, the middle ear and the mastoids. They can reach the brain either directly through the bone, especially in areas where the bone plate is thin, or through veins (diploic veins, dural venous sinuses, intracerebral veins). The various protective layers may also help contain infections within certain spaces or planes.

6) Photophobia is linked with the receptor of light in eyes and the nerve conduction to brain. In meningitis, due to affection of brain, those patients get sensitivity of light. Nausea is due to raised intracranial pressure.

7) CSF is produced by choroid plexus of brain from the brain.After it's production, it is circulated through brain