Healthcare and Medicine Reference
In-Depth Information
Box 7.4 Postdural puncture headache
Following LP continued leak of CSF through the dural puncture
site can lead to traction on the cranial meninges. This can cause a
headache with the following characteristics:
constant
L3-L4 interspace
dull
occipital or bifrontal
postural - relieved by lying down; worse on sitting or standing
meningism may be present
onset is usually within 24-48 hours of LP
30% incidence with 22G needle
Risk is minimised by using atraumatic needles (Whitacre, Sprotte)
of small gauge, but CSF collection can take a long time if needles
smaller than 22G are used. There is no evidence that the amount of
CSF taken or lying fl at after LP reduces the risk.
Management involves rest, oral analgesics and maintaining
hydration. All cases will resolve with time but if symptoms are
severe, liaise with an anaesthetist to consider an epidural blood
patch. For this 20 mL of the patient's blood is taken from a vein
under aseptic conditions and injected into the epidural space at
the level of the LP. This blood will clot and plug the hole preventing
further CSF leak. Immediate relief is obtained in >90% of cases.
1% incidence with 26G needle.
Figure 7.8 Identifi cation of the L3-L4 intervertebral space.
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Advance the needle slowly. You will get feedback of the needle's
progress as it passes through the ligaments, and often feel a pop
or click as the resistance from the ligamentum fl avum and dura
is overcome at a depth of approximately 4-6 cm (may be shal-
lower or deeper in particularly slim or obese patients). Stop
advancing the needle and withdraw the stylet. The CSF should
fl ow freely (Figure 7.7f). Note that even with defi nite dural
puncture it can take a few seconds for the CSF fl ow to be seen,
especially if narrower gauge needles are used and the patient is
in the lateral position.
If bony resistance is felt on advancing the needle, withdraw the
the end of the needle. Normal value is 5-20 cmH 2 O with the
patient in the lateral position.
Collect 5-10 drops (approx 1 mL) of CSF into three sequentially
2
numbered universal containers and also into a fl uoride tube
(grey top) for glucose measurement (Figure 7.7g).
Remove the needle and apply a dressing.
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3
needle and introducer back to the subcutaneous tissue, redirect
them about 15° cephalad and reinsert. Continue to repeat this
manoeuvre if further bony contact is met. If this manoeuvre
is not successful check the patient's position and ensure your
needle insertion and advancement are in the midline. It can be
easy to stray from the midline especially with the patient in the
lateral position. If this fails, repeat the whole procedure at the
L4/L5 interspace. Do not attempt lumbar puncture at L2/L3 or
above as spinal cord damage has been reported.
If you still encounter problems the paramedian approach can
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Send samples for appropriate investigations. For suspected men-
ingitis send for urgent microscopy, culture, protein and glucose
(send blood for plasma glucose measurement as well).
Other possible tests include cytology, virology, TB culture, syphi-
5
lis serology, oligoclonal bands and xanthochromia.
Monitor the patient's CNS observations and blood pressure reg-
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ularly. Be aware of the possibility of a postdural puncture head-
ache (Box 7.4).
Complications
Back pain Localised soft tissue trauma at injection site is common
and may last a few days.
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be attempted, or seek help from a more senior member of the
team. For those patients that still present a challenge, seek assis-
tance from clinicians who regularly perform lumbar punctures -
the neurologists and anaesthetists.
Postdural puncture headache (PDPH) See Box 7.4.
Paramedian approach
After local anaesthesia, insert the needle 1-2 cm lateral to the
Neurological sequelae —Temporary symptoms of paraesthesia or
motor weakness may result from needle damage or stretching of
a nerve root. The majority resolve within a few weeks. Permanent
neurological damage is extremely rare (less than 1 in 10 000) and
should be assessed by a neurologist.
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upper border of the spinous process perpendicular to the skin.
Bony resistance will be felt as the vertebral lamina is contacted.
Withdraw the needle slightly and reinsert, aiming approximately
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15° medially and 30° cephalad. The needle should now pass over the
vertebral lamina and a pop will be felt as the dura is punctured.
Infection —Meningitis, encephalitis or epidural abscess are very rare
but can result if strict aseptic technique is not followed. If focal neu-
rology develops and an epidural abscess is suspected then an urgent
MRI is necessary to confi rm the diagnosis followed by emergency
neurosurgical drainage. Antimicrobials are given as appropriate.
Sampling
Once lumbar puncture is successful it is possible to measure the
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CSF pressure by attaching a manometer via a three-way tap to
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