2006-10-07 08:23:44 · 6 answers · asked by Kit S 1 in Health ➔ General Health Care ➔ Other - General Health Care
When you perform a lumbar puncture you remove fluid from the spinal cord. This is the same fluid which is present inside the brain and in raised ICP is under higher pressure. So if you take fluid from the base of the cord this is under lower pressure and creates a pressure gradient. The higher pressures in the brain can then push the brain and upper spinal cord downwards (Coning). This can do all manner of horrible things to the patient.
2006-10-07 08:30:15 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Your brain is contained in your skull, but there is a hole in the base of your skull that connects to your neck - this allows the nerves from your spinal cord to connect to your brain.
CSF (cerebrospinal fluid) circulates around your brain and spinal cord. The CSF helps to cushion your brain, and keep it "floating" inside your skull.
Imagine a bucket of water with a hole in it. Imagine a sheet of tissue paper floating in the bucket. As the water empties out of the bucket through the hole, the tissue is pulled through the hole to some degree. Imagine looking at the bottom of the bucket - you'd see the tissue paper bulging through the hole, wouldn't you?
Normally, we can cope well with having a little CSF removed from that closed system around the brain and spinal cord. Sometimes we experience headaches as a side effect - because there is lower than usual CSF pressure, but it's not normally a problem.
However, if a patient has raised intracranial pressure, a lumbar puncture is contraindicated, as one of the reasons for raised intracranial pressure is that the brain is tending to herniate or bulge down through the opening at the base of the skull.
By lowering the CSF levels around it during a lumbar puncture, the risk is that you would cause the brain to bulge down or herniate more (think of the bucket). That could put the patient's life at serious risk, and the results gained from looking at the CSF would not merit the risk.
Hope that makes sense.
2006-10-07 09:01:16 · answer #2 · answered by RM 6 · 2⤊ 0⤋
Brain and spinal cord are 2 solid structures that are virtually floating in a fluid called cerebro-spinal fluid (CSF). When you do lumbar puncture, you are tapping this CSF. In patients with raised ICP, if you puncture dura, the CSF will gush out of sub arachnoid space with force. As a result, the brain will descend down into the spinal canal via foramen magnum ( the opening in the skull through will brain continues as spinal cord). Most of the vital centres are located in the caudal brain. Descent of brain into spinal canal can cause compression of these vital centres, leading to cessation of respiration, loss of autonomic tone leading to gross vasodilatation, severe hypotension. Death is inevitable in most of the cases.
The best way to avoid this manslaughter is to do Fundoscopy before LP.
2006-10-07 09:06:20 · answer #3 · answered by Vivax 4 · 0⤊ 0⤋
because then the CSF tried to leak out and the brain stem herniates through the small orifice at the bottom of the skull which getss stuck causing immediate death, good luck
2006-10-07 08:26:35 · answer #4 · answered by HK3738 7 · 0⤊ 0⤋
because then the intercranial will fall, make a mess and you'll have to buy a dustpan and brush
2006-10-07 08:37:45 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Because the brain may get pushed into the spinal canal.
2006-10-07 08:26:17 · answer #6 · answered by novangelis 7 · 1⤊ 0⤋