Why do Drs do a CT before doing a lumbar puncture?

Answer 1

If there is any brain swelling, pulling out the fluid for a lumbar puncture can pull part of the brain into spinal canal. Its called herniation and it can cause damage by compressing brain and spinal cord tissues. A CT is used if there is any reason clinically to suspect swelling to determine if it is safe to do a lumbar puncture.

Answer 2

Most of the time, it's because they learned the habit in training and their practice never matured. There are a small number of people with structural abnormalities in the brain and increased intracranial pressure. There's a small risk of herniation when the lumbar puncture decreases volume and pressure below the level of the structural obstruction, and the result can be catastrophic. Because of this, doctors in training are often taught to get a CT before LP in order to identify those abnormalities. They have a hard and fast rule while in training and get into the habit. In clinical practice, almost all lumbar punctures are done on people who obviously don't have a risk of herniation (the patients with structural abnormalities of that sort are generally pretty obvious), and experienced physicians can normally forgo the CT, but old habits die hard, so the CT's are ordered.

Answer 3

I think because on CT Dr's can see the changes in brain and spinal cord, an than take a CS fluid for analysis. Sometime LP is contraindicated because of possibility of herniation of cerebellum.

Answer 4

http://www.medscape.com/viewarticle/420288?src=search

Complications are very rare. MRI and CT scan give detailed information.
Lumbar puncture is now done only for chemical analysis of CSF, culture and to know CSF pressure.

Answer 5

so they do not puncture the spinal cord and paralyze you