What is the primary purpose of a lumbar puncture?

What is the primary purpose of a lumbar puncture?

• A. To inject anesthetic into the spine.
• B. To measure electrical activity in the brain.
• C. To alter spinal cord function with electrical stimulation.
• D. To withdraw CSF for diagnostic testing.

Answer: (D)

Accessing the lumbar subarachnoid space to obtain cerebrospinal fluid is the primary function of a lumbar puncture. By withdrawing CSF, clinicians can analyze its components—cell counts, protein, glucose, microbiology cultures, and sometimes DNA/PCR tests—to diagnose infections like meningitis, bleeding such as subarachnoid hemorrhage, inflammatory or autoimmune diseases, and other CNS conditions. Opening pressure can also be measured to assess intracranial pressure. While lumbar punctures can be used to deliver intrathecal medications in some cases, the main purpose in routine diagnostics is CSF sampling. The other options describe different procedures: injecting anesthetic into the spine is spinal or epidural anesthesia, not the goal of a lumbar puncture; measuring electrical activity in the brain is done with EEG; altering spinal cord function with electrical stimulation refers to other neurostimulation techniques.

Accessing the lumbar subarachnoid space to obtain cerebrospinal fluid is the primary function of a lumbar puncture. By withdrawing CSF, clinicians can analyze its components—cell counts, protein, glucose, microbiology cultures, and sometimes DNA/PCR tests—to diagnose infections like meningitis, bleeding such as subarachnoid hemorrhage, inflammatory or autoimmune diseases, and other CNS conditions. Opening pressure can also be measured to assess intracranial pressure. While lumbar punctures can be used to deliver intrathecal medications in some cases, the main purpose in routine diagnostics is CSF sampling.

The other options describe different procedures: injecting anesthetic into the spine is spinal or epidural anesthesia, not the goal of a lumbar puncture; measuring electrical activity in the brain is done with EEG; altering spinal cord function with electrical stimulation refers to other neurostimulation techniques.